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* [PATCH 00/10] Allocation APIs
@ 2024-03-25 19:54 Wedson Almeida Filho
  2024-03-25 19:54 ` [PATCH 01/10] rust: kernel: move `allocator` module under `alloc` Wedson Almeida Filho
                   ` (9 more replies)
  0 siblings, 10 replies; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-25 19:54 UTC (permalink / raw)
  To: rust-for-linux
  Cc: Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
	linux-kernel, Wedson Almeida Filho

From: Wedson Almeida Filho <walmeida@microsoft.com>

Revamp how we use the `alloc` crate.

We currently have a fork of the crate with changes to `Vec`; other
changes have been upstreamed (to the Rust project). This series removes
the fork and exposes all the functionality as extension traits.

Additionally, it also introduces allocation flag parameters to all
functions that may result in allocations (e.g., `Box::new`, `Arc::new`,
`Vec::push`, etc.) without the `try_` prefix -- the names are available
because we build `alloc` with `no_global_oom_handling`.

Lastly, the series also removes our reliance on the `allocator_api`
unstable feature.

Long term, we still want to make such functionality available in
upstream Rust, but this allows us to make progress now and reduces our
maintainance burden.

In summary:
1. Removes `alloc` fork
2. Removes use of `allocator_api` unstable feature
3. Introduces flags (e.g., GFP_KERNEL, GFP_ATOMIC) when allocating

Wedson Almeida Filho (10):
  rust: kernel: move `allocator` module under `alloc`
  rust: alloc: introduce the `VecExt` trait
  kbuild: use the upstream `alloc` crate
  rust: alloc: remove our fork of the `alloc` crate
  rust: alloc: introduce allocation flags
  rust: alloc: introduce the `BoxExt` trait
  rust: alloc: update `VecExt` to take allocation flags
  rust: sync: update `Arc` and `UniqueArc` to take allocation flags
  rust: init: update `init` module to take allocation flags
  rust: kernel: remove usage of `allocator_api` unstable feature

 rust/Makefile                        |   16 +-
 rust/alloc/README.md                 |   36 -
 rust/alloc/alloc.rs                  |  452 ----
 rust/alloc/boxed.rs                  | 2463 -----------------
 rust/alloc/collections/mod.rs        |  160 --
 rust/alloc/lib.rs                    |  288 --
 rust/alloc/raw_vec.rs                |  611 -----
 rust/alloc/slice.rs                  |  890 -------
 rust/alloc/vec/drain.rs              |  255 --
 rust/alloc/vec/extract_if.rs         |  115 -
 rust/alloc/vec/into_iter.rs          |  454 ----
 rust/alloc/vec/is_zero.rs            |  204 --
 rust/alloc/vec/mod.rs                | 3683 --------------------------
 rust/alloc/vec/partial_eq.rs         |   49 -
 rust/alloc/vec/set_len_on_drop.rs    |   35 -
 rust/alloc/vec/spec_extend.rs        |  119 -
 rust/bindings/bindings_helper.h      |    3 +
 rust/kernel/alloc.rs                 |   68 +
 rust/kernel/{ => alloc}/allocator.rs |    6 +-
 rust/kernel/alloc/boxext.rs          |   60 +
 rust/kernel/alloc/vecext.rs          |  120 +
 rust/kernel/error.rs                 |   13 +-
 rust/kernel/init.rs                  |   57 +-
 rust/kernel/lib.rs                   |    5 +-
 rust/kernel/prelude.rs               |    2 +
 rust/kernel/str.rs                   |    6 +-
 rust/kernel/sync/arc.rs              |   44 +-
 rust/kernel/sync/condvar.rs          |    2 +-
 rust/kernel/sync/lock/mutex.rs       |    2 +-
 rust/kernel/sync/lock/spinlock.rs    |    2 +-
 rust/kernel/types.rs                 |    4 +-
 rust/kernel/workqueue.rs             |   14 +-
 samples/rust/rust_minimal.rs         |    6 +-
 samples/rust/rust_print.rs           |    4 +-
 scripts/generate_rust_analyzer.py    |    2 +-
 35 files changed, 340 insertions(+), 9910 deletions(-)
 delete mode 100644 rust/alloc/README.md
 delete mode 100644 rust/alloc/alloc.rs
 delete mode 100644 rust/alloc/boxed.rs
 delete mode 100644 rust/alloc/collections/mod.rs
 delete mode 100644 rust/alloc/lib.rs
 delete mode 100644 rust/alloc/raw_vec.rs
 delete mode 100644 rust/alloc/slice.rs
 delete mode 100644 rust/alloc/vec/drain.rs
 delete mode 100644 rust/alloc/vec/extract_if.rs
 delete mode 100644 rust/alloc/vec/into_iter.rs
 delete mode 100644 rust/alloc/vec/is_zero.rs
 delete mode 100644 rust/alloc/vec/mod.rs
 delete mode 100644 rust/alloc/vec/partial_eq.rs
 delete mode 100644 rust/alloc/vec/set_len_on_drop.rs
 delete mode 100644 rust/alloc/vec/spec_extend.rs
 create mode 100644 rust/kernel/alloc.rs
 rename rust/kernel/{ => alloc}/allocator.rs (96%)
 create mode 100644 rust/kernel/alloc/boxext.rs
 create mode 100644 rust/kernel/alloc/vecext.rs


base-commit: 768409cff6cc89fe1194da880537a09857b6e4db
-- 
2.34.1


^ permalink raw reply	[flat|nested] 30+ messages in thread

* [PATCH 01/10] rust: kernel: move `allocator` module under `alloc`
  2024-03-25 19:54 [PATCH 00/10] Allocation APIs Wedson Almeida Filho
@ 2024-03-25 19:54 ` Wedson Almeida Filho
  2024-03-25 21:56   ` Benno Lossin
  2024-03-25 19:54 ` [PATCH 02/10] rust: alloc: introduce the `VecExt` trait Wedson Almeida Filho
                   ` (8 subsequent siblings)
  9 siblings, 1 reply; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-25 19:54 UTC (permalink / raw)
  To: rust-for-linux
  Cc: Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
	linux-kernel, Wedson Almeida Filho

From: Wedson Almeida Filho <walmeida@microsoft.com>

We will add more to the `alloc` module in subsequent patches (e.g.,
allocation flags and extension traits).

Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
---
 rust/kernel/alloc.rs                 | 7 +++++++
 rust/kernel/{ => alloc}/allocator.rs | 0
 rust/kernel/lib.rs                   | 4 +---
 3 files changed, 8 insertions(+), 3 deletions(-)
 create mode 100644 rust/kernel/alloc.rs
 rename rust/kernel/{ => alloc}/allocator.rs (100%)

diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
new file mode 100644
index 000000000000..ccd4149932c3
--- /dev/null
+++ b/rust/kernel/alloc.rs
@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Allocation support.
+
+#[cfg(not(test))]
+#[cfg(not(testlib))]
+mod allocator;
diff --git a/rust/kernel/allocator.rs b/rust/kernel/alloc/allocator.rs
similarity index 100%
rename from rust/kernel/allocator.rs
rename to rust/kernel/alloc/allocator.rs
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index be68d5e567b1..51f30e55bd00 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -28,9 +28,7 @@
 // Allow proc-macros to refer to `::kernel` inside the `kernel` crate (this crate).
 extern crate self as kernel;
 
-#[cfg(not(test))]
-#[cfg(not(testlib))]
-mod allocator;
+pub mod alloc;
 mod build_assert;
 pub mod error;
 pub mod init;
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread

* [PATCH 02/10] rust: alloc: introduce the `VecExt` trait
  2024-03-25 19:54 [PATCH 00/10] Allocation APIs Wedson Almeida Filho
  2024-03-25 19:54 ` [PATCH 01/10] rust: kernel: move `allocator` module under `alloc` Wedson Almeida Filho
@ 2024-03-25 19:54 ` Wedson Almeida Filho
  2024-03-25 22:05   ` Benno Lossin
  2024-03-25 19:54 ` [PATCH 03/10] kbuild: use the upstream `alloc` crate Wedson Almeida Filho
                   ` (7 subsequent siblings)
  9 siblings, 1 reply; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-25 19:54 UTC (permalink / raw)
  To: rust-for-linux
  Cc: Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
	linux-kernel, Wedson Almeida Filho

From: Wedson Almeida Filho <walmeida@microsoft.com>

Make `try_with_capacity`, `try_push`, and `try_extend_from_slice`
methods available in `Vec` even though it doesn't implement them. It is
implemented with `try_reserve` and `push_within_capacity`.

This is in preparation for switching to the upstream `alloc` crate.

Suggested-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
---
 rust/kernel/alloc.rs        |  1 +
 rust/kernel/alloc/vecext.rs | 52 +++++++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs          |  1 +
 rust/kernel/prelude.rs      |  2 ++
 4 files changed, 56 insertions(+)
 create mode 100644 rust/kernel/alloc/vecext.rs

diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
index ccd4149932c3..8ad57a2e693e 100644
--- a/rust/kernel/alloc.rs
+++ b/rust/kernel/alloc.rs
@@ -5,3 +5,4 @@
 #[cfg(not(test))]
 #[cfg(not(testlib))]
 mod allocator;
+pub mod vecext;
diff --git a/rust/kernel/alloc/vecext.rs b/rust/kernel/alloc/vecext.rs
new file mode 100644
index 000000000000..59e92bab534e
--- /dev/null
+++ b/rust/kernel/alloc/vecext.rs
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Extensions to [`Vec`] for fallible allocations.
+
+use alloc::{collections::TryReserveError, vec::Vec};
+use core::result::Result;
+
+/// Extensions to [`Vec`].
+pub trait VecExt<T>: Sized {
+    /// Creates a new [`Vec`] instance with at least the given capacity.
+    fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError>;
+
+    /// Appends an element to the back of the [`Vec`] instance.
+    fn try_push(&mut self, v: T) -> Result<(), TryReserveError>;
+
+    /// Pushes clones of the elements of slice into the [`Vec`] instance.
+    fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError>
+    where
+        T: Clone;
+}
+
+impl<T> VecExt<T> for Vec<T> {
+    fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError> {
+        let mut v = Vec::new();
+        v.try_reserve(capacity)?;
+        Ok(v)
+    }
+
+    fn try_push(&mut self, v: T) -> Result<(), TryReserveError> {
+        if let Err(retry) = self.push_within_capacity(v) {
+            self.try_reserve(1)?;
+            let _ = self.push_within_capacity(retry);
+        }
+        Ok(())
+    }
+
+    fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError>
+    where
+        T: Clone,
+    {
+        let extra_cap = self.capacity() - self.len();
+        if extra_cap > 0 {
+            self.try_reserve(extra_cap)?;
+        }
+
+        for item in other {
+            self.try_push(item.clone())?;
+        }
+
+        Ok(())
+    }
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 51f30e55bd00..7f2841a18d05 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -19,6 +19,7 @@
 #![feature(offset_of)]
 #![feature(receiver_trait)]
 #![feature(unsize)]
+#![feature(vec_push_within_capacity)]
 
 // Ensure conditional compilation based on the kernel configuration works;
 // otherwise we may silently break things like initcall handling.
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index ae21600970b3..a0177f195dec 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -14,6 +14,8 @@
 #[doc(no_inline)]
 pub use core::pin::Pin;
 
+pub use crate::alloc::vecext::VecExt;
+
 #[doc(no_inline)]
 pub use alloc::{boxed::Box, vec::Vec};
 
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread

* [PATCH 03/10] kbuild: use the upstream `alloc` crate
  2024-03-25 19:54 [PATCH 00/10] Allocation APIs Wedson Almeida Filho
  2024-03-25 19:54 ` [PATCH 01/10] rust: kernel: move `allocator` module under `alloc` Wedson Almeida Filho
  2024-03-25 19:54 ` [PATCH 02/10] rust: alloc: introduce the `VecExt` trait Wedson Almeida Filho
@ 2024-03-25 19:54 ` Wedson Almeida Filho
  2024-03-25 19:54 ` [PATCH 04/10] rust: alloc: remove our fork of the " Wedson Almeida Filho
                   ` (6 subsequent siblings)
  9 siblings, 0 replies; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-25 19:54 UTC (permalink / raw)
  To: rust-for-linux
  Cc: Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
	linux-kernel, Wedson Almeida Filho

From: Wedson Almeida Filho <walmeida@microsoft.com>

Switch away from our fork of the `alloc` crate. We remove it altogether
in the next commit.

Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
---
 rust/Makefile                     | 16 +++-------------
 rust/kernel/str.rs                |  1 +
 scripts/generate_rust_analyzer.py |  2 +-
 3 files changed, 5 insertions(+), 14 deletions(-)

diff --git a/rust/Makefile b/rust/Makefile
index a78fcf4004b0..fcb26b53880b 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -61,15 +61,9 @@ core-cfgs = \
     --cfg no_fp_fmt_parse
 
 alloc-cfgs = \
-    --cfg no_borrow \
-    --cfg no_fmt \
     --cfg no_global_oom_handling \
-    --cfg no_macros \
     --cfg no_rc \
-    --cfg no_str \
-    --cfg no_string \
-    --cfg no_sync \
-    --cfg no_thin
+    --cfg no_sync
 
 quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $<
       cmd_rustdoc = \
@@ -123,7 +117,7 @@ rustdoc-compiler_builtins: $(src)/compiler_builtins.rs rustdoc-core FORCE
 # due to things that are "configured out" vs. entirely non-existing ones.
 rustdoc-alloc: private rustc_target_flags = $(alloc-cfgs) \
     -Arustdoc::broken_intra_doc_links
-rustdoc-alloc: $(src)/alloc/lib.rs rustdoc-core rustdoc-compiler_builtins FORCE
+rustdoc-alloc: $(RUST_LIB_SRC)/alloc/src/lib.rs rustdoc-core rustdoc-compiler_builtins FORCE
 	+$(call if_changed,rustdoc)
 
 rustdoc-kernel: private rustc_target_flags = --extern alloc \
@@ -219,8 +213,6 @@ rusttest: rusttest-macros rusttest-kernel
 #   - `cargo` only considers the use case of building the standard library
 #     to use it in a given package. Thus we need to create a dummy package
 #     and pick the generated libraries from there.
-#   - Since we only keep a subset of upstream `alloc` in-tree, we need
-#     to recreate it on the fly by putting our sources on top.
 #   - The usual ways of modifying the dependency graph in `cargo` do not seem
 #     to apply for the `-Zbuild-std` steps, thus we have to mislead it
 #     by modifying the sources in the sysroot.
@@ -239,8 +231,6 @@ quiet_cmd_rustsysroot = RUSTSYSROOT
 	rm -rf $(objtree)/$(obj)/test; \
 	mkdir -p $(objtree)/$(obj)/test; \
 	cp -a $(rustc_sysroot) $(objtree)/$(obj)/test/sysroot; \
-	cp -r $(srctree)/$(src)/alloc/* \
-		$(objtree)/$(obj)/test/sysroot/lib/rustlib/src/rust/library/alloc/src; \
 	echo '\#!/bin/sh' > $(objtree)/$(obj)/test/rustc_sysroot; \
 	echo "$(RUSTC) --sysroot=$(abspath $(objtree)/$(obj)/test/sysroot) \"\$$@\"" \
 		>> $(objtree)/$(obj)/test/rustc_sysroot; \
@@ -444,7 +434,7 @@ $(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE
 $(obj)/alloc.o: private skip_clippy = 1
 $(obj)/alloc.o: private skip_flags = -Dunreachable_pub
 $(obj)/alloc.o: private rustc_target_flags = $(alloc-cfgs)
-$(obj)/alloc.o: $(src)/alloc/lib.rs $(obj)/compiler_builtins.o FORCE
+$(obj)/alloc.o: $(RUST_LIB_SRC)/alloc/src/lib.rs $(obj)/compiler_builtins.o FORCE
 	+$(call if_changed_dep,rustc_library)
 
 $(obj)/build_error.o: $(src)/build_error.rs $(obj)/compiler_builtins.o FORCE
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 925ced8fdc61..183748328d43 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -2,6 +2,7 @@
 
 //! String representations.
 
+use crate::alloc::vecext::VecExt;
 use alloc::alloc::AllocError;
 use alloc::vec::Vec;
 use core::fmt::{self, Write};
diff --git a/scripts/generate_rust_analyzer.py b/scripts/generate_rust_analyzer.py
index fc52bc41d3e7..f270c7b0cf34 100755
--- a/scripts/generate_rust_analyzer.py
+++ b/scripts/generate_rust_analyzer.py
@@ -66,7 +66,7 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs):
 
     append_crate(
         "alloc",
-        srctree / "rust" / "alloc" / "lib.rs",
+        sysroot_src / "alloc" / "src" / "lib.rs",
         ["core", "compiler_builtins"],
         cfg=crates_cfgs.get("alloc", []),
     )
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread

* [PATCH 04/10] rust: alloc: remove our fork of the `alloc` crate
  2024-03-25 19:54 [PATCH 00/10] Allocation APIs Wedson Almeida Filho
                   ` (2 preceding siblings ...)
  2024-03-25 19:54 ` [PATCH 03/10] kbuild: use the upstream `alloc` crate Wedson Almeida Filho
@ 2024-03-25 19:54 ` Wedson Almeida Filho
  2024-03-25 22:24   ` Benno Lossin
  2024-03-25 19:54 ` [PATCH 05/10] rust: alloc: introduce allocation flags Wedson Almeida Filho
                   ` (5 subsequent siblings)
  9 siblings, 1 reply; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-25 19:54 UTC (permalink / raw)
  To: rust-for-linux
  Cc: Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
	linux-kernel, Wedson Almeida Filho

From: Wedson Almeida Filho <walmeida@microsoft.com>

It is not used anymore as `VecExt` now provides the functionality we
depend on.

Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
---
 rust/alloc/README.md              |   36 -
 rust/alloc/alloc.rs               |  452 ----
 rust/alloc/boxed.rs               | 2463 -------------------
 rust/alloc/collections/mod.rs     |  160 --
 rust/alloc/lib.rs                 |  288 ---
 rust/alloc/raw_vec.rs             |  611 -----
 rust/alloc/slice.rs               |  890 -------
 rust/alloc/vec/drain.rs           |  255 --
 rust/alloc/vec/extract_if.rs      |  115 -
 rust/alloc/vec/into_iter.rs       |  454 ----
 rust/alloc/vec/is_zero.rs         |  204 --
 rust/alloc/vec/mod.rs             | 3683 -----------------------------
 rust/alloc/vec/partial_eq.rs      |   49 -
 rust/alloc/vec/set_len_on_drop.rs |   35 -
 rust/alloc/vec/spec_extend.rs     |  119 -
 15 files changed, 9814 deletions(-)
 delete mode 100644 rust/alloc/README.md
 delete mode 100644 rust/alloc/alloc.rs
 delete mode 100644 rust/alloc/boxed.rs
 delete mode 100644 rust/alloc/collections/mod.rs
 delete mode 100644 rust/alloc/lib.rs
 delete mode 100644 rust/alloc/raw_vec.rs
 delete mode 100644 rust/alloc/slice.rs
 delete mode 100644 rust/alloc/vec/drain.rs
 delete mode 100644 rust/alloc/vec/extract_if.rs
 delete mode 100644 rust/alloc/vec/into_iter.rs
 delete mode 100644 rust/alloc/vec/is_zero.rs
 delete mode 100644 rust/alloc/vec/mod.rs
 delete mode 100644 rust/alloc/vec/partial_eq.rs
 delete mode 100644 rust/alloc/vec/set_len_on_drop.rs
 delete mode 100644 rust/alloc/vec/spec_extend.rs

diff --git a/rust/alloc/README.md b/rust/alloc/README.md
deleted file mode 100644
index eb6f22e94ebf..000000000000
--- a/rust/alloc/README.md
+++ /dev/null
@@ -1,36 +0,0 @@
-# `alloc`
-
-These source files come from the Rust standard library, hosted in
-the <https://github.com/rust-lang/rust> repository, licensed under
-"Apache-2.0 OR MIT" and adapted for kernel use. For copyright details,
-see <https://github.com/rust-lang/rust/blob/master/COPYRIGHT>.
-
-Please note that these files should be kept as close as possible to
-upstream. In general, only additions should be performed (e.g. new
-methods). Eventually, changes should make it into upstream so that,
-at some point, this fork can be dropped from the kernel tree.
-
-The Rust upstream version on top of which these files are based matches
-the output of `scripts/min-tool-version.sh rustc`.
-
-
-## Rationale
-
-On one hand, kernel folks wanted to keep `alloc` in-tree to have more
-freedom in both workflow and actual features if actually needed
-(e.g. receiver types if we ended up using them), which is reasonable.
-
-On the other hand, Rust folks wanted to keep `alloc` as close as
-upstream as possible and avoid as much divergence as possible, which
-is also reasonable.
-
-We agreed on a middle-ground: we would keep a subset of `alloc`
-in-tree that would be as small and as close as possible to upstream.
-Then, upstream can start adding the functions that we add to `alloc`
-etc., until we reach a point where the kernel already knows exactly
-what it needs in `alloc` and all the new methods are merged into
-upstream, so that we can drop `alloc` from the kernel tree and go back
-to using the upstream one.
-
-By doing this, the kernel can go a bit faster now, and Rust can
-slowly incorporate and discuss the changes as needed.
diff --git a/rust/alloc/alloc.rs b/rust/alloc/alloc.rs
deleted file mode 100644
index abb791cc2371..000000000000
--- a/rust/alloc/alloc.rs
+++ /dev/null
@@ -1,452 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-//! Memory allocation APIs
-
-#![stable(feature = "alloc_module", since = "1.28.0")]
-
-#[cfg(not(test))]
-use core::intrinsics;
-
-#[cfg(not(test))]
-use core::ptr::{self, NonNull};
-
-#[stable(feature = "alloc_module", since = "1.28.0")]
-#[doc(inline)]
-pub use core::alloc::*;
-
-#[cfg(test)]
-mod tests;
-
-extern "Rust" {
-    // These are the magic symbols to call the global allocator. rustc generates
-    // them to call `__rg_alloc` etc. if there is a `#[global_allocator]` attribute
-    // (the code expanding that attribute macro generates those functions), or to call
-    // the default implementations in std (`__rdl_alloc` etc. in `library/std/src/alloc.rs`)
-    // otherwise.
-    // The rustc fork of LLVM 14 and earlier also special-cases these function names to be able to optimize them
-    // like `malloc`, `realloc`, and `free`, respectively.
-    #[rustc_allocator]
-    #[rustc_nounwind]
-    fn __rust_alloc(size: usize, align: usize) -> *mut u8;
-    #[rustc_deallocator]
-    #[rustc_nounwind]
-    fn __rust_dealloc(ptr: *mut u8, size: usize, align: usize);
-    #[rustc_reallocator]
-    #[rustc_nounwind]
-    fn __rust_realloc(ptr: *mut u8, old_size: usize, align: usize, new_size: usize) -> *mut u8;
-    #[rustc_allocator_zeroed]
-    #[rustc_nounwind]
-    fn __rust_alloc_zeroed(size: usize, align: usize) -> *mut u8;
-
-    static __rust_no_alloc_shim_is_unstable: u8;
-}
-
-/// The global memory allocator.
-///
-/// This type implements the [`Allocator`] trait by forwarding calls
-/// to the allocator registered with the `#[global_allocator]` attribute
-/// if there is one, or the `std` crate’s default.
-///
-/// Note: while this type is unstable, the functionality it provides can be
-/// accessed through the [free functions in `alloc`](self#functions).
-#[unstable(feature = "allocator_api", issue = "32838")]
-#[derive(Copy, Clone, Default, Debug)]
-#[cfg(not(test))]
-pub struct Global;
-
-#[cfg(test)]
-pub use std::alloc::Global;
-
-/// Allocate memory with the global allocator.
-///
-/// This function forwards calls to the [`GlobalAlloc::alloc`] method
-/// of the allocator registered with the `#[global_allocator]` attribute
-/// if there is one, or the `std` crate’s default.
-///
-/// This function is expected to be deprecated in favor of the `alloc` method
-/// of the [`Global`] type when it and the [`Allocator`] trait become stable.
-///
-/// # Safety
-///
-/// See [`GlobalAlloc::alloc`].
-///
-/// # Examples
-///
-/// ```
-/// use std::alloc::{alloc, dealloc, handle_alloc_error, Layout};
-///
-/// unsafe {
-///     let layout = Layout::new::<u16>();
-///     let ptr = alloc(layout);
-///     if ptr.is_null() {
-///         handle_alloc_error(layout);
-///     }
-///
-///     *(ptr as *mut u16) = 42;
-///     assert_eq!(*(ptr as *mut u16), 42);
-///
-///     dealloc(ptr, layout);
-/// }
-/// ```
-#[stable(feature = "global_alloc", since = "1.28.0")]
-#[must_use = "losing the pointer will leak memory"]
-#[inline]
-pub unsafe fn alloc(layout: Layout) -> *mut u8 {
-    unsafe {
-        // Make sure we don't accidentally allow omitting the allocator shim in
-        // stable code until it is actually stabilized.
-        core::ptr::read_volatile(&__rust_no_alloc_shim_is_unstable);
-
-        __rust_alloc(layout.size(), layout.align())
-    }
-}
-
-/// Deallocate memory with the global allocator.
-///
-/// This function forwards calls to the [`GlobalAlloc::dealloc`] method
-/// of the allocator registered with the `#[global_allocator]` attribute
-/// if there is one, or the `std` crate’s default.
-///
-/// This function is expected to be deprecated in favor of the `dealloc` method
-/// of the [`Global`] type when it and the [`Allocator`] trait become stable.
-///
-/// # Safety
-///
-/// See [`GlobalAlloc::dealloc`].
-#[stable(feature = "global_alloc", since = "1.28.0")]
-#[inline]
-pub unsafe fn dealloc(ptr: *mut u8, layout: Layout) {
-    unsafe { __rust_dealloc(ptr, layout.size(), layout.align()) }
-}
-
-/// Reallocate memory with the global allocator.
-///
-/// This function forwards calls to the [`GlobalAlloc::realloc`] method
-/// of the allocator registered with the `#[global_allocator]` attribute
-/// if there is one, or the `std` crate’s default.
-///
-/// This function is expected to be deprecated in favor of the `realloc` method
-/// of the [`Global`] type when it and the [`Allocator`] trait become stable.
-///
-/// # Safety
-///
-/// See [`GlobalAlloc::realloc`].
-#[stable(feature = "global_alloc", since = "1.28.0")]
-#[must_use = "losing the pointer will leak memory"]
-#[inline]
-pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
-    unsafe { __rust_realloc(ptr, layout.size(), layout.align(), new_size) }
-}
-
-/// Allocate zero-initialized memory with the global allocator.
-///
-/// This function forwards calls to the [`GlobalAlloc::alloc_zeroed`] method
-/// of the allocator registered with the `#[global_allocator]` attribute
-/// if there is one, or the `std` crate’s default.
-///
-/// This function is expected to be deprecated in favor of the `alloc_zeroed` method
-/// of the [`Global`] type when it and the [`Allocator`] trait become stable.
-///
-/// # Safety
-///
-/// See [`GlobalAlloc::alloc_zeroed`].
-///
-/// # Examples
-///
-/// ```
-/// use std::alloc::{alloc_zeroed, dealloc, Layout};
-///
-/// unsafe {
-///     let layout = Layout::new::<u16>();
-///     let ptr = alloc_zeroed(layout);
-///
-///     assert_eq!(*(ptr as *mut u16), 0);
-///
-///     dealloc(ptr, layout);
-/// }
-/// ```
-#[stable(feature = "global_alloc", since = "1.28.0")]
-#[must_use = "losing the pointer will leak memory"]
-#[inline]
-pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 {
-    unsafe { __rust_alloc_zeroed(layout.size(), layout.align()) }
-}
-
-#[cfg(not(test))]
-impl Global {
-    #[inline]
-    fn alloc_impl(&self, layout: Layout, zeroed: bool) -> Result<NonNull<[u8]>, AllocError> {
-        match layout.size() {
-            0 => Ok(NonNull::slice_from_raw_parts(layout.dangling(), 0)),
-            // SAFETY: `layout` is non-zero in size,
-            size => unsafe {
-                let raw_ptr = if zeroed { alloc_zeroed(layout) } else { alloc(layout) };
-                let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?;
-                Ok(NonNull::slice_from_raw_parts(ptr, size))
-            },
-        }
-    }
-
-    // SAFETY: Same as `Allocator::grow`
-    #[inline]
-    unsafe fn grow_impl(
-        &self,
-        ptr: NonNull<u8>,
-        old_layout: Layout,
-        new_layout: Layout,
-        zeroed: bool,
-    ) -> Result<NonNull<[u8]>, AllocError> {
-        debug_assert!(
-            new_layout.size() >= old_layout.size(),
-            "`new_layout.size()` must be greater than or equal to `old_layout.size()`"
-        );
-
-        match old_layout.size() {
-            0 => self.alloc_impl(new_layout, zeroed),
-
-            // SAFETY: `new_size` is non-zero as `old_size` is greater than or equal to `new_size`
-            // as required by safety conditions. Other conditions must be upheld by the caller
-            old_size if old_layout.align() == new_layout.align() => unsafe {
-                let new_size = new_layout.size();
-
-                // `realloc` probably checks for `new_size >= old_layout.size()` or something similar.
-                intrinsics::assume(new_size >= old_layout.size());
-
-                let raw_ptr = realloc(ptr.as_ptr(), old_layout, new_size);
-                let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?;
-                if zeroed {
-                    raw_ptr.add(old_size).write_bytes(0, new_size - old_size);
-                }
-                Ok(NonNull::slice_from_raw_parts(ptr, new_size))
-            },
-
-            // SAFETY: because `new_layout.size()` must be greater than or equal to `old_size`,
-            // both the old and new memory allocation are valid for reads and writes for `old_size`
-            // bytes. Also, because the old allocation wasn't yet deallocated, it cannot overlap
-            // `new_ptr`. Thus, the call to `copy_nonoverlapping` is safe. The safety contract
-            // for `dealloc` must be upheld by the caller.
-            old_size => unsafe {
-                let new_ptr = self.alloc_impl(new_layout, zeroed)?;
-                ptr::copy_nonoverlapping(ptr.as_ptr(), new_ptr.as_mut_ptr(), old_size);
-                self.deallocate(ptr, old_layout);
-                Ok(new_ptr)
-            },
-        }
-    }
-}
-
-#[unstable(feature = "allocator_api", issue = "32838")]
-#[cfg(not(test))]
-unsafe impl Allocator for Global {
-    #[inline]
-    fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
-        self.alloc_impl(layout, false)
-    }
-
-    #[inline]
-    fn allocate_zeroed(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
-        self.alloc_impl(layout, true)
-    }
-
-    #[inline]
-    unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
-        if layout.size() != 0 {
-            // SAFETY: `layout` is non-zero in size,
-            // other conditions must be upheld by the caller
-            unsafe { dealloc(ptr.as_ptr(), layout) }
-        }
-    }
-
-    #[inline]
-    unsafe fn grow(
-        &self,
-        ptr: NonNull<u8>,
-        old_layout: Layout,
-        new_layout: Layout,
-    ) -> Result<NonNull<[u8]>, AllocError> {
-        // SAFETY: all conditions must be upheld by the caller
-        unsafe { self.grow_impl(ptr, old_layout, new_layout, false) }
-    }
-
-    #[inline]
-    unsafe fn grow_zeroed(
-        &self,
-        ptr: NonNull<u8>,
-        old_layout: Layout,
-        new_layout: Layout,
-    ) -> Result<NonNull<[u8]>, AllocError> {
-        // SAFETY: all conditions must be upheld by the caller
-        unsafe { self.grow_impl(ptr, old_layout, new_layout, true) }
-    }
-
-    #[inline]
-    unsafe fn shrink(
-        &self,
-        ptr: NonNull<u8>,
-        old_layout: Layout,
-        new_layout: Layout,
-    ) -> Result<NonNull<[u8]>, AllocError> {
-        debug_assert!(
-            new_layout.size() <= old_layout.size(),
-            "`new_layout.size()` must be smaller than or equal to `old_layout.size()`"
-        );
-
-        match new_layout.size() {
-            // SAFETY: conditions must be upheld by the caller
-            0 => unsafe {
-                self.deallocate(ptr, old_layout);
-                Ok(NonNull::slice_from_raw_parts(new_layout.dangling(), 0))
-            },
-
-            // SAFETY: `new_size` is non-zero. Other conditions must be upheld by the caller
-            new_size if old_layout.align() == new_layout.align() => unsafe {
-                // `realloc` probably checks for `new_size <= old_layout.size()` or something similar.
-                intrinsics::assume(new_size <= old_layout.size());
-
-                let raw_ptr = realloc(ptr.as_ptr(), old_layout, new_size);
-                let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?;
-                Ok(NonNull::slice_from_raw_parts(ptr, new_size))
-            },
-
-            // SAFETY: because `new_size` must be smaller than or equal to `old_layout.size()`,
-            // both the old and new memory allocation are valid for reads and writes for `new_size`
-            // bytes. Also, because the old allocation wasn't yet deallocated, it cannot overlap
-            // `new_ptr`. Thus, the call to `copy_nonoverlapping` is safe. The safety contract
-            // for `dealloc` must be upheld by the caller.
-            new_size => unsafe {
-                let new_ptr = self.allocate(new_layout)?;
-                ptr::copy_nonoverlapping(ptr.as_ptr(), new_ptr.as_mut_ptr(), new_size);
-                self.deallocate(ptr, old_layout);
-                Ok(new_ptr)
-            },
-        }
-    }
-}
-
-/// The allocator for unique pointers.
-#[cfg(all(not(no_global_oom_handling), not(test)))]
-#[lang = "exchange_malloc"]
-#[inline]
-unsafe fn exchange_malloc(size: usize, align: usize) -> *mut u8 {
-    let layout = unsafe { Layout::from_size_align_unchecked(size, align) };
-    match Global.allocate(layout) {
-        Ok(ptr) => ptr.as_mut_ptr(),
-        Err(_) => handle_alloc_error(layout),
-    }
-}
-
-// # Allocation error handler
-
-#[cfg(not(no_global_oom_handling))]
-extern "Rust" {
-    // This is the magic symbol to call the global alloc error handler. rustc generates
-    // it to call `__rg_oom` if there is a `#[alloc_error_handler]`, or to call the
-    // default implementations below (`__rdl_oom`) otherwise.
-    fn __rust_alloc_error_handler(size: usize, align: usize) -> !;
-}
-
-/// Signal a memory allocation error.
-///
-/// Callers of memory allocation APIs wishing to cease execution
-/// in response to an allocation error are encouraged to call this function,
-/// rather than directly invoking [`panic!`] or similar.
-///
-/// This function is guaranteed to diverge (not return normally with a value), but depending on
-/// global configuration, it may either panic (resulting in unwinding or aborting as per
-/// configuration for all panics), or abort the process (with no unwinding).
-///
-/// The default behavior is:
-///
-///  * If the binary links against `std` (typically the case), then
-///   print a message to standard error and abort the process.
-///   This behavior can be replaced with [`set_alloc_error_hook`] and [`take_alloc_error_hook`].
-///   Future versions of Rust may panic by default instead.
-///
-/// * If the binary does not link against `std` (all of its crates are marked
-///   [`#![no_std]`][no_std]), then call [`panic!`] with a message.
-///   [The panic handler] applies as to any panic.
-///
-/// [`set_alloc_error_hook`]: ../../std/alloc/fn.set_alloc_error_hook.html
-/// [`take_alloc_error_hook`]: ../../std/alloc/fn.take_alloc_error_hook.html
-/// [The panic handler]: https://doc.rust-lang.org/reference/runtime.html#the-panic_handler-attribute
-/// [no_std]: https://doc.rust-lang.org/reference/names/preludes.html#the-no_std-attribute
-#[stable(feature = "global_alloc", since = "1.28.0")]
-#[rustc_const_unstable(feature = "const_alloc_error", issue = "92523")]
-#[cfg(all(not(no_global_oom_handling), not(test)))]
-#[cold]
-pub const fn handle_alloc_error(layout: Layout) -> ! {
-    const fn ct_error(_: Layout) -> ! {
-        panic!("allocation failed");
-    }
-
-    #[inline]
-    fn rt_error(layout: Layout) -> ! {
-        unsafe {
-            __rust_alloc_error_handler(layout.size(), layout.align());
-        }
-    }
-
-    #[cfg(not(feature = "panic_immediate_abort"))]
-    unsafe {
-        core::intrinsics::const_eval_select((layout,), ct_error, rt_error)
-    }
-
-    #[cfg(feature = "panic_immediate_abort")]
-    ct_error(layout)
-}
-
-// For alloc test `std::alloc::handle_alloc_error` can be used directly.
-#[cfg(all(not(no_global_oom_handling), test))]
-pub use std::alloc::handle_alloc_error;
-
-#[cfg(all(not(no_global_oom_handling), not(test)))]
-#[doc(hidden)]
-#[allow(unused_attributes)]
-#[unstable(feature = "alloc_internals", issue = "none")]
-pub mod __alloc_error_handler {
-    // called via generated `__rust_alloc_error_handler` if there is no
-    // `#[alloc_error_handler]`.
-    #[rustc_std_internal_symbol]
-    pub unsafe fn __rdl_oom(size: usize, _align: usize) -> ! {
-        extern "Rust" {
-            // This symbol is emitted by rustc next to __rust_alloc_error_handler.
-            // Its value depends on the -Zoom={panic,abort} compiler option.
-            static __rust_alloc_error_handler_should_panic: u8;
-        }
-
-        if unsafe { __rust_alloc_error_handler_should_panic != 0 } {
-            panic!("memory allocation of {size} bytes failed")
-        } else {
-            core::panicking::panic_nounwind_fmt(
-                format_args!("memory allocation of {size} bytes failed"),
-                /* force_no_backtrace */ false,
-            )
-        }
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-/// Specialize clones into pre-allocated, uninitialized memory.
-/// Used by `Box::clone` and `Rc`/`Arc::make_mut`.
-pub(crate) trait WriteCloneIntoRaw: Sized {
-    unsafe fn write_clone_into_raw(&self, target: *mut Self);
-}
-
-#[cfg(not(no_global_oom_handling))]
-impl<T: Clone> WriteCloneIntoRaw for T {
-    #[inline]
-    default unsafe fn write_clone_into_raw(&self, target: *mut Self) {
-        // Having allocated *first* may allow the optimizer to create
-        // the cloned value in-place, skipping the local and move.
-        unsafe { target.write(self.clone()) };
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-impl<T: Copy> WriteCloneIntoRaw for T {
-    #[inline]
-    unsafe fn write_clone_into_raw(&self, target: *mut Self) {
-        // We can always copy in-place, without ever involving a local value.
-        unsafe { target.copy_from_nonoverlapping(self, 1) };
-    }
-}
diff --git a/rust/alloc/boxed.rs b/rust/alloc/boxed.rs
deleted file mode 100644
index c93a22a5c97f..000000000000
--- a/rust/alloc/boxed.rs
+++ /dev/null
@@ -1,2463 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-//! The `Box<T>` type for heap allocation.
-//!
-//! [`Box<T>`], casually referred to as a 'box', provides the simplest form of
-//! heap allocation in Rust. Boxes provide ownership for this allocation, and
-//! drop their contents when they go out of scope. Boxes also ensure that they
-//! never allocate more than `isize::MAX` bytes.
-//!
-//! # Examples
-//!
-//! Move a value from the stack to the heap by creating a [`Box`]:
-//!
-//! ```
-//! let val: u8 = 5;
-//! let boxed: Box<u8> = Box::new(val);
-//! ```
-//!
-//! Move a value from a [`Box`] back to the stack by [dereferencing]:
-//!
-//! ```
-//! let boxed: Box<u8> = Box::new(5);
-//! let val: u8 = *boxed;
-//! ```
-//!
-//! Creating a recursive data structure:
-//!
-//! ```
-//! #[derive(Debug)]
-//! enum List<T> {
-//!     Cons(T, Box<List<T>>),
-//!     Nil,
-//! }
-//!
-//! let list: List<i32> = List::Cons(1, Box::new(List::Cons(2, Box::new(List::Nil))));
-//! println!("{list:?}");
-//! ```
-//!
-//! This will print `Cons(1, Cons(2, Nil))`.
-//!
-//! Recursive structures must be boxed, because if the definition of `Cons`
-//! looked like this:
-//!
-//! ```compile_fail,E0072
-//! # enum List<T> {
-//! Cons(T, List<T>),
-//! # }
-//! ```
-//!
-//! It wouldn't work. This is because the size of a `List` depends on how many
-//! elements are in the list, and so we don't know how much memory to allocate
-//! for a `Cons`. By introducing a [`Box<T>`], which has a defined size, we know how
-//! big `Cons` needs to be.
-//!
-//! # Memory layout
-//!
-//! For non-zero-sized values, a [`Box`] will use the [`Global`] allocator for
-//! its allocation. It is valid to convert both ways between a [`Box`] and a
-//! raw pointer allocated with the [`Global`] allocator, given that the
-//! [`Layout`] used with the allocator is correct for the type. More precisely,
-//! a `value: *mut T` that has been allocated with the [`Global`] allocator
-//! with `Layout::for_value(&*value)` may be converted into a box using
-//! [`Box::<T>::from_raw(value)`]. Conversely, the memory backing a `value: *mut
-//! T` obtained from [`Box::<T>::into_raw`] may be deallocated using the
-//! [`Global`] allocator with [`Layout::for_value(&*value)`].
-//!
-//! For zero-sized values, the `Box` pointer still has to be [valid] for reads
-//! and writes and sufficiently aligned. In particular, casting any aligned
-//! non-zero integer literal to a raw pointer produces a valid pointer, but a
-//! pointer pointing into previously allocated memory that since got freed is
-//! not valid. The recommended way to build a Box to a ZST if `Box::new` cannot
-//! be used is to use [`ptr::NonNull::dangling`].
-//!
-//! So long as `T: Sized`, a `Box<T>` is guaranteed to be represented
-//! as a single pointer and is also ABI-compatible with C pointers
-//! (i.e. the C type `T*`). This means that if you have extern "C"
-//! Rust functions that will be called from C, you can define those
-//! Rust functions using `Box<T>` types, and use `T*` as corresponding
-//! type on the C side. As an example, consider this C header which
-//! declares functions that create and destroy some kind of `Foo`
-//! value:
-//!
-//! ```c
-//! /* C header */
-//!
-//! /* Returns ownership to the caller */
-//! struct Foo* foo_new(void);
-//!
-//! /* Takes ownership from the caller; no-op when invoked with null */
-//! void foo_delete(struct Foo*);
-//! ```
-//!
-//! These two functions might be implemented in Rust as follows. Here, the
-//! `struct Foo*` type from C is translated to `Box<Foo>`, which captures
-//! the ownership constraints. Note also that the nullable argument to
-//! `foo_delete` is represented in Rust as `Option<Box<Foo>>`, since `Box<Foo>`
-//! cannot be null.
-//!
-//! ```
-//! #[repr(C)]
-//! pub struct Foo;
-//!
-//! #[no_mangle]
-//! pub extern "C" fn foo_new() -> Box<Foo> {
-//!     Box::new(Foo)
-//! }
-//!
-//! #[no_mangle]
-//! pub extern "C" fn foo_delete(_: Option<Box<Foo>>) {}
-//! ```
-//!
-//! Even though `Box<T>` has the same representation and C ABI as a C pointer,
-//! this does not mean that you can convert an arbitrary `T*` into a `Box<T>`
-//! and expect things to work. `Box<T>` values will always be fully aligned,
-//! non-null pointers. Moreover, the destructor for `Box<T>` will attempt to
-//! free the value with the global allocator. In general, the best practice
-//! is to only use `Box<T>` for pointers that originated from the global
-//! allocator.
-//!
-//! **Important.** At least at present, you should avoid using
-//! `Box<T>` types for functions that are defined in C but invoked
-//! from Rust. In those cases, you should directly mirror the C types
-//! as closely as possible. Using types like `Box<T>` where the C
-//! definition is just using `T*` can lead to undefined behavior, as
-//! described in [rust-lang/unsafe-code-guidelines#198][ucg#198].
-//!
-//! # Considerations for unsafe code
-//!
-//! **Warning: This section is not normative and is subject to change, possibly
-//! being relaxed in the future! It is a simplified summary of the rules
-//! currently implemented in the compiler.**
-//!
-//! The aliasing rules for `Box<T>` are the same as for `&mut T`. `Box<T>`
-//! asserts uniqueness over its content. Using raw pointers derived from a box
-//! after that box has been mutated through, moved or borrowed as `&mut T`
-//! is not allowed. For more guidance on working with box from unsafe code, see
-//! [rust-lang/unsafe-code-guidelines#326][ucg#326].
-//!
-//!
-//! [ucg#198]: https://github.com/rust-lang/unsafe-code-guidelines/issues/198
-//! [ucg#326]: https://github.com/rust-lang/unsafe-code-guidelines/issues/326
-//! [dereferencing]: core::ops::Deref
-//! [`Box::<T>::from_raw(value)`]: Box::from_raw
-//! [`Global`]: crate::alloc::Global
-//! [`Layout`]: crate::alloc::Layout
-//! [`Layout::for_value(&*value)`]: crate::alloc::Layout::for_value
-//! [valid]: ptr#safety
-
-#![stable(feature = "rust1", since = "1.0.0")]
-
-use core::any::Any;
-use core::async_iter::AsyncIterator;
-use core::borrow;
-use core::cmp::Ordering;
-use core::error::Error;
-use core::fmt;
-use core::future::Future;
-use core::hash::{Hash, Hasher};
-use core::iter::FusedIterator;
-use core::marker::Tuple;
-use core::marker::Unsize;
-use core::mem::{self, SizedTypeProperties};
-use core::ops::{
-    CoerceUnsized, Coroutine, CoroutineState, Deref, DerefMut, DispatchFromDyn, Receiver,
-};
-use core::pin::Pin;
-use core::ptr::{self, NonNull, Unique};
-use core::task::{Context, Poll};
-
-#[cfg(not(no_global_oom_handling))]
-use crate::alloc::{handle_alloc_error, WriteCloneIntoRaw};
-use crate::alloc::{AllocError, Allocator, Global, Layout};
-#[cfg(not(no_global_oom_handling))]
-use crate::borrow::Cow;
-use crate::raw_vec::RawVec;
-#[cfg(not(no_global_oom_handling))]
-use crate::str::from_boxed_utf8_unchecked;
-#[cfg(not(no_global_oom_handling))]
-use crate::string::String;
-#[cfg(not(no_global_oom_handling))]
-use crate::vec::Vec;
-
-#[cfg(not(no_thin))]
-#[unstable(feature = "thin_box", issue = "92791")]
-pub use thin::ThinBox;
-
-#[cfg(not(no_thin))]
-mod thin;
-
-/// A pointer type that uniquely owns a heap allocation of type `T`.
-///
-/// See the [module-level documentation](../../std/boxed/index.html) for more.
-#[lang = "owned_box"]
-#[fundamental]
-#[stable(feature = "rust1", since = "1.0.0")]
-// The declaration of the `Box` struct must be kept in sync with the
-// `alloc::alloc::box_free` function or ICEs will happen. See the comment
-// on `box_free` for more details.
-pub struct Box<
-    T: ?Sized,
-    #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,
->(Unique<T>, A);
-
-impl<T> Box<T> {
-    /// Allocates memory on the heap and then places `x` into it.
-    ///
-    /// This doesn't actually allocate if `T` is zero-sized.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let five = Box::new(5);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[inline(always)]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    #[must_use]
-    #[rustc_diagnostic_item = "box_new"]
-    pub fn new(x: T) -> Self {
-        #[rustc_box]
-        Box::new(x)
-    }
-
-    /// Constructs a new box with uninitialized contents.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(new_uninit)]
-    ///
-    /// let mut five = Box::<u32>::new_uninit();
-    ///
-    /// let five = unsafe {
-    ///     // Deferred initialization:
-    ///     five.as_mut_ptr().write(5);
-    ///
-    ///     five.assume_init()
-    /// };
-    ///
-    /// assert_eq!(*five, 5)
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_uninit", issue = "63291")]
-    #[must_use]
-    #[inline]
-    pub fn new_uninit() -> Box<mem::MaybeUninit<T>> {
-        Self::new_uninit_in(Global)
-    }
-
-    /// Constructs a new `Box` with uninitialized contents, with the memory
-    /// being filled with `0` bytes.
-    ///
-    /// See [`MaybeUninit::zeroed`][zeroed] for examples of correct and incorrect usage
-    /// of this method.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(new_uninit)]
-    ///
-    /// let zero = Box::<u32>::new_zeroed();
-    /// let zero = unsafe { zero.assume_init() };
-    ///
-    /// assert_eq!(*zero, 0)
-    /// ```
-    ///
-    /// [zeroed]: mem::MaybeUninit::zeroed
-    #[cfg(not(no_global_oom_handling))]
-    #[inline]
-    #[unstable(feature = "new_uninit", issue = "63291")]
-    #[must_use]
-    pub fn new_zeroed() -> Box<mem::MaybeUninit<T>> {
-        Self::new_zeroed_in(Global)
-    }
-
-    /// Constructs a new `Pin<Box<T>>`. If `T` does not implement [`Unpin`], then
-    /// `x` will be pinned in memory and unable to be moved.
-    ///
-    /// Constructing and pinning of the `Box` can also be done in two steps: `Box::pin(x)`
-    /// does the same as <code>[Box::into_pin]\([Box::new]\(x))</code>. Consider using
-    /// [`into_pin`](Box::into_pin) if you already have a `Box<T>`, or if you want to
-    /// construct a (pinned) `Box` in a different way than with [`Box::new`].
-    #[cfg(not(no_global_oom_handling))]
-    #[stable(feature = "pin", since = "1.33.0")]
-    #[must_use]
-    #[inline(always)]
-    pub fn pin(x: T) -> Pin<Box<T>> {
-        Box::new(x).into()
-    }
-
-    /// Allocates memory on the heap then places `x` into it,
-    /// returning an error if the allocation fails
-    ///
-    /// This doesn't actually allocate if `T` is zero-sized.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api)]
-    ///
-    /// let five = Box::try_new(5)?;
-    /// # Ok::<(), std::alloc::AllocError>(())
-    /// ```
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[inline]
-    pub fn try_new(x: T) -> Result<Self, AllocError> {
-        Self::try_new_in(x, Global)
-    }
-
-    /// Constructs a new box with uninitialized contents on the heap,
-    /// returning an error if the allocation fails
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api, new_uninit)]
-    ///
-    /// let mut five = Box::<u32>::try_new_uninit()?;
-    ///
-    /// let five = unsafe {
-    ///     // Deferred initialization:
-    ///     five.as_mut_ptr().write(5);
-    ///
-    ///     five.assume_init()
-    /// };
-    ///
-    /// assert_eq!(*five, 5);
-    /// # Ok::<(), std::alloc::AllocError>(())
-    /// ```
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
-    #[inline]
-    pub fn try_new_uninit() -> Result<Box<mem::MaybeUninit<T>>, AllocError> {
-        Box::try_new_uninit_in(Global)
-    }
-
-    /// Constructs a new `Box` with uninitialized contents, with the memory
-    /// being filled with `0` bytes on the heap
-    ///
-    /// See [`MaybeUninit::zeroed`][zeroed] for examples of correct and incorrect usage
-    /// of this method.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api, new_uninit)]
-    ///
-    /// let zero = Box::<u32>::try_new_zeroed()?;
-    /// let zero = unsafe { zero.assume_init() };
-    ///
-    /// assert_eq!(*zero, 0);
-    /// # Ok::<(), std::alloc::AllocError>(())
-    /// ```
-    ///
-    /// [zeroed]: mem::MaybeUninit::zeroed
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
-    #[inline]
-    pub fn try_new_zeroed() -> Result<Box<mem::MaybeUninit<T>>, AllocError> {
-        Box::try_new_zeroed_in(Global)
-    }
-}
-
-impl<T, A: Allocator> Box<T, A> {
-    /// Allocates memory in the given allocator then places `x` into it.
-    ///
-    /// This doesn't actually allocate if `T` is zero-sized.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// let five = Box::new_in(5, System);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[must_use]
-    #[inline]
-    pub fn new_in(x: T, alloc: A) -> Self
-    where
-        A: Allocator,
-    {
-        let mut boxed = Self::new_uninit_in(alloc);
-        unsafe {
-            boxed.as_mut_ptr().write(x);
-            boxed.assume_init()
-        }
-    }
-
-    /// Allocates memory in the given allocator then places `x` into it,
-    /// returning an error if the allocation fails
-    ///
-    /// This doesn't actually allocate if `T` is zero-sized.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// let five = Box::try_new_in(5, System)?;
-    /// # Ok::<(), std::alloc::AllocError>(())
-    /// ```
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[inline]
-    pub fn try_new_in(x: T, alloc: A) -> Result<Self, AllocError>
-    where
-        A: Allocator,
-    {
-        let mut boxed = Self::try_new_uninit_in(alloc)?;
-        unsafe {
-            boxed.as_mut_ptr().write(x);
-            Ok(boxed.assume_init())
-        }
-    }
-
-    /// Constructs a new box with uninitialized contents in the provided allocator.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api, new_uninit)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// let mut five = Box::<u32, _>::new_uninit_in(System);
-    ///
-    /// let five = unsafe {
-    ///     // Deferred initialization:
-    ///     five.as_mut_ptr().write(5);
-    ///
-    ///     five.assume_init()
-    /// };
-    ///
-    /// assert_eq!(*five, 5)
-    /// ```
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[cfg(not(no_global_oom_handling))]
-    #[must_use]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
-    pub fn new_uninit_in(alloc: A) -> Box<mem::MaybeUninit<T>, A>
-    where
-        A: Allocator,
-    {
-        let layout = Layout::new::<mem::MaybeUninit<T>>();
-        // NOTE: Prefer match over unwrap_or_else since closure sometimes not inlineable.
-        // That would make code size bigger.
-        match Box::try_new_uninit_in(alloc) {
-            Ok(m) => m,
-            Err(_) => handle_alloc_error(layout),
-        }
-    }
-
-    /// Constructs a new box with uninitialized contents in the provided allocator,
-    /// returning an error if the allocation fails
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api, new_uninit)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// let mut five = Box::<u32, _>::try_new_uninit_in(System)?;
-    ///
-    /// let five = unsafe {
-    ///     // Deferred initialization:
-    ///     five.as_mut_ptr().write(5);
-    ///
-    ///     five.assume_init()
-    /// };
-    ///
-    /// assert_eq!(*five, 5);
-    /// # Ok::<(), std::alloc::AllocError>(())
-    /// ```
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
-    pub fn try_new_uninit_in(alloc: A) -> Result<Box<mem::MaybeUninit<T>, A>, AllocError>
-    where
-        A: Allocator,
-    {
-        let ptr = if T::IS_ZST {
-            NonNull::dangling()
-        } else {
-            let layout = Layout::new::<mem::MaybeUninit<T>>();
-            alloc.allocate(layout)?.cast()
-        };
-        unsafe { Ok(Box::from_raw_in(ptr.as_ptr(), alloc)) }
-    }
-
-    /// Constructs a new `Box` with uninitialized contents, with the memory
-    /// being filled with `0` bytes in the provided allocator.
-    ///
-    /// See [`MaybeUninit::zeroed`][zeroed] for examples of correct and incorrect usage
-    /// of this method.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api, new_uninit)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// let zero = Box::<u32, _>::new_zeroed_in(System);
-    /// let zero = unsafe { zero.assume_init() };
-    ///
-    /// assert_eq!(*zero, 0)
-    /// ```
-    ///
-    /// [zeroed]: mem::MaybeUninit::zeroed
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[cfg(not(no_global_oom_handling))]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
-    #[must_use]
-    pub fn new_zeroed_in(alloc: A) -> Box<mem::MaybeUninit<T>, A>
-    where
-        A: Allocator,
-    {
-        let layout = Layout::new::<mem::MaybeUninit<T>>();
-        // NOTE: Prefer match over unwrap_or_else since closure sometimes not inlineable.
-        // That would make code size bigger.
-        match Box::try_new_zeroed_in(alloc) {
-            Ok(m) => m,
-            Err(_) => handle_alloc_error(layout),
-        }
-    }
-
-    /// Constructs a new `Box` with uninitialized contents, with the memory
-    /// being filled with `0` bytes in the provided allocator,
-    /// returning an error if the allocation fails,
-    ///
-    /// See [`MaybeUninit::zeroed`][zeroed] for examples of correct and incorrect usage
-    /// of this method.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api, new_uninit)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// let zero = Box::<u32, _>::try_new_zeroed_in(System)?;
-    /// let zero = unsafe { zero.assume_init() };
-    ///
-    /// assert_eq!(*zero, 0);
-    /// # Ok::<(), std::alloc::AllocError>(())
-    /// ```
-    ///
-    /// [zeroed]: mem::MaybeUninit::zeroed
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
-    pub fn try_new_zeroed_in(alloc: A) -> Result<Box<mem::MaybeUninit<T>, A>, AllocError>
-    where
-        A: Allocator,
-    {
-        let ptr = if T::IS_ZST {
-            NonNull::dangling()
-        } else {
-            let layout = Layout::new::<mem::MaybeUninit<T>>();
-            alloc.allocate_zeroed(layout)?.cast()
-        };
-        unsafe { Ok(Box::from_raw_in(ptr.as_ptr(), alloc)) }
-    }
-
-    /// Constructs a new `Pin<Box<T, A>>`. If `T` does not implement [`Unpin`], then
-    /// `x` will be pinned in memory and unable to be moved.
-    ///
-    /// Constructing and pinning of the `Box` can also be done in two steps: `Box::pin_in(x, alloc)`
-    /// does the same as <code>[Box::into_pin]\([Box::new_in]\(x, alloc))</code>. Consider using
-    /// [`into_pin`](Box::into_pin) if you already have a `Box<T, A>`, or if you want to
-    /// construct a (pinned) `Box` in a different way than with [`Box::new_in`].
-    #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[must_use]
-    #[inline(always)]
-    pub fn pin_in(x: T, alloc: A) -> Pin<Self>
-    where
-        A: 'static + Allocator,
-    {
-        Self::into_pin(Self::new_in(x, alloc))
-    }
-
-    /// Converts a `Box<T>` into a `Box<[T]>`
-    ///
-    /// This conversion does not allocate on the heap and happens in place.
-    #[unstable(feature = "box_into_boxed_slice", issue = "71582")]
-    pub fn into_boxed_slice(boxed: Self) -> Box<[T], A> {
-        let (raw, alloc) = Box::into_raw_with_allocator(boxed);
-        unsafe { Box::from_raw_in(raw as *mut [T; 1], alloc) }
-    }
-
-    /// Consumes the `Box`, returning the wrapped value.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(box_into_inner)]
-    ///
-    /// let c = Box::new(5);
-    ///
-    /// assert_eq!(Box::into_inner(c), 5);
-    /// ```
-    #[unstable(feature = "box_into_inner", issue = "80437")]
-    #[inline]
-    pub fn into_inner(boxed: Self) -> T {
-        *boxed
-    }
-}
-
-impl<T> Box<[T]> {
-    /// Constructs a new boxed slice with uninitialized contents.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(new_uninit)]
-    ///
-    /// let mut values = Box::<[u32]>::new_uninit_slice(3);
-    ///
-    /// let values = unsafe {
-    ///     // Deferred initialization:
-    ///     values[0].as_mut_ptr().write(1);
-    ///     values[1].as_mut_ptr().write(2);
-    ///     values[2].as_mut_ptr().write(3);
-    ///
-    ///     values.assume_init()
-    /// };
-    ///
-    /// assert_eq!(*values, [1, 2, 3])
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_uninit", issue = "63291")]
-    #[must_use]
-    pub fn new_uninit_slice(len: usize) -> Box<[mem::MaybeUninit<T>]> {
-        unsafe { RawVec::with_capacity(len).into_box(len) }
-    }
-
-    /// Constructs a new boxed slice with uninitialized contents, with the memory
-    /// being filled with `0` bytes.
-    ///
-    /// See [`MaybeUninit::zeroed`][zeroed] for examples of correct and incorrect usage
-    /// of this method.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(new_uninit)]
-    ///
-    /// let values = Box::<[u32]>::new_zeroed_slice(3);
-    /// let values = unsafe { values.assume_init() };
-    ///
-    /// assert_eq!(*values, [0, 0, 0])
-    /// ```
-    ///
-    /// [zeroed]: mem::MaybeUninit::zeroed
-    #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_uninit", issue = "63291")]
-    #[must_use]
-    pub fn new_zeroed_slice(len: usize) -> Box<[mem::MaybeUninit<T>]> {
-        unsafe { RawVec::with_capacity_zeroed(len).into_box(len) }
-    }
-
-    /// Constructs a new boxed slice with uninitialized contents. Returns an error if
-    /// the allocation fails
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api, new_uninit)]
-    ///
-    /// let mut values = Box::<[u32]>::try_new_uninit_slice(3)?;
-    /// let values = unsafe {
-    ///     // Deferred initialization:
-    ///     values[0].as_mut_ptr().write(1);
-    ///     values[1].as_mut_ptr().write(2);
-    ///     values[2].as_mut_ptr().write(3);
-    ///     values.assume_init()
-    /// };
-    ///
-    /// assert_eq!(*values, [1, 2, 3]);
-    /// # Ok::<(), std::alloc::AllocError>(())
-    /// ```
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[inline]
-    pub fn try_new_uninit_slice(len: usize) -> Result<Box<[mem::MaybeUninit<T>]>, AllocError> {
-        let ptr = if T::IS_ZST || len == 0 {
-            NonNull::dangling()
-        } else {
-            let layout = match Layout::array::<mem::MaybeUninit<T>>(len) {
-                Ok(l) => l,
-                Err(_) => return Err(AllocError),
-            };
-            Global.allocate(layout)?.cast()
-        };
-        unsafe { Ok(RawVec::from_raw_parts_in(ptr.as_ptr(), len, Global).into_box(len)) }
-    }
-
-    /// Constructs a new boxed slice with uninitialized contents, with the memory
-    /// being filled with `0` bytes. Returns an error if the allocation fails
-    ///
-    /// See [`MaybeUninit::zeroed`][zeroed] for examples of correct and incorrect usage
-    /// of this method.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api, new_uninit)]
-    ///
-    /// let values = Box::<[u32]>::try_new_zeroed_slice(3)?;
-    /// let values = unsafe { values.assume_init() };
-    ///
-    /// assert_eq!(*values, [0, 0, 0]);
-    /// # Ok::<(), std::alloc::AllocError>(())
-    /// ```
-    ///
-    /// [zeroed]: mem::MaybeUninit::zeroed
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[inline]
-    pub fn try_new_zeroed_slice(len: usize) -> Result<Box<[mem::MaybeUninit<T>]>, AllocError> {
-        let ptr = if T::IS_ZST || len == 0 {
-            NonNull::dangling()
-        } else {
-            let layout = match Layout::array::<mem::MaybeUninit<T>>(len) {
-                Ok(l) => l,
-                Err(_) => return Err(AllocError),
-            };
-            Global.allocate_zeroed(layout)?.cast()
-        };
-        unsafe { Ok(RawVec::from_raw_parts_in(ptr.as_ptr(), len, Global).into_box(len)) }
-    }
-}
-
-impl<T, A: Allocator> Box<[T], A> {
-    /// Constructs a new boxed slice with uninitialized contents in the provided allocator.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api, new_uninit)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// let mut values = Box::<[u32], _>::new_uninit_slice_in(3, System);
-    ///
-    /// let values = unsafe {
-    ///     // Deferred initialization:
-    ///     values[0].as_mut_ptr().write(1);
-    ///     values[1].as_mut_ptr().write(2);
-    ///     values[2].as_mut_ptr().write(3);
-    ///
-    ///     values.assume_init()
-    /// };
-    ///
-    /// assert_eq!(*values, [1, 2, 3])
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
-    #[must_use]
-    pub fn new_uninit_slice_in(len: usize, alloc: A) -> Box<[mem::MaybeUninit<T>], A> {
-        unsafe { RawVec::with_capacity_in(len, alloc).into_box(len) }
-    }
-
-    /// Constructs a new boxed slice with uninitialized contents in the provided allocator,
-    /// with the memory being filled with `0` bytes.
-    ///
-    /// See [`MaybeUninit::zeroed`][zeroed] for examples of correct and incorrect usage
-    /// of this method.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api, new_uninit)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// let values = Box::<[u32], _>::new_zeroed_slice_in(3, System);
-    /// let values = unsafe { values.assume_init() };
-    ///
-    /// assert_eq!(*values, [0, 0, 0])
-    /// ```
-    ///
-    /// [zeroed]: mem::MaybeUninit::zeroed
-    #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
-    #[must_use]
-    pub fn new_zeroed_slice_in(len: usize, alloc: A) -> Box<[mem::MaybeUninit<T>], A> {
-        unsafe { RawVec::with_capacity_zeroed_in(len, alloc).into_box(len) }
-    }
-}
-
-impl<T, A: Allocator> Box<mem::MaybeUninit<T>, A> {
-    /// Converts to `Box<T, A>`.
-    ///
-    /// # Safety
-    ///
-    /// As with [`MaybeUninit::assume_init`],
-    /// it is up to the caller to guarantee that the value
-    /// really is in an initialized state.
-    /// Calling this when the content is not yet fully initialized
-    /// causes immediate undefined behavior.
-    ///
-    /// [`MaybeUninit::assume_init`]: mem::MaybeUninit::assume_init
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(new_uninit)]
-    ///
-    /// let mut five = Box::<u32>::new_uninit();
-    ///
-    /// let five: Box<u32> = unsafe {
-    ///     // Deferred initialization:
-    ///     five.as_mut_ptr().write(5);
-    ///
-    ///     five.assume_init()
-    /// };
-    ///
-    /// assert_eq!(*five, 5)
-    /// ```
-    #[unstable(feature = "new_uninit", issue = "63291")]
-    #[inline]
-    pub unsafe fn assume_init(self) -> Box<T, A> {
-        let (raw, alloc) = Box::into_raw_with_allocator(self);
-        unsafe { Box::from_raw_in(raw as *mut T, alloc) }
-    }
-
-    /// Writes the value and converts to `Box<T, A>`.
-    ///
-    /// This method converts the box similarly to [`Box::assume_init`] but
-    /// writes `value` into it before conversion thus guaranteeing safety.
-    /// In some scenarios use of this method may improve performance because
-    /// the compiler may be able to optimize copying from stack.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(new_uninit)]
-    ///
-    /// let big_box = Box::<[usize; 1024]>::new_uninit();
-    ///
-    /// let mut array = [0; 1024];
-    /// for (i, place) in array.iter_mut().enumerate() {
-    ///     *place = i;
-    /// }
-    ///
-    /// // The optimizer may be able to elide this copy, so previous code writes
-    /// // to heap directly.
-    /// let big_box = Box::write(big_box, array);
-    ///
-    /// for (i, x) in big_box.iter().enumerate() {
-    ///     assert_eq!(*x, i);
-    /// }
-    /// ```
-    #[unstable(feature = "new_uninit", issue = "63291")]
-    #[inline]
-    pub fn write(mut boxed: Self, value: T) -> Box<T, A> {
-        unsafe {
-            (*boxed).write(value);
-            boxed.assume_init()
-        }
-    }
-}
-
-impl<T, A: Allocator> Box<[mem::MaybeUninit<T>], A> {
-    /// Converts to `Box<[T], A>`.
-    ///
-    /// # Safety
-    ///
-    /// As with [`MaybeUninit::assume_init`],
-    /// it is up to the caller to guarantee that the values
-    /// really are in an initialized state.
-    /// Calling this when the content is not yet fully initialized
-    /// causes immediate undefined behavior.
-    ///
-    /// [`MaybeUninit::assume_init`]: mem::MaybeUninit::assume_init
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(new_uninit)]
-    ///
-    /// let mut values = Box::<[u32]>::new_uninit_slice(3);
-    ///
-    /// let values = unsafe {
-    ///     // Deferred initialization:
-    ///     values[0].as_mut_ptr().write(1);
-    ///     values[1].as_mut_ptr().write(2);
-    ///     values[2].as_mut_ptr().write(3);
-    ///
-    ///     values.assume_init()
-    /// };
-    ///
-    /// assert_eq!(*values, [1, 2, 3])
-    /// ```
-    #[unstable(feature = "new_uninit", issue = "63291")]
-    #[inline]
-    pub unsafe fn assume_init(self) -> Box<[T], A> {
-        let (raw, alloc) = Box::into_raw_with_allocator(self);
-        unsafe { Box::from_raw_in(raw as *mut [T], alloc) }
-    }
-}
-
-impl<T: ?Sized> Box<T> {
-    /// Constructs a box from a raw pointer.
-    ///
-    /// After calling this function, the raw pointer is owned by the
-    /// resulting `Box`. Specifically, the `Box` destructor will call
-    /// the destructor of `T` and free the allocated memory. For this
-    /// to be safe, the memory must have been allocated in accordance
-    /// with the [memory layout] used by `Box` .
-    ///
-    /// # Safety
-    ///
-    /// This function is unsafe because improper use may lead to
-    /// memory problems. For example, a double-free may occur if the
-    /// function is called twice on the same raw pointer.
-    ///
-    /// The safety conditions are described in the [memory layout] section.
-    ///
-    /// # Examples
-    ///
-    /// Recreate a `Box` which was previously converted to a raw pointer
-    /// using [`Box::into_raw`]:
-    /// ```
-    /// let x = Box::new(5);
-    /// let ptr = Box::into_raw(x);
-    /// let x = unsafe { Box::from_raw(ptr) };
-    /// ```
-    /// Manually create a `Box` from scratch by using the global allocator:
-    /// ```
-    /// use std::alloc::{alloc, Layout};
-    ///
-    /// unsafe {
-    ///     let ptr = alloc(Layout::new::<i32>()) as *mut i32;
-    ///     // In general .write is required to avoid attempting to destruct
-    ///     // the (uninitialized) previous contents of `ptr`, though for this
-    ///     // simple example `*ptr = 5` would have worked as well.
-    ///     ptr.write(5);
-    ///     let x = Box::from_raw(ptr);
-    /// }
-    /// ```
-    ///
-    /// [memory layout]: self#memory-layout
-    /// [`Layout`]: crate::Layout
-    #[stable(feature = "box_raw", since = "1.4.0")]
-    #[inline]
-    #[must_use = "call `drop(Box::from_raw(ptr))` if you intend to drop the `Box`"]
-    pub unsafe fn from_raw(raw: *mut T) -> Self {
-        unsafe { Self::from_raw_in(raw, Global) }
-    }
-}
-
-impl<T: ?Sized, A: Allocator> Box<T, A> {
-    /// Constructs a box from a raw pointer in the given allocator.
-    ///
-    /// After calling this function, the raw pointer is owned by the
-    /// resulting `Box`. Specifically, the `Box` destructor will call
-    /// the destructor of `T` and free the allocated memory. For this
-    /// to be safe, the memory must have been allocated in accordance
-    /// with the [memory layout] used by `Box` .
-    ///
-    /// # Safety
-    ///
-    /// This function is unsafe because improper use may lead to
-    /// memory problems. For example, a double-free may occur if the
-    /// function is called twice on the same raw pointer.
-    ///
-    ///
-    /// # Examples
-    ///
-    /// Recreate a `Box` which was previously converted to a raw pointer
-    /// using [`Box::into_raw_with_allocator`]:
-    /// ```
-    /// #![feature(allocator_api)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// let x = Box::new_in(5, System);
-    /// let (ptr, alloc) = Box::into_raw_with_allocator(x);
-    /// let x = unsafe { Box::from_raw_in(ptr, alloc) };
-    /// ```
-    /// Manually create a `Box` from scratch by using the system allocator:
-    /// ```
-    /// #![feature(allocator_api, slice_ptr_get)]
-    ///
-    /// use std::alloc::{Allocator, Layout, System};
-    ///
-    /// unsafe {
-    ///     let ptr = System.allocate(Layout::new::<i32>())?.as_mut_ptr() as *mut i32;
-    ///     // In general .write is required to avoid attempting to destruct
-    ///     // the (uninitialized) previous contents of `ptr`, though for this
-    ///     // simple example `*ptr = 5` would have worked as well.
-    ///     ptr.write(5);
-    ///     let x = Box::from_raw_in(ptr, System);
-    /// }
-    /// # Ok::<(), std::alloc::AllocError>(())
-    /// ```
-    ///
-    /// [memory layout]: self#memory-layout
-    /// [`Layout`]: crate::Layout
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[rustc_const_unstable(feature = "const_box", issue = "92521")]
-    #[inline]
-    pub const unsafe fn from_raw_in(raw: *mut T, alloc: A) -> Self {
-        Box(unsafe { Unique::new_unchecked(raw) }, alloc)
-    }
-
-    /// Consumes the `Box`, returning a wrapped raw pointer.
-    ///
-    /// The pointer will be properly aligned and non-null.
-    ///
-    /// After calling this function, the caller is responsible for the
-    /// memory previously managed by the `Box`. In particular, the
-    /// caller should properly destroy `T` and release the memory, taking
-    /// into account the [memory layout] used by `Box`. The easiest way to
-    /// do this is to convert the raw pointer back into a `Box` with the
-    /// [`Box::from_raw`] function, allowing the `Box` destructor to perform
-    /// the cleanup.
-    ///
-    /// Note: this is an associated function, which means that you have
-    /// to call it as `Box::into_raw(b)` instead of `b.into_raw()`. This
-    /// is so that there is no conflict with a method on the inner type.
-    ///
-    /// # Examples
-    /// Converting the raw pointer back into a `Box` with [`Box::from_raw`]
-    /// for automatic cleanup:
-    /// ```
-    /// let x = Box::new(String::from("Hello"));
-    /// let ptr = Box::into_raw(x);
-    /// let x = unsafe { Box::from_raw(ptr) };
-    /// ```
-    /// Manual cleanup by explicitly running the destructor and deallocating
-    /// the memory:
-    /// ```
-    /// use std::alloc::{dealloc, Layout};
-    /// use std::ptr;
-    ///
-    /// let x = Box::new(String::from("Hello"));
-    /// let ptr = Box::into_raw(x);
-    /// unsafe {
-    ///     ptr::drop_in_place(ptr);
-    ///     dealloc(ptr as *mut u8, Layout::new::<String>());
-    /// }
-    /// ```
-    /// Note: This is equivalent to the following:
-    /// ```
-    /// let x = Box::new(String::from("Hello"));
-    /// let ptr = Box::into_raw(x);
-    /// unsafe {
-    ///     drop(Box::from_raw(ptr));
-    /// }
-    /// ```
-    ///
-    /// [memory layout]: self#memory-layout
-    #[stable(feature = "box_raw", since = "1.4.0")]
-    #[inline]
-    pub fn into_raw(b: Self) -> *mut T {
-        Self::into_raw_with_allocator(b).0
-    }
-
-    /// Consumes the `Box`, returning a wrapped raw pointer and the allocator.
-    ///
-    /// The pointer will be properly aligned and non-null.
-    ///
-    /// After calling this function, the caller is responsible for the
-    /// memory previously managed by the `Box`. In particular, the
-    /// caller should properly destroy `T` and release the memory, taking
-    /// into account the [memory layout] used by `Box`. The easiest way to
-    /// do this is to convert the raw pointer back into a `Box` with the
-    /// [`Box::from_raw_in`] function, allowing the `Box` destructor to perform
-    /// the cleanup.
-    ///
-    /// Note: this is an associated function, which means that you have
-    /// to call it as `Box::into_raw_with_allocator(b)` instead of `b.into_raw_with_allocator()`. This
-    /// is so that there is no conflict with a method on the inner type.
-    ///
-    /// # Examples
-    /// Converting the raw pointer back into a `Box` with [`Box::from_raw_in`]
-    /// for automatic cleanup:
-    /// ```
-    /// #![feature(allocator_api)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// let x = Box::new_in(String::from("Hello"), System);
-    /// let (ptr, alloc) = Box::into_raw_with_allocator(x);
-    /// let x = unsafe { Box::from_raw_in(ptr, alloc) };
-    /// ```
-    /// Manual cleanup by explicitly running the destructor and deallocating
-    /// the memory:
-    /// ```
-    /// #![feature(allocator_api)]
-    ///
-    /// use std::alloc::{Allocator, Layout, System};
-    /// use std::ptr::{self, NonNull};
-    ///
-    /// let x = Box::new_in(String::from("Hello"), System);
-    /// let (ptr, alloc) = Box::into_raw_with_allocator(x);
-    /// unsafe {
-    ///     ptr::drop_in_place(ptr);
-    ///     let non_null = NonNull::new_unchecked(ptr);
-    ///     alloc.deallocate(non_null.cast(), Layout::new::<String>());
-    /// }
-    /// ```
-    ///
-    /// [memory layout]: self#memory-layout
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[inline]
-    pub fn into_raw_with_allocator(b: Self) -> (*mut T, A) {
-        let (leaked, alloc) = Box::into_unique(b);
-        (leaked.as_ptr(), alloc)
-    }
-
-    #[unstable(
-        feature = "ptr_internals",
-        issue = "none",
-        reason = "use `Box::leak(b).into()` or `Unique::from(Box::leak(b))` instead"
-    )]
-    #[inline]
-    #[doc(hidden)]
-    pub fn into_unique(b: Self) -> (Unique<T>, A) {
-        // Box is recognized as a "unique pointer" by Stacked Borrows, but internally it is a
-        // raw pointer for the type system. Turning it directly into a raw pointer would not be
-        // recognized as "releasing" the unique pointer to permit aliased raw accesses,
-        // so all raw pointer methods have to go through `Box::leak`. Turning *that* to a raw pointer
-        // behaves correctly.
-        let alloc = unsafe { ptr::read(&b.1) };
-        (Unique::from(Box::leak(b)), alloc)
-    }
-
-    /// Returns a reference to the underlying allocator.
-    ///
-    /// Note: this is an associated function, which means that you have
-    /// to call it as `Box::allocator(&b)` instead of `b.allocator()`. This
-    /// is so that there is no conflict with a method on the inner type.
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[rustc_const_unstable(feature = "const_box", issue = "92521")]
-    #[inline]
-    pub const fn allocator(b: &Self) -> &A {
-        &b.1
-    }
-
-    /// Consumes and leaks the `Box`, returning a mutable reference,
-    /// `&'a mut T`. Note that the type `T` must outlive the chosen lifetime
-    /// `'a`. If the type has only static references, or none at all, then this
-    /// may be chosen to be `'static`.
-    ///
-    /// This function is mainly useful for data that lives for the remainder of
-    /// the program's life. Dropping the returned reference will cause a memory
-    /// leak. If this is not acceptable, the reference should first be wrapped
-    /// with the [`Box::from_raw`] function producing a `Box`. This `Box` can
-    /// then be dropped which will properly destroy `T` and release the
-    /// allocated memory.
-    ///
-    /// Note: this is an associated function, which means that you have
-    /// to call it as `Box::leak(b)` instead of `b.leak()`. This
-    /// is so that there is no conflict with a method on the inner type.
-    ///
-    /// # Examples
-    ///
-    /// Simple usage:
-    ///
-    /// ```
-    /// let x = Box::new(41);
-    /// let static_ref: &'static mut usize = Box::leak(x);
-    /// *static_ref += 1;
-    /// assert_eq!(*static_ref, 42);
-    /// ```
-    ///
-    /// Unsized data:
-    ///
-    /// ```
-    /// let x = vec![1, 2, 3].into_boxed_slice();
-    /// let static_ref = Box::leak(x);
-    /// static_ref[0] = 4;
-    /// assert_eq!(*static_ref, [4, 2, 3]);
-    /// ```
-    #[stable(feature = "box_leak", since = "1.26.0")]
-    #[inline]
-    pub fn leak<'a>(b: Self) -> &'a mut T
-    where
-        A: 'a,
-    {
-        unsafe { &mut *mem::ManuallyDrop::new(b).0.as_ptr() }
-    }
-
-    /// Converts a `Box<T>` into a `Pin<Box<T>>`. If `T` does not implement [`Unpin`], then
-    /// `*boxed` will be pinned in memory and unable to be moved.
-    ///
-    /// This conversion does not allocate on the heap and happens in place.
-    ///
-    /// This is also available via [`From`].
-    ///
-    /// Constructing and pinning a `Box` with <code>Box::into_pin([Box::new]\(x))</code>
-    /// can also be written more concisely using <code>[Box::pin]\(x)</code>.
-    /// This `into_pin` method is useful if you already have a `Box<T>`, or you are
-    /// constructing a (pinned) `Box` in a different way than with [`Box::new`].
-    ///
-    /// # Notes
-    ///
-    /// It's not recommended that crates add an impl like `From<Box<T>> for Pin<T>`,
-    /// as it'll introduce an ambiguity when calling `Pin::from`.
-    /// A demonstration of such a poor impl is shown below.
-    ///
-    /// ```compile_fail
-    /// # use std::pin::Pin;
-    /// struct Foo; // A type defined in this crate.
-    /// impl From<Box<()>> for Pin<Foo> {
-    ///     fn from(_: Box<()>) -> Pin<Foo> {
-    ///         Pin::new(Foo)
-    ///     }
-    /// }
-    ///
-    /// let foo = Box::new(());
-    /// let bar = Pin::from(foo);
-    /// ```
-    #[stable(feature = "box_into_pin", since = "1.63.0")]
-    #[rustc_const_unstable(feature = "const_box", issue = "92521")]
-    pub const fn into_pin(boxed: Self) -> Pin<Self>
-    where
-        A: 'static,
-    {
-        // It's not possible to move or replace the insides of a `Pin<Box<T>>`
-        // when `T: !Unpin`, so it's safe to pin it directly without any
-        // additional requirements.
-        unsafe { Pin::new_unchecked(boxed) }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-unsafe impl<#[may_dangle] T: ?Sized, A: Allocator> Drop for Box<T, A> {
-    #[inline]
-    fn drop(&mut self) {
-        // the T in the Box is dropped by the compiler before the destructor is run
-
-        let ptr = self.0;
-
-        unsafe {
-            let layout = Layout::for_value_raw(ptr.as_ptr());
-            if layout.size() != 0 {
-                self.1.deallocate(From::from(ptr.cast()), layout);
-            }
-        }
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Default> Default for Box<T> {
-    /// Creates a `Box<T>`, with the `Default` value for T.
-    #[inline]
-    fn default() -> Self {
-        Box::new(T::default())
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T> Default for Box<[T]> {
-    #[inline]
-    fn default() -> Self {
-        let ptr: Unique<[T]> = Unique::<[T; 0]>::dangling();
-        Box(ptr, Global)
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "default_box_extra", since = "1.17.0")]
-impl Default for Box<str> {
-    #[inline]
-    fn default() -> Self {
-        // SAFETY: This is the same as `Unique::cast<U>` but with an unsized `U = str`.
-        let ptr: Unique<str> = unsafe {
-            let bytes: Unique<[u8]> = Unique::<[u8; 0]>::dangling();
-            Unique::new_unchecked(bytes.as_ptr() as *mut str)
-        };
-        Box(ptr, Global)
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Clone, A: Allocator + Clone> Clone for Box<T, A> {
-    /// Returns a new box with a `clone()` of this box's contents.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let x = Box::new(5);
-    /// let y = x.clone();
-    ///
-    /// // The value is the same
-    /// assert_eq!(x, y);
-    ///
-    /// // But they are unique objects
-    /// assert_ne!(&*x as *const i32, &*y as *const i32);
-    /// ```
-    #[inline]
-    fn clone(&self) -> Self {
-        // Pre-allocate memory to allow writing the cloned value directly.
-        let mut boxed = Self::new_uninit_in(self.1.clone());
-        unsafe {
-            (**self).write_clone_into_raw(boxed.as_mut_ptr());
-            boxed.assume_init()
-        }
-    }
-
-    /// Copies `source`'s contents into `self` without creating a new allocation.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let x = Box::new(5);
-    /// let mut y = Box::new(10);
-    /// let yp: *const i32 = &*y;
-    ///
-    /// y.clone_from(&x);
-    ///
-    /// // The value is the same
-    /// assert_eq!(x, y);
-    ///
-    /// // And no allocation occurred
-    /// assert_eq!(yp, &*y);
-    /// ```
-    #[inline]
-    fn clone_from(&mut self, source: &Self) {
-        (**self).clone_from(&(**source));
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "box_slice_clone", since = "1.3.0")]
-impl Clone for Box<str> {
-    fn clone(&self) -> Self {
-        // this makes a copy of the data
-        let buf: Box<[u8]> = self.as_bytes().into();
-        unsafe { from_boxed_utf8_unchecked(buf) }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized + PartialEq, A: Allocator> PartialEq for Box<T, A> {
-    #[inline]
-    fn eq(&self, other: &Self) -> bool {
-        PartialEq::eq(&**self, &**other)
-    }
-    #[inline]
-    fn ne(&self, other: &Self) -> bool {
-        PartialEq::ne(&**self, &**other)
-    }
-}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized + PartialOrd, A: Allocator> PartialOrd for Box<T, A> {
-    #[inline]
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        PartialOrd::partial_cmp(&**self, &**other)
-    }
-    #[inline]
-    fn lt(&self, other: &Self) -> bool {
-        PartialOrd::lt(&**self, &**other)
-    }
-    #[inline]
-    fn le(&self, other: &Self) -> bool {
-        PartialOrd::le(&**self, &**other)
-    }
-    #[inline]
-    fn ge(&self, other: &Self) -> bool {
-        PartialOrd::ge(&**self, &**other)
-    }
-    #[inline]
-    fn gt(&self, other: &Self) -> bool {
-        PartialOrd::gt(&**self, &**other)
-    }
-}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized + Ord, A: Allocator> Ord for Box<T, A> {
-    #[inline]
-    fn cmp(&self, other: &Self) -> Ordering {
-        Ord::cmp(&**self, &**other)
-    }
-}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized + Eq, A: Allocator> Eq for Box<T, A> {}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized + Hash, A: Allocator> Hash for Box<T, A> {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        (**self).hash(state);
-    }
-}
-
-#[stable(feature = "indirect_hasher_impl", since = "1.22.0")]
-impl<T: ?Sized + Hasher, A: Allocator> Hasher for Box<T, A> {
-    fn finish(&self) -> u64 {
-        (**self).finish()
-    }
-    fn write(&mut self, bytes: &[u8]) {
-        (**self).write(bytes)
-    }
-    fn write_u8(&mut self, i: u8) {
-        (**self).write_u8(i)
-    }
-    fn write_u16(&mut self, i: u16) {
-        (**self).write_u16(i)
-    }
-    fn write_u32(&mut self, i: u32) {
-        (**self).write_u32(i)
-    }
-    fn write_u64(&mut self, i: u64) {
-        (**self).write_u64(i)
-    }
-    fn write_u128(&mut self, i: u128) {
-        (**self).write_u128(i)
-    }
-    fn write_usize(&mut self, i: usize) {
-        (**self).write_usize(i)
-    }
-    fn write_i8(&mut self, i: i8) {
-        (**self).write_i8(i)
-    }
-    fn write_i16(&mut self, i: i16) {
-        (**self).write_i16(i)
-    }
-    fn write_i32(&mut self, i: i32) {
-        (**self).write_i32(i)
-    }
-    fn write_i64(&mut self, i: i64) {
-        (**self).write_i64(i)
-    }
-    fn write_i128(&mut self, i: i128) {
-        (**self).write_i128(i)
-    }
-    fn write_isize(&mut self, i: isize) {
-        (**self).write_isize(i)
-    }
-    fn write_length_prefix(&mut self, len: usize) {
-        (**self).write_length_prefix(len)
-    }
-    fn write_str(&mut self, s: &str) {
-        (**self).write_str(s)
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "from_for_ptrs", since = "1.6.0")]
-impl<T> From<T> for Box<T> {
-    /// Converts a `T` into a `Box<T>`
-    ///
-    /// The conversion allocates on the heap and moves `t`
-    /// from the stack into it.
-    ///
-    /// # Examples
-    ///
-    /// ```rust
-    /// let x = 5;
-    /// let boxed = Box::new(5);
-    ///
-    /// assert_eq!(Box::from(x), boxed);
-    /// ```
-    fn from(t: T) -> Self {
-        Box::new(t)
-    }
-}
-
-#[stable(feature = "pin", since = "1.33.0")]
-impl<T: ?Sized, A: Allocator> From<Box<T, A>> for Pin<Box<T, A>>
-where
-    A: 'static,
-{
-    /// Converts a `Box<T>` into a `Pin<Box<T>>`. If `T` does not implement [`Unpin`], then
-    /// `*boxed` will be pinned in memory and unable to be moved.
-    ///
-    /// This conversion does not allocate on the heap and happens in place.
-    ///
-    /// This is also available via [`Box::into_pin`].
-    ///
-    /// Constructing and pinning a `Box` with <code><Pin<Box\<T>>>::from([Box::new]\(x))</code>
-    /// can also be written more concisely using <code>[Box::pin]\(x)</code>.
-    /// This `From` implementation is useful if you already have a `Box<T>`, or you are
-    /// constructing a (pinned) `Box` in a different way than with [`Box::new`].
-    fn from(boxed: Box<T, A>) -> Self {
-        Box::into_pin(boxed)
-    }
-}
-
-/// Specialization trait used for `From<&[T]>`.
-#[cfg(not(no_global_oom_handling))]
-trait BoxFromSlice<T> {
-    fn from_slice(slice: &[T]) -> Self;
-}
-
-#[cfg(not(no_global_oom_handling))]
-impl<T: Clone> BoxFromSlice<T> for Box<[T]> {
-    #[inline]
-    default fn from_slice(slice: &[T]) -> Self {
-        slice.to_vec().into_boxed_slice()
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-impl<T: Copy> BoxFromSlice<T> for Box<[T]> {
-    #[inline]
-    fn from_slice(slice: &[T]) -> Self {
-        let len = slice.len();
-        let buf = RawVec::with_capacity(len);
-        unsafe {
-            ptr::copy_nonoverlapping(slice.as_ptr(), buf.ptr(), len);
-            buf.into_box(slice.len()).assume_init()
-        }
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "box_from_slice", since = "1.17.0")]
-impl<T: Clone> From<&[T]> for Box<[T]> {
-    /// Converts a `&[T]` into a `Box<[T]>`
-    ///
-    /// This conversion allocates on the heap
-    /// and performs a copy of `slice` and its contents.
-    ///
-    /// # Examples
-    /// ```rust
-    /// // create a &[u8] which will be used to create a Box<[u8]>
-    /// let slice: &[u8] = &[104, 101, 108, 108, 111];
-    /// let boxed_slice: Box<[u8]> = Box::from(slice);
-    ///
-    /// println!("{boxed_slice:?}");
-    /// ```
-    #[inline]
-    fn from(slice: &[T]) -> Box<[T]> {
-        <Self as BoxFromSlice<T>>::from_slice(slice)
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "box_from_cow", since = "1.45.0")]
-impl<T: Clone> From<Cow<'_, [T]>> for Box<[T]> {
-    /// Converts a `Cow<'_, [T]>` into a `Box<[T]>`
-    ///
-    /// When `cow` is the `Cow::Borrowed` variant, this
-    /// conversion allocates on the heap and copies the
-    /// underlying slice. Otherwise, it will try to reuse the owned
-    /// `Vec`'s allocation.
-    #[inline]
-    fn from(cow: Cow<'_, [T]>) -> Box<[T]> {
-        match cow {
-            Cow::Borrowed(slice) => Box::from(slice),
-            Cow::Owned(slice) => Box::from(slice),
-        }
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "box_from_slice", since = "1.17.0")]
-impl From<&str> for Box<str> {
-    /// Converts a `&str` into a `Box<str>`
-    ///
-    /// This conversion allocates on the heap
-    /// and performs a copy of `s`.
-    ///
-    /// # Examples
-    ///
-    /// ```rust
-    /// let boxed: Box<str> = Box::from("hello");
-    /// println!("{boxed}");
-    /// ```
-    #[inline]
-    fn from(s: &str) -> Box<str> {
-        unsafe { from_boxed_utf8_unchecked(Box::from(s.as_bytes())) }
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "box_from_cow", since = "1.45.0")]
-impl From<Cow<'_, str>> for Box<str> {
-    /// Converts a `Cow<'_, str>` into a `Box<str>`
-    ///
-    /// When `cow` is the `Cow::Borrowed` variant, this
-    /// conversion allocates on the heap and copies the
-    /// underlying `str`. Otherwise, it will try to reuse the owned
-    /// `String`'s allocation.
-    ///
-    /// # Examples
-    ///
-    /// ```rust
-    /// use std::borrow::Cow;
-    ///
-    /// let unboxed = Cow::Borrowed("hello");
-    /// let boxed: Box<str> = Box::from(unboxed);
-    /// println!("{boxed}");
-    /// ```
-    ///
-    /// ```rust
-    /// # use std::borrow::Cow;
-    /// let unboxed = Cow::Owned("hello".to_string());
-    /// let boxed: Box<str> = Box::from(unboxed);
-    /// println!("{boxed}");
-    /// ```
-    #[inline]
-    fn from(cow: Cow<'_, str>) -> Box<str> {
-        match cow {
-            Cow::Borrowed(s) => Box::from(s),
-            Cow::Owned(s) => Box::from(s),
-        }
-    }
-}
-
-#[stable(feature = "boxed_str_conv", since = "1.19.0")]
-impl<A: Allocator> From<Box<str, A>> for Box<[u8], A> {
-    /// Converts a `Box<str>` into a `Box<[u8]>`
-    ///
-    /// This conversion does not allocate on the heap and happens in place.
-    ///
-    /// # Examples
-    /// ```rust
-    /// // create a Box<str> which will be used to create a Box<[u8]>
-    /// let boxed: Box<str> = Box::from("hello");
-    /// let boxed_str: Box<[u8]> = Box::from(boxed);
-    ///
-    /// // create a &[u8] which will be used to create a Box<[u8]>
-    /// let slice: &[u8] = &[104, 101, 108, 108, 111];
-    /// let boxed_slice = Box::from(slice);
-    ///
-    /// assert_eq!(boxed_slice, boxed_str);
-    /// ```
-    #[inline]
-    fn from(s: Box<str, A>) -> Self {
-        let (raw, alloc) = Box::into_raw_with_allocator(s);
-        unsafe { Box::from_raw_in(raw as *mut [u8], alloc) }
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "box_from_array", since = "1.45.0")]
-impl<T, const N: usize> From<[T; N]> for Box<[T]> {
-    /// Converts a `[T; N]` into a `Box<[T]>`
-    ///
-    /// This conversion moves the array to newly heap-allocated memory.
-    ///
-    /// # Examples
-    ///
-    /// ```rust
-    /// let boxed: Box<[u8]> = Box::from([4, 2]);
-    /// println!("{boxed:?}");
-    /// ```
-    fn from(array: [T; N]) -> Box<[T]> {
-        Box::new(array)
-    }
-}
-
-/// Casts a boxed slice to a boxed array.
-///
-/// # Safety
-///
-/// `boxed_slice.len()` must be exactly `N`.
-unsafe fn boxed_slice_as_array_unchecked<T, A: Allocator, const N: usize>(
-    boxed_slice: Box<[T], A>,
-) -> Box<[T; N], A> {
-    debug_assert_eq!(boxed_slice.len(), N);
-
-    let (ptr, alloc) = Box::into_raw_with_allocator(boxed_slice);
-    // SAFETY: Pointer and allocator came from an existing box,
-    // and our safety condition requires that the length is exactly `N`
-    unsafe { Box::from_raw_in(ptr as *mut [T; N], alloc) }
-}
-
-#[stable(feature = "boxed_slice_try_from", since = "1.43.0")]
-impl<T, const N: usize> TryFrom<Box<[T]>> for Box<[T; N]> {
-    type Error = Box<[T]>;
-
-    /// Attempts to convert a `Box<[T]>` into a `Box<[T; N]>`.
-    ///
-    /// The conversion occurs in-place and does not require a
-    /// new memory allocation.
-    ///
-    /// # Errors
-    ///
-    /// Returns the old `Box<[T]>` in the `Err` variant if
-    /// `boxed_slice.len()` does not equal `N`.
-    fn try_from(boxed_slice: Box<[T]>) -> Result<Self, Self::Error> {
-        if boxed_slice.len() == N {
-            Ok(unsafe { boxed_slice_as_array_unchecked(boxed_slice) })
-        } else {
-            Err(boxed_slice)
-        }
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "boxed_array_try_from_vec", since = "1.66.0")]
-impl<T, const N: usize> TryFrom<Vec<T>> for Box<[T; N]> {
-    type Error = Vec<T>;
-
-    /// Attempts to convert a `Vec<T>` into a `Box<[T; N]>`.
-    ///
-    /// Like [`Vec::into_boxed_slice`], this is in-place if `vec.capacity() == N`,
-    /// but will require a reallocation otherwise.
-    ///
-    /// # Errors
-    ///
-    /// Returns the original `Vec<T>` in the `Err` variant if
-    /// `boxed_slice.len()` does not equal `N`.
-    ///
-    /// # Examples
-    ///
-    /// This can be used with [`vec!`] to create an array on the heap:
-    ///
-    /// ```
-    /// let state: Box<[f32; 100]> = vec![1.0; 100].try_into().unwrap();
-    /// assert_eq!(state.len(), 100);
-    /// ```
-    fn try_from(vec: Vec<T>) -> Result<Self, Self::Error> {
-        if vec.len() == N {
-            let boxed_slice = vec.into_boxed_slice();
-            Ok(unsafe { boxed_slice_as_array_unchecked(boxed_slice) })
-        } else {
-            Err(vec)
-        }
-    }
-}
-
-impl<A: Allocator> Box<dyn Any, A> {
-    /// Attempt to downcast the box to a concrete type.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::any::Any;
-    ///
-    /// fn print_if_string(value: Box<dyn Any>) {
-    ///     if let Ok(string) = value.downcast::<String>() {
-    ///         println!("String ({}): {}", string.len(), string);
-    ///     }
-    /// }
-    ///
-    /// let my_string = "Hello World".to_string();
-    /// print_if_string(Box::new(my_string));
-    /// print_if_string(Box::new(0i8));
-    /// ```
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn downcast<T: Any>(self) -> Result<Box<T, A>, Self> {
-        if self.is::<T>() { unsafe { Ok(self.downcast_unchecked::<T>()) } } else { Err(self) }
-    }
-
-    /// Downcasts the box to a concrete type.
-    ///
-    /// For a safe alternative see [`downcast`].
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(downcast_unchecked)]
-    ///
-    /// use std::any::Any;
-    ///
-    /// let x: Box<dyn Any> = Box::new(1_usize);
-    ///
-    /// unsafe {
-    ///     assert_eq!(*x.downcast_unchecked::<usize>(), 1);
-    /// }
-    /// ```
-    ///
-    /// # Safety
-    ///
-    /// The contained value must be of type `T`. Calling this method
-    /// with the incorrect type is *undefined behavior*.
-    ///
-    /// [`downcast`]: Self::downcast
-    #[inline]
-    #[unstable(feature = "downcast_unchecked", issue = "90850")]
-    pub unsafe fn downcast_unchecked<T: Any>(self) -> Box<T, A> {
-        debug_assert!(self.is::<T>());
-        unsafe {
-            let (raw, alloc): (*mut dyn Any, _) = Box::into_raw_with_allocator(self);
-            Box::from_raw_in(raw as *mut T, alloc)
-        }
-    }
-}
-
-impl<A: Allocator> Box<dyn Any + Send, A> {
-    /// Attempt to downcast the box to a concrete type.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::any::Any;
-    ///
-    /// fn print_if_string(value: Box<dyn Any + Send>) {
-    ///     if let Ok(string) = value.downcast::<String>() {
-    ///         println!("String ({}): {}", string.len(), string);
-    ///     }
-    /// }
-    ///
-    /// let my_string = "Hello World".to_string();
-    /// print_if_string(Box::new(my_string));
-    /// print_if_string(Box::new(0i8));
-    /// ```
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn downcast<T: Any>(self) -> Result<Box<T, A>, Self> {
-        if self.is::<T>() { unsafe { Ok(self.downcast_unchecked::<T>()) } } else { Err(self) }
-    }
-
-    /// Downcasts the box to a concrete type.
-    ///
-    /// For a safe alternative see [`downcast`].
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(downcast_unchecked)]
-    ///
-    /// use std::any::Any;
-    ///
-    /// let x: Box<dyn Any + Send> = Box::new(1_usize);
-    ///
-    /// unsafe {
-    ///     assert_eq!(*x.downcast_unchecked::<usize>(), 1);
-    /// }
-    /// ```
-    ///
-    /// # Safety
-    ///
-    /// The contained value must be of type `T`. Calling this method
-    /// with the incorrect type is *undefined behavior*.
-    ///
-    /// [`downcast`]: Self::downcast
-    #[inline]
-    #[unstable(feature = "downcast_unchecked", issue = "90850")]
-    pub unsafe fn downcast_unchecked<T: Any>(self) -> Box<T, A> {
-        debug_assert!(self.is::<T>());
-        unsafe {
-            let (raw, alloc): (*mut (dyn Any + Send), _) = Box::into_raw_with_allocator(self);
-            Box::from_raw_in(raw as *mut T, alloc)
-        }
-    }
-}
-
-impl<A: Allocator> Box<dyn Any + Send + Sync, A> {
-    /// Attempt to downcast the box to a concrete type.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::any::Any;
-    ///
-    /// fn print_if_string(value: Box<dyn Any + Send + Sync>) {
-    ///     if let Ok(string) = value.downcast::<String>() {
-    ///         println!("String ({}): {}", string.len(), string);
-    ///     }
-    /// }
-    ///
-    /// let my_string = "Hello World".to_string();
-    /// print_if_string(Box::new(my_string));
-    /// print_if_string(Box::new(0i8));
-    /// ```
-    #[inline]
-    #[stable(feature = "box_send_sync_any_downcast", since = "1.51.0")]
-    pub fn downcast<T: Any>(self) -> Result<Box<T, A>, Self> {
-        if self.is::<T>() { unsafe { Ok(self.downcast_unchecked::<T>()) } } else { Err(self) }
-    }
-
-    /// Downcasts the box to a concrete type.
-    ///
-    /// For a safe alternative see [`downcast`].
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(downcast_unchecked)]
-    ///
-    /// use std::any::Any;
-    ///
-    /// let x: Box<dyn Any + Send + Sync> = Box::new(1_usize);
-    ///
-    /// unsafe {
-    ///     assert_eq!(*x.downcast_unchecked::<usize>(), 1);
-    /// }
-    /// ```
-    ///
-    /// # Safety
-    ///
-    /// The contained value must be of type `T`. Calling this method
-    /// with the incorrect type is *undefined behavior*.
-    ///
-    /// [`downcast`]: Self::downcast
-    #[inline]
-    #[unstable(feature = "downcast_unchecked", issue = "90850")]
-    pub unsafe fn downcast_unchecked<T: Any>(self) -> Box<T, A> {
-        debug_assert!(self.is::<T>());
-        unsafe {
-            let (raw, alloc): (*mut (dyn Any + Send + Sync), _) =
-                Box::into_raw_with_allocator(self);
-            Box::from_raw_in(raw as *mut T, alloc)
-        }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: fmt::Display + ?Sized, A: Allocator> fmt::Display for Box<T, A> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Display::fmt(&**self, f)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: fmt::Debug + ?Sized, A: Allocator> fmt::Debug for Box<T, A> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Debug::fmt(&**self, f)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized, A: Allocator> fmt::Pointer for Box<T, A> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        // It's not possible to extract the inner Uniq directly from the Box,
-        // instead we cast it to a *const which aliases the Unique
-        let ptr: *const T = &**self;
-        fmt::Pointer::fmt(&ptr, f)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized, A: Allocator> Deref for Box<T, A> {
-    type Target = T;
-
-    fn deref(&self) -> &T {
-        &**self
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized, A: Allocator> DerefMut for Box<T, A> {
-    fn deref_mut(&mut self) -> &mut T {
-        &mut **self
-    }
-}
-
-#[unstable(feature = "receiver_trait", issue = "none")]
-impl<T: ?Sized, A: Allocator> Receiver for Box<T, A> {}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<I: Iterator + ?Sized, A: Allocator> Iterator for Box<I, A> {
-    type Item = I::Item;
-    fn next(&mut self) -> Option<I::Item> {
-        (**self).next()
-    }
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        (**self).size_hint()
-    }
-    fn nth(&mut self, n: usize) -> Option<I::Item> {
-        (**self).nth(n)
-    }
-    fn last(self) -> Option<I::Item> {
-        BoxIter::last(self)
-    }
-}
-
-trait BoxIter {
-    type Item;
-    fn last(self) -> Option<Self::Item>;
-}
-
-impl<I: Iterator + ?Sized, A: Allocator> BoxIter for Box<I, A> {
-    type Item = I::Item;
-    default fn last(self) -> Option<I::Item> {
-        #[inline]
-        fn some<T>(_: Option<T>, x: T) -> Option<T> {
-            Some(x)
-        }
-
-        self.fold(None, some)
-    }
-}
-
-/// Specialization for sized `I`s that uses `I`s implementation of `last()`
-/// instead of the default.
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<I: Iterator, A: Allocator> BoxIter for Box<I, A> {
-    fn last(self) -> Option<I::Item> {
-        (*self).last()
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<I: DoubleEndedIterator + ?Sized, A: Allocator> DoubleEndedIterator for Box<I, A> {
-    fn next_back(&mut self) -> Option<I::Item> {
-        (**self).next_back()
-    }
-    fn nth_back(&mut self, n: usize) -> Option<I::Item> {
-        (**self).nth_back(n)
-    }
-}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<I: ExactSizeIterator + ?Sized, A: Allocator> ExactSizeIterator for Box<I, A> {
-    fn len(&self) -> usize {
-        (**self).len()
-    }
-    fn is_empty(&self) -> bool {
-        (**self).is_empty()
-    }
-}
-
-#[stable(feature = "fused", since = "1.26.0")]
-impl<I: FusedIterator + ?Sized, A: Allocator> FusedIterator for Box<I, A> {}
-
-#[stable(feature = "boxed_closure_impls", since = "1.35.0")]
-impl<Args: Tuple, F: FnOnce<Args> + ?Sized, A: Allocator> FnOnce<Args> for Box<F, A> {
-    type Output = <F as FnOnce<Args>>::Output;
-
-    extern "rust-call" fn call_once(self, args: Args) -> Self::Output {
-        <F as FnOnce<Args>>::call_once(*self, args)
-    }
-}
-
-#[stable(feature = "boxed_closure_impls", since = "1.35.0")]
-impl<Args: Tuple, F: FnMut<Args> + ?Sized, A: Allocator> FnMut<Args> for Box<F, A> {
-    extern "rust-call" fn call_mut(&mut self, args: Args) -> Self::Output {
-        <F as FnMut<Args>>::call_mut(self, args)
-    }
-}
-
-#[stable(feature = "boxed_closure_impls", since = "1.35.0")]
-impl<Args: Tuple, F: Fn<Args> + ?Sized, A: Allocator> Fn<Args> for Box<F, A> {
-    extern "rust-call" fn call(&self, args: Args) -> Self::Output {
-        <F as Fn<Args>>::call(self, args)
-    }
-}
-
-#[unstable(feature = "coerce_unsized", issue = "18598")]
-impl<T: ?Sized + Unsize<U>, U: ?Sized, A: Allocator> CoerceUnsized<Box<U, A>> for Box<T, A> {}
-
-#[unstable(feature = "dispatch_from_dyn", issue = "none")]
-impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<Box<U>> for Box<T, Global> {}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "boxed_slice_from_iter", since = "1.32.0")]
-impl<I> FromIterator<I> for Box<[I]> {
-    fn from_iter<T: IntoIterator<Item = I>>(iter: T) -> Self {
-        iter.into_iter().collect::<Vec<_>>().into_boxed_slice()
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "box_slice_clone", since = "1.3.0")]
-impl<T: Clone, A: Allocator + Clone> Clone for Box<[T], A> {
-    fn clone(&self) -> Self {
-        let alloc = Box::allocator(self).clone();
-        self.to_vec_in(alloc).into_boxed_slice()
-    }
-
-    fn clone_from(&mut self, other: &Self) {
-        if self.len() == other.len() {
-            self.clone_from_slice(&other);
-        } else {
-            *self = other.clone();
-        }
-    }
-}
-
-#[stable(feature = "box_borrow", since = "1.1.0")]
-impl<T: ?Sized, A: Allocator> borrow::Borrow<T> for Box<T, A> {
-    fn borrow(&self) -> &T {
-        &**self
-    }
-}
-
-#[stable(feature = "box_borrow", since = "1.1.0")]
-impl<T: ?Sized, A: Allocator> borrow::BorrowMut<T> for Box<T, A> {
-    fn borrow_mut(&mut self) -> &mut T {
-        &mut **self
-    }
-}
-
-#[stable(since = "1.5.0", feature = "smart_ptr_as_ref")]
-impl<T: ?Sized, A: Allocator> AsRef<T> for Box<T, A> {
-    fn as_ref(&self) -> &T {
-        &**self
-    }
-}
-
-#[stable(since = "1.5.0", feature = "smart_ptr_as_ref")]
-impl<T: ?Sized, A: Allocator> AsMut<T> for Box<T, A> {
-    fn as_mut(&mut self) -> &mut T {
-        &mut **self
-    }
-}
-
-/* Nota bene
- *
- *  We could have chosen not to add this impl, and instead have written a
- *  function of Pin<Box<T>> to Pin<T>. Such a function would not be sound,
- *  because Box<T> implements Unpin even when T does not, as a result of
- *  this impl.
- *
- *  We chose this API instead of the alternative for a few reasons:
- *      - Logically, it is helpful to understand pinning in regard to the
- *        memory region being pointed to. For this reason none of the
- *        standard library pointer types support projecting through a pin
- *        (Box<T> is the only pointer type in std for which this would be
- *        safe.)
- *      - It is in practice very useful to have Box<T> be unconditionally
- *        Unpin because of trait objects, for which the structural auto
- *        trait functionality does not apply (e.g., Box<dyn Foo> would
- *        otherwise not be Unpin).
- *
- *  Another type with the same semantics as Box but only a conditional
- *  implementation of `Unpin` (where `T: Unpin`) would be valid/safe, and
- *  could have a method to project a Pin<T> from it.
- */
-#[stable(feature = "pin", since = "1.33.0")]
-impl<T: ?Sized, A: Allocator> Unpin for Box<T, A> where A: 'static {}
-
-#[unstable(feature = "coroutine_trait", issue = "43122")]
-impl<G: ?Sized + Coroutine<R> + Unpin, R, A: Allocator> Coroutine<R> for Box<G, A>
-where
-    A: 'static,
-{
-    type Yield = G::Yield;
-    type Return = G::Return;
-
-    fn resume(mut self: Pin<&mut Self>, arg: R) -> CoroutineState<Self::Yield, Self::Return> {
-        G::resume(Pin::new(&mut *self), arg)
-    }
-}
-
-#[unstable(feature = "coroutine_trait", issue = "43122")]
-impl<G: ?Sized + Coroutine<R>, R, A: Allocator> Coroutine<R> for Pin<Box<G, A>>
-where
-    A: 'static,
-{
-    type Yield = G::Yield;
-    type Return = G::Return;
-
-    fn resume(mut self: Pin<&mut Self>, arg: R) -> CoroutineState<Self::Yield, Self::Return> {
-        G::resume((*self).as_mut(), arg)
-    }
-}
-
-#[stable(feature = "futures_api", since = "1.36.0")]
-impl<F: ?Sized + Future + Unpin, A: Allocator> Future for Box<F, A>
-where
-    A: 'static,
-{
-    type Output = F::Output;
-
-    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        F::poll(Pin::new(&mut *self), cx)
-    }
-}
-
-#[unstable(feature = "async_iterator", issue = "79024")]
-impl<S: ?Sized + AsyncIterator + Unpin> AsyncIterator for Box<S> {
-    type Item = S::Item;
-
-    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
-        Pin::new(&mut **self).poll_next(cx)
-    }
-
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        (**self).size_hint()
-    }
-}
-
-impl dyn Error {
-    #[inline]
-    #[stable(feature = "error_downcast", since = "1.3.0")]
-    #[rustc_allow_incoherent_impl]
-    /// Attempts to downcast the box to a concrete type.
-    pub fn downcast<T: Error + 'static>(self: Box<Self>) -> Result<Box<T>, Box<dyn Error>> {
-        if self.is::<T>() {
-            unsafe {
-                let raw: *mut dyn Error = Box::into_raw(self);
-                Ok(Box::from_raw(raw as *mut T))
-            }
-        } else {
-            Err(self)
-        }
-    }
-}
-
-impl dyn Error + Send {
-    #[inline]
-    #[stable(feature = "error_downcast", since = "1.3.0")]
-    #[rustc_allow_incoherent_impl]
-    /// Attempts to downcast the box to a concrete type.
-    pub fn downcast<T: Error + 'static>(self: Box<Self>) -> Result<Box<T>, Box<dyn Error + Send>> {
-        let err: Box<dyn Error> = self;
-        <dyn Error>::downcast(err).map_err(|s| unsafe {
-            // Reapply the `Send` marker.
-            Box::from_raw(Box::into_raw(s) as *mut (dyn Error + Send))
-        })
-    }
-}
-
-impl dyn Error + Send + Sync {
-    #[inline]
-    #[stable(feature = "error_downcast", since = "1.3.0")]
-    #[rustc_allow_incoherent_impl]
-    /// Attempts to downcast the box to a concrete type.
-    pub fn downcast<T: Error + 'static>(self: Box<Self>) -> Result<Box<T>, Box<Self>> {
-        let err: Box<dyn Error> = self;
-        <dyn Error>::downcast(err).map_err(|s| unsafe {
-            // Reapply the `Send + Sync` marker.
-            Box::from_raw(Box::into_raw(s) as *mut (dyn Error + Send + Sync))
-        })
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, E: Error + 'a> From<E> for Box<dyn Error + 'a> {
-    /// Converts a type of [`Error`] into a box of dyn [`Error`].
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::error::Error;
-    /// use std::fmt;
-    /// use std::mem;
-    ///
-    /// #[derive(Debug)]
-    /// struct AnError;
-    ///
-    /// impl fmt::Display for AnError {
-    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-    ///         write!(f, "An error")
-    ///     }
-    /// }
-    ///
-    /// impl Error for AnError {}
-    ///
-    /// let an_error = AnError;
-    /// assert!(0 == mem::size_of_val(&an_error));
-    /// let a_boxed_error = Box::<dyn Error>::from(an_error);
-    /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
-    /// ```
-    fn from(err: E) -> Box<dyn Error + 'a> {
-        Box::new(err)
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, E: Error + Send + Sync + 'a> From<E> for Box<dyn Error + Send + Sync + 'a> {
-    /// Converts a type of [`Error`] + [`Send`] + [`Sync`] into a box of
-    /// dyn [`Error`] + [`Send`] + [`Sync`].
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::error::Error;
-    /// use std::fmt;
-    /// use std::mem;
-    ///
-    /// #[derive(Debug)]
-    /// struct AnError;
-    ///
-    /// impl fmt::Display for AnError {
-    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-    ///         write!(f, "An error")
-    ///     }
-    /// }
-    ///
-    /// impl Error for AnError {}
-    ///
-    /// unsafe impl Send for AnError {}
-    ///
-    /// unsafe impl Sync for AnError {}
-    ///
-    /// let an_error = AnError;
-    /// assert!(0 == mem::size_of_val(&an_error));
-    /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(an_error);
-    /// assert!(
-    ///     mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
-    /// ```
-    fn from(err: E) -> Box<dyn Error + Send + Sync + 'a> {
-        Box::new(err)
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl From<String> for Box<dyn Error + Send + Sync> {
-    /// Converts a [`String`] into a box of dyn [`Error`] + [`Send`] + [`Sync`].
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::error::Error;
-    /// use std::mem;
-    ///
-    /// let a_string_error = "a string error".to_string();
-    /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_string_error);
-    /// assert!(
-    ///     mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
-    /// ```
-    #[inline]
-    fn from(err: String) -> Box<dyn Error + Send + Sync> {
-        struct StringError(String);
-
-        impl Error for StringError {
-            #[allow(deprecated)]
-            fn description(&self) -> &str {
-                &self.0
-            }
-        }
-
-        impl fmt::Display for StringError {
-            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-                fmt::Display::fmt(&self.0, f)
-            }
-        }
-
-        // Purposefully skip printing "StringError(..)"
-        impl fmt::Debug for StringError {
-            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-                fmt::Debug::fmt(&self.0, f)
-            }
-        }
-
-        Box::new(StringError(err))
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "string_box_error", since = "1.6.0")]
-impl From<String> for Box<dyn Error> {
-    /// Converts a [`String`] into a box of dyn [`Error`].
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::error::Error;
-    /// use std::mem;
-    ///
-    /// let a_string_error = "a string error".to_string();
-    /// let a_boxed_error = Box::<dyn Error>::from(a_string_error);
-    /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
-    /// ```
-    fn from(str_err: String) -> Box<dyn Error> {
-        let err1: Box<dyn Error + Send + Sync> = From::from(str_err);
-        let err2: Box<dyn Error> = err1;
-        err2
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> From<&str> for Box<dyn Error + Send + Sync + 'a> {
-    /// Converts a [`str`] into a box of dyn [`Error`] + [`Send`] + [`Sync`].
-    ///
-    /// [`str`]: prim@str
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::error::Error;
-    /// use std::mem;
-    ///
-    /// let a_str_error = "a str error";
-    /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_str_error);
-    /// assert!(
-    ///     mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
-    /// ```
-    #[inline]
-    fn from(err: &str) -> Box<dyn Error + Send + Sync + 'a> {
-        From::from(String::from(err))
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "string_box_error", since = "1.6.0")]
-impl From<&str> for Box<dyn Error> {
-    /// Converts a [`str`] into a box of dyn [`Error`].
-    ///
-    /// [`str`]: prim@str
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::error::Error;
-    /// use std::mem;
-    ///
-    /// let a_str_error = "a str error";
-    /// let a_boxed_error = Box::<dyn Error>::from(a_str_error);
-    /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
-    /// ```
-    fn from(err: &str) -> Box<dyn Error> {
-        From::from(String::from(err))
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "cow_box_error", since = "1.22.0")]
-impl<'a, 'b> From<Cow<'b, str>> for Box<dyn Error + Send + Sync + 'a> {
-    /// Converts a [`Cow`] into a box of dyn [`Error`] + [`Send`] + [`Sync`].
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::error::Error;
-    /// use std::mem;
-    /// use std::borrow::Cow;
-    ///
-    /// let a_cow_str_error = Cow::from("a str error");
-    /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_cow_str_error);
-    /// assert!(
-    ///     mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
-    /// ```
-    fn from(err: Cow<'b, str>) -> Box<dyn Error + Send + Sync + 'a> {
-        From::from(String::from(err))
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "cow_box_error", since = "1.22.0")]
-impl<'a> From<Cow<'a, str>> for Box<dyn Error> {
-    /// Converts a [`Cow`] into a box of dyn [`Error`].
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::error::Error;
-    /// use std::mem;
-    /// use std::borrow::Cow;
-    ///
-    /// let a_cow_str_error = Cow::from("a str error");
-    /// let a_boxed_error = Box::<dyn Error>::from(a_cow_str_error);
-    /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
-    /// ```
-    fn from(err: Cow<'a, str>) -> Box<dyn Error> {
-        From::from(String::from(err))
-    }
-}
-
-#[stable(feature = "box_error", since = "1.8.0")]
-impl<T: core::error::Error> core::error::Error for Box<T> {
-    #[allow(deprecated, deprecated_in_future)]
-    fn description(&self) -> &str {
-        core::error::Error::description(&**self)
-    }
-
-    #[allow(deprecated)]
-    fn cause(&self) -> Option<&dyn core::error::Error> {
-        core::error::Error::cause(&**self)
-    }
-
-    fn source(&self) -> Option<&(dyn core::error::Error + 'static)> {
-        core::error::Error::source(&**self)
-    }
-
-    fn provide<'b>(&'b self, request: &mut core::error::Request<'b>) {
-        core::error::Error::provide(&**self, request);
-    }
-}
diff --git a/rust/alloc/collections/mod.rs b/rust/alloc/collections/mod.rs
deleted file mode 100644
index 00ffb3b97365..000000000000
--- a/rust/alloc/collections/mod.rs
+++ /dev/null
@@ -1,160 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-//! Collection types.
-
-#![stable(feature = "rust1", since = "1.0.0")]
-
-#[cfg(not(no_global_oom_handling))]
-pub mod binary_heap;
-#[cfg(not(no_global_oom_handling))]
-mod btree;
-#[cfg(not(no_global_oom_handling))]
-pub mod linked_list;
-#[cfg(not(no_global_oom_handling))]
-pub mod vec_deque;
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-pub mod btree_map {
-    //! An ordered map based on a B-Tree.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub use super::btree::map::*;
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-pub mod btree_set {
-    //! An ordered set based on a B-Tree.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub use super::btree::set::*;
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-#[doc(no_inline)]
-pub use binary_heap::BinaryHeap;
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-#[doc(no_inline)]
-pub use btree_map::BTreeMap;
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-#[doc(no_inline)]
-pub use btree_set::BTreeSet;
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-#[doc(no_inline)]
-pub use linked_list::LinkedList;
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-#[doc(no_inline)]
-pub use vec_deque::VecDeque;
-
-use crate::alloc::{Layout, LayoutError};
-use core::fmt::Display;
-
-/// The error type for `try_reserve` methods.
-#[derive(Clone, PartialEq, Eq, Debug)]
-#[stable(feature = "try_reserve", since = "1.57.0")]
-pub struct TryReserveError {
-    kind: TryReserveErrorKind,
-}
-
-impl TryReserveError {
-    /// Details about the allocation that caused the error
-    #[inline]
-    #[must_use]
-    #[unstable(
-        feature = "try_reserve_kind",
-        reason = "Uncertain how much info should be exposed",
-        issue = "48043"
-    )]
-    pub fn kind(&self) -> TryReserveErrorKind {
-        self.kind.clone()
-    }
-}
-
-/// Details of the allocation that caused a `TryReserveError`
-#[derive(Clone, PartialEq, Eq, Debug)]
-#[unstable(
-    feature = "try_reserve_kind",
-    reason = "Uncertain how much info should be exposed",
-    issue = "48043"
-)]
-pub enum TryReserveErrorKind {
-    /// Error due to the computed capacity exceeding the collection's maximum
-    /// (usually `isize::MAX` bytes).
-    CapacityOverflow,
-
-    /// The memory allocator returned an error
-    AllocError {
-        /// The layout of allocation request that failed
-        layout: Layout,
-
-        #[doc(hidden)]
-        #[unstable(
-            feature = "container_error_extra",
-            issue = "none",
-            reason = "\
-            Enable exposing the allocator’s custom error value \
-            if an associated type is added in the future: \
-            https://github.com/rust-lang/wg-allocators/issues/23"
-        )]
-        non_exhaustive: (),
-    },
-}
-
-#[unstable(
-    feature = "try_reserve_kind",
-    reason = "Uncertain how much info should be exposed",
-    issue = "48043"
-)]
-impl From<TryReserveErrorKind> for TryReserveError {
-    #[inline]
-    fn from(kind: TryReserveErrorKind) -> Self {
-        Self { kind }
-    }
-}
-
-#[unstable(feature = "try_reserve_kind", reason = "new API", issue = "48043")]
-impl From<LayoutError> for TryReserveErrorKind {
-    /// Always evaluates to [`TryReserveErrorKind::CapacityOverflow`].
-    #[inline]
-    fn from(_: LayoutError) -> Self {
-        TryReserveErrorKind::CapacityOverflow
-    }
-}
-
-#[stable(feature = "try_reserve", since = "1.57.0")]
-impl Display for TryReserveError {
-    fn fmt(
-        &self,
-        fmt: &mut core::fmt::Formatter<'_>,
-    ) -> core::result::Result<(), core::fmt::Error> {
-        fmt.write_str("memory allocation failed")?;
-        let reason = match self.kind {
-            TryReserveErrorKind::CapacityOverflow => {
-                " because the computed capacity exceeded the collection's maximum"
-            }
-            TryReserveErrorKind::AllocError { .. } => {
-                " because the memory allocator returned an error"
-            }
-        };
-        fmt.write_str(reason)
-    }
-}
-
-/// An intermediate trait for specialization of `Extend`.
-#[doc(hidden)]
-#[cfg(not(no_global_oom_handling))]
-trait SpecExtend<I: IntoIterator> {
-    /// Extends `self` with the contents of the given iterator.
-    fn spec_extend(&mut self, iter: I);
-}
-
-#[stable(feature = "try_reserve", since = "1.57.0")]
-impl core::error::Error for TryReserveError {}
diff --git a/rust/alloc/lib.rs b/rust/alloc/lib.rs
deleted file mode 100644
index 36f79c075593..000000000000
--- a/rust/alloc/lib.rs
+++ /dev/null
@@ -1,288 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-//! # The Rust core allocation and collections library
-//!
-//! This library provides smart pointers and collections for managing
-//! heap-allocated values.
-//!
-//! This library, like core, normally doesn’t need to be used directly
-//! since its contents are re-exported in the [`std` crate](../std/index.html).
-//! Crates that use the `#![no_std]` attribute however will typically
-//! not depend on `std`, so they’d use this crate instead.
-//!
-//! ## Boxed values
-//!
-//! The [`Box`] type is a smart pointer type. There can only be one owner of a
-//! [`Box`], and the owner can decide to mutate the contents, which live on the
-//! heap.
-//!
-//! This type can be sent among threads efficiently as the size of a `Box` value
-//! is the same as that of a pointer. Tree-like data structures are often built
-//! with boxes because each node often has only one owner, the parent.
-//!
-//! ## Reference counted pointers
-//!
-//! The [`Rc`] type is a non-threadsafe reference-counted pointer type intended
-//! for sharing memory within a thread. An [`Rc`] pointer wraps a type, `T`, and
-//! only allows access to `&T`, a shared reference.
-//!
-//! This type is useful when inherited mutability (such as using [`Box`]) is too
-//! constraining for an application, and is often paired with the [`Cell`] or
-//! [`RefCell`] types in order to allow mutation.
-//!
-//! ## Atomically reference counted pointers
-//!
-//! The [`Arc`] type is the threadsafe equivalent of the [`Rc`] type. It
-//! provides all the same functionality of [`Rc`], except it requires that the
-//! contained type `T` is shareable. Additionally, [`Arc<T>`][`Arc`] is itself
-//! sendable while [`Rc<T>`][`Rc`] is not.
-//!
-//! This type allows for shared access to the contained data, and is often
-//! paired with synchronization primitives such as mutexes to allow mutation of
-//! shared resources.
-//!
-//! ## Collections
-//!
-//! Implementations of the most common general purpose data structures are
-//! defined in this library. They are re-exported through the
-//! [standard collections library](../std/collections/index.html).
-//!
-//! ## Heap interfaces
-//!
-//! The [`alloc`](alloc/index.html) module defines the low-level interface to the
-//! default global allocator. It is not compatible with the libc allocator API.
-//!
-//! [`Arc`]: sync
-//! [`Box`]: boxed
-//! [`Cell`]: core::cell
-//! [`Rc`]: rc
-//! [`RefCell`]: core::cell
-
-// To run alloc tests without x.py without ending up with two copies of alloc, Miri needs to be
-// able to "empty" this crate. See <https://github.com/rust-lang/miri-test-libstd/issues/4>.
-// rustc itself never sets the feature, so this line has no effect there.
-#![cfg(any(not(feature = "miri-test-libstd"), test, doctest))]
-//
-#![allow(unused_attributes)]
-#![stable(feature = "alloc", since = "1.36.0")]
-#![doc(
-    html_playground_url = "https://play.rust-lang.org/",
-    issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
-    test(no_crate_inject, attr(allow(unused_variables), deny(warnings)))
-)]
-#![doc(cfg_hide(
-    not(test),
-    not(any(test, bootstrap)),
-    any(not(feature = "miri-test-libstd"), test, doctest),
-    no_global_oom_handling,
-    not(no_global_oom_handling),
-    not(no_rc),
-    not(no_sync),
-    target_has_atomic = "ptr"
-))]
-#![doc(rust_logo)]
-#![feature(rustdoc_internals)]
-#![no_std]
-#![needs_allocator]
-// Lints:
-#![deny(unsafe_op_in_unsafe_fn)]
-#![deny(fuzzy_provenance_casts)]
-#![warn(deprecated_in_future)]
-#![warn(missing_debug_implementations)]
-#![warn(missing_docs)]
-#![allow(explicit_outlives_requirements)]
-#![warn(multiple_supertrait_upcastable)]
-#![allow(internal_features)]
-#![allow(rustdoc::redundant_explicit_links)]
-//
-// Library features:
-// tidy-alphabetical-start
-#![cfg_attr(not(no_global_oom_handling), feature(const_alloc_error))]
-#![cfg_attr(not(no_global_oom_handling), feature(const_btree_len))]
-#![cfg_attr(test, feature(is_sorted))]
-#![cfg_attr(test, feature(new_uninit))]
-#![feature(alloc_layout_extra)]
-#![feature(allocator_api)]
-#![feature(array_chunks)]
-#![feature(array_into_iter_constructors)]
-#![feature(array_methods)]
-#![feature(array_windows)]
-#![feature(ascii_char)]
-#![feature(assert_matches)]
-#![feature(async_iterator)]
-#![feature(coerce_unsized)]
-#![feature(const_align_of_val)]
-#![feature(const_box)]
-#![cfg_attr(not(no_borrow), feature(const_cow_is_borrowed))]
-#![feature(const_eval_select)]
-#![feature(const_maybe_uninit_as_mut_ptr)]
-#![feature(const_maybe_uninit_write)]
-#![feature(const_pin)]
-#![feature(const_refs_to_cell)]
-#![feature(const_size_of_val)]
-#![feature(const_waker)]
-#![feature(core_intrinsics)]
-#![feature(core_panic)]
-#![feature(deprecated_suggestion)]
-#![feature(dispatch_from_dyn)]
-#![feature(error_generic_member_access)]
-#![feature(error_in_core)]
-#![feature(exact_size_is_empty)]
-#![feature(extend_one)]
-#![feature(fmt_internals)]
-#![feature(fn_traits)]
-#![feature(hasher_prefixfree_extras)]
-#![feature(inline_const)]
-#![feature(inplace_iteration)]
-#![feature(iter_advance_by)]
-#![feature(iter_next_chunk)]
-#![feature(iter_repeat_n)]
-#![feature(layout_for_ptr)]
-#![feature(maybe_uninit_slice)]
-#![feature(maybe_uninit_uninit_array)]
-#![feature(maybe_uninit_uninit_array_transpose)]
-#![feature(pattern)]
-#![feature(ptr_internals)]
-#![feature(ptr_metadata)]
-#![feature(ptr_sub_ptr)]
-#![feature(receiver_trait)]
-#![feature(set_ptr_value)]
-#![feature(sized_type_properties)]
-#![feature(slice_from_ptr_range)]
-#![feature(slice_group_by)]
-#![feature(slice_ptr_get)]
-#![feature(slice_ptr_len)]
-#![feature(slice_range)]
-#![feature(std_internals)]
-#![feature(str_internals)]
-#![feature(strict_provenance)]
-#![feature(trusted_fused)]
-#![feature(trusted_len)]
-#![feature(trusted_random_access)]
-#![feature(try_trait_v2)]
-#![feature(tuple_trait)]
-#![feature(unchecked_math)]
-#![feature(unicode_internals)]
-#![feature(unsize)]
-#![feature(utf8_chunks)]
-// tidy-alphabetical-end
-//
-// Language features:
-// tidy-alphabetical-start
-#![cfg_attr(not(test), feature(coroutine_trait))]
-#![cfg_attr(test, feature(panic_update_hook))]
-#![cfg_attr(test, feature(test))]
-#![feature(allocator_internals)]
-#![feature(allow_internal_unstable)]
-#![feature(associated_type_bounds)]
-#![feature(c_unwind)]
-#![feature(cfg_sanitize)]
-#![feature(const_mut_refs)]
-#![feature(const_precise_live_drops)]
-#![feature(const_ptr_write)]
-#![feature(const_trait_impl)]
-#![feature(const_try)]
-#![feature(dropck_eyepatch)]
-#![feature(exclusive_range_pattern)]
-#![feature(fundamental)]
-#![feature(hashmap_internals)]
-#![feature(lang_items)]
-#![feature(min_specialization)]
-#![feature(multiple_supertrait_upcastable)]
-#![feature(negative_impls)]
-#![feature(never_type)]
-#![feature(pointer_is_aligned)]
-#![feature(rustc_allow_const_fn_unstable)]
-#![feature(rustc_attrs)]
-#![feature(slice_internals)]
-#![feature(staged_api)]
-#![feature(stmt_expr_attributes)]
-#![feature(unboxed_closures)]
-#![feature(unsized_fn_params)]
-#![feature(with_negative_coherence)]
-// tidy-alphabetical-end
-//
-// Rustdoc features:
-#![feature(doc_cfg)]
-#![feature(doc_cfg_hide)]
-// Technically, this is a bug in rustdoc: rustdoc sees the documentation on `#[lang = slice_alloc]`
-// blocks is for `&[T]`, which also has documentation using this feature in `core`, and gets mad
-// that the feature-gate isn't enabled. Ideally, it wouldn't check for the feature gate for docs
-// from other crates, but since this can only appear for lang items, it doesn't seem worth fixing.
-#![feature(intra_doc_pointers)]
-
-// Allow testing this library
-#[cfg(test)]
-#[macro_use]
-extern crate std;
-#[cfg(test)]
-extern crate test;
-#[cfg(test)]
-mod testing;
-
-// Module with internal macros used by other modules (needs to be included before other modules).
-#[cfg(not(no_macros))]
-#[macro_use]
-mod macros;
-
-mod raw_vec;
-
-// Heaps provided for low-level allocation strategies
-
-pub mod alloc;
-
-// Primitive types using the heaps above
-
-// Need to conditionally define the mod from `boxed.rs` to avoid
-// duplicating the lang-items when building in test cfg; but also need
-// to allow code to have `use boxed::Box;` declarations.
-#[cfg(not(test))]
-pub mod boxed;
-#[cfg(test)]
-mod boxed {
-    pub use std::boxed::Box;
-}
-#[cfg(not(no_borrow))]
-pub mod borrow;
-pub mod collections;
-#[cfg(all(not(no_rc), not(no_sync), not(no_global_oom_handling)))]
-pub mod ffi;
-#[cfg(not(no_fmt))]
-pub mod fmt;
-#[cfg(not(no_rc))]
-pub mod rc;
-pub mod slice;
-#[cfg(not(no_str))]
-pub mod str;
-#[cfg(not(no_string))]
-pub mod string;
-#[cfg(all(not(no_rc), not(no_sync), target_has_atomic = "ptr"))]
-pub mod sync;
-#[cfg(all(not(no_global_oom_handling), not(no_rc), not(no_sync), target_has_atomic = "ptr"))]
-pub mod task;
-#[cfg(test)]
-mod tests;
-pub mod vec;
-
-#[doc(hidden)]
-#[unstable(feature = "liballoc_internals", issue = "none", reason = "implementation detail")]
-pub mod __export {
-    pub use core::format_args;
-}
-
-#[cfg(test)]
-#[allow(dead_code)] // Not used in all configurations
-pub(crate) mod test_helpers {
-    /// Copied from `std::test_helpers::test_rng`, since these tests rely on the
-    /// seed not being the same for every RNG invocation too.
-    pub(crate) fn test_rng() -> rand_xorshift::XorShiftRng {
-        use std::hash::{BuildHasher, Hash, Hasher};
-        let mut hasher = std::hash::RandomState::new().build_hasher();
-        std::panic::Location::caller().hash(&mut hasher);
-        let hc64 = hasher.finish();
-        let seed_vec =
-            hc64.to_le_bytes().into_iter().chain(0u8..8).collect::<crate::vec::Vec<u8>>();
-        let seed: [u8; 16] = seed_vec.as_slice().try_into().unwrap();
-        rand::SeedableRng::from_seed(seed)
-    }
-}
diff --git a/rust/alloc/raw_vec.rs b/rust/alloc/raw_vec.rs
deleted file mode 100644
index 98b6abf30af6..000000000000
--- a/rust/alloc/raw_vec.rs
+++ /dev/null
@@ -1,611 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-#![unstable(feature = "raw_vec_internals", reason = "unstable const warnings", issue = "none")]
-
-use core::alloc::LayoutError;
-use core::cmp;
-use core::intrinsics;
-use core::mem::{self, ManuallyDrop, MaybeUninit, SizedTypeProperties};
-use core::ptr::{self, NonNull, Unique};
-use core::slice;
-
-#[cfg(not(no_global_oom_handling))]
-use crate::alloc::handle_alloc_error;
-use crate::alloc::{Allocator, Global, Layout};
-use crate::boxed::Box;
-use crate::collections::TryReserveError;
-use crate::collections::TryReserveErrorKind::*;
-
-#[cfg(test)]
-mod tests;
-
-enum AllocInit {
-    /// The contents of the new memory are uninitialized.
-    Uninitialized,
-    /// The new memory is guaranteed to be zeroed.
-    #[allow(dead_code)]
-    Zeroed,
-}
-
-#[repr(transparent)]
-#[cfg_attr(target_pointer_width = "16", rustc_layout_scalar_valid_range_end(0x7fff))]
-#[cfg_attr(target_pointer_width = "32", rustc_layout_scalar_valid_range_end(0x7fff_ffff))]
-#[cfg_attr(target_pointer_width = "64", rustc_layout_scalar_valid_range_end(0x7fff_ffff_ffff_ffff))]
-struct Cap(usize);
-
-impl Cap {
-    const ZERO: Cap = unsafe { Cap(0) };
-}
-
-/// A low-level utility for more ergonomically allocating, reallocating, and deallocating
-/// a buffer of memory on the heap without having to worry about all the corner cases
-/// involved. This type is excellent for building your own data structures like Vec and VecDeque.
-/// In particular:
-///
-/// * Produces `Unique::dangling()` on zero-sized types.
-/// * Produces `Unique::dangling()` on zero-length allocations.
-/// * Avoids freeing `Unique::dangling()`.
-/// * Catches all overflows in capacity computations (promotes them to "capacity overflow" panics).
-/// * Guards against 32-bit systems allocating more than isize::MAX bytes.
-/// * Guards against overflowing your length.
-/// * Calls `handle_alloc_error` for fallible allocations.
-/// * Contains a `ptr::Unique` and thus endows the user with all related benefits.
-/// * Uses the excess returned from the allocator to use the largest available capacity.
-///
-/// This type does not in anyway inspect the memory that it manages. When dropped it *will*
-/// free its memory, but it *won't* try to drop its contents. It is up to the user of `RawVec`
-/// to handle the actual things *stored* inside of a `RawVec`.
-///
-/// Note that the excess of a zero-sized types is always infinite, so `capacity()` always returns
-/// `usize::MAX`. This means that you need to be careful when round-tripping this type with a
-/// `Box<[T]>`, since `capacity()` won't yield the length.
-#[allow(missing_debug_implementations)]
-pub(crate) struct RawVec<T, A: Allocator = Global> {
-    ptr: Unique<T>,
-    /// Never used for ZSTs; it's `capacity()`'s responsibility to return usize::MAX in that case.
-    ///
-    /// # Safety
-    ///
-    /// `cap` must be in the `0..=isize::MAX` range.
-    cap: Cap,
-    alloc: A,
-}
-
-impl<T> RawVec<T, Global> {
-    /// HACK(Centril): This exists because stable `const fn` can only call stable `const fn`, so
-    /// they cannot call `Self::new()`.
-    ///
-    /// If you change `RawVec<T>::new` or dependencies, please take care to not introduce anything
-    /// that would truly const-call something unstable.
-    pub const NEW: Self = Self::new();
-
-    /// Creates the biggest possible `RawVec` (on the system heap)
-    /// without allocating. If `T` has positive size, then this makes a
-    /// `RawVec` with capacity `0`. If `T` is zero-sized, then it makes a
-    /// `RawVec` with capacity `usize::MAX`. Useful for implementing
-    /// delayed allocation.
-    #[must_use]
-    pub const fn new() -> Self {
-        Self::new_in(Global)
-    }
-
-    /// Creates a `RawVec` (on the system heap) with exactly the
-    /// capacity and alignment requirements for a `[T; capacity]`. This is
-    /// equivalent to calling `RawVec::new` when `capacity` is `0` or `T` is
-    /// zero-sized. Note that if `T` is zero-sized this means you will
-    /// *not* get a `RawVec` with the requested capacity.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the requested capacity exceeds `isize::MAX` bytes.
-    ///
-    /// # Aborts
-    ///
-    /// Aborts on OOM.
-    #[cfg(not(any(no_global_oom_handling, test)))]
-    #[must_use]
-    #[inline]
-    pub fn with_capacity(capacity: usize) -> Self {
-        Self::with_capacity_in(capacity, Global)
-    }
-
-    /// Like `with_capacity`, but guarantees the buffer is zeroed.
-    #[cfg(not(any(no_global_oom_handling, test)))]
-    #[must_use]
-    #[inline]
-    pub fn with_capacity_zeroed(capacity: usize) -> Self {
-        Self::with_capacity_zeroed_in(capacity, Global)
-    }
-}
-
-impl<T, A: Allocator> RawVec<T, A> {
-    // Tiny Vecs are dumb. Skip to:
-    // - 8 if the element size is 1, because any heap allocators is likely
-    //   to round up a request of less than 8 bytes to at least 8 bytes.
-    // - 4 if elements are moderate-sized (<= 1 KiB).
-    // - 1 otherwise, to avoid wasting too much space for very short Vecs.
-    pub(crate) const MIN_NON_ZERO_CAP: usize = if mem::size_of::<T>() == 1 {
-        8
-    } else if mem::size_of::<T>() <= 1024 {
-        4
-    } else {
-        1
-    };
-
-    /// Like `new`, but parameterized over the choice of allocator for
-    /// the returned `RawVec`.
-    pub const fn new_in(alloc: A) -> Self {
-        // `cap: 0` means "unallocated". zero-sized types are ignored.
-        Self { ptr: Unique::dangling(), cap: Cap::ZERO, alloc }
-    }
-
-    /// Like `with_capacity`, but parameterized over the choice of
-    /// allocator for the returned `RawVec`.
-    #[cfg(not(no_global_oom_handling))]
-    #[inline]
-    pub fn with_capacity_in(capacity: usize, alloc: A) -> Self {
-        Self::allocate_in(capacity, AllocInit::Uninitialized, alloc)
-    }
-
-    /// Like `try_with_capacity`, but parameterized over the choice of
-    /// allocator for the returned `RawVec`.
-    #[inline]
-    pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result<Self, TryReserveError> {
-        Self::try_allocate_in(capacity, AllocInit::Uninitialized, alloc)
-    }
-
-    /// Like `with_capacity_zeroed`, but parameterized over the choice
-    /// of allocator for the returned `RawVec`.
-    #[cfg(not(no_global_oom_handling))]
-    #[inline]
-    pub fn with_capacity_zeroed_in(capacity: usize, alloc: A) -> Self {
-        Self::allocate_in(capacity, AllocInit::Zeroed, alloc)
-    }
-
-    /// Converts the entire buffer into `Box<[MaybeUninit<T>]>` with the specified `len`.
-    ///
-    /// Note that this will correctly reconstitute any `cap` changes
-    /// that may have been performed. (See description of type for details.)
-    ///
-    /// # Safety
-    ///
-    /// * `len` must be greater than or equal to the most recently requested capacity, and
-    /// * `len` must be less than or equal to `self.capacity()`.
-    ///
-    /// Note, that the requested capacity and `self.capacity()` could differ, as
-    /// an allocator could overallocate and return a greater memory block than requested.
-    pub unsafe fn into_box(self, len: usize) -> Box<[MaybeUninit<T>], A> {
-        // Sanity-check one half of the safety requirement (we cannot check the other half).
-        debug_assert!(
-            len <= self.capacity(),
-            "`len` must be smaller than or equal to `self.capacity()`"
-        );
-
-        let me = ManuallyDrop::new(self);
-        unsafe {
-            let slice = slice::from_raw_parts_mut(me.ptr() as *mut MaybeUninit<T>, len);
-            Box::from_raw_in(slice, ptr::read(&me.alloc))
-        }
-    }
-
-    #[cfg(not(no_global_oom_handling))]
-    fn allocate_in(capacity: usize, init: AllocInit, alloc: A) -> Self {
-        // Don't allocate here because `Drop` will not deallocate when `capacity` is 0.
-        if T::IS_ZST || capacity == 0 {
-            Self::new_in(alloc)
-        } else {
-            // We avoid `unwrap_or_else` here because it bloats the amount of
-            // LLVM IR generated.
-            let layout = match Layout::array::<T>(capacity) {
-                Ok(layout) => layout,
-                Err(_) => capacity_overflow(),
-            };
-            match alloc_guard(layout.size()) {
-                Ok(_) => {}
-                Err(_) => capacity_overflow(),
-            }
-            let result = match init {
-                AllocInit::Uninitialized => alloc.allocate(layout),
-                AllocInit::Zeroed => alloc.allocate_zeroed(layout),
-            };
-            let ptr = match result {
-                Ok(ptr) => ptr,
-                Err(_) => handle_alloc_error(layout),
-            };
-
-            // Allocators currently return a `NonNull<[u8]>` whose length
-            // matches the size requested. If that ever changes, the capacity
-            // here should change to `ptr.len() / mem::size_of::<T>()`.
-            Self {
-                ptr: unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) },
-                cap: unsafe { Cap(capacity) },
-                alloc,
-            }
-        }
-    }
-
-    fn try_allocate_in(capacity: usize, init: AllocInit, alloc: A) -> Result<Self, TryReserveError> {
-        // Don't allocate here because `Drop` will not deallocate when `capacity` is 0.
-        if T::IS_ZST || capacity == 0 {
-            return Ok(Self::new_in(alloc));
-        }
-
-        let layout = Layout::array::<T>(capacity).map_err(|_| CapacityOverflow)?;
-        alloc_guard(layout.size())?;
-        let result = match init {
-            AllocInit::Uninitialized => alloc.allocate(layout),
-            AllocInit::Zeroed => alloc.allocate_zeroed(layout),
-        };
-        let ptr = result.map_err(|_| AllocError { layout, non_exhaustive: () })?;
-
-        // Allocators currently return a `NonNull<[u8]>` whose length
-        // matches the size requested. If that ever changes, the capacity
-        // here should change to `ptr.len() / mem::size_of::<T>()`.
-        Ok(Self {
-            ptr: unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) },
-            cap: unsafe { Cap(capacity) },
-            alloc,
-        })
-    }
-
-    /// Reconstitutes a `RawVec` from a pointer, capacity, and allocator.
-    ///
-    /// # Safety
-    ///
-    /// The `ptr` must be allocated (via the given allocator `alloc`), and with the given
-    /// `capacity`.
-    /// The `capacity` cannot exceed `isize::MAX` for sized types. (only a concern on 32-bit
-    /// systems). For ZSTs capacity is ignored.
-    /// If the `ptr` and `capacity` come from a `RawVec` created via `alloc`, then this is
-    /// guaranteed.
-    #[inline]
-    pub unsafe fn from_raw_parts_in(ptr: *mut T, capacity: usize, alloc: A) -> Self {
-        let cap = if T::IS_ZST { Cap::ZERO } else { unsafe { Cap(capacity) } };
-        Self { ptr: unsafe { Unique::new_unchecked(ptr) }, cap, alloc }
-    }
-
-    /// Gets a raw pointer to the start of the allocation. Note that this is
-    /// `Unique::dangling()` if `capacity == 0` or `T` is zero-sized. In the former case, you must
-    /// be careful.
-    #[inline]
-    pub fn ptr(&self) -> *mut T {
-        self.ptr.as_ptr()
-    }
-
-    /// Gets the capacity of the allocation.
-    ///
-    /// This will always be `usize::MAX` if `T` is zero-sized.
-    #[inline(always)]
-    pub fn capacity(&self) -> usize {
-        if T::IS_ZST { usize::MAX } else { self.cap.0 }
-    }
-
-    /// Returns a shared reference to the allocator backing this `RawVec`.
-    pub fn allocator(&self) -> &A {
-        &self.alloc
-    }
-
-    fn current_memory(&self) -> Option<(NonNull<u8>, Layout)> {
-        if T::IS_ZST || self.cap.0 == 0 {
-            None
-        } else {
-            // We could use Layout::array here which ensures the absence of isize and usize overflows
-            // and could hypothetically handle differences between stride and size, but this memory
-            // has already been allocated so we know it can't overflow and currently rust does not
-            // support such types. So we can do better by skipping some checks and avoid an unwrap.
-            let _: () = const { assert!(mem::size_of::<T>() % mem::align_of::<T>() == 0) };
-            unsafe {
-                let align = mem::align_of::<T>();
-                let size = mem::size_of::<T>().unchecked_mul(self.cap.0);
-                let layout = Layout::from_size_align_unchecked(size, align);
-                Some((self.ptr.cast().into(), layout))
-            }
-        }
-    }
-
-    /// Ensures that the buffer contains at least enough space to hold `len +
-    /// additional` elements. If it doesn't already have enough capacity, will
-    /// reallocate enough space plus comfortable slack space to get amortized
-    /// *O*(1) behavior. Will limit this behavior if it would needlessly cause
-    /// itself to panic.
-    ///
-    /// If `len` exceeds `self.capacity()`, this may fail to actually allocate
-    /// the requested space. This is not really unsafe, but the unsafe
-    /// code *you* write that relies on the behavior of this function may break.
-    ///
-    /// This is ideal for implementing a bulk-push operation like `extend`.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the new capacity exceeds `isize::MAX` bytes.
-    ///
-    /// # Aborts
-    ///
-    /// Aborts on OOM.
-    #[cfg(not(no_global_oom_handling))]
-    #[inline]
-    pub fn reserve(&mut self, len: usize, additional: usize) {
-        // Callers expect this function to be very cheap when there is already sufficient capacity.
-        // Therefore, we move all the resizing and error-handling logic from grow_amortized and
-        // handle_reserve behind a call, while making sure that this function is likely to be
-        // inlined as just a comparison and a call if the comparison fails.
-        #[cold]
-        fn do_reserve_and_handle<T, A: Allocator>(
-            slf: &mut RawVec<T, A>,
-            len: usize,
-            additional: usize,
-        ) {
-            handle_reserve(slf.grow_amortized(len, additional));
-        }
-
-        if self.needs_to_grow(len, additional) {
-            do_reserve_and_handle(self, len, additional);
-        }
-    }
-
-    /// A specialized version of `reserve()` used only by the hot and
-    /// oft-instantiated `Vec::push()`, which does its own capacity check.
-    #[cfg(not(no_global_oom_handling))]
-    #[inline(never)]
-    pub fn reserve_for_push(&mut self, len: usize) {
-        handle_reserve(self.grow_amortized(len, 1));
-    }
-
-    /// The same as `reserve`, but returns on errors instead of panicking or aborting.
-    pub fn try_reserve(&mut self, len: usize, additional: usize) -> Result<(), TryReserveError> {
-        if self.needs_to_grow(len, additional) {
-            self.grow_amortized(len, additional)?;
-        }
-        unsafe {
-            // Inform the optimizer that the reservation has succeeded or wasn't needed
-            core::intrinsics::assume(!self.needs_to_grow(len, additional));
-        }
-        Ok(())
-    }
-
-    /// The same as `reserve_for_push`, but returns on errors instead of panicking or aborting.
-    #[inline(never)]
-    pub fn try_reserve_for_push(&mut self, len: usize) -> Result<(), TryReserveError> {
-        self.grow_amortized(len, 1)
-    }
-
-    /// Ensures that the buffer contains at least enough space to hold `len +
-    /// additional` elements. If it doesn't already, will reallocate the
-    /// minimum possible amount of memory necessary. Generally this will be
-    /// exactly the amount of memory necessary, but in principle the allocator
-    /// is free to give back more than we asked for.
-    ///
-    /// If `len` exceeds `self.capacity()`, this may fail to actually allocate
-    /// the requested space. This is not really unsafe, but the unsafe code
-    /// *you* write that relies on the behavior of this function may break.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the new capacity exceeds `isize::MAX` bytes.
-    ///
-    /// # Aborts
-    ///
-    /// Aborts on OOM.
-    #[cfg(not(no_global_oom_handling))]
-    pub fn reserve_exact(&mut self, len: usize, additional: usize) {
-        handle_reserve(self.try_reserve_exact(len, additional));
-    }
-
-    /// The same as `reserve_exact`, but returns on errors instead of panicking or aborting.
-    pub fn try_reserve_exact(
-        &mut self,
-        len: usize,
-        additional: usize,
-    ) -> Result<(), TryReserveError> {
-        if self.needs_to_grow(len, additional) {
-            self.grow_exact(len, additional)?;
-        }
-        unsafe {
-            // Inform the optimizer that the reservation has succeeded or wasn't needed
-            core::intrinsics::assume(!self.needs_to_grow(len, additional));
-        }
-        Ok(())
-    }
-
-    /// Shrinks the buffer down to the specified capacity. If the given amount
-    /// is 0, actually completely deallocates.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the given amount is *larger* than the current capacity.
-    ///
-    /// # Aborts
-    ///
-    /// Aborts on OOM.
-    #[cfg(not(no_global_oom_handling))]
-    pub fn shrink_to_fit(&mut self, cap: usize) {
-        handle_reserve(self.shrink(cap));
-    }
-}
-
-impl<T, A: Allocator> RawVec<T, A> {
-    /// Returns if the buffer needs to grow to fulfill the needed extra capacity.
-    /// Mainly used to make inlining reserve-calls possible without inlining `grow`.
-    fn needs_to_grow(&self, len: usize, additional: usize) -> bool {
-        additional > self.capacity().wrapping_sub(len)
-    }
-
-    /// # Safety:
-    ///
-    /// `cap` must not exceed `isize::MAX`.
-    unsafe fn set_ptr_and_cap(&mut self, ptr: NonNull<[u8]>, cap: usize) {
-        // Allocators currently return a `NonNull<[u8]>` whose length matches
-        // the size requested. If that ever changes, the capacity here should
-        // change to `ptr.len() / mem::size_of::<T>()`.
-        self.ptr = unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) };
-        self.cap = unsafe { Cap(cap) };
-    }
-
-    // This method is usually instantiated many times. So we want it to be as
-    // small as possible, to improve compile times. But we also want as much of
-    // its contents to be statically computable as possible, to make the
-    // generated code run faster. Therefore, this method is carefully written
-    // so that all of the code that depends on `T` is within it, while as much
-    // of the code that doesn't depend on `T` as possible is in functions that
-    // are non-generic over `T`.
-    fn grow_amortized(&mut self, len: usize, additional: usize) -> Result<(), TryReserveError> {
-        // This is ensured by the calling contexts.
-        debug_assert!(additional > 0);
-
-        if T::IS_ZST {
-            // Since we return a capacity of `usize::MAX` when `elem_size` is
-            // 0, getting to here necessarily means the `RawVec` is overfull.
-            return Err(CapacityOverflow.into());
-        }
-
-        // Nothing we can really do about these checks, sadly.
-        let required_cap = len.checked_add(additional).ok_or(CapacityOverflow)?;
-
-        // This guarantees exponential growth. The doubling cannot overflow
-        // because `cap <= isize::MAX` and the type of `cap` is `usize`.
-        let cap = cmp::max(self.cap.0 * 2, required_cap);
-        let cap = cmp::max(Self::MIN_NON_ZERO_CAP, cap);
-
-        let new_layout = Layout::array::<T>(cap);
-
-        // `finish_grow` is non-generic over `T`.
-        let ptr = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?;
-        // SAFETY: finish_grow would have resulted in a capacity overflow if we tried to allocate more than isize::MAX items
-        unsafe { self.set_ptr_and_cap(ptr, cap) };
-        Ok(())
-    }
-
-    // The constraints on this method are much the same as those on
-    // `grow_amortized`, but this method is usually instantiated less often so
-    // it's less critical.
-    fn grow_exact(&mut self, len: usize, additional: usize) -> Result<(), TryReserveError> {
-        if T::IS_ZST {
-            // Since we return a capacity of `usize::MAX` when the type size is
-            // 0, getting to here necessarily means the `RawVec` is overfull.
-            return Err(CapacityOverflow.into());
-        }
-
-        let cap = len.checked_add(additional).ok_or(CapacityOverflow)?;
-        let new_layout = Layout::array::<T>(cap);
-
-        // `finish_grow` is non-generic over `T`.
-        let ptr = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?;
-        // SAFETY: finish_grow would have resulted in a capacity overflow if we tried to allocate more than isize::MAX items
-        unsafe {
-            self.set_ptr_and_cap(ptr, cap);
-        }
-        Ok(())
-    }
-
-    #[cfg(not(no_global_oom_handling))]
-    fn shrink(&mut self, cap: usize) -> Result<(), TryReserveError> {
-        assert!(cap <= self.capacity(), "Tried to shrink to a larger capacity");
-
-        let (ptr, layout) = if let Some(mem) = self.current_memory() { mem } else { return Ok(()) };
-        // See current_memory() why this assert is here
-        let _: () = const { assert!(mem::size_of::<T>() % mem::align_of::<T>() == 0) };
-
-        // If shrinking to 0, deallocate the buffer. We don't reach this point
-        // for the T::IS_ZST case since current_memory() will have returned
-        // None.
-        if cap == 0 {
-            unsafe { self.alloc.deallocate(ptr, layout) };
-            self.ptr = Unique::dangling();
-            self.cap = Cap::ZERO;
-        } else {
-            let ptr = unsafe {
-                // `Layout::array` cannot overflow here because it would have
-                // overflowed earlier when capacity was larger.
-                let new_size = mem::size_of::<T>().unchecked_mul(cap);
-                let new_layout = Layout::from_size_align_unchecked(new_size, layout.align());
-                self.alloc
-                    .shrink(ptr, layout, new_layout)
-                    .map_err(|_| AllocError { layout: new_layout, non_exhaustive: () })?
-            };
-            // SAFETY: if the allocation is valid, then the capacity is too
-            unsafe {
-                self.set_ptr_and_cap(ptr, cap);
-            }
-        }
-        Ok(())
-    }
-}
-
-// This function is outside `RawVec` to minimize compile times. See the comment
-// above `RawVec::grow_amortized` for details. (The `A` parameter isn't
-// significant, because the number of different `A` types seen in practice is
-// much smaller than the number of `T` types.)
-#[inline(never)]
-fn finish_grow<A>(
-    new_layout: Result<Layout, LayoutError>,
-    current_memory: Option<(NonNull<u8>, Layout)>,
-    alloc: &mut A,
-) -> Result<NonNull<[u8]>, TryReserveError>
-where
-    A: Allocator,
-{
-    // Check for the error here to minimize the size of `RawVec::grow_*`.
-    let new_layout = new_layout.map_err(|_| CapacityOverflow)?;
-
-    alloc_guard(new_layout.size())?;
-
-    let memory = if let Some((ptr, old_layout)) = current_memory {
-        debug_assert_eq!(old_layout.align(), new_layout.align());
-        unsafe {
-            // The allocator checks for alignment equality
-            intrinsics::assume(old_layout.align() == new_layout.align());
-            alloc.grow(ptr, old_layout, new_layout)
-        }
-    } else {
-        alloc.allocate(new_layout)
-    };
-
-    memory.map_err(|_| AllocError { layout: new_layout, non_exhaustive: () }.into())
-}
-
-unsafe impl<#[may_dangle] T, A: Allocator> Drop for RawVec<T, A> {
-    /// Frees the memory owned by the `RawVec` *without* trying to drop its contents.
-    fn drop(&mut self) {
-        if let Some((ptr, layout)) = self.current_memory() {
-            unsafe { self.alloc.deallocate(ptr, layout) }
-        }
-    }
-}
-
-// Central function for reserve error handling.
-#[cfg(not(no_global_oom_handling))]
-#[inline]
-fn handle_reserve(result: Result<(), TryReserveError>) {
-    match result.map_err(|e| e.kind()) {
-        Err(CapacityOverflow) => capacity_overflow(),
-        Err(AllocError { layout, .. }) => handle_alloc_error(layout),
-        Ok(()) => { /* yay */ }
-    }
-}
-
-// We need to guarantee the following:
-// * We don't ever allocate `> isize::MAX` byte-size objects.
-// * We don't overflow `usize::MAX` and actually allocate too little.
-//
-// On 64-bit we just need to check for overflow since trying to allocate
-// `> isize::MAX` bytes will surely fail. On 32-bit and 16-bit we need to add
-// an extra guard for this in case we're running on a platform which can use
-// all 4GB in user-space, e.g., PAE or x32.
-
-#[inline]
-fn alloc_guard(alloc_size: usize) -> Result<(), TryReserveError> {
-    if usize::BITS < 64 && alloc_size > isize::MAX as usize {
-        Err(CapacityOverflow.into())
-    } else {
-        Ok(())
-    }
-}
-
-// One central function responsible for reporting capacity overflows. This'll
-// ensure that the code generation related to these panics is minimal as there's
-// only one location which panics rather than a bunch throughout the module.
-#[cfg(not(no_global_oom_handling))]
-#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
-fn capacity_overflow() -> ! {
-    panic!("capacity overflow");
-}
diff --git a/rust/alloc/slice.rs b/rust/alloc/slice.rs
deleted file mode 100644
index 1181836da5f4..000000000000
--- a/rust/alloc/slice.rs
+++ /dev/null
@@ -1,890 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-//! Utilities for the slice primitive type.
-//!
-//! *[See also the slice primitive type](slice).*
-//!
-//! Most of the structs in this module are iterator types which can only be created
-//! using a certain function. For example, `slice.iter()` yields an [`Iter`].
-//!
-//! A few functions are provided to create a slice from a value reference
-//! or from a raw pointer.
-#![stable(feature = "rust1", since = "1.0.0")]
-// Many of the usings in this module are only used in the test configuration.
-// It's cleaner to just turn off the unused_imports warning than to fix them.
-#![cfg_attr(test, allow(unused_imports, dead_code))]
-
-use core::borrow::{Borrow, BorrowMut};
-#[cfg(not(no_global_oom_handling))]
-use core::cmp::Ordering::{self, Less};
-#[cfg(not(no_global_oom_handling))]
-use core::mem::{self, SizedTypeProperties};
-#[cfg(not(no_global_oom_handling))]
-use core::ptr;
-#[cfg(not(no_global_oom_handling))]
-use core::slice::sort;
-
-use crate::alloc::Allocator;
-#[cfg(not(no_global_oom_handling))]
-use crate::alloc::{self, Global};
-#[cfg(not(no_global_oom_handling))]
-use crate::borrow::ToOwned;
-use crate::boxed::Box;
-use crate::vec::Vec;
-
-#[cfg(test)]
-mod tests;
-
-#[unstable(feature = "slice_range", issue = "76393")]
-pub use core::slice::range;
-#[unstable(feature = "array_chunks", issue = "74985")]
-pub use core::slice::ArrayChunks;
-#[unstable(feature = "array_chunks", issue = "74985")]
-pub use core::slice::ArrayChunksMut;
-#[unstable(feature = "array_windows", issue = "75027")]
-pub use core::slice::ArrayWindows;
-#[stable(feature = "inherent_ascii_escape", since = "1.60.0")]
-pub use core::slice::EscapeAscii;
-#[stable(feature = "slice_get_slice", since = "1.28.0")]
-pub use core::slice::SliceIndex;
-#[stable(feature = "from_ref", since = "1.28.0")]
-pub use core::slice::{from_mut, from_ref};
-#[unstable(feature = "slice_from_ptr_range", issue = "89792")]
-pub use core::slice::{from_mut_ptr_range, from_ptr_range};
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::slice::{from_raw_parts, from_raw_parts_mut};
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::slice::{Chunks, Windows};
-#[stable(feature = "chunks_exact", since = "1.31.0")]
-pub use core::slice::{ChunksExact, ChunksExactMut};
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::slice::{ChunksMut, Split, SplitMut};
-#[unstable(feature = "slice_group_by", issue = "80552")]
-pub use core::slice::{GroupBy, GroupByMut};
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::slice::{Iter, IterMut};
-#[stable(feature = "rchunks", since = "1.31.0")]
-pub use core::slice::{RChunks, RChunksExact, RChunksExactMut, RChunksMut};
-#[stable(feature = "slice_rsplit", since = "1.27.0")]
-pub use core::slice::{RSplit, RSplitMut};
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::slice::{RSplitN, RSplitNMut, SplitN, SplitNMut};
-#[stable(feature = "split_inclusive", since = "1.51.0")]
-pub use core::slice::{SplitInclusive, SplitInclusiveMut};
-
-////////////////////////////////////////////////////////////////////////////////
-// Basic slice extension methods
-////////////////////////////////////////////////////////////////////////////////
-
-// HACK(japaric) needed for the implementation of `vec!` macro during testing
-// N.B., see the `hack` module in this file for more details.
-#[cfg(test)]
-pub use hack::into_vec;
-
-// HACK(japaric) needed for the implementation of `Vec::clone` during testing
-// N.B., see the `hack` module in this file for more details.
-#[cfg(test)]
-pub use hack::to_vec;
-
-// HACK(japaric): With cfg(test) `impl [T]` is not available, these three
-// functions are actually methods that are in `impl [T]` but not in
-// `core::slice::SliceExt` - we need to supply these functions for the
-// `test_permutations` test
-pub(crate) mod hack {
-    use core::alloc::Allocator;
-
-    use crate::boxed::Box;
-    use crate::vec::Vec;
-
-    // We shouldn't add inline attribute to this since this is used in
-    // `vec!` macro mostly and causes perf regression. See #71204 for
-    // discussion and perf results.
-    pub fn into_vec<T, A: Allocator>(b: Box<[T], A>) -> Vec<T, A> {
-        unsafe {
-            let len = b.len();
-            let (b, alloc) = Box::into_raw_with_allocator(b);
-            Vec::from_raw_parts_in(b as *mut T, len, len, alloc)
-        }
-    }
-
-    #[cfg(not(no_global_oom_handling))]
-    #[inline]
-    pub fn to_vec<T: ConvertVec, A: Allocator>(s: &[T], alloc: A) -> Vec<T, A> {
-        T::to_vec(s, alloc)
-    }
-
-    #[cfg(not(no_global_oom_handling))]
-    pub trait ConvertVec {
-        fn to_vec<A: Allocator>(s: &[Self], alloc: A) -> Vec<Self, A>
-        where
-            Self: Sized;
-    }
-
-    #[cfg(not(no_global_oom_handling))]
-    impl<T: Clone> ConvertVec for T {
-        #[inline]
-        default fn to_vec<A: Allocator>(s: &[Self], alloc: A) -> Vec<Self, A> {
-            struct DropGuard<'a, T, A: Allocator> {
-                vec: &'a mut Vec<T, A>,
-                num_init: usize,
-            }
-            impl<'a, T, A: Allocator> Drop for DropGuard<'a, T, A> {
-                #[inline]
-                fn drop(&mut self) {
-                    // SAFETY:
-                    // items were marked initialized in the loop below
-                    unsafe {
-                        self.vec.set_len(self.num_init);
-                    }
-                }
-            }
-            let mut vec = Vec::with_capacity_in(s.len(), alloc);
-            let mut guard = DropGuard { vec: &mut vec, num_init: 0 };
-            let slots = guard.vec.spare_capacity_mut();
-            // .take(slots.len()) is necessary for LLVM to remove bounds checks
-            // and has better codegen than zip.
-            for (i, b) in s.iter().enumerate().take(slots.len()) {
-                guard.num_init = i;
-                slots[i].write(b.clone());
-            }
-            core::mem::forget(guard);
-            // SAFETY:
-            // the vec was allocated and initialized above to at least this length.
-            unsafe {
-                vec.set_len(s.len());
-            }
-            vec
-        }
-    }
-
-    #[cfg(not(no_global_oom_handling))]
-    impl<T: Copy> ConvertVec for T {
-        #[inline]
-        fn to_vec<A: Allocator>(s: &[Self], alloc: A) -> Vec<Self, A> {
-            let mut v = Vec::with_capacity_in(s.len(), alloc);
-            // SAFETY:
-            // allocated above with the capacity of `s`, and initialize to `s.len()` in
-            // ptr::copy_to_non_overlapping below.
-            unsafe {
-                s.as_ptr().copy_to_nonoverlapping(v.as_mut_ptr(), s.len());
-                v.set_len(s.len());
-            }
-            v
-        }
-    }
-}
-
-#[cfg(not(test))]
-impl<T> [T] {
-    /// Sorts the slice.
-    ///
-    /// This sort is stable (i.e., does not reorder equal elements) and *O*(*n* \* log(*n*)) worst-case.
-    ///
-    /// When applicable, unstable sorting is preferred because it is generally faster than stable
-    /// sorting and it doesn't allocate auxiliary memory.
-    /// See [`sort_unstable`](slice::sort_unstable).
-    ///
-    /// # Current implementation
-    ///
-    /// The current algorithm is an adaptive, iterative merge sort inspired by
-    /// [timsort](https://en.wikipedia.org/wiki/Timsort).
-    /// It is designed to be very fast in cases where the slice is nearly sorted, or consists of
-    /// two or more sorted sequences concatenated one after another.
-    ///
-    /// Also, it allocates temporary storage half the size of `self`, but for short slices a
-    /// non-allocating insertion sort is used instead.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut v = [-5, 4, 1, -3, 2];
-    ///
-    /// v.sort();
-    /// assert!(v == [-5, -3, 1, 2, 4]);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[rustc_allow_incoherent_impl]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    #[inline]
-    pub fn sort(&mut self)
-    where
-        T: Ord,
-    {
-        stable_sort(self, T::lt);
-    }
-
-    /// Sorts the slice with a comparator function.
-    ///
-    /// This sort is stable (i.e., does not reorder equal elements) and *O*(*n* \* log(*n*)) worst-case.
-    ///
-    /// The comparator function must define a total ordering for the elements in the slice. If
-    /// the ordering is not total, the order of the elements is unspecified. An order is a
-    /// total order if it is (for all `a`, `b` and `c`):
-    ///
-    /// * total and antisymmetric: exactly one of `a < b`, `a == b` or `a > b` is true, and
-    /// * transitive, `a < b` and `b < c` implies `a < c`. The same must hold for both `==` and `>`.
-    ///
-    /// For example, while [`f64`] doesn't implement [`Ord`] because `NaN != NaN`, we can use
-    /// `partial_cmp` as our sort function when we know the slice doesn't contain a `NaN`.
-    ///
-    /// ```
-    /// let mut floats = [5f64, 4.0, 1.0, 3.0, 2.0];
-    /// floats.sort_by(|a, b| a.partial_cmp(b).unwrap());
-    /// assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]);
-    /// ```
-    ///
-    /// When applicable, unstable sorting is preferred because it is generally faster than stable
-    /// sorting and it doesn't allocate auxiliary memory.
-    /// See [`sort_unstable_by`](slice::sort_unstable_by).
-    ///
-    /// # Current implementation
-    ///
-    /// The current algorithm is an adaptive, iterative merge sort inspired by
-    /// [timsort](https://en.wikipedia.org/wiki/Timsort).
-    /// It is designed to be very fast in cases where the slice is nearly sorted, or consists of
-    /// two or more sorted sequences concatenated one after another.
-    ///
-    /// Also, it allocates temporary storage half the size of `self`, but for short slices a
-    /// non-allocating insertion sort is used instead.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut v = [5, 4, 1, 3, 2];
-    /// v.sort_by(|a, b| a.cmp(b));
-    /// assert!(v == [1, 2, 3, 4, 5]);
-    ///
-    /// // reverse sorting
-    /// v.sort_by(|a, b| b.cmp(a));
-    /// assert!(v == [5, 4, 3, 2, 1]);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[rustc_allow_incoherent_impl]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    #[inline]
-    pub fn sort_by<F>(&mut self, mut compare: F)
-    where
-        F: FnMut(&T, &T) -> Ordering,
-    {
-        stable_sort(self, |a, b| compare(a, b) == Less);
-    }
-
-    /// Sorts the slice with a key extraction function.
-    ///
-    /// This sort is stable (i.e., does not reorder equal elements) and *O*(*m* \* *n* \* log(*n*))
-    /// worst-case, where the key function is *O*(*m*).
-    ///
-    /// For expensive key functions (e.g. functions that are not simple property accesses or
-    /// basic operations), [`sort_by_cached_key`](slice::sort_by_cached_key) is likely to be
-    /// significantly faster, as it does not recompute element keys.
-    ///
-    /// When applicable, unstable sorting is preferred because it is generally faster than stable
-    /// sorting and it doesn't allocate auxiliary memory.
-    /// See [`sort_unstable_by_key`](slice::sort_unstable_by_key).
-    ///
-    /// # Current implementation
-    ///
-    /// The current algorithm is an adaptive, iterative merge sort inspired by
-    /// [timsort](https://en.wikipedia.org/wiki/Timsort).
-    /// It is designed to be very fast in cases where the slice is nearly sorted, or consists of
-    /// two or more sorted sequences concatenated one after another.
-    ///
-    /// Also, it allocates temporary storage half the size of `self`, but for short slices a
-    /// non-allocating insertion sort is used instead.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut v = [-5i32, 4, 1, -3, 2];
-    ///
-    /// v.sort_by_key(|k| k.abs());
-    /// assert!(v == [1, 2, -3, 4, -5]);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[rustc_allow_incoherent_impl]
-    #[stable(feature = "slice_sort_by_key", since = "1.7.0")]
-    #[inline]
-    pub fn sort_by_key<K, F>(&mut self, mut f: F)
-    where
-        F: FnMut(&T) -> K,
-        K: Ord,
-    {
-        stable_sort(self, |a, b| f(a).lt(&f(b)));
-    }
-
-    /// Sorts the slice with a key extraction function.
-    ///
-    /// During sorting, the key function is called at most once per element, by using
-    /// temporary storage to remember the results of key evaluation.
-    /// The order of calls to the key function is unspecified and may change in future versions
-    /// of the standard library.
-    ///
-    /// This sort is stable (i.e., does not reorder equal elements) and *O*(*m* \* *n* + *n* \* log(*n*))
-    /// worst-case, where the key function is *O*(*m*).
-    ///
-    /// For simple key functions (e.g., functions that are property accesses or
-    /// basic operations), [`sort_by_key`](slice::sort_by_key) is likely to be
-    /// faster.
-    ///
-    /// # Current implementation
-    ///
-    /// The current algorithm is based on [pattern-defeating quicksort][pdqsort] by Orson Peters,
-    /// which combines the fast average case of randomized quicksort with the fast worst case of
-    /// heapsort, while achieving linear time on slices with certain patterns. It uses some
-    /// randomization to avoid degenerate cases, but with a fixed seed to always provide
-    /// deterministic behavior.
-    ///
-    /// In the worst case, the algorithm allocates temporary storage in a `Vec<(K, usize)>` the
-    /// length of the slice.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut v = [-5i32, 4, 32, -3, 2];
-    ///
-    /// v.sort_by_cached_key(|k| k.to_string());
-    /// assert!(v == [-3, -5, 2, 32, 4]);
-    /// ```
-    ///
-    /// [pdqsort]: https://github.com/orlp/pdqsort
-    #[cfg(not(no_global_oom_handling))]
-    #[rustc_allow_incoherent_impl]
-    #[stable(feature = "slice_sort_by_cached_key", since = "1.34.0")]
-    #[inline]
-    pub fn sort_by_cached_key<K, F>(&mut self, f: F)
-    where
-        F: FnMut(&T) -> K,
-        K: Ord,
-    {
-        // Helper macro for indexing our vector by the smallest possible type, to reduce allocation.
-        macro_rules! sort_by_key {
-            ($t:ty, $slice:ident, $f:ident) => {{
-                let mut indices: Vec<_> =
-                    $slice.iter().map($f).enumerate().map(|(i, k)| (k, i as $t)).collect();
-                // The elements of `indices` are unique, as they are indexed, so any sort will be
-                // stable with respect to the original slice. We use `sort_unstable` here because
-                // it requires less memory allocation.
-                indices.sort_unstable();
-                for i in 0..$slice.len() {
-                    let mut index = indices[i].1;
-                    while (index as usize) < i {
-                        index = indices[index as usize].1;
-                    }
-                    indices[i].1 = index;
-                    $slice.swap(i, index as usize);
-                }
-            }};
-        }
-
-        let sz_u8 = mem::size_of::<(K, u8)>();
-        let sz_u16 = mem::size_of::<(K, u16)>();
-        let sz_u32 = mem::size_of::<(K, u32)>();
-        let sz_usize = mem::size_of::<(K, usize)>();
-
-        let len = self.len();
-        if len < 2 {
-            return;
-        }
-        if sz_u8 < sz_u16 && len <= (u8::MAX as usize) {
-            return sort_by_key!(u8, self, f);
-        }
-        if sz_u16 < sz_u32 && len <= (u16::MAX as usize) {
-            return sort_by_key!(u16, self, f);
-        }
-        if sz_u32 < sz_usize && len <= (u32::MAX as usize) {
-            return sort_by_key!(u32, self, f);
-        }
-        sort_by_key!(usize, self, f)
-    }
-
-    /// Copies `self` into a new `Vec`.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let s = [10, 40, 30];
-    /// let x = s.to_vec();
-    /// // Here, `s` and `x` can be modified independently.
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[rustc_allow_incoherent_impl]
-    #[rustc_conversion_suggestion]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    #[inline]
-    pub fn to_vec(&self) -> Vec<T>
-    where
-        T: Clone,
-    {
-        self.to_vec_in(Global)
-    }
-
-    /// Copies `self` into a new `Vec` with an allocator.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// let s = [10, 40, 30];
-    /// let x = s.to_vec_in(System);
-    /// // Here, `s` and `x` can be modified independently.
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[rustc_allow_incoherent_impl]
-    #[inline]
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    pub fn to_vec_in<A: Allocator>(&self, alloc: A) -> Vec<T, A>
-    where
-        T: Clone,
-    {
-        // N.B., see the `hack` module in this file for more details.
-        hack::to_vec(self, alloc)
-    }
-
-    /// Converts `self` into a vector without clones or allocation.
-    ///
-    /// The resulting vector can be converted back into a box via
-    /// `Vec<T>`'s `into_boxed_slice` method.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let s: Box<[i32]> = Box::new([10, 40, 30]);
-    /// let x = s.into_vec();
-    /// // `s` cannot be used anymore because it has been converted into `x`.
-    ///
-    /// assert_eq!(x, vec![10, 40, 30]);
-    /// ```
-    #[rustc_allow_incoherent_impl]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    #[inline]
-    pub fn into_vec<A: Allocator>(self: Box<Self, A>) -> Vec<T, A> {
-        // N.B., see the `hack` module in this file for more details.
-        hack::into_vec(self)
-    }
-
-    /// Creates a vector by copying a slice `n` times.
-    ///
-    /// # Panics
-    ///
-    /// This function will panic if the capacity would overflow.
-    ///
-    /// # Examples
-    ///
-    /// Basic usage:
-    ///
-    /// ```
-    /// assert_eq!([1, 2].repeat(3), vec![1, 2, 1, 2, 1, 2]);
-    /// ```
-    ///
-    /// A panic upon overflow:
-    ///
-    /// ```should_panic
-    /// // this will panic at runtime
-    /// b"0123456789abcdef".repeat(usize::MAX);
-    /// ```
-    #[rustc_allow_incoherent_impl]
-    #[cfg(not(no_global_oom_handling))]
-    #[stable(feature = "repeat_generic_slice", since = "1.40.0")]
-    pub fn repeat(&self, n: usize) -> Vec<T>
-    where
-        T: Copy,
-    {
-        if n == 0 {
-            return Vec::new();
-        }
-
-        // If `n` is larger than zero, it can be split as
-        // `n = 2^expn + rem (2^expn > rem, expn >= 0, rem >= 0)`.
-        // `2^expn` is the number represented by the leftmost '1' bit of `n`,
-        // and `rem` is the remaining part of `n`.
-
-        // Using `Vec` to access `set_len()`.
-        let capacity = self.len().checked_mul(n).expect("capacity overflow");
-        let mut buf = Vec::with_capacity(capacity);
-
-        // `2^expn` repetition is done by doubling `buf` `expn`-times.
-        buf.extend(self);
-        {
-            let mut m = n >> 1;
-            // If `m > 0`, there are remaining bits up to the leftmost '1'.
-            while m > 0 {
-                // `buf.extend(buf)`:
-                unsafe {
-                    ptr::copy_nonoverlapping(
-                        buf.as_ptr(),
-                        (buf.as_mut_ptr() as *mut T).add(buf.len()),
-                        buf.len(),
-                    );
-                    // `buf` has capacity of `self.len() * n`.
-                    let buf_len = buf.len();
-                    buf.set_len(buf_len * 2);
-                }
-
-                m >>= 1;
-            }
-        }
-
-        // `rem` (`= n - 2^expn`) repetition is done by copying
-        // first `rem` repetitions from `buf` itself.
-        let rem_len = capacity - buf.len(); // `self.len() * rem`
-        if rem_len > 0 {
-            // `buf.extend(buf[0 .. rem_len])`:
-            unsafe {
-                // This is non-overlapping since `2^expn > rem`.
-                ptr::copy_nonoverlapping(
-                    buf.as_ptr(),
-                    (buf.as_mut_ptr() as *mut T).add(buf.len()),
-                    rem_len,
-                );
-                // `buf.len() + rem_len` equals to `buf.capacity()` (`= self.len() * n`).
-                buf.set_len(capacity);
-            }
-        }
-        buf
-    }
-
-    /// Flattens a slice of `T` into a single value `Self::Output`.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// assert_eq!(["hello", "world"].concat(), "helloworld");
-    /// assert_eq!([[1, 2], [3, 4]].concat(), [1, 2, 3, 4]);
-    /// ```
-    #[rustc_allow_incoherent_impl]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn concat<Item: ?Sized>(&self) -> <Self as Concat<Item>>::Output
-    where
-        Self: Concat<Item>,
-    {
-        Concat::concat(self)
-    }
-
-    /// Flattens a slice of `T` into a single value `Self::Output`, placing a
-    /// given separator between each.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// assert_eq!(["hello", "world"].join(" "), "hello world");
-    /// assert_eq!([[1, 2], [3, 4]].join(&0), [1, 2, 0, 3, 4]);
-    /// assert_eq!([[1, 2], [3, 4]].join(&[0, 0][..]), [1, 2, 0, 0, 3, 4]);
-    /// ```
-    #[rustc_allow_incoherent_impl]
-    #[stable(feature = "rename_connect_to_join", since = "1.3.0")]
-    pub fn join<Separator>(&self, sep: Separator) -> <Self as Join<Separator>>::Output
-    where
-        Self: Join<Separator>,
-    {
-        Join::join(self, sep)
-    }
-
-    /// Flattens a slice of `T` into a single value `Self::Output`, placing a
-    /// given separator between each.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// # #![allow(deprecated)]
-    /// assert_eq!(["hello", "world"].connect(" "), "hello world");
-    /// assert_eq!([[1, 2], [3, 4]].connect(&0), [1, 2, 0, 3, 4]);
-    /// ```
-    #[rustc_allow_incoherent_impl]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    #[deprecated(since = "1.3.0", note = "renamed to join", suggestion = "join")]
-    pub fn connect<Separator>(&self, sep: Separator) -> <Self as Join<Separator>>::Output
-    where
-        Self: Join<Separator>,
-    {
-        Join::join(self, sep)
-    }
-}
-
-#[cfg(not(test))]
-impl [u8] {
-    /// Returns a vector containing a copy of this slice where each byte
-    /// is mapped to its ASCII upper case equivalent.
-    ///
-    /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
-    /// but non-ASCII letters are unchanged.
-    ///
-    /// To uppercase the value in-place, use [`make_ascii_uppercase`].
-    ///
-    /// [`make_ascii_uppercase`]: slice::make_ascii_uppercase
-    #[cfg(not(no_global_oom_handling))]
-    #[rustc_allow_incoherent_impl]
-    #[must_use = "this returns the uppercase bytes as a new Vec, \
-                  without modifying the original"]
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
-    #[inline]
-    pub fn to_ascii_uppercase(&self) -> Vec<u8> {
-        let mut me = self.to_vec();
-        me.make_ascii_uppercase();
-        me
-    }
-
-    /// Returns a vector containing a copy of this slice where each byte
-    /// is mapped to its ASCII lower case equivalent.
-    ///
-    /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
-    /// but non-ASCII letters are unchanged.
-    ///
-    /// To lowercase the value in-place, use [`make_ascii_lowercase`].
-    ///
-    /// [`make_ascii_lowercase`]: slice::make_ascii_lowercase
-    #[cfg(not(no_global_oom_handling))]
-    #[rustc_allow_incoherent_impl]
-    #[must_use = "this returns the lowercase bytes as a new Vec, \
-                  without modifying the original"]
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
-    #[inline]
-    pub fn to_ascii_lowercase(&self) -> Vec<u8> {
-        let mut me = self.to_vec();
-        me.make_ascii_lowercase();
-        me
-    }
-}
-
-////////////////////////////////////////////////////////////////////////////////
-// Extension traits for slices over specific kinds of data
-////////////////////////////////////////////////////////////////////////////////
-
-/// Helper trait for [`[T]::concat`](slice::concat).
-///
-/// Note: the `Item` type parameter is not used in this trait,
-/// but it allows impls to be more generic.
-/// Without it, we get this error:
-///
-/// ```error
-/// error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predica
-///    --> library/alloc/src/slice.rs:608:6
-///     |
-/// 608 | impl<T: Clone, V: Borrow<[T]>> Concat for [V] {
-///     |      ^ unconstrained type parameter
-/// ```
-///
-/// This is because there could exist `V` types with multiple `Borrow<[_]>` impls,
-/// such that multiple `T` types would apply:
-///
-/// ```
-/// # #[allow(dead_code)]
-/// pub struct Foo(Vec<u32>, Vec<String>);
-///
-/// impl std::borrow::Borrow<[u32]> for Foo {
-///     fn borrow(&self) -> &[u32] { &self.0 }
-/// }
-///
-/// impl std::borrow::Borrow<[String]> for Foo {
-///     fn borrow(&self) -> &[String] { &self.1 }
-/// }
-/// ```
-#[unstable(feature = "slice_concat_trait", issue = "27747")]
-pub trait Concat<Item: ?Sized> {
-    #[unstable(feature = "slice_concat_trait", issue = "27747")]
-    /// The resulting type after concatenation
-    type Output;
-
-    /// Implementation of [`[T]::concat`](slice::concat)
-    #[unstable(feature = "slice_concat_trait", issue = "27747")]
-    fn concat(slice: &Self) -> Self::Output;
-}
-
-/// Helper trait for [`[T]::join`](slice::join)
-#[unstable(feature = "slice_concat_trait", issue = "27747")]
-pub trait Join<Separator> {
-    #[unstable(feature = "slice_concat_trait", issue = "27747")]
-    /// The resulting type after concatenation
-    type Output;
-
-    /// Implementation of [`[T]::join`](slice::join)
-    #[unstable(feature = "slice_concat_trait", issue = "27747")]
-    fn join(slice: &Self, sep: Separator) -> Self::Output;
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[unstable(feature = "slice_concat_ext", issue = "27747")]
-impl<T: Clone, V: Borrow<[T]>> Concat<T> for [V] {
-    type Output = Vec<T>;
-
-    fn concat(slice: &Self) -> Vec<T> {
-        let size = slice.iter().map(|slice| slice.borrow().len()).sum();
-        let mut result = Vec::with_capacity(size);
-        for v in slice {
-            result.extend_from_slice(v.borrow())
-        }
-        result
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[unstable(feature = "slice_concat_ext", issue = "27747")]
-impl<T: Clone, V: Borrow<[T]>> Join<&T> for [V] {
-    type Output = Vec<T>;
-
-    fn join(slice: &Self, sep: &T) -> Vec<T> {
-        let mut iter = slice.iter();
-        let first = match iter.next() {
-            Some(first) => first,
-            None => return vec![],
-        };
-        let size = slice.iter().map(|v| v.borrow().len()).sum::<usize>() + slice.len() - 1;
-        let mut result = Vec::with_capacity(size);
-        result.extend_from_slice(first.borrow());
-
-        for v in iter {
-            result.push(sep.clone());
-            result.extend_from_slice(v.borrow())
-        }
-        result
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[unstable(feature = "slice_concat_ext", issue = "27747")]
-impl<T: Clone, V: Borrow<[T]>> Join<&[T]> for [V] {
-    type Output = Vec<T>;
-
-    fn join(slice: &Self, sep: &[T]) -> Vec<T> {
-        let mut iter = slice.iter();
-        let first = match iter.next() {
-            Some(first) => first,
-            None => return vec![],
-        };
-        let size =
-            slice.iter().map(|v| v.borrow().len()).sum::<usize>() + sep.len() * (slice.len() - 1);
-        let mut result = Vec::with_capacity(size);
-        result.extend_from_slice(first.borrow());
-
-        for v in iter {
-            result.extend_from_slice(sep);
-            result.extend_from_slice(v.borrow())
-        }
-        result
-    }
-}
-
-////////////////////////////////////////////////////////////////////////////////
-// Standard trait implementations for slices
-////////////////////////////////////////////////////////////////////////////////
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, A: Allocator> Borrow<[T]> for Vec<T, A> {
-    fn borrow(&self) -> &[T] {
-        &self[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, A: Allocator> BorrowMut<[T]> for Vec<T, A> {
-    fn borrow_mut(&mut self) -> &mut [T] {
-        &mut self[..]
-    }
-}
-
-// Specializable trait for implementing ToOwned::clone_into. This is
-// public in the crate and has the Allocator parameter so that
-// vec::clone_from use it too.
-#[cfg(not(no_global_oom_handling))]
-pub(crate) trait SpecCloneIntoVec<T, A: Allocator> {
-    fn clone_into(&self, target: &mut Vec<T, A>);
-}
-
-#[cfg(not(no_global_oom_handling))]
-impl<T: Clone, A: Allocator> SpecCloneIntoVec<T, A> for [T] {
-    default fn clone_into(&self, target: &mut Vec<T, A>) {
-        // drop anything in target that will not be overwritten
-        target.truncate(self.len());
-
-        // target.len <= self.len due to the truncate above, so the
-        // slices here are always in-bounds.
-        let (init, tail) = self.split_at(target.len());
-
-        // reuse the contained values' allocations/resources.
-        target.clone_from_slice(init);
-        target.extend_from_slice(tail);
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-impl<T: Copy, A: Allocator> SpecCloneIntoVec<T, A> for [T] {
-    fn clone_into(&self, target: &mut Vec<T, A>) {
-        target.clear();
-        target.extend_from_slice(self);
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Clone> ToOwned for [T] {
-    type Owned = Vec<T>;
-    #[cfg(not(test))]
-    fn to_owned(&self) -> Vec<T> {
-        self.to_vec()
-    }
-
-    #[cfg(test)]
-    fn to_owned(&self) -> Vec<T> {
-        hack::to_vec(self, Global)
-    }
-
-    fn clone_into(&self, target: &mut Vec<T>) {
-        SpecCloneIntoVec::clone_into(self, target);
-    }
-}
-
-////////////////////////////////////////////////////////////////////////////////
-// Sorting
-////////////////////////////////////////////////////////////////////////////////
-
-#[inline]
-#[cfg(not(no_global_oom_handling))]
-fn stable_sort<T, F>(v: &mut [T], mut is_less: F)
-where
-    F: FnMut(&T, &T) -> bool,
-{
-    if T::IS_ZST {
-        // Sorting has no meaningful behavior on zero-sized types. Do nothing.
-        return;
-    }
-
-    let elem_alloc_fn = |len: usize| -> *mut T {
-        // SAFETY: Creating the layout is safe as long as merge_sort never calls this with len >
-        // v.len(). Alloc in general will only be used as 'shadow-region' to store temporary swap
-        // elements.
-        unsafe { alloc::alloc(alloc::Layout::array::<T>(len).unwrap_unchecked()) as *mut T }
-    };
-
-    let elem_dealloc_fn = |buf_ptr: *mut T, len: usize| {
-        // SAFETY: Creating the layout is safe as long as merge_sort never calls this with len >
-        // v.len(). The caller must ensure that buf_ptr was created by elem_alloc_fn with the same
-        // len.
-        unsafe {
-            alloc::dealloc(buf_ptr as *mut u8, alloc::Layout::array::<T>(len).unwrap_unchecked());
-        }
-    };
-
-    let run_alloc_fn = |len: usize| -> *mut sort::TimSortRun {
-        // SAFETY: Creating the layout is safe as long as merge_sort never calls this with an
-        // obscene length or 0.
-        unsafe {
-            alloc::alloc(alloc::Layout::array::<sort::TimSortRun>(len).unwrap_unchecked())
-                as *mut sort::TimSortRun
-        }
-    };
-
-    let run_dealloc_fn = |buf_ptr: *mut sort::TimSortRun, len: usize| {
-        // SAFETY: The caller must ensure that buf_ptr was created by elem_alloc_fn with the same
-        // len.
-        unsafe {
-            alloc::dealloc(
-                buf_ptr as *mut u8,
-                alloc::Layout::array::<sort::TimSortRun>(len).unwrap_unchecked(),
-            );
-        }
-    };
-
-    sort::merge_sort(v, &mut is_less, elem_alloc_fn, elem_dealloc_fn, run_alloc_fn, run_dealloc_fn);
-}
diff --git a/rust/alloc/vec/drain.rs b/rust/alloc/vec/drain.rs
deleted file mode 100644
index 78177a9e2ad0..000000000000
--- a/rust/alloc/vec/drain.rs
+++ /dev/null
@@ -1,255 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-use crate::alloc::{Allocator, Global};
-use core::fmt;
-use core::iter::{FusedIterator, TrustedLen};
-use core::mem::{self, ManuallyDrop, SizedTypeProperties};
-use core::ptr::{self, NonNull};
-use core::slice::{self};
-
-use super::Vec;
-
-/// A draining iterator for `Vec<T>`.
-///
-/// This `struct` is created by [`Vec::drain`].
-/// See its documentation for more.
-///
-/// # Example
-///
-/// ```
-/// let mut v = vec![0, 1, 2];
-/// let iter: std::vec::Drain<'_, _> = v.drain(..);
-/// ```
-#[stable(feature = "drain", since = "1.6.0")]
-pub struct Drain<
-    'a,
-    T: 'a,
-    #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + 'a = Global,
-> {
-    /// Index of tail to preserve
-    pub(super) tail_start: usize,
-    /// Length of tail
-    pub(super) tail_len: usize,
-    /// Current remaining range to remove
-    pub(super) iter: slice::Iter<'a, T>,
-    pub(super) vec: NonNull<Vec<T, A>>,
-}
-
-#[stable(feature = "collection_debug", since = "1.17.0")]
-impl<T: fmt::Debug, A: Allocator> fmt::Debug for Drain<'_, T, A> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_tuple("Drain").field(&self.iter.as_slice()).finish()
-    }
-}
-
-impl<'a, T, A: Allocator> Drain<'a, T, A> {
-    /// Returns the remaining items of this iterator as a slice.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec!['a', 'b', 'c'];
-    /// let mut drain = vec.drain(..);
-    /// assert_eq!(drain.as_slice(), &['a', 'b', 'c']);
-    /// let _ = drain.next().unwrap();
-    /// assert_eq!(drain.as_slice(), &['b', 'c']);
-    /// ```
-    #[must_use]
-    #[stable(feature = "vec_drain_as_slice", since = "1.46.0")]
-    pub fn as_slice(&self) -> &[T] {
-        self.iter.as_slice()
-    }
-
-    /// Returns a reference to the underlying allocator.
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[must_use]
-    #[inline]
-    pub fn allocator(&self) -> &A {
-        unsafe { self.vec.as_ref().allocator() }
-    }
-
-    /// Keep unyielded elements in the source `Vec`.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(drain_keep_rest)]
-    ///
-    /// let mut vec = vec!['a', 'b', 'c'];
-    /// let mut drain = vec.drain(..);
-    ///
-    /// assert_eq!(drain.next().unwrap(), 'a');
-    ///
-    /// // This call keeps 'b' and 'c' in the vec.
-    /// drain.keep_rest();
-    ///
-    /// // If we wouldn't call `keep_rest()`,
-    /// // `vec` would be empty.
-    /// assert_eq!(vec, ['b', 'c']);
-    /// ```
-    #[unstable(feature = "drain_keep_rest", issue = "101122")]
-    pub fn keep_rest(self) {
-        // At this moment layout looks like this:
-        //
-        // [head] [yielded by next] [unyielded] [yielded by next_back] [tail]
-        //        ^-- start         \_________/-- unyielded_len        \____/-- self.tail_len
-        //                          ^-- unyielded_ptr                  ^-- tail
-        //
-        // Normally `Drop` impl would drop [unyielded] and then move [tail] to the `start`.
-        // Here we want to
-        // 1. Move [unyielded] to `start`
-        // 2. Move [tail] to a new start at `start + len(unyielded)`
-        // 3. Update length of the original vec to `len(head) + len(unyielded) + len(tail)`
-        //    a. In case of ZST, this is the only thing we want to do
-        // 4. Do *not* drop self, as everything is put in a consistent state already, there is nothing to do
-        let mut this = ManuallyDrop::new(self);
-
-        unsafe {
-            let source_vec = this.vec.as_mut();
-
-            let start = source_vec.len();
-            let tail = this.tail_start;
-
-            let unyielded_len = this.iter.len();
-            let unyielded_ptr = this.iter.as_slice().as_ptr();
-
-            // ZSTs have no identity, so we don't need to move them around.
-            if !T::IS_ZST {
-                let start_ptr = source_vec.as_mut_ptr().add(start);
-
-                // memmove back unyielded elements
-                if unyielded_ptr != start_ptr {
-                    let src = unyielded_ptr;
-                    let dst = start_ptr;
-
-                    ptr::copy(src, dst, unyielded_len);
-                }
-
-                // memmove back untouched tail
-                if tail != (start + unyielded_len) {
-                    let src = source_vec.as_ptr().add(tail);
-                    let dst = start_ptr.add(unyielded_len);
-                    ptr::copy(src, dst, this.tail_len);
-                }
-            }
-
-            source_vec.set_len(start + unyielded_len + this.tail_len);
-        }
-    }
-}
-
-#[stable(feature = "vec_drain_as_slice", since = "1.46.0")]
-impl<'a, T, A: Allocator> AsRef<[T]> for Drain<'a, T, A> {
-    fn as_ref(&self) -> &[T] {
-        self.as_slice()
-    }
-}
-
-#[stable(feature = "drain", since = "1.6.0")]
-unsafe impl<T: Sync, A: Sync + Allocator> Sync for Drain<'_, T, A> {}
-#[stable(feature = "drain", since = "1.6.0")]
-unsafe impl<T: Send, A: Send + Allocator> Send for Drain<'_, T, A> {}
-
-#[stable(feature = "drain", since = "1.6.0")]
-impl<T, A: Allocator> Iterator for Drain<'_, T, A> {
-    type Item = T;
-
-    #[inline]
-    fn next(&mut self) -> Option<T> {
-        self.iter.next().map(|elt| unsafe { ptr::read(elt as *const _) })
-    }
-
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        self.iter.size_hint()
-    }
-}
-
-#[stable(feature = "drain", since = "1.6.0")]
-impl<T, A: Allocator> DoubleEndedIterator for Drain<'_, T, A> {
-    #[inline]
-    fn next_back(&mut self) -> Option<T> {
-        self.iter.next_back().map(|elt| unsafe { ptr::read(elt as *const _) })
-    }
-}
-
-#[stable(feature = "drain", since = "1.6.0")]
-impl<T, A: Allocator> Drop for Drain<'_, T, A> {
-    fn drop(&mut self) {
-        /// Moves back the un-`Drain`ed elements to restore the original `Vec`.
-        struct DropGuard<'r, 'a, T, A: Allocator>(&'r mut Drain<'a, T, A>);
-
-        impl<'r, 'a, T, A: Allocator> Drop for DropGuard<'r, 'a, T, A> {
-            fn drop(&mut self) {
-                if self.0.tail_len > 0 {
-                    unsafe {
-                        let source_vec = self.0.vec.as_mut();
-                        // memmove back untouched tail, update to new length
-                        let start = source_vec.len();
-                        let tail = self.0.tail_start;
-                        if tail != start {
-                            let src = source_vec.as_ptr().add(tail);
-                            let dst = source_vec.as_mut_ptr().add(start);
-                            ptr::copy(src, dst, self.0.tail_len);
-                        }
-                        source_vec.set_len(start + self.0.tail_len);
-                    }
-                }
-            }
-        }
-
-        let iter = mem::take(&mut self.iter);
-        let drop_len = iter.len();
-
-        let mut vec = self.vec;
-
-        if T::IS_ZST {
-            // ZSTs have no identity, so we don't need to move them around, we only need to drop the correct amount.
-            // this can be achieved by manipulating the Vec length instead of moving values out from `iter`.
-            unsafe {
-                let vec = vec.as_mut();
-                let old_len = vec.len();
-                vec.set_len(old_len + drop_len + self.tail_len);
-                vec.truncate(old_len + self.tail_len);
-            }
-
-            return;
-        }
-
-        // ensure elements are moved back into their appropriate places, even when drop_in_place panics
-        let _guard = DropGuard(self);
-
-        if drop_len == 0 {
-            return;
-        }
-
-        // as_slice() must only be called when iter.len() is > 0 because
-        // it also gets touched by vec::Splice which may turn it into a dangling pointer
-        // which would make it and the vec pointer point to different allocations which would
-        // lead to invalid pointer arithmetic below.
-        let drop_ptr = iter.as_slice().as_ptr();
-
-        unsafe {
-            // drop_ptr comes from a slice::Iter which only gives us a &[T] but for drop_in_place
-            // a pointer with mutable provenance is necessary. Therefore we must reconstruct
-            // it from the original vec but also avoid creating a &mut to the front since that could
-            // invalidate raw pointers to it which some unsafe code might rely on.
-            let vec_ptr = vec.as_mut().as_mut_ptr();
-            let drop_offset = drop_ptr.sub_ptr(vec_ptr);
-            let to_drop = ptr::slice_from_raw_parts_mut(vec_ptr.add(drop_offset), drop_len);
-            ptr::drop_in_place(to_drop);
-        }
-    }
-}
-
-#[stable(feature = "drain", since = "1.6.0")]
-impl<T, A: Allocator> ExactSizeIterator for Drain<'_, T, A> {
-    fn is_empty(&self) -> bool {
-        self.iter.is_empty()
-    }
-}
-
-#[unstable(feature = "trusted_len", issue = "37572")]
-unsafe impl<T, A: Allocator> TrustedLen for Drain<'_, T, A> {}
-
-#[stable(feature = "fused", since = "1.26.0")]
-impl<T, A: Allocator> FusedIterator for Drain<'_, T, A> {}
diff --git a/rust/alloc/vec/extract_if.rs b/rust/alloc/vec/extract_if.rs
deleted file mode 100644
index f314a51d4d3d..000000000000
--- a/rust/alloc/vec/extract_if.rs
+++ /dev/null
@@ -1,115 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-use crate::alloc::{Allocator, Global};
-use core::ptr;
-use core::slice;
-
-use super::Vec;
-
-/// An iterator which uses a closure to determine if an element should be removed.
-///
-/// This struct is created by [`Vec::extract_if`].
-/// See its documentation for more.
-///
-/// # Example
-///
-/// ```
-/// #![feature(extract_if)]
-///
-/// let mut v = vec![0, 1, 2];
-/// let iter: std::vec::ExtractIf<'_, _, _> = v.extract_if(|x| *x % 2 == 0);
-/// ```
-#[unstable(feature = "extract_if", reason = "recently added", issue = "43244")]
-#[derive(Debug)]
-#[must_use = "iterators are lazy and do nothing unless consumed"]
-pub struct ExtractIf<
-    'a,
-    T,
-    F,
-    #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,
-> where
-    F: FnMut(&mut T) -> bool,
-{
-    pub(super) vec: &'a mut Vec<T, A>,
-    /// The index of the item that will be inspected by the next call to `next`.
-    pub(super) idx: usize,
-    /// The number of items that have been drained (removed) thus far.
-    pub(super) del: usize,
-    /// The original length of `vec` prior to draining.
-    pub(super) old_len: usize,
-    /// The filter test predicate.
-    pub(super) pred: F,
-}
-
-impl<T, F, A: Allocator> ExtractIf<'_, T, F, A>
-where
-    F: FnMut(&mut T) -> bool,
-{
-    /// Returns a reference to the underlying allocator.
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[inline]
-    pub fn allocator(&self) -> &A {
-        self.vec.allocator()
-    }
-}
-
-#[unstable(feature = "extract_if", reason = "recently added", issue = "43244")]
-impl<T, F, A: Allocator> Iterator for ExtractIf<'_, T, F, A>
-where
-    F: FnMut(&mut T) -> bool,
-{
-    type Item = T;
-
-    fn next(&mut self) -> Option<T> {
-        unsafe {
-            while self.idx < self.old_len {
-                let i = self.idx;
-                let v = slice::from_raw_parts_mut(self.vec.as_mut_ptr(), self.old_len);
-                let drained = (self.pred)(&mut v[i]);
-                // Update the index *after* the predicate is called. If the index
-                // is updated prior and the predicate panics, the element at this
-                // index would be leaked.
-                self.idx += 1;
-                if drained {
-                    self.del += 1;
-                    return Some(ptr::read(&v[i]));
-                } else if self.del > 0 {
-                    let del = self.del;
-                    let src: *const T = &v[i];
-                    let dst: *mut T = &mut v[i - del];
-                    ptr::copy_nonoverlapping(src, dst, 1);
-                }
-            }
-            None
-        }
-    }
-
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        (0, Some(self.old_len - self.idx))
-    }
-}
-
-#[unstable(feature = "extract_if", reason = "recently added", issue = "43244")]
-impl<T, F, A: Allocator> Drop for ExtractIf<'_, T, F, A>
-where
-    F: FnMut(&mut T) -> bool,
-{
-    fn drop(&mut self) {
-        unsafe {
-            if self.idx < self.old_len && self.del > 0 {
-                // This is a pretty messed up state, and there isn't really an
-                // obviously right thing to do. We don't want to keep trying
-                // to execute `pred`, so we just backshift all the unprocessed
-                // elements and tell the vec that they still exist. The backshift
-                // is required to prevent a double-drop of the last successfully
-                // drained item prior to a panic in the predicate.
-                let ptr = self.vec.as_mut_ptr();
-                let src = ptr.add(self.idx);
-                let dst = src.sub(self.del);
-                let tail_len = self.old_len - self.idx;
-                src.copy_to(dst, tail_len);
-            }
-            self.vec.set_len(self.old_len - self.del);
-        }
-    }
-}
diff --git a/rust/alloc/vec/into_iter.rs b/rust/alloc/vec/into_iter.rs
deleted file mode 100644
index 136bfe94af6c..000000000000
--- a/rust/alloc/vec/into_iter.rs
+++ /dev/null
@@ -1,454 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-#[cfg(not(no_global_oom_handling))]
-use super::AsVecIntoIter;
-use crate::alloc::{Allocator, Global};
-#[cfg(not(no_global_oom_handling))]
-use crate::collections::VecDeque;
-use crate::raw_vec::RawVec;
-use core::array;
-use core::fmt;
-use core::iter::{
-    FusedIterator, InPlaceIterable, SourceIter, TrustedFused, TrustedLen,
-    TrustedRandomAccessNoCoerce,
-};
-use core::marker::PhantomData;
-use core::mem::{self, ManuallyDrop, MaybeUninit, SizedTypeProperties};
-use core::num::NonZeroUsize;
-#[cfg(not(no_global_oom_handling))]
-use core::ops::Deref;
-use core::ptr::{self, NonNull};
-use core::slice::{self};
-
-/// An iterator that moves out of a vector.
-///
-/// This `struct` is created by the `into_iter` method on [`Vec`](super::Vec)
-/// (provided by the [`IntoIterator`] trait).
-///
-/// # Example
-///
-/// ```
-/// let v = vec![0, 1, 2];
-/// let iter: std::vec::IntoIter<_> = v.into_iter();
-/// ```
-#[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_insignificant_dtor]
-pub struct IntoIter<
-    T,
-    #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,
-> {
-    pub(super) buf: NonNull<T>,
-    pub(super) phantom: PhantomData<T>,
-    pub(super) cap: usize,
-    // the drop impl reconstructs a RawVec from buf, cap and alloc
-    // to avoid dropping the allocator twice we need to wrap it into ManuallyDrop
-    pub(super) alloc: ManuallyDrop<A>,
-    pub(super) ptr: *const T,
-    pub(super) end: *const T, // If T is a ZST, this is actually ptr+len. This encoding is picked so that
-                              // ptr == end is a quick test for the Iterator being empty, that works
-                              // for both ZST and non-ZST.
-}
-
-#[stable(feature = "vec_intoiter_debug", since = "1.13.0")]
-impl<T: fmt::Debug, A: Allocator> fmt::Debug for IntoIter<T, A> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_tuple("IntoIter").field(&self.as_slice()).finish()
-    }
-}
-
-impl<T, A: Allocator> IntoIter<T, A> {
-    /// Returns the remaining items of this iterator as a slice.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let vec = vec!['a', 'b', 'c'];
-    /// let mut into_iter = vec.into_iter();
-    /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']);
-    /// let _ = into_iter.next().unwrap();
-    /// assert_eq!(into_iter.as_slice(), &['b', 'c']);
-    /// ```
-    #[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")]
-    pub fn as_slice(&self) -> &[T] {
-        unsafe { slice::from_raw_parts(self.ptr, self.len()) }
-    }
-
-    /// Returns the remaining items of this iterator as a mutable slice.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let vec = vec!['a', 'b', 'c'];
-    /// let mut into_iter = vec.into_iter();
-    /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']);
-    /// into_iter.as_mut_slice()[2] = 'z';
-    /// assert_eq!(into_iter.next().unwrap(), 'a');
-    /// assert_eq!(into_iter.next().unwrap(), 'b');
-    /// assert_eq!(into_iter.next().unwrap(), 'z');
-    /// ```
-    #[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")]
-    pub fn as_mut_slice(&mut self) -> &mut [T] {
-        unsafe { &mut *self.as_raw_mut_slice() }
-    }
-
-    /// Returns a reference to the underlying allocator.
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[inline]
-    pub fn allocator(&self) -> &A {
-        &self.alloc
-    }
-
-    fn as_raw_mut_slice(&mut self) -> *mut [T] {
-        ptr::slice_from_raw_parts_mut(self.ptr as *mut T, self.len())
-    }
-
-    /// Drops remaining elements and relinquishes the backing allocation.
-    /// This method guarantees it won't panic before relinquishing
-    /// the backing allocation.
-    ///
-    /// This is roughly equivalent to the following, but more efficient
-    ///
-    /// ```
-    /// # let mut into_iter = Vec::<u8>::with_capacity(10).into_iter();
-    /// let mut into_iter = std::mem::replace(&mut into_iter, Vec::new().into_iter());
-    /// (&mut into_iter).for_each(drop);
-    /// std::mem::forget(into_iter);
-    /// ```
-    ///
-    /// This method is used by in-place iteration, refer to the vec::in_place_collect
-    /// documentation for an overview.
-    #[cfg(not(no_global_oom_handling))]
-    pub(super) fn forget_allocation_drop_remaining(&mut self) {
-        let remaining = self.as_raw_mut_slice();
-
-        // overwrite the individual fields instead of creating a new
-        // struct and then overwriting &mut self.
-        // this creates less assembly
-        self.cap = 0;
-        self.buf = unsafe { NonNull::new_unchecked(RawVec::NEW.ptr()) };
-        self.ptr = self.buf.as_ptr();
-        self.end = self.buf.as_ptr();
-
-        // Dropping the remaining elements can panic, so this needs to be
-        // done only after updating the other fields.
-        unsafe {
-            ptr::drop_in_place(remaining);
-        }
-    }
-
-    /// Forgets to Drop the remaining elements while still allowing the backing allocation to be freed.
-    pub(crate) fn forget_remaining_elements(&mut self) {
-        // For th ZST case, it is crucial that we mutate `end` here, not `ptr`.
-        // `ptr` must stay aligned, while `end` may be unaligned.
-        self.end = self.ptr;
-    }
-
-    #[cfg(not(no_global_oom_handling))]
-    #[inline]
-    pub(crate) fn into_vecdeque(self) -> VecDeque<T, A> {
-        // Keep our `Drop` impl from dropping the elements and the allocator
-        let mut this = ManuallyDrop::new(self);
-
-        // SAFETY: This allocation originally came from a `Vec`, so it passes
-        // all those checks. We have `this.buf` ≤ `this.ptr` ≤ `this.end`,
-        // so the `sub_ptr`s below cannot wrap, and will produce a well-formed
-        // range. `end` ≤ `buf + cap`, so the range will be in-bounds.
-        // Taking `alloc` is ok because nothing else is going to look at it,
-        // since our `Drop` impl isn't going to run so there's no more code.
-        unsafe {
-            let buf = this.buf.as_ptr();
-            let initialized = if T::IS_ZST {
-                // All the pointers are the same for ZSTs, so it's fine to
-                // say that they're all at the beginning of the "allocation".
-                0..this.len()
-            } else {
-                this.ptr.sub_ptr(buf)..this.end.sub_ptr(buf)
-            };
-            let cap = this.cap;
-            let alloc = ManuallyDrop::take(&mut this.alloc);
-            VecDeque::from_contiguous_raw_parts_in(buf, initialized, cap, alloc)
-        }
-    }
-}
-
-#[stable(feature = "vec_intoiter_as_ref", since = "1.46.0")]
-impl<T, A: Allocator> AsRef<[T]> for IntoIter<T, A> {
-    fn as_ref(&self) -> &[T] {
-        self.as_slice()
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-unsafe impl<T: Send, A: Allocator + Send> Send for IntoIter<T, A> {}
-#[stable(feature = "rust1", since = "1.0.0")]
-unsafe impl<T: Sync, A: Allocator + Sync> Sync for IntoIter<T, A> {}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, A: Allocator> Iterator for IntoIter<T, A> {
-    type Item = T;
-
-    #[inline]
-    fn next(&mut self) -> Option<T> {
-        if self.ptr == self.end {
-            None
-        } else if T::IS_ZST {
-            // `ptr` has to stay where it is to remain aligned, so we reduce the length by 1 by
-            // reducing the `end`.
-            self.end = self.end.wrapping_byte_sub(1);
-
-            // Make up a value of this ZST.
-            Some(unsafe { mem::zeroed() })
-        } else {
-            let old = self.ptr;
-            self.ptr = unsafe { self.ptr.add(1) };
-
-            Some(unsafe { ptr::read(old) })
-        }
-    }
-
-    #[inline]
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        let exact = if T::IS_ZST {
-            self.end.addr().wrapping_sub(self.ptr.addr())
-        } else {
-            unsafe { self.end.sub_ptr(self.ptr) }
-        };
-        (exact, Some(exact))
-    }
-
-    #[inline]
-    fn advance_by(&mut self, n: usize) -> Result<(), NonZeroUsize> {
-        let step_size = self.len().min(n);
-        let to_drop = ptr::slice_from_raw_parts_mut(self.ptr as *mut T, step_size);
-        if T::IS_ZST {
-            // See `next` for why we sub `end` here.
-            self.end = self.end.wrapping_byte_sub(step_size);
-        } else {
-            // SAFETY: the min() above ensures that step_size is in bounds
-            self.ptr = unsafe { self.ptr.add(step_size) };
-        }
-        // SAFETY: the min() above ensures that step_size is in bounds
-        unsafe {
-            ptr::drop_in_place(to_drop);
-        }
-        NonZeroUsize::new(n - step_size).map_or(Ok(()), Err)
-    }
-
-    #[inline]
-    fn count(self) -> usize {
-        self.len()
-    }
-
-    #[inline]
-    fn next_chunk<const N: usize>(&mut self) -> Result<[T; N], core::array::IntoIter<T, N>> {
-        let mut raw_ary = MaybeUninit::uninit_array();
-
-        let len = self.len();
-
-        if T::IS_ZST {
-            if len < N {
-                self.forget_remaining_elements();
-                // Safety: ZSTs can be conjured ex nihilo, only the amount has to be correct
-                return Err(unsafe { array::IntoIter::new_unchecked(raw_ary, 0..len) });
-            }
-
-            self.end = self.end.wrapping_byte_sub(N);
-            // Safety: ditto
-            return Ok(unsafe { raw_ary.transpose().assume_init() });
-        }
-
-        if len < N {
-            // Safety: `len` indicates that this many elements are available and we just checked that
-            // it fits into the array.
-            unsafe {
-                ptr::copy_nonoverlapping(self.ptr, raw_ary.as_mut_ptr() as *mut T, len);
-                self.forget_remaining_elements();
-                return Err(array::IntoIter::new_unchecked(raw_ary, 0..len));
-            }
-        }
-
-        // Safety: `len` is larger than the array size. Copy a fixed amount here to fully initialize
-        // the array.
-        return unsafe {
-            ptr::copy_nonoverlapping(self.ptr, raw_ary.as_mut_ptr() as *mut T, N);
-            self.ptr = self.ptr.add(N);
-            Ok(raw_ary.transpose().assume_init())
-        };
-    }
-
-    unsafe fn __iterator_get_unchecked(&mut self, i: usize) -> Self::Item
-    where
-        Self: TrustedRandomAccessNoCoerce,
-    {
-        // SAFETY: the caller must guarantee that `i` is in bounds of the
-        // `Vec<T>`, so `i` cannot overflow an `isize`, and the `self.ptr.add(i)`
-        // is guaranteed to pointer to an element of the `Vec<T>` and
-        // thus guaranteed to be valid to dereference.
-        //
-        // Also note the implementation of `Self: TrustedRandomAccess` requires
-        // that `T: Copy` so reading elements from the buffer doesn't invalidate
-        // them for `Drop`.
-        unsafe { if T::IS_ZST { mem::zeroed() } else { ptr::read(self.ptr.add(i)) } }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, A: Allocator> DoubleEndedIterator for IntoIter<T, A> {
-    #[inline]
-    fn next_back(&mut self) -> Option<T> {
-        if self.end == self.ptr {
-            None
-        } else if T::IS_ZST {
-            // See above for why 'ptr.offset' isn't used
-            self.end = self.end.wrapping_byte_sub(1);
-
-            // Make up a value of this ZST.
-            Some(unsafe { mem::zeroed() })
-        } else {
-            self.end = unsafe { self.end.sub(1) };
-
-            Some(unsafe { ptr::read(self.end) })
-        }
-    }
-
-    #[inline]
-    fn advance_back_by(&mut self, n: usize) -> Result<(), NonZeroUsize> {
-        let step_size = self.len().min(n);
-        if T::IS_ZST {
-            // SAFETY: same as for advance_by()
-            self.end = self.end.wrapping_byte_sub(step_size);
-        } else {
-            // SAFETY: same as for advance_by()
-            self.end = unsafe { self.end.sub(step_size) };
-        }
-        let to_drop = ptr::slice_from_raw_parts_mut(self.end as *mut T, step_size);
-        // SAFETY: same as for advance_by()
-        unsafe {
-            ptr::drop_in_place(to_drop);
-        }
-        NonZeroUsize::new(n - step_size).map_or(Ok(()), Err)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, A: Allocator> ExactSizeIterator for IntoIter<T, A> {
-    fn is_empty(&self) -> bool {
-        self.ptr == self.end
-    }
-}
-
-#[stable(feature = "fused", since = "1.26.0")]
-impl<T, A: Allocator> FusedIterator for IntoIter<T, A> {}
-
-#[doc(hidden)]
-#[unstable(issue = "none", feature = "trusted_fused")]
-unsafe impl<T, A: Allocator> TrustedFused for IntoIter<T, A> {}
-
-#[unstable(feature = "trusted_len", issue = "37572")]
-unsafe impl<T, A: Allocator> TrustedLen for IntoIter<T, A> {}
-
-#[stable(feature = "default_iters", since = "1.70.0")]
-impl<T, A> Default for IntoIter<T, A>
-where
-    A: Allocator + Default,
-{
-    /// Creates an empty `vec::IntoIter`.
-    ///
-    /// ```
-    /// # use std::vec;
-    /// let iter: vec::IntoIter<u8> = Default::default();
-    /// assert_eq!(iter.len(), 0);
-    /// assert_eq!(iter.as_slice(), &[]);
-    /// ```
-    fn default() -> Self {
-        super::Vec::new_in(Default::default()).into_iter()
-    }
-}
-
-#[doc(hidden)]
-#[unstable(issue = "none", feature = "std_internals")]
-#[rustc_unsafe_specialization_marker]
-pub trait NonDrop {}
-
-// T: Copy as approximation for !Drop since get_unchecked does not advance self.ptr
-// and thus we can't implement drop-handling
-#[unstable(issue = "none", feature = "std_internals")]
-impl<T: Copy> NonDrop for T {}
-
-#[doc(hidden)]
-#[unstable(issue = "none", feature = "std_internals")]
-// TrustedRandomAccess (without NoCoerce) must not be implemented because
-// subtypes/supertypes of `T` might not be `NonDrop`
-unsafe impl<T, A: Allocator> TrustedRandomAccessNoCoerce for IntoIter<T, A>
-where
-    T: NonDrop,
-{
-    const MAY_HAVE_SIDE_EFFECT: bool = false;
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "vec_into_iter_clone", since = "1.8.0")]
-impl<T: Clone, A: Allocator + Clone> Clone for IntoIter<T, A> {
-    #[cfg(not(test))]
-    fn clone(&self) -> Self {
-        self.as_slice().to_vec_in(self.alloc.deref().clone()).into_iter()
-    }
-    #[cfg(test)]
-    fn clone(&self) -> Self {
-        crate::slice::to_vec(self.as_slice(), self.alloc.deref().clone()).into_iter()
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-unsafe impl<#[may_dangle] T, A: Allocator> Drop for IntoIter<T, A> {
-    fn drop(&mut self) {
-        struct DropGuard<'a, T, A: Allocator>(&'a mut IntoIter<T, A>);
-
-        impl<T, A: Allocator> Drop for DropGuard<'_, T, A> {
-            fn drop(&mut self) {
-                unsafe {
-                    // `IntoIter::alloc` is not used anymore after this and will be dropped by RawVec
-                    let alloc = ManuallyDrop::take(&mut self.0.alloc);
-                    // RawVec handles deallocation
-                    let _ = RawVec::from_raw_parts_in(self.0.buf.as_ptr(), self.0.cap, alloc);
-                }
-            }
-        }
-
-        let guard = DropGuard(self);
-        // destroy the remaining elements
-        unsafe {
-            ptr::drop_in_place(guard.0.as_raw_mut_slice());
-        }
-        // now `guard` will be dropped and do the rest
-    }
-}
-
-// In addition to the SAFETY invariants of the following three unsafe traits
-// also refer to the vec::in_place_collect module documentation to get an overview
-#[unstable(issue = "none", feature = "inplace_iteration")]
-#[doc(hidden)]
-unsafe impl<T, A: Allocator> InPlaceIterable for IntoIter<T, A> {
-    const EXPAND_BY: Option<NonZeroUsize> = NonZeroUsize::new(1);
-    const MERGE_BY: Option<NonZeroUsize> = NonZeroUsize::new(1);
-}
-
-#[unstable(issue = "none", feature = "inplace_iteration")]
-#[doc(hidden)]
-unsafe impl<T, A: Allocator> SourceIter for IntoIter<T, A> {
-    type Source = Self;
-
-    #[inline]
-    unsafe fn as_inner(&mut self) -> &mut Self::Source {
-        self
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-unsafe impl<T> AsVecIntoIter for IntoIter<T> {
-    type Item = T;
-
-    fn as_into_iter(&mut self) -> &mut IntoIter<Self::Item> {
-        self
-    }
-}
diff --git a/rust/alloc/vec/is_zero.rs b/rust/alloc/vec/is_zero.rs
deleted file mode 100644
index d928dcf90e80..000000000000
--- a/rust/alloc/vec/is_zero.rs
+++ /dev/null
@@ -1,204 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-use core::num::{Saturating, Wrapping};
-
-use crate::boxed::Box;
-
-#[rustc_specialization_trait]
-pub(super) unsafe trait IsZero {
-    /// Whether this value's representation is all zeros,
-    /// or can be represented with all zeroes.
-    fn is_zero(&self) -> bool;
-}
-
-macro_rules! impl_is_zero {
-    ($t:ty, $is_zero:expr) => {
-        unsafe impl IsZero for $t {
-            #[inline]
-            fn is_zero(&self) -> bool {
-                $is_zero(*self)
-            }
-        }
-    };
-}
-
-impl_is_zero!(i8, |x| x == 0); // It is needed to impl for arrays and tuples of i8.
-impl_is_zero!(i16, |x| x == 0);
-impl_is_zero!(i32, |x| x == 0);
-impl_is_zero!(i64, |x| x == 0);
-impl_is_zero!(i128, |x| x == 0);
-impl_is_zero!(isize, |x| x == 0);
-
-impl_is_zero!(u8, |x| x == 0); // It is needed to impl for arrays and tuples of u8.
-impl_is_zero!(u16, |x| x == 0);
-impl_is_zero!(u32, |x| x == 0);
-impl_is_zero!(u64, |x| x == 0);
-impl_is_zero!(u128, |x| x == 0);
-impl_is_zero!(usize, |x| x == 0);
-
-impl_is_zero!(bool, |x| x == false);
-impl_is_zero!(char, |x| x == '\0');
-
-impl_is_zero!(f32, |x: f32| x.to_bits() == 0);
-impl_is_zero!(f64, |x: f64| x.to_bits() == 0);
-
-unsafe impl<T> IsZero for *const T {
-    #[inline]
-    fn is_zero(&self) -> bool {
-        (*self).is_null()
-    }
-}
-
-unsafe impl<T> IsZero for *mut T {
-    #[inline]
-    fn is_zero(&self) -> bool {
-        (*self).is_null()
-    }
-}
-
-unsafe impl<T: IsZero, const N: usize> IsZero for [T; N] {
-    #[inline]
-    fn is_zero(&self) -> bool {
-        // Because this is generated as a runtime check, it's not obvious that
-        // it's worth doing if the array is really long. The threshold here
-        // is largely arbitrary, but was picked because as of 2022-07-01 LLVM
-        // fails to const-fold the check in `vec![[1; 32]; n]`
-        // See https://github.com/rust-lang/rust/pull/97581#issuecomment-1166628022
-        // Feel free to tweak if you have better evidence.
-
-        N <= 16 && self.iter().all(IsZero::is_zero)
-    }
-}
-
-// This is recursive macro.
-macro_rules! impl_for_tuples {
-    // Stopper
-    () => {
-        // No use for implementing for empty tuple because it is ZST.
-    };
-    ($first_arg:ident $(,$rest:ident)*) => {
-        unsafe impl <$first_arg: IsZero, $($rest: IsZero,)*> IsZero for ($first_arg, $($rest,)*){
-            #[inline]
-            fn is_zero(&self) -> bool{
-                // Destructure tuple to N references
-                // Rust allows to hide generic params by local variable names.
-                #[allow(non_snake_case)]
-                let ($first_arg, $($rest,)*) = self;
-
-                $first_arg.is_zero()
-                    $( && $rest.is_zero() )*
-            }
-        }
-
-        impl_for_tuples!($($rest),*);
-    }
-}
-
-impl_for_tuples!(A, B, C, D, E, F, G, H);
-
-// `Option<&T>` and `Option<Box<T>>` are guaranteed to represent `None` as null.
-// For fat pointers, the bytes that would be the pointer metadata in the `Some`
-// variant are padding in the `None` variant, so ignoring them and
-// zero-initializing instead is ok.
-// `Option<&mut T>` never implements `Clone`, so there's no need for an impl of
-// `SpecFromElem`.
-
-unsafe impl<T: ?Sized> IsZero for Option<&T> {
-    #[inline]
-    fn is_zero(&self) -> bool {
-        self.is_none()
-    }
-}
-
-unsafe impl<T: ?Sized> IsZero for Option<Box<T>> {
-    #[inline]
-    fn is_zero(&self) -> bool {
-        self.is_none()
-    }
-}
-
-// `Option<num::NonZeroU32>` and similar have a representation guarantee that
-// they're the same size as the corresponding `u32` type, as well as a guarantee
-// that transmuting between `NonZeroU32` and `Option<num::NonZeroU32>` works.
-// While the documentation officially makes it UB to transmute from `None`,
-// we're the standard library so we can make extra inferences, and we know that
-// the only niche available to represent `None` is the one that's all zeros.
-
-macro_rules! impl_is_zero_option_of_nonzero {
-    ($($t:ident,)+) => {$(
-        unsafe impl IsZero for Option<core::num::$t> {
-            #[inline]
-            fn is_zero(&self) -> bool {
-                self.is_none()
-            }
-        }
-    )+};
-}
-
-impl_is_zero_option_of_nonzero!(
-    NonZeroU8,
-    NonZeroU16,
-    NonZeroU32,
-    NonZeroU64,
-    NonZeroU128,
-    NonZeroI8,
-    NonZeroI16,
-    NonZeroI32,
-    NonZeroI64,
-    NonZeroI128,
-    NonZeroUsize,
-    NonZeroIsize,
-);
-
-macro_rules! impl_is_zero_option_of_num {
-    ($($t:ty,)+) => {$(
-        unsafe impl IsZero for Option<$t> {
-            #[inline]
-            fn is_zero(&self) -> bool {
-                const {
-                    let none: Self = unsafe { core::mem::MaybeUninit::zeroed().assume_init() };
-                    assert!(none.is_none());
-                }
-                self.is_none()
-            }
-        }
-    )+};
-}
-
-impl_is_zero_option_of_num!(u8, u16, u32, u64, u128, i8, i16, i32, i64, i128, usize, isize,);
-
-unsafe impl<T: IsZero> IsZero for Wrapping<T> {
-    #[inline]
-    fn is_zero(&self) -> bool {
-        self.0.is_zero()
-    }
-}
-
-unsafe impl<T: IsZero> IsZero for Saturating<T> {
-    #[inline]
-    fn is_zero(&self) -> bool {
-        self.0.is_zero()
-    }
-}
-
-macro_rules! impl_for_optional_bool {
-    ($($t:ty,)+) => {$(
-        unsafe impl IsZero for $t {
-            #[inline]
-            fn is_zero(&self) -> bool {
-                // SAFETY: This is *not* a stable layout guarantee, but
-                // inside `core` we're allowed to rely on the current rustc
-                // behaviour that options of bools will be one byte with
-                // no padding, so long as they're nested less than 254 deep.
-                let raw: u8 = unsafe { core::mem::transmute(*self) };
-                raw == 0
-            }
-        }
-    )+};
-}
-impl_for_optional_bool! {
-    Option<bool>,
-    Option<Option<bool>>,
-    Option<Option<Option<bool>>>,
-    // Could go further, but not worth the metadata overhead
-}
diff --git a/rust/alloc/vec/mod.rs b/rust/alloc/vec/mod.rs
deleted file mode 100644
index 220fb9d6f45b..000000000000
--- a/rust/alloc/vec/mod.rs
+++ /dev/null
@@ -1,3683 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-//! A contiguous growable array type with heap-allocated contents, written
-//! `Vec<T>`.
-//!
-//! Vectors have *O*(1) indexing, amortized *O*(1) push (to the end) and
-//! *O*(1) pop (from the end).
-//!
-//! Vectors ensure they never allocate more than `isize::MAX` bytes.
-//!
-//! # Examples
-//!
-//! You can explicitly create a [`Vec`] with [`Vec::new`]:
-//!
-//! ```
-//! let v: Vec<i32> = Vec::new();
-//! ```
-//!
-//! ...or by using the [`vec!`] macro:
-//!
-//! ```
-//! let v: Vec<i32> = vec![];
-//!
-//! let v = vec![1, 2, 3, 4, 5];
-//!
-//! let v = vec![0; 10]; // ten zeroes
-//! ```
-//!
-//! You can [`push`] values onto the end of a vector (which will grow the vector
-//! as needed):
-//!
-//! ```
-//! let mut v = vec![1, 2];
-//!
-//! v.push(3);
-//! ```
-//!
-//! Popping values works in much the same way:
-//!
-//! ```
-//! let mut v = vec![1, 2];
-//!
-//! let two = v.pop();
-//! ```
-//!
-//! Vectors also support indexing (through the [`Index`] and [`IndexMut`] traits):
-//!
-//! ```
-//! let mut v = vec![1, 2, 3];
-//! let three = v[2];
-//! v[1] = v[1] + 5;
-//! ```
-//!
-//! [`push`]: Vec::push
-
-#![stable(feature = "rust1", since = "1.0.0")]
-
-#[cfg(not(no_global_oom_handling))]
-use core::cmp;
-use core::cmp::Ordering;
-use core::fmt;
-use core::hash::{Hash, Hasher};
-use core::iter;
-use core::marker::PhantomData;
-use core::mem::{self, ManuallyDrop, MaybeUninit, SizedTypeProperties};
-use core::ops::{self, Index, IndexMut, Range, RangeBounds};
-use core::ptr::{self, NonNull};
-use core::slice::{self, SliceIndex};
-
-use crate::alloc::{Allocator, Global};
-#[cfg(not(no_borrow))]
-use crate::borrow::{Cow, ToOwned};
-use crate::boxed::Box;
-use crate::collections::{TryReserveError, TryReserveErrorKind};
-use crate::raw_vec::RawVec;
-
-#[unstable(feature = "extract_if", reason = "recently added", issue = "43244")]
-pub use self::extract_if::ExtractIf;
-
-mod extract_if;
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "vec_splice", since = "1.21.0")]
-pub use self::splice::Splice;
-
-#[cfg(not(no_global_oom_handling))]
-mod splice;
-
-#[stable(feature = "drain", since = "1.6.0")]
-pub use self::drain::Drain;
-
-mod drain;
-
-#[cfg(not(no_borrow))]
-#[cfg(not(no_global_oom_handling))]
-mod cow;
-
-#[cfg(not(no_global_oom_handling))]
-pub(crate) use self::in_place_collect::AsVecIntoIter;
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use self::into_iter::IntoIter;
-
-mod into_iter;
-
-#[cfg(not(no_global_oom_handling))]
-use self::is_zero::IsZero;
-
-#[cfg(not(no_global_oom_handling))]
-mod is_zero;
-
-#[cfg(not(no_global_oom_handling))]
-mod in_place_collect;
-
-mod partial_eq;
-
-#[cfg(not(no_global_oom_handling))]
-use self::spec_from_elem::SpecFromElem;
-
-#[cfg(not(no_global_oom_handling))]
-mod spec_from_elem;
-
-use self::set_len_on_drop::SetLenOnDrop;
-
-mod set_len_on_drop;
-
-#[cfg(not(no_global_oom_handling))]
-use self::in_place_drop::{InPlaceDrop, InPlaceDstDataSrcBufDrop};
-
-#[cfg(not(no_global_oom_handling))]
-mod in_place_drop;
-
-#[cfg(not(no_global_oom_handling))]
-use self::spec_from_iter_nested::SpecFromIterNested;
-
-#[cfg(not(no_global_oom_handling))]
-mod spec_from_iter_nested;
-
-#[cfg(not(no_global_oom_handling))]
-use self::spec_from_iter::SpecFromIter;
-
-#[cfg(not(no_global_oom_handling))]
-mod spec_from_iter;
-
-#[cfg(not(no_global_oom_handling))]
-use self::spec_extend::SpecExtend;
-
-use self::spec_extend::TrySpecExtend;
-
-mod spec_extend;
-
-/// A contiguous growable array type, written as `Vec<T>`, short for 'vector'.
-///
-/// # Examples
-///
-/// ```
-/// let mut vec = Vec::new();
-/// vec.push(1);
-/// vec.push(2);
-///
-/// assert_eq!(vec.len(), 2);
-/// assert_eq!(vec[0], 1);
-///
-/// assert_eq!(vec.pop(), Some(2));
-/// assert_eq!(vec.len(), 1);
-///
-/// vec[0] = 7;
-/// assert_eq!(vec[0], 7);
-///
-/// vec.extend([1, 2, 3]);
-///
-/// for x in &vec {
-///     println!("{x}");
-/// }
-/// assert_eq!(vec, [7, 1, 2, 3]);
-/// ```
-///
-/// The [`vec!`] macro is provided for convenient initialization:
-///
-/// ```
-/// let mut vec1 = vec![1, 2, 3];
-/// vec1.push(4);
-/// let vec2 = Vec::from([1, 2, 3, 4]);
-/// assert_eq!(vec1, vec2);
-/// ```
-///
-/// It can also initialize each element of a `Vec<T>` with a given value.
-/// This may be more efficient than performing allocation and initialization
-/// in separate steps, especially when initializing a vector of zeros:
-///
-/// ```
-/// let vec = vec![0; 5];
-/// assert_eq!(vec, [0, 0, 0, 0, 0]);
-///
-/// // The following is equivalent, but potentially slower:
-/// let mut vec = Vec::with_capacity(5);
-/// vec.resize(5, 0);
-/// assert_eq!(vec, [0, 0, 0, 0, 0]);
-/// ```
-///
-/// For more information, see
-/// [Capacity and Reallocation](#capacity-and-reallocation).
-///
-/// Use a `Vec<T>` as an efficient stack:
-///
-/// ```
-/// let mut stack = Vec::new();
-///
-/// stack.push(1);
-/// stack.push(2);
-/// stack.push(3);
-///
-/// while let Some(top) = stack.pop() {
-///     // Prints 3, 2, 1
-///     println!("{top}");
-/// }
-/// ```
-///
-/// # Indexing
-///
-/// The `Vec` type allows access to values by index, because it implements the
-/// [`Index`] trait. An example will be more explicit:
-///
-/// ```
-/// let v = vec![0, 2, 4, 6];
-/// println!("{}", v[1]); // it will display '2'
-/// ```
-///
-/// However be careful: if you try to access an index which isn't in the `Vec`,
-/// your software will panic! You cannot do this:
-///
-/// ```should_panic
-/// let v = vec![0, 2, 4, 6];
-/// println!("{}", v[6]); // it will panic!
-/// ```
-///
-/// Use [`get`] and [`get_mut`] if you want to check whether the index is in
-/// the `Vec`.
-///
-/// # Slicing
-///
-/// A `Vec` can be mutable. On the other hand, slices are read-only objects.
-/// To get a [slice][prim@slice], use [`&`]. Example:
-///
-/// ```
-/// fn read_slice(slice: &[usize]) {
-///     // ...
-/// }
-///
-/// let v = vec![0, 1];
-/// read_slice(&v);
-///
-/// // ... and that's all!
-/// // you can also do it like this:
-/// let u: &[usize] = &v;
-/// // or like this:
-/// let u: &[_] = &v;
-/// ```
-///
-/// In Rust, it's more common to pass slices as arguments rather than vectors
-/// when you just want to provide read access. The same goes for [`String`] and
-/// [`&str`].
-///
-/// # Capacity and reallocation
-///
-/// The capacity of a vector is the amount of space allocated for any future
-/// elements that will be added onto the vector. This is not to be confused with
-/// the *length* of a vector, which specifies the number of actual elements
-/// within the vector. If a vector's length exceeds its capacity, its capacity
-/// will automatically be increased, but its elements will have to be
-/// reallocated.
-///
-/// For example, a vector with capacity 10 and length 0 would be an empty vector
-/// with space for 10 more elements. Pushing 10 or fewer elements onto the
-/// vector will not change its capacity or cause reallocation to occur. However,
-/// if the vector's length is increased to 11, it will have to reallocate, which
-/// can be slow. For this reason, it is recommended to use [`Vec::with_capacity`]
-/// whenever possible to specify how big the vector is expected to get.
-///
-/// # Guarantees
-///
-/// Due to its incredibly fundamental nature, `Vec` makes a lot of guarantees
-/// about its design. This ensures that it's as low-overhead as possible in
-/// the general case, and can be correctly manipulated in primitive ways
-/// by unsafe code. Note that these guarantees refer to an unqualified `Vec<T>`.
-/// If additional type parameters are added (e.g., to support custom allocators),
-/// overriding their defaults may change the behavior.
-///
-/// Most fundamentally, `Vec` is and always will be a (pointer, capacity, length)
-/// triplet. No more, no less. The order of these fields is completely
-/// unspecified, and you should use the appropriate methods to modify these.
-/// The pointer will never be null, so this type is null-pointer-optimized.
-///
-/// However, the pointer might not actually point to allocated memory. In particular,
-/// if you construct a `Vec` with capacity 0 via [`Vec::new`], [`vec![]`][`vec!`],
-/// [`Vec::with_capacity(0)`][`Vec::with_capacity`], or by calling [`shrink_to_fit`]
-/// on an empty Vec, it will not allocate memory. Similarly, if you store zero-sized
-/// types inside a `Vec`, it will not allocate space for them. *Note that in this case
-/// the `Vec` might not report a [`capacity`] of 0*. `Vec` will allocate if and only
-/// if <code>[mem::size_of::\<T>]\() * [capacity]\() > 0</code>. In general, `Vec`'s allocation
-/// details are very subtle --- if you intend to allocate memory using a `Vec`
-/// and use it for something else (either to pass to unsafe code, or to build your
-/// own memory-backed collection), be sure to deallocate this memory by using
-/// `from_raw_parts` to recover the `Vec` and then dropping it.
-///
-/// If a `Vec` *has* allocated memory, then the memory it points to is on the heap
-/// (as defined by the allocator Rust is configured to use by default), and its
-/// pointer points to [`len`] initialized, contiguous elements in order (what
-/// you would see if you coerced it to a slice), followed by <code>[capacity] - [len]</code>
-/// logically uninitialized, contiguous elements.
-///
-/// A vector containing the elements `'a'` and `'b'` with capacity 4 can be
-/// visualized as below. The top part is the `Vec` struct, it contains a
-/// pointer to the head of the allocation in the heap, length and capacity.
-/// The bottom part is the allocation on the heap, a contiguous memory block.
-///
-/// ```text
-///             ptr      len  capacity
-///        +--------+--------+--------+
-///        | 0x0123 |      2 |      4 |
-///        +--------+--------+--------+
-///             |
-///             v
-/// Heap   +--------+--------+--------+--------+
-///        |    'a' |    'b' | uninit | uninit |
-///        +--------+--------+--------+--------+
-/// ```
-///
-/// - **uninit** represents memory that is not initialized, see [`MaybeUninit`].
-/// - Note: the ABI is not stable and `Vec` makes no guarantees about its memory
-///   layout (including the order of fields).
-///
-/// `Vec` will never perform a "small optimization" where elements are actually
-/// stored on the stack for two reasons:
-///
-/// * It would make it more difficult for unsafe code to correctly manipulate
-///   a `Vec`. The contents of a `Vec` wouldn't have a stable address if it were
-///   only moved, and it would be more difficult to determine if a `Vec` had
-///   actually allocated memory.
-///
-/// * It would penalize the general case, incurring an additional branch
-///   on every access.
-///
-/// `Vec` will never automatically shrink itself, even if completely empty. This
-/// ensures no unnecessary allocations or deallocations occur. Emptying a `Vec`
-/// and then filling it back up to the same [`len`] should incur no calls to
-/// the allocator. If you wish to free up unused memory, use
-/// [`shrink_to_fit`] or [`shrink_to`].
-///
-/// [`push`] and [`insert`] will never (re)allocate if the reported capacity is
-/// sufficient. [`push`] and [`insert`] *will* (re)allocate if
-/// <code>[len] == [capacity]</code>. That is, the reported capacity is completely
-/// accurate, and can be relied on. It can even be used to manually free the memory
-/// allocated by a `Vec` if desired. Bulk insertion methods *may* reallocate, even
-/// when not necessary.
-///
-/// `Vec` does not guarantee any particular growth strategy when reallocating
-/// when full, nor when [`reserve`] is called. The current strategy is basic
-/// and it may prove desirable to use a non-constant growth factor. Whatever
-/// strategy is used will of course guarantee *O*(1) amortized [`push`].
-///
-/// `vec![x; n]`, `vec![a, b, c, d]`, and
-/// [`Vec::with_capacity(n)`][`Vec::with_capacity`], will all produce a `Vec`
-/// with exactly the requested capacity. If <code>[len] == [capacity]</code>,
-/// (as is the case for the [`vec!`] macro), then a `Vec<T>` can be converted to
-/// and from a [`Box<[T]>`][owned slice] without reallocating or moving the elements.
-///
-/// `Vec` will not specifically overwrite any data that is removed from it,
-/// but also won't specifically preserve it. Its uninitialized memory is
-/// scratch space that it may use however it wants. It will generally just do
-/// whatever is most efficient or otherwise easy to implement. Do not rely on
-/// removed data to be erased for security purposes. Even if you drop a `Vec`, its
-/// buffer may simply be reused by another allocation. Even if you zero a `Vec`'s memory
-/// first, that might not actually happen because the optimizer does not consider
-/// this a side-effect that must be preserved. There is one case which we will
-/// not break, however: using `unsafe` code to write to the excess capacity,
-/// and then increasing the length to match, is always valid.
-///
-/// Currently, `Vec` does not guarantee the order in which elements are dropped.
-/// The order has changed in the past and may change again.
-///
-/// [`get`]: slice::get
-/// [`get_mut`]: slice::get_mut
-/// [`String`]: crate::string::String
-/// [`&str`]: type@str
-/// [`shrink_to_fit`]: Vec::shrink_to_fit
-/// [`shrink_to`]: Vec::shrink_to
-/// [capacity]: Vec::capacity
-/// [`capacity`]: Vec::capacity
-/// [mem::size_of::\<T>]: core::mem::size_of
-/// [len]: Vec::len
-/// [`len`]: Vec::len
-/// [`push`]: Vec::push
-/// [`insert`]: Vec::insert
-/// [`reserve`]: Vec::reserve
-/// [`MaybeUninit`]: core::mem::MaybeUninit
-/// [owned slice]: Box
-#[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "Vec")]
-#[rustc_insignificant_dtor]
-pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> {
-    buf: RawVec<T, A>,
-    len: usize,
-}
-
-////////////////////////////////////////////////////////////////////////////////
-// Inherent methods
-////////////////////////////////////////////////////////////////////////////////
-
-impl<T> Vec<T> {
-    /// Constructs a new, empty `Vec<T>`.
-    ///
-    /// The vector will not allocate until elements are pushed onto it.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// # #![allow(unused_mut)]
-    /// let mut vec: Vec<i32> = Vec::new();
-    /// ```
-    #[inline]
-    #[rustc_const_stable(feature = "const_vec_new", since = "1.39.0")]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    #[must_use]
-    pub const fn new() -> Self {
-        Vec { buf: RawVec::NEW, len: 0 }
-    }
-
-    /// Constructs a new, empty `Vec<T>` with at least the specified capacity.
-    ///
-    /// The vector will be able to hold at least `capacity` elements without
-    /// reallocating. This method is allowed to allocate for more elements than
-    /// `capacity`. If `capacity` is 0, the vector will not allocate.
-    ///
-    /// It is important to note that although the returned vector has the
-    /// minimum *capacity* specified, the vector will have a zero *length*. For
-    /// an explanation of the difference between length and capacity, see
-    /// *[Capacity and reallocation]*.
-    ///
-    /// If it is important to know the exact allocated capacity of a `Vec`,
-    /// always use the [`capacity`] method after construction.
-    ///
-    /// For `Vec<T>` where `T` is a zero-sized type, there will be no allocation
-    /// and the capacity will always be `usize::MAX`.
-    ///
-    /// [Capacity and reallocation]: #capacity-and-reallocation
-    /// [`capacity`]: Vec::capacity
-    ///
-    /// # Panics
-    ///
-    /// Panics if the new capacity exceeds `isize::MAX` bytes.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = Vec::with_capacity(10);
-    ///
-    /// // The vector contains no items, even though it has capacity for more
-    /// assert_eq!(vec.len(), 0);
-    /// assert!(vec.capacity() >= 10);
-    ///
-    /// // These are all done without reallocating...
-    /// for i in 0..10 {
-    ///     vec.push(i);
-    /// }
-    /// assert_eq!(vec.len(), 10);
-    /// assert!(vec.capacity() >= 10);
-    ///
-    /// // ...but this may make the vector reallocate
-    /// vec.push(11);
-    /// assert_eq!(vec.len(), 11);
-    /// assert!(vec.capacity() >= 11);
-    ///
-    /// // A vector of a zero-sized type will always over-allocate, since no
-    /// // allocation is necessary
-    /// let vec_units = Vec::<()>::with_capacity(10);
-    /// assert_eq!(vec_units.capacity(), usize::MAX);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    #[must_use]
-    pub fn with_capacity(capacity: usize) -> Self {
-        Self::with_capacity_in(capacity, Global)
-    }
-
-    /// Tries to construct a new, empty `Vec<T>` with at least the specified capacity.
-    ///
-    /// The vector will be able to hold at least `capacity` elements without
-    /// reallocating. This method is allowed to allocate for more elements than
-    /// `capacity`. If `capacity` is 0, the vector will not allocate.
-    ///
-    /// It is important to note that although the returned vector has the
-    /// minimum *capacity* specified, the vector will have a zero *length*. For
-    /// an explanation of the difference between length and capacity, see
-    /// *[Capacity and reallocation]*.
-    ///
-    /// If it is important to know the exact allocated capacity of a `Vec`,
-    /// always use the [`capacity`] method after construction.
-    ///
-    /// For `Vec<T>` where `T` is a zero-sized type, there will be no allocation
-    /// and the capacity will always be `usize::MAX`.
-    ///
-    /// [Capacity and reallocation]: #capacity-and-reallocation
-    /// [`capacity`]: Vec::capacity
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = Vec::try_with_capacity(10).unwrap();
-    ///
-    /// // The vector contains no items, even though it has capacity for more
-    /// assert_eq!(vec.len(), 0);
-    /// assert!(vec.capacity() >= 10);
-    ///
-    /// // These are all done without reallocating...
-    /// for i in 0..10 {
-    ///     vec.push(i);
-    /// }
-    /// assert_eq!(vec.len(), 10);
-    /// assert!(vec.capacity() >= 10);
-    ///
-    /// // ...but this may make the vector reallocate
-    /// vec.push(11);
-    /// assert_eq!(vec.len(), 11);
-    /// assert!(vec.capacity() >= 11);
-    ///
-    /// let mut result = Vec::try_with_capacity(usize::MAX);
-    /// assert!(result.is_err());
-    ///
-    /// // A vector of a zero-sized type will always over-allocate, since no
-    /// // allocation is necessary
-    /// let vec_units = Vec::<()>::try_with_capacity(10).unwrap();
-    /// assert_eq!(vec_units.capacity(), usize::MAX);
-    /// ```
-    #[inline]
-    #[stable(feature = "kernel", since = "1.0.0")]
-    pub fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError> {
-        Self::try_with_capacity_in(capacity, Global)
-    }
-
-    /// Creates a `Vec<T>` directly from a pointer, a capacity, and a length.
-    ///
-    /// # Safety
-    ///
-    /// This is highly unsafe, due to the number of invariants that aren't
-    /// checked:
-    ///
-    /// * `ptr` must have been allocated using the global allocator, such as via
-    ///   the [`alloc::alloc`] function.
-    /// * `T` needs to have the same alignment as what `ptr` was allocated with.
-    ///   (`T` having a less strict alignment is not sufficient, the alignment really
-    ///   needs to be equal to satisfy the [`dealloc`] requirement that memory must be
-    ///   allocated and deallocated with the same layout.)
-    /// * The size of `T` times the `capacity` (ie. the allocated size in bytes) needs
-    ///   to be the same size as the pointer was allocated with. (Because similar to
-    ///   alignment, [`dealloc`] must be called with the same layout `size`.)
-    /// * `length` needs to be less than or equal to `capacity`.
-    /// * The first `length` values must be properly initialized values of type `T`.
-    /// * `capacity` needs to be the capacity that the pointer was allocated with.
-    /// * The allocated size in bytes must be no larger than `isize::MAX`.
-    ///   See the safety documentation of [`pointer::offset`].
-    ///
-    /// These requirements are always upheld by any `ptr` that has been allocated
-    /// via `Vec<T>`. Other allocation sources are allowed if the invariants are
-    /// upheld.
-    ///
-    /// Violating these may cause problems like corrupting the allocator's
-    /// internal data structures. For example it is normally **not** safe
-    /// to build a `Vec<u8>` from a pointer to a C `char` array with length
-    /// `size_t`, doing so is only safe if the array was initially allocated by
-    /// a `Vec` or `String`.
-    /// It's also not safe to build one from a `Vec<u16>` and its length, because
-    /// the allocator cares about the alignment, and these two types have different
-    /// alignments. The buffer was allocated with alignment 2 (for `u16`), but after
-    /// turning it into a `Vec<u8>` it'll be deallocated with alignment 1. To avoid
-    /// these issues, it is often preferable to do casting/transmuting using
-    /// [`slice::from_raw_parts`] instead.
-    ///
-    /// The ownership of `ptr` is effectively transferred to the
-    /// `Vec<T>` which may then deallocate, reallocate or change the
-    /// contents of memory pointed to by the pointer at will. Ensure
-    /// that nothing else uses the pointer after calling this
-    /// function.
-    ///
-    /// [`String`]: crate::string::String
-    /// [`alloc::alloc`]: crate::alloc::alloc
-    /// [`dealloc`]: crate::alloc::GlobalAlloc::dealloc
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::ptr;
-    /// use std::mem;
-    ///
-    /// let v = vec![1, 2, 3];
-    ///
-    // FIXME Update this when vec_into_raw_parts is stabilized
-    /// // Prevent running `v`'s destructor so we are in complete control
-    /// // of the allocation.
-    /// let mut v = mem::ManuallyDrop::new(v);
-    ///
-    /// // Pull out the various important pieces of information about `v`
-    /// let p = v.as_mut_ptr();
-    /// let len = v.len();
-    /// let cap = v.capacity();
-    ///
-    /// unsafe {
-    ///     // Overwrite memory with 4, 5, 6
-    ///     for i in 0..len {
-    ///         ptr::write(p.add(i), 4 + i);
-    ///     }
-    ///
-    ///     // Put everything back together into a Vec
-    ///     let rebuilt = Vec::from_raw_parts(p, len, cap);
-    ///     assert_eq!(rebuilt, [4, 5, 6]);
-    /// }
-    /// ```
-    ///
-    /// Using memory that was allocated elsewhere:
-    ///
-    /// ```rust
-    /// use std::alloc::{alloc, Layout};
-    ///
-    /// fn main() {
-    ///     let layout = Layout::array::<u32>(16).expect("overflow cannot happen");
-    ///
-    ///     let vec = unsafe {
-    ///         let mem = alloc(layout).cast::<u32>();
-    ///         if mem.is_null() {
-    ///             return;
-    ///         }
-    ///
-    ///         mem.write(1_000_000);
-    ///
-    ///         Vec::from_raw_parts(mem, 1, 16)
-    ///     };
-    ///
-    ///     assert_eq!(vec, &[1_000_000]);
-    ///     assert_eq!(vec.capacity(), 16);
-    /// }
-    /// ```
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Self {
-        unsafe { Self::from_raw_parts_in(ptr, length, capacity, Global) }
-    }
-}
-
-impl<T, A: Allocator> Vec<T, A> {
-    /// Constructs a new, empty `Vec<T, A>`.
-    ///
-    /// The vector will not allocate until elements are pushed onto it.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// # #[allow(unused_mut)]
-    /// let mut vec: Vec<i32, _> = Vec::new_in(System);
-    /// ```
-    #[inline]
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    pub const fn new_in(alloc: A) -> Self {
-        Vec { buf: RawVec::new_in(alloc), len: 0 }
-    }
-
-    /// Constructs a new, empty `Vec<T, A>` with at least the specified capacity
-    /// with the provided allocator.
-    ///
-    /// The vector will be able to hold at least `capacity` elements without
-    /// reallocating. This method is allowed to allocate for more elements than
-    /// `capacity`. If `capacity` is 0, the vector will not allocate.
-    ///
-    /// It is important to note that although the returned vector has the
-    /// minimum *capacity* specified, the vector will have a zero *length*. For
-    /// an explanation of the difference between length and capacity, see
-    /// *[Capacity and reallocation]*.
-    ///
-    /// If it is important to know the exact allocated capacity of a `Vec`,
-    /// always use the [`capacity`] method after construction.
-    ///
-    /// For `Vec<T, A>` where `T` is a zero-sized type, there will be no allocation
-    /// and the capacity will always be `usize::MAX`.
-    ///
-    /// [Capacity and reallocation]: #capacity-and-reallocation
-    /// [`capacity`]: Vec::capacity
-    ///
-    /// # Panics
-    ///
-    /// Panics if the new capacity exceeds `isize::MAX` bytes.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// let mut vec = Vec::with_capacity_in(10, System);
-    ///
-    /// // The vector contains no items, even though it has capacity for more
-    /// assert_eq!(vec.len(), 0);
-    /// assert!(vec.capacity() >= 10);
-    ///
-    /// // These are all done without reallocating...
-    /// for i in 0..10 {
-    ///     vec.push(i);
-    /// }
-    /// assert_eq!(vec.len(), 10);
-    /// assert!(vec.capacity() >= 10);
-    ///
-    /// // ...but this may make the vector reallocate
-    /// vec.push(11);
-    /// assert_eq!(vec.len(), 11);
-    /// assert!(vec.capacity() >= 11);
-    ///
-    /// // A vector of a zero-sized type will always over-allocate, since no
-    /// // allocation is necessary
-    /// let vec_units = Vec::<(), System>::with_capacity_in(10, System);
-    /// assert_eq!(vec_units.capacity(), usize::MAX);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[inline]
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    pub fn with_capacity_in(capacity: usize, alloc: A) -> Self {
-        Vec { buf: RawVec::with_capacity_in(capacity, alloc), len: 0 }
-    }
-
-    /// Tries to construct a new, empty `Vec<T, A>` with at least the specified capacity
-    /// with the provided allocator.
-    ///
-    /// The vector will be able to hold at least `capacity` elements without
-    /// reallocating. This method is allowed to allocate for more elements than
-    /// `capacity`. If `capacity` is 0, the vector will not allocate.
-    ///
-    /// It is important to note that although the returned vector has the
-    /// minimum *capacity* specified, the vector will have a zero *length*. For
-    /// an explanation of the difference between length and capacity, see
-    /// *[Capacity and reallocation]*.
-    ///
-    /// If it is important to know the exact allocated capacity of a `Vec`,
-    /// always use the [`capacity`] method after construction.
-    ///
-    /// For `Vec<T, A>` where `T` is a zero-sized type, there will be no allocation
-    /// and the capacity will always be `usize::MAX`.
-    ///
-    /// [Capacity and reallocation]: #capacity-and-reallocation
-    /// [`capacity`]: Vec::capacity
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// let mut vec = Vec::try_with_capacity_in(10, System).unwrap();
-    ///
-    /// // The vector contains no items, even though it has capacity for more
-    /// assert_eq!(vec.len(), 0);
-    /// assert!(vec.capacity() >= 10);
-    ///
-    /// // These are all done without reallocating...
-    /// for i in 0..10 {
-    ///     vec.push(i);
-    /// }
-    /// assert_eq!(vec.len(), 10);
-    /// assert!(vec.capacity() >= 10);
-    ///
-    /// // ...but this may make the vector reallocate
-    /// vec.push(11);
-    /// assert_eq!(vec.len(), 11);
-    /// assert!(vec.capacity() >= 11);
-    ///
-    /// let mut result = Vec::try_with_capacity_in(usize::MAX, System);
-    /// assert!(result.is_err());
-    ///
-    /// // A vector of a zero-sized type will always over-allocate, since no
-    /// // allocation is necessary
-    /// let vec_units = Vec::<(), System>::try_with_capacity_in(10, System).unwrap();
-    /// assert_eq!(vec_units.capacity(), usize::MAX);
-    /// ```
-    #[inline]
-    #[stable(feature = "kernel", since = "1.0.0")]
-    pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result<Self, TryReserveError> {
-        Ok(Vec { buf: RawVec::try_with_capacity_in(capacity, alloc)?, len: 0 })
-    }
-
-    /// Creates a `Vec<T, A>` directly from a pointer, a capacity, a length,
-    /// and an allocator.
-    ///
-    /// # Safety
-    ///
-    /// This is highly unsafe, due to the number of invariants that aren't
-    /// checked:
-    ///
-    /// * `ptr` must be [*currently allocated*] via the given allocator `alloc`.
-    /// * `T` needs to have the same alignment as what `ptr` was allocated with.
-    ///   (`T` having a less strict alignment is not sufficient, the alignment really
-    ///   needs to be equal to satisfy the [`dealloc`] requirement that memory must be
-    ///   allocated and deallocated with the same layout.)
-    /// * The size of `T` times the `capacity` (ie. the allocated size in bytes) needs
-    ///   to be the same size as the pointer was allocated with. (Because similar to
-    ///   alignment, [`dealloc`] must be called with the same layout `size`.)
-    /// * `length` needs to be less than or equal to `capacity`.
-    /// * The first `length` values must be properly initialized values of type `T`.
-    /// * `capacity` needs to [*fit*] the layout size that the pointer was allocated with.
-    /// * The allocated size in bytes must be no larger than `isize::MAX`.
-    ///   See the safety documentation of [`pointer::offset`].
-    ///
-    /// These requirements are always upheld by any `ptr` that has been allocated
-    /// via `Vec<T, A>`. Other allocation sources are allowed if the invariants are
-    /// upheld.
-    ///
-    /// Violating these may cause problems like corrupting the allocator's
-    /// internal data structures. For example it is **not** safe
-    /// to build a `Vec<u8>` from a pointer to a C `char` array with length `size_t`.
-    /// It's also not safe to build one from a `Vec<u16>` and its length, because
-    /// the allocator cares about the alignment, and these two types have different
-    /// alignments. The buffer was allocated with alignment 2 (for `u16`), but after
-    /// turning it into a `Vec<u8>` it'll be deallocated with alignment 1.
-    ///
-    /// The ownership of `ptr` is effectively transferred to the
-    /// `Vec<T>` which may then deallocate, reallocate or change the
-    /// contents of memory pointed to by the pointer at will. Ensure
-    /// that nothing else uses the pointer after calling this
-    /// function.
-    ///
-    /// [`String`]: crate::string::String
-    /// [`dealloc`]: crate::alloc::GlobalAlloc::dealloc
-    /// [*currently allocated*]: crate::alloc::Allocator#currently-allocated-memory
-    /// [*fit*]: crate::alloc::Allocator#memory-fitting
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// use std::ptr;
-    /// use std::mem;
-    ///
-    /// let mut v = Vec::with_capacity_in(3, System);
-    /// v.push(1);
-    /// v.push(2);
-    /// v.push(3);
-    ///
-    // FIXME Update this when vec_into_raw_parts is stabilized
-    /// // Prevent running `v`'s destructor so we are in complete control
-    /// // of the allocation.
-    /// let mut v = mem::ManuallyDrop::new(v);
-    ///
-    /// // Pull out the various important pieces of information about `v`
-    /// let p = v.as_mut_ptr();
-    /// let len = v.len();
-    /// let cap = v.capacity();
-    /// let alloc = v.allocator();
-    ///
-    /// unsafe {
-    ///     // Overwrite memory with 4, 5, 6
-    ///     for i in 0..len {
-    ///         ptr::write(p.add(i), 4 + i);
-    ///     }
-    ///
-    ///     // Put everything back together into a Vec
-    ///     let rebuilt = Vec::from_raw_parts_in(p, len, cap, alloc.clone());
-    ///     assert_eq!(rebuilt, [4, 5, 6]);
-    /// }
-    /// ```
-    ///
-    /// Using memory that was allocated elsewhere:
-    ///
-    /// ```rust
-    /// #![feature(allocator_api)]
-    ///
-    /// use std::alloc::{AllocError, Allocator, Global, Layout};
-    ///
-    /// fn main() {
-    ///     let layout = Layout::array::<u32>(16).expect("overflow cannot happen");
-    ///
-    ///     let vec = unsafe {
-    ///         let mem = match Global.allocate(layout) {
-    ///             Ok(mem) => mem.cast::<u32>().as_ptr(),
-    ///             Err(AllocError) => return,
-    ///         };
-    ///
-    ///         mem.write(1_000_000);
-    ///
-    ///         Vec::from_raw_parts_in(mem, 1, 16, Global)
-    ///     };
-    ///
-    ///     assert_eq!(vec, &[1_000_000]);
-    ///     assert_eq!(vec.capacity(), 16);
-    /// }
-    /// ```
-    #[inline]
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    pub unsafe fn from_raw_parts_in(ptr: *mut T, length: usize, capacity: usize, alloc: A) -> Self {
-        unsafe { Vec { buf: RawVec::from_raw_parts_in(ptr, capacity, alloc), len: length } }
-    }
-
-    /// Decomposes a `Vec<T>` into its raw components.
-    ///
-    /// Returns the raw pointer to the underlying data, the length of
-    /// the vector (in elements), and the allocated capacity of the
-    /// data (in elements). These are the same arguments in the same
-    /// order as the arguments to [`from_raw_parts`].
-    ///
-    /// After calling this function, the caller is responsible for the
-    /// memory previously managed by the `Vec`. The only way to do
-    /// this is to convert the raw pointer, length, and capacity back
-    /// into a `Vec` with the [`from_raw_parts`] function, allowing
-    /// the destructor to perform the cleanup.
-    ///
-    /// [`from_raw_parts`]: Vec::from_raw_parts
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(vec_into_raw_parts)]
-    /// let v: Vec<i32> = vec![-1, 0, 1];
-    ///
-    /// let (ptr, len, cap) = v.into_raw_parts();
-    ///
-    /// let rebuilt = unsafe {
-    ///     // We can now make changes to the components, such as
-    ///     // transmuting the raw pointer to a compatible type.
-    ///     let ptr = ptr as *mut u32;
-    ///
-    ///     Vec::from_raw_parts(ptr, len, cap)
-    /// };
-    /// assert_eq!(rebuilt, [4294967295, 0, 1]);
-    /// ```
-    #[unstable(feature = "vec_into_raw_parts", reason = "new API", issue = "65816")]
-    pub fn into_raw_parts(self) -> (*mut T, usize, usize) {
-        let mut me = ManuallyDrop::new(self);
-        (me.as_mut_ptr(), me.len(), me.capacity())
-    }
-
-    /// Decomposes a `Vec<T>` into its raw components.
-    ///
-    /// Returns the raw pointer to the underlying data, the length of the vector (in elements),
-    /// the allocated capacity of the data (in elements), and the allocator. These are the same
-    /// arguments in the same order as the arguments to [`from_raw_parts_in`].
-    ///
-    /// After calling this function, the caller is responsible for the
-    /// memory previously managed by the `Vec`. The only way to do
-    /// this is to convert the raw pointer, length, and capacity back
-    /// into a `Vec` with the [`from_raw_parts_in`] function, allowing
-    /// the destructor to perform the cleanup.
-    ///
-    /// [`from_raw_parts_in`]: Vec::from_raw_parts_in
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(allocator_api, vec_into_raw_parts)]
-    ///
-    /// use std::alloc::System;
-    ///
-    /// let mut v: Vec<i32, System> = Vec::new_in(System);
-    /// v.push(-1);
-    /// v.push(0);
-    /// v.push(1);
-    ///
-    /// let (ptr, len, cap, alloc) = v.into_raw_parts_with_alloc();
-    ///
-    /// let rebuilt = unsafe {
-    ///     // We can now make changes to the components, such as
-    ///     // transmuting the raw pointer to a compatible type.
-    ///     let ptr = ptr as *mut u32;
-    ///
-    ///     Vec::from_raw_parts_in(ptr, len, cap, alloc)
-    /// };
-    /// assert_eq!(rebuilt, [4294967295, 0, 1]);
-    /// ```
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "vec_into_raw_parts", reason = "new API", issue = "65816")]
-    pub fn into_raw_parts_with_alloc(self) -> (*mut T, usize, usize, A) {
-        let mut me = ManuallyDrop::new(self);
-        let len = me.len();
-        let capacity = me.capacity();
-        let ptr = me.as_mut_ptr();
-        let alloc = unsafe { ptr::read(me.allocator()) };
-        (ptr, len, capacity, alloc)
-    }
-
-    /// Returns the total number of elements the vector can hold without
-    /// reallocating.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec: Vec<i32> = Vec::with_capacity(10);
-    /// vec.push(42);
-    /// assert!(vec.capacity() >= 10);
-    /// ```
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn capacity(&self) -> usize {
-        self.buf.capacity()
-    }
-
-    /// Reserves capacity for at least `additional` more elements to be inserted
-    /// in the given `Vec<T>`. The collection may reserve more space to
-    /// speculatively avoid frequent reallocations. After calling `reserve`,
-    /// capacity will be greater than or equal to `self.len() + additional`.
-    /// Does nothing if capacity is already sufficient.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the new capacity exceeds `isize::MAX` bytes.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1];
-    /// vec.reserve(10);
-    /// assert!(vec.capacity() >= 11);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn reserve(&mut self, additional: usize) {
-        self.buf.reserve(self.len, additional);
-    }
-
-    /// Reserves the minimum capacity for at least `additional` more elements to
-    /// be inserted in the given `Vec<T>`. Unlike [`reserve`], this will not
-    /// deliberately over-allocate to speculatively avoid frequent allocations.
-    /// After calling `reserve_exact`, capacity will be greater than or equal to
-    /// `self.len() + additional`. Does nothing if the capacity is already
-    /// sufficient.
-    ///
-    /// Note that the allocator may give the collection more space than it
-    /// requests. Therefore, capacity can not be relied upon to be precisely
-    /// minimal. Prefer [`reserve`] if future insertions are expected.
-    ///
-    /// [`reserve`]: Vec::reserve
-    ///
-    /// # Panics
-    ///
-    /// Panics if the new capacity exceeds `isize::MAX` bytes.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1];
-    /// vec.reserve_exact(10);
-    /// assert!(vec.capacity() >= 11);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn reserve_exact(&mut self, additional: usize) {
-        self.buf.reserve_exact(self.len, additional);
-    }
-
-    /// Tries to reserve capacity for at least `additional` more elements to be inserted
-    /// in the given `Vec<T>`. The collection may reserve more space to speculatively avoid
-    /// frequent reallocations. After calling `try_reserve`, capacity will be
-    /// greater than or equal to `self.len() + additional` if it returns
-    /// `Ok(())`. Does nothing if capacity is already sufficient. This method
-    /// preserves the contents even if an error occurs.
-    ///
-    /// # Errors
-    ///
-    /// If the capacity overflows, or the allocator reports a failure, then an error
-    /// is returned.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::collections::TryReserveError;
-    ///
-    /// fn process_data(data: &[u32]) -> Result<Vec<u32>, TryReserveError> {
-    ///     let mut output = Vec::new();
-    ///
-    ///     // Pre-reserve the memory, exiting if we can't
-    ///     output.try_reserve(data.len())?;
-    ///
-    ///     // Now we know this can't OOM in the middle of our complex work
-    ///     output.extend(data.iter().map(|&val| {
-    ///         val * 2 + 5 // very complicated
-    ///     }));
-    ///
-    ///     Ok(output)
-    /// }
-    /// # process_data(&[1, 2, 3]).expect("why is the test harness OOMing on 12 bytes?");
-    /// ```
-    #[stable(feature = "try_reserve", since = "1.57.0")]
-    pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
-        self.buf.try_reserve(self.len, additional)
-    }
-
-    /// Tries to reserve the minimum capacity for at least `additional`
-    /// elements to be inserted in the given `Vec<T>`. Unlike [`try_reserve`],
-    /// this will not deliberately over-allocate to speculatively avoid frequent
-    /// allocations. After calling `try_reserve_exact`, capacity will be greater
-    /// than or equal to `self.len() + additional` if it returns `Ok(())`.
-    /// Does nothing if the capacity is already sufficient.
-    ///
-    /// Note that the allocator may give the collection more space than it
-    /// requests. Therefore, capacity can not be relied upon to be precisely
-    /// minimal. Prefer [`try_reserve`] if future insertions are expected.
-    ///
-    /// [`try_reserve`]: Vec::try_reserve
-    ///
-    /// # Errors
-    ///
-    /// If the capacity overflows, or the allocator reports a failure, then an error
-    /// is returned.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::collections::TryReserveError;
-    ///
-    /// fn process_data(data: &[u32]) -> Result<Vec<u32>, TryReserveError> {
-    ///     let mut output = Vec::new();
-    ///
-    ///     // Pre-reserve the memory, exiting if we can't
-    ///     output.try_reserve_exact(data.len())?;
-    ///
-    ///     // Now we know this can't OOM in the middle of our complex work
-    ///     output.extend(data.iter().map(|&val| {
-    ///         val * 2 + 5 // very complicated
-    ///     }));
-    ///
-    ///     Ok(output)
-    /// }
-    /// # process_data(&[1, 2, 3]).expect("why is the test harness OOMing on 12 bytes?");
-    /// ```
-    #[stable(feature = "try_reserve", since = "1.57.0")]
-    pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), TryReserveError> {
-        self.buf.try_reserve_exact(self.len, additional)
-    }
-
-    /// Shrinks the capacity of the vector as much as possible.
-    ///
-    /// It will drop down as close as possible to the length but the allocator
-    /// may still inform the vector that there is space for a few more elements.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = Vec::with_capacity(10);
-    /// vec.extend([1, 2, 3]);
-    /// assert!(vec.capacity() >= 10);
-    /// vec.shrink_to_fit();
-    /// assert!(vec.capacity() >= 3);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn shrink_to_fit(&mut self) {
-        // The capacity is never less than the length, and there's nothing to do when
-        // they are equal, so we can avoid the panic case in `RawVec::shrink_to_fit`
-        // by only calling it with a greater capacity.
-        if self.capacity() > self.len {
-            self.buf.shrink_to_fit(self.len);
-        }
-    }
-
-    /// Shrinks the capacity of the vector with a lower bound.
-    ///
-    /// The capacity will remain at least as large as both the length
-    /// and the supplied value.
-    ///
-    /// If the current capacity is less than the lower limit, this is a no-op.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = Vec::with_capacity(10);
-    /// vec.extend([1, 2, 3]);
-    /// assert!(vec.capacity() >= 10);
-    /// vec.shrink_to(4);
-    /// assert!(vec.capacity() >= 4);
-    /// vec.shrink_to(0);
-    /// assert!(vec.capacity() >= 3);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[stable(feature = "shrink_to", since = "1.56.0")]
-    pub fn shrink_to(&mut self, min_capacity: usize) {
-        if self.capacity() > min_capacity {
-            self.buf.shrink_to_fit(cmp::max(self.len, min_capacity));
-        }
-    }
-
-    /// Converts the vector into [`Box<[T]>`][owned slice].
-    ///
-    /// If the vector has excess capacity, its items will be moved into a
-    /// newly-allocated buffer with exactly the right capacity.
-    ///
-    /// [owned slice]: Box
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let v = vec![1, 2, 3];
-    ///
-    /// let slice = v.into_boxed_slice();
-    /// ```
-    ///
-    /// Any excess capacity is removed:
-    ///
-    /// ```
-    /// let mut vec = Vec::with_capacity(10);
-    /// vec.extend([1, 2, 3]);
-    ///
-    /// assert!(vec.capacity() >= 10);
-    /// let slice = vec.into_boxed_slice();
-    /// assert_eq!(slice.into_vec().capacity(), 3);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn into_boxed_slice(mut self) -> Box<[T], A> {
-        unsafe {
-            self.shrink_to_fit();
-            let me = ManuallyDrop::new(self);
-            let buf = ptr::read(&me.buf);
-            let len = me.len();
-            buf.into_box(len).assume_init()
-        }
-    }
-
-    /// Shortens the vector, keeping the first `len` elements and dropping
-    /// the rest.
-    ///
-    /// If `len` is greater or equal to the vector's current length, this has
-    /// no effect.
-    ///
-    /// The [`drain`] method can emulate `truncate`, but causes the excess
-    /// elements to be returned instead of dropped.
-    ///
-    /// Note that this method has no effect on the allocated capacity
-    /// of the vector.
-    ///
-    /// # Examples
-    ///
-    /// Truncating a five element vector to two elements:
-    ///
-    /// ```
-    /// let mut vec = vec![1, 2, 3, 4, 5];
-    /// vec.truncate(2);
-    /// assert_eq!(vec, [1, 2]);
-    /// ```
-    ///
-    /// No truncation occurs when `len` is greater than the vector's current
-    /// length:
-    ///
-    /// ```
-    /// let mut vec = vec![1, 2, 3];
-    /// vec.truncate(8);
-    /// assert_eq!(vec, [1, 2, 3]);
-    /// ```
-    ///
-    /// Truncating when `len == 0` is equivalent to calling the [`clear`]
-    /// method.
-    ///
-    /// ```
-    /// let mut vec = vec![1, 2, 3];
-    /// vec.truncate(0);
-    /// assert_eq!(vec, []);
-    /// ```
-    ///
-    /// [`clear`]: Vec::clear
-    /// [`drain`]: Vec::drain
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn truncate(&mut self, len: usize) {
-        // This is safe because:
-        //
-        // * the slice passed to `drop_in_place` is valid; the `len > self.len`
-        //   case avoids creating an invalid slice, and
-        // * the `len` of the vector is shrunk before calling `drop_in_place`,
-        //   such that no value will be dropped twice in case `drop_in_place`
-        //   were to panic once (if it panics twice, the program aborts).
-        unsafe {
-            // Note: It's intentional that this is `>` and not `>=`.
-            //       Changing it to `>=` has negative performance
-            //       implications in some cases. See #78884 for more.
-            if len > self.len {
-                return;
-            }
-            let remaining_len = self.len - len;
-            let s = ptr::slice_from_raw_parts_mut(self.as_mut_ptr().add(len), remaining_len);
-            self.len = len;
-            ptr::drop_in_place(s);
-        }
-    }
-
-    /// Extracts a slice containing the entire vector.
-    ///
-    /// Equivalent to `&s[..]`.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::io::{self, Write};
-    /// let buffer = vec![1, 2, 3, 5, 8];
-    /// io::sink().write(buffer.as_slice()).unwrap();
-    /// ```
-    #[inline]
-    #[stable(feature = "vec_as_slice", since = "1.7.0")]
-    pub fn as_slice(&self) -> &[T] {
-        self
-    }
-
-    /// Extracts a mutable slice of the entire vector.
-    ///
-    /// Equivalent to `&mut s[..]`.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::io::{self, Read};
-    /// let mut buffer = vec![0; 3];
-    /// io::repeat(0b101).read_exact(buffer.as_mut_slice()).unwrap();
-    /// ```
-    #[inline]
-    #[stable(feature = "vec_as_slice", since = "1.7.0")]
-    pub fn as_mut_slice(&mut self) -> &mut [T] {
-        self
-    }
-
-    /// Returns a raw pointer to the vector's buffer, or a dangling raw pointer
-    /// valid for zero sized reads if the vector didn't allocate.
-    ///
-    /// The caller must ensure that the vector outlives the pointer this
-    /// function returns, or else it will end up pointing to garbage.
-    /// Modifying the vector may cause its buffer to be reallocated,
-    /// which would also make any pointers to it invalid.
-    ///
-    /// The caller must also ensure that the memory the pointer (non-transitively) points to
-    /// is never written to (except inside an `UnsafeCell`) using this pointer or any pointer
-    /// derived from it. If you need to mutate the contents of the slice, use [`as_mut_ptr`].
-    ///
-    /// This method guarantees that for the purpose of the aliasing model, this method
-    /// does not materialize a reference to the underlying slice, and thus the returned pointer
-    /// will remain valid when mixed with other calls to [`as_ptr`] and [`as_mut_ptr`].
-    /// Note that calling other methods that materialize mutable references to the slice,
-    /// or mutable references to specific elements you are planning on accessing through this pointer,
-    /// as well as writing to those elements, may still invalidate this pointer.
-    /// See the second example below for how this guarantee can be used.
-    ///
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let x = vec![1, 2, 4];
-    /// let x_ptr = x.as_ptr();
-    ///
-    /// unsafe {
-    ///     for i in 0..x.len() {
-    ///         assert_eq!(*x_ptr.add(i), 1 << i);
-    ///     }
-    /// }
-    /// ```
-    ///
-    /// Due to the aliasing guarantee, the following code is legal:
-    ///
-    /// ```rust
-    /// unsafe {
-    ///     let mut v = vec![0, 1, 2];
-    ///     let ptr1 = v.as_ptr();
-    ///     let _ = ptr1.read();
-    ///     let ptr2 = v.as_mut_ptr().offset(2);
-    ///     ptr2.write(2);
-    ///     // Notably, the write to `ptr2` did *not* invalidate `ptr1`
-    ///     // because it mutated a different element:
-    ///     let _ = ptr1.read();
-    /// }
-    /// ```
-    ///
-    /// [`as_mut_ptr`]: Vec::as_mut_ptr
-    /// [`as_ptr`]: Vec::as_ptr
-    #[stable(feature = "vec_as_ptr", since = "1.37.0")]
-    #[rustc_never_returns_null_ptr]
-    #[inline]
-    pub fn as_ptr(&self) -> *const T {
-        // We shadow the slice method of the same name to avoid going through
-        // `deref`, which creates an intermediate reference.
-        self.buf.ptr()
-    }
-
-    /// Returns an unsafe mutable pointer to the vector's buffer, or a dangling
-    /// raw pointer valid for zero sized reads if the vector didn't allocate.
-    ///
-    /// The caller must ensure that the vector outlives the pointer this
-    /// function returns, or else it will end up pointing to garbage.
-    /// Modifying the vector may cause its buffer to be reallocated,
-    /// which would also make any pointers to it invalid.
-    ///
-    /// This method guarantees that for the purpose of the aliasing model, this method
-    /// does not materialize a reference to the underlying slice, and thus the returned pointer
-    /// will remain valid when mixed with other calls to [`as_ptr`] and [`as_mut_ptr`].
-    /// Note that calling other methods that materialize references to the slice,
-    /// or references to specific elements you are planning on accessing through this pointer,
-    /// may still invalidate this pointer.
-    /// See the second example below for how this guarantee can be used.
-    ///
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// // Allocate vector big enough for 4 elements.
-    /// let size = 4;
-    /// let mut x: Vec<i32> = Vec::with_capacity(size);
-    /// let x_ptr = x.as_mut_ptr();
-    ///
-    /// // Initialize elements via raw pointer writes, then set length.
-    /// unsafe {
-    ///     for i in 0..size {
-    ///         *x_ptr.add(i) = i as i32;
-    ///     }
-    ///     x.set_len(size);
-    /// }
-    /// assert_eq!(&*x, &[0, 1, 2, 3]);
-    /// ```
-    ///
-    /// Due to the aliasing guarantee, the following code is legal:
-    ///
-    /// ```rust
-    /// unsafe {
-    ///     let mut v = vec![0];
-    ///     let ptr1 = v.as_mut_ptr();
-    ///     ptr1.write(1);
-    ///     let ptr2 = v.as_mut_ptr();
-    ///     ptr2.write(2);
-    ///     // Notably, the write to `ptr2` did *not* invalidate `ptr1`:
-    ///     ptr1.write(3);
-    /// }
-    /// ```
-    ///
-    /// [`as_mut_ptr`]: Vec::as_mut_ptr
-    /// [`as_ptr`]: Vec::as_ptr
-    #[stable(feature = "vec_as_ptr", since = "1.37.0")]
-    #[rustc_never_returns_null_ptr]
-    #[inline]
-    pub fn as_mut_ptr(&mut self) -> *mut T {
-        // We shadow the slice method of the same name to avoid going through
-        // `deref_mut`, which creates an intermediate reference.
-        self.buf.ptr()
-    }
-
-    /// Returns a reference to the underlying allocator.
-    #[unstable(feature = "allocator_api", issue = "32838")]
-    #[inline]
-    pub fn allocator(&self) -> &A {
-        self.buf.allocator()
-    }
-
-    /// Forces the length of the vector to `new_len`.
-    ///
-    /// This is a low-level operation that maintains none of the normal
-    /// invariants of the type. Normally changing the length of a vector
-    /// is done using one of the safe operations instead, such as
-    /// [`truncate`], [`resize`], [`extend`], or [`clear`].
-    ///
-    /// [`truncate`]: Vec::truncate
-    /// [`resize`]: Vec::resize
-    /// [`extend`]: Extend::extend
-    /// [`clear`]: Vec::clear
-    ///
-    /// # Safety
-    ///
-    /// - `new_len` must be less than or equal to [`capacity()`].
-    /// - The elements at `old_len..new_len` must be initialized.
-    ///
-    /// [`capacity()`]: Vec::capacity
-    ///
-    /// # Examples
-    ///
-    /// This method can be useful for situations in which the vector
-    /// is serving as a buffer for other code, particularly over FFI:
-    ///
-    /// ```no_run
-    /// # #![allow(dead_code)]
-    /// # // This is just a minimal skeleton for the doc example;
-    /// # // don't use this as a starting point for a real library.
-    /// # pub struct StreamWrapper { strm: *mut std::ffi::c_void }
-    /// # const Z_OK: i32 = 0;
-    /// # extern "C" {
-    /// #     fn deflateGetDictionary(
-    /// #         strm: *mut std::ffi::c_void,
-    /// #         dictionary: *mut u8,
-    /// #         dictLength: *mut usize,
-    /// #     ) -> i32;
-    /// # }
-    /// # impl StreamWrapper {
-    /// pub fn get_dictionary(&self) -> Option<Vec<u8>> {
-    ///     // Per the FFI method's docs, "32768 bytes is always enough".
-    ///     let mut dict = Vec::with_capacity(32_768);
-    ///     let mut dict_length = 0;
-    ///     // SAFETY: When `deflateGetDictionary` returns `Z_OK`, it holds that:
-    ///     // 1. `dict_length` elements were initialized.
-    ///     // 2. `dict_length` <= the capacity (32_768)
-    ///     // which makes `set_len` safe to call.
-    ///     unsafe {
-    ///         // Make the FFI call...
-    ///         let r = deflateGetDictionary(self.strm, dict.as_mut_ptr(), &mut dict_length);
-    ///         if r == Z_OK {
-    ///             // ...and update the length to what was initialized.
-    ///             dict.set_len(dict_length);
-    ///             Some(dict)
-    ///         } else {
-    ///             None
-    ///         }
-    ///     }
-    /// }
-    /// # }
-    /// ```
-    ///
-    /// While the following example is sound, there is a memory leak since
-    /// the inner vectors were not freed prior to the `set_len` call:
-    ///
-    /// ```
-    /// let mut vec = vec![vec![1, 0, 0],
-    ///                    vec![0, 1, 0],
-    ///                    vec![0, 0, 1]];
-    /// // SAFETY:
-    /// // 1. `old_len..0` is empty so no elements need to be initialized.
-    /// // 2. `0 <= capacity` always holds whatever `capacity` is.
-    /// unsafe {
-    ///     vec.set_len(0);
-    /// }
-    /// ```
-    ///
-    /// Normally, here, one would use [`clear`] instead to correctly drop
-    /// the contents and thus not leak memory.
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub unsafe fn set_len(&mut self, new_len: usize) {
-        debug_assert!(new_len <= self.capacity());
-
-        self.len = new_len;
-    }
-
-    /// Removes an element from the vector and returns it.
-    ///
-    /// The removed element is replaced by the last element of the vector.
-    ///
-    /// This does not preserve ordering, but is *O*(1).
-    /// If you need to preserve the element order, use [`remove`] instead.
-    ///
-    /// [`remove`]: Vec::remove
-    ///
-    /// # Panics
-    ///
-    /// Panics if `index` is out of bounds.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut v = vec!["foo", "bar", "baz", "qux"];
-    ///
-    /// assert_eq!(v.swap_remove(1), "bar");
-    /// assert_eq!(v, ["foo", "qux", "baz"]);
-    ///
-    /// assert_eq!(v.swap_remove(0), "foo");
-    /// assert_eq!(v, ["baz", "qux"]);
-    /// ```
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn swap_remove(&mut self, index: usize) -> T {
-        #[cold]
-        #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
-        #[track_caller]
-        fn assert_failed(index: usize, len: usize) -> ! {
-            panic!("swap_remove index (is {index}) should be < len (is {len})");
-        }
-
-        let len = self.len();
-        if index >= len {
-            assert_failed(index, len);
-        }
-        unsafe {
-            // We replace self[index] with the last element. Note that if the
-            // bounds check above succeeds there must be a last element (which
-            // can be self[index] itself).
-            let value = ptr::read(self.as_ptr().add(index));
-            let base_ptr = self.as_mut_ptr();
-            ptr::copy(base_ptr.add(len - 1), base_ptr.add(index), 1);
-            self.set_len(len - 1);
-            value
-        }
-    }
-
-    /// Inserts an element at position `index` within the vector, shifting all
-    /// elements after it to the right.
-    ///
-    /// # Panics
-    ///
-    /// Panics if `index > len`.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1, 2, 3];
-    /// vec.insert(1, 4);
-    /// assert_eq!(vec, [1, 4, 2, 3]);
-    /// vec.insert(4, 5);
-    /// assert_eq!(vec, [1, 4, 2, 3, 5]);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn insert(&mut self, index: usize, element: T) {
-        #[cold]
-        #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
-        #[track_caller]
-        fn assert_failed(index: usize, len: usize) -> ! {
-            panic!("insertion index (is {index}) should be <= len (is {len})");
-        }
-
-        let len = self.len();
-
-        // space for the new element
-        if len == self.buf.capacity() {
-            self.reserve(1);
-        }
-
-        unsafe {
-            // infallible
-            // The spot to put the new value
-            {
-                let p = self.as_mut_ptr().add(index);
-                if index < len {
-                    // Shift everything over to make space. (Duplicating the
-                    // `index`th element into two consecutive places.)
-                    ptr::copy(p, p.add(1), len - index);
-                } else if index == len {
-                    // No elements need shifting.
-                } else {
-                    assert_failed(index, len);
-                }
-                // Write it in, overwriting the first copy of the `index`th
-                // element.
-                ptr::write(p, element);
-            }
-            self.set_len(len + 1);
-        }
-    }
-
-    /// Removes and returns the element at position `index` within the vector,
-    /// shifting all elements after it to the left.
-    ///
-    /// Note: Because this shifts over the remaining elements, it has a
-    /// worst-case performance of *O*(*n*). If you don't need the order of elements
-    /// to be preserved, use [`swap_remove`] instead. If you'd like to remove
-    /// elements from the beginning of the `Vec`, consider using
-    /// [`VecDeque::pop_front`] instead.
-    ///
-    /// [`swap_remove`]: Vec::swap_remove
-    /// [`VecDeque::pop_front`]: crate::collections::VecDeque::pop_front
-    ///
-    /// # Panics
-    ///
-    /// Panics if `index` is out of bounds.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut v = vec![1, 2, 3];
-    /// assert_eq!(v.remove(1), 2);
-    /// assert_eq!(v, [1, 3]);
-    /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
-    #[track_caller]
-    pub fn remove(&mut self, index: usize) -> T {
-        #[cold]
-        #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
-        #[track_caller]
-        fn assert_failed(index: usize, len: usize) -> ! {
-            panic!("removal index (is {index}) should be < len (is {len})");
-        }
-
-        let len = self.len();
-        if index >= len {
-            assert_failed(index, len);
-        }
-        unsafe {
-            // infallible
-            let ret;
-            {
-                // the place we are taking from.
-                let ptr = self.as_mut_ptr().add(index);
-                // copy it out, unsafely having a copy of the value on
-                // the stack and in the vector at the same time.
-                ret = ptr::read(ptr);
-
-                // Shift everything down to fill in that spot.
-                ptr::copy(ptr.add(1), ptr, len - index - 1);
-            }
-            self.set_len(len - 1);
-            ret
-        }
-    }
-
-    /// Retains only the elements specified by the predicate.
-    ///
-    /// In other words, remove all elements `e` for which `f(&e)` returns `false`.
-    /// This method operates in place, visiting each element exactly once in the
-    /// original order, and preserves the order of the retained elements.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1, 2, 3, 4];
-    /// vec.retain(|&x| x % 2 == 0);
-    /// assert_eq!(vec, [2, 4]);
-    /// ```
-    ///
-    /// Because the elements are visited exactly once in the original order,
-    /// external state may be used to decide which elements to keep.
-    ///
-    /// ```
-    /// let mut vec = vec![1, 2, 3, 4, 5];
-    /// let keep = [false, true, true, false, true];
-    /// let mut iter = keep.iter();
-    /// vec.retain(|_| *iter.next().unwrap());
-    /// assert_eq!(vec, [2, 3, 5]);
-    /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn retain<F>(&mut self, mut f: F)
-    where
-        F: FnMut(&T) -> bool,
-    {
-        self.retain_mut(|elem| f(elem));
-    }
-
-    /// Retains only the elements specified by the predicate, passing a mutable reference to it.
-    ///
-    /// In other words, remove all elements `e` such that `f(&mut e)` returns `false`.
-    /// This method operates in place, visiting each element exactly once in the
-    /// original order, and preserves the order of the retained elements.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1, 2, 3, 4];
-    /// vec.retain_mut(|x| if *x <= 3 {
-    ///     *x += 1;
-    ///     true
-    /// } else {
-    ///     false
-    /// });
-    /// assert_eq!(vec, [2, 3, 4]);
-    /// ```
-    #[stable(feature = "vec_retain_mut", since = "1.61.0")]
-    pub fn retain_mut<F>(&mut self, mut f: F)
-    where
-        F: FnMut(&mut T) -> bool,
-    {
-        let original_len = self.len();
-        // Avoid double drop if the drop guard is not executed,
-        // since we may make some holes during the process.
-        unsafe { self.set_len(0) };
-
-        // Vec: [Kept, Kept, Hole, Hole, Hole, Hole, Unchecked, Unchecked]
-        //      |<-              processed len   ->| ^- next to check
-        //                  |<-  deleted cnt     ->|
-        //      |<-              original_len                          ->|
-        // Kept: Elements which predicate returns true on.
-        // Hole: Moved or dropped element slot.
-        // Unchecked: Unchecked valid elements.
-        //
-        // This drop guard will be invoked when predicate or `drop` of element panicked.
-        // It shifts unchecked elements to cover holes and `set_len` to the correct length.
-        // In cases when predicate and `drop` never panick, it will be optimized out.
-        struct BackshiftOnDrop<'a, T, A: Allocator> {
-            v: &'a mut Vec<T, A>,
-            processed_len: usize,
-            deleted_cnt: usize,
-            original_len: usize,
-        }
-
-        impl<T, A: Allocator> Drop for BackshiftOnDrop<'_, T, A> {
-            fn drop(&mut self) {
-                if self.deleted_cnt > 0 {
-                    // SAFETY: Trailing unchecked items must be valid since we never touch them.
-                    unsafe {
-                        ptr::copy(
-                            self.v.as_ptr().add(self.processed_len),
-                            self.v.as_mut_ptr().add(self.processed_len - self.deleted_cnt),
-                            self.original_len - self.processed_len,
-                        );
-                    }
-                }
-                // SAFETY: After filling holes, all items are in contiguous memory.
-                unsafe {
-                    self.v.set_len(self.original_len - self.deleted_cnt);
-                }
-            }
-        }
-
-        let mut g = BackshiftOnDrop { v: self, processed_len: 0, deleted_cnt: 0, original_len };
-
-        fn process_loop<F, T, A: Allocator, const DELETED: bool>(
-            original_len: usize,
-            f: &mut F,
-            g: &mut BackshiftOnDrop<'_, T, A>,
-        ) where
-            F: FnMut(&mut T) -> bool,
-        {
-            while g.processed_len != original_len {
-                // SAFETY: Unchecked element must be valid.
-                let cur = unsafe { &mut *g.v.as_mut_ptr().add(g.processed_len) };
-                if !f(cur) {
-                    // Advance early to avoid double drop if `drop_in_place` panicked.
-                    g.processed_len += 1;
-                    g.deleted_cnt += 1;
-                    // SAFETY: We never touch this element again after dropped.
-                    unsafe { ptr::drop_in_place(cur) };
-                    // We already advanced the counter.
-                    if DELETED {
-                        continue;
-                    } else {
-                        break;
-                    }
-                }
-                if DELETED {
-                    // SAFETY: `deleted_cnt` > 0, so the hole slot must not overlap with current element.
-                    // We use copy for move, and never touch this element again.
-                    unsafe {
-                        let hole_slot = g.v.as_mut_ptr().add(g.processed_len - g.deleted_cnt);
-                        ptr::copy_nonoverlapping(cur, hole_slot, 1);
-                    }
-                }
-                g.processed_len += 1;
-            }
-        }
-
-        // Stage 1: Nothing was deleted.
-        process_loop::<F, T, A, false>(original_len, &mut f, &mut g);
-
-        // Stage 2: Some elements were deleted.
-        process_loop::<F, T, A, true>(original_len, &mut f, &mut g);
-
-        // All item are processed. This can be optimized to `set_len` by LLVM.
-        drop(g);
-    }
-
-    /// Removes all but the first of consecutive elements in the vector that resolve to the same
-    /// key.
-    ///
-    /// If the vector is sorted, this removes all duplicates.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![10, 20, 21, 30, 20];
-    ///
-    /// vec.dedup_by_key(|i| *i / 10);
-    ///
-    /// assert_eq!(vec, [10, 20, 30, 20]);
-    /// ```
-    #[stable(feature = "dedup_by", since = "1.16.0")]
-    #[inline]
-    pub fn dedup_by_key<F, K>(&mut self, mut key: F)
-    where
-        F: FnMut(&mut T) -> K,
-        K: PartialEq,
-    {
-        self.dedup_by(|a, b| key(a) == key(b))
-    }
-
-    /// Removes all but the first of consecutive elements in the vector satisfying a given equality
-    /// relation.
-    ///
-    /// The `same_bucket` function is passed references to two elements from the vector and
-    /// must determine if the elements compare equal. The elements are passed in opposite order
-    /// from their order in the slice, so if `same_bucket(a, b)` returns `true`, `a` is removed.
-    ///
-    /// If the vector is sorted, this removes all duplicates.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec!["foo", "bar", "Bar", "baz", "bar"];
-    ///
-    /// vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b));
-    ///
-    /// assert_eq!(vec, ["foo", "bar", "baz", "bar"]);
-    /// ```
-    #[stable(feature = "dedup_by", since = "1.16.0")]
-    pub fn dedup_by<F>(&mut self, mut same_bucket: F)
-    where
-        F: FnMut(&mut T, &mut T) -> bool,
-    {
-        let len = self.len();
-        if len <= 1 {
-            return;
-        }
-
-        // Check if we ever want to remove anything.
-        // This allows to use copy_non_overlapping in next cycle.
-        // And avoids any memory writes if we don't need to remove anything.
-        let mut first_duplicate_idx: usize = 1;
-        let start = self.as_mut_ptr();
-        while first_duplicate_idx != len {
-            let found_duplicate = unsafe {
-                // SAFETY: first_duplicate always in range [1..len)
-                // Note that we start iteration from 1 so we never overflow.
-                let prev = start.add(first_duplicate_idx.wrapping_sub(1));
-                let current = start.add(first_duplicate_idx);
-                // We explicitly say in docs that references are reversed.
-                same_bucket(&mut *current, &mut *prev)
-            };
-            if found_duplicate {
-                break;
-            }
-            first_duplicate_idx += 1;
-        }
-        // Don't need to remove anything.
-        // We cannot get bigger than len.
-        if first_duplicate_idx == len {
-            return;
-        }
-
-        /* INVARIANT: vec.len() > read > write > write-1 >= 0 */
-        struct FillGapOnDrop<'a, T, A: core::alloc::Allocator> {
-            /* Offset of the element we want to check if it is duplicate */
-            read: usize,
-
-            /* Offset of the place where we want to place the non-duplicate
-             * when we find it. */
-            write: usize,
-
-            /* The Vec that would need correction if `same_bucket` panicked */
-            vec: &'a mut Vec<T, A>,
-        }
-
-        impl<'a, T, A: core::alloc::Allocator> Drop for FillGapOnDrop<'a, T, A> {
-            fn drop(&mut self) {
-                /* This code gets executed when `same_bucket` panics */
-
-                /* SAFETY: invariant guarantees that `read - write`
-                 * and `len - read` never overflow and that the copy is always
-                 * in-bounds. */
-                unsafe {
-                    let ptr = self.vec.as_mut_ptr();
-                    let len = self.vec.len();
-
-                    /* How many items were left when `same_bucket` panicked.
-                     * Basically vec[read..].len() */
-                    let items_left = len.wrapping_sub(self.read);
-
-                    /* Pointer to first item in vec[write..write+items_left] slice */
-                    let dropped_ptr = ptr.add(self.write);
-                    /* Pointer to first item in vec[read..] slice */
-                    let valid_ptr = ptr.add(self.read);
-
-                    /* Copy `vec[read..]` to `vec[write..write+items_left]`.
-                     * The slices can overlap, so `copy_nonoverlapping` cannot be used */
-                    ptr::copy(valid_ptr, dropped_ptr, items_left);
-
-                    /* How many items have been already dropped
-                     * Basically vec[read..write].len() */
-                    let dropped = self.read.wrapping_sub(self.write);
-
-                    self.vec.set_len(len - dropped);
-                }
-            }
-        }
-
-        /* Drop items while going through Vec, it should be more efficient than
-         * doing slice partition_dedup + truncate */
-
-        // Construct gap first and then drop item to avoid memory corruption if `T::drop` panics.
-        let mut gap =
-            FillGapOnDrop { read: first_duplicate_idx + 1, write: first_duplicate_idx, vec: self };
-        unsafe {
-            // SAFETY: we checked that first_duplicate_idx in bounds before.
-            // If drop panics, `gap` would remove this item without drop.
-            ptr::drop_in_place(start.add(first_duplicate_idx));
-        }
-
-        /* SAFETY: Because of the invariant, read_ptr, prev_ptr and write_ptr
-         * are always in-bounds and read_ptr never aliases prev_ptr */
-        unsafe {
-            while gap.read < len {
-                let read_ptr = start.add(gap.read);
-                let prev_ptr = start.add(gap.write.wrapping_sub(1));
-
-                // We explicitly say in docs that references are reversed.
-                let found_duplicate = same_bucket(&mut *read_ptr, &mut *prev_ptr);
-                if found_duplicate {
-                    // Increase `gap.read` now since the drop may panic.
-                    gap.read += 1;
-                    /* We have found duplicate, drop it in-place */
-                    ptr::drop_in_place(read_ptr);
-                } else {
-                    let write_ptr = start.add(gap.write);
-
-                    /* read_ptr cannot be equal to write_ptr because at this point
-                     * we guaranteed to skip at least one element (before loop starts).
-                     */
-                    ptr::copy_nonoverlapping(read_ptr, write_ptr, 1);
-
-                    /* We have filled that place, so go further */
-                    gap.write += 1;
-                    gap.read += 1;
-                }
-            }
-
-            /* Technically we could let `gap` clean up with its Drop, but
-             * when `same_bucket` is guaranteed to not panic, this bloats a little
-             * the codegen, so we just do it manually */
-            gap.vec.set_len(gap.write);
-            mem::forget(gap);
-        }
-    }
-
-    /// Appends an element to the back of a collection.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the new capacity exceeds `isize::MAX` bytes.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1, 2];
-    /// vec.push(3);
-    /// assert_eq!(vec, [1, 2, 3]);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn push(&mut self, value: T) {
-        // This will panic or abort if we would allocate > isize::MAX bytes
-        // or if the length increment would overflow for zero-sized types.
-        if self.len == self.buf.capacity() {
-            self.buf.reserve_for_push(self.len);
-        }
-        unsafe {
-            let end = self.as_mut_ptr().add(self.len);
-            ptr::write(end, value);
-            self.len += 1;
-        }
-    }
-
-    /// Tries to append an element to the back of a collection.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1, 2];
-    /// vec.try_push(3).unwrap();
-    /// assert_eq!(vec, [1, 2, 3]);
-    /// ```
-    #[inline]
-    #[stable(feature = "kernel", since = "1.0.0")]
-    pub fn try_push(&mut self, value: T) -> Result<(), TryReserveError> {
-        if self.len == self.buf.capacity() {
-            self.buf.try_reserve_for_push(self.len)?;
-        }
-        unsafe {
-            let end = self.as_mut_ptr().add(self.len);
-            ptr::write(end, value);
-            self.len += 1;
-        }
-        Ok(())
-    }
-
-    /// Appends an element if there is sufficient spare capacity, otherwise an error is returned
-    /// with the element.
-    ///
-    /// Unlike [`push`] this method will not reallocate when there's insufficient capacity.
-    /// The caller should use [`reserve`] or [`try_reserve`] to ensure that there is enough capacity.
-    ///
-    /// [`push`]: Vec::push
-    /// [`reserve`]: Vec::reserve
-    /// [`try_reserve`]: Vec::try_reserve
-    ///
-    /// # Examples
-    ///
-    /// A manual, panic-free alternative to [`FromIterator`]:
-    ///
-    /// ```
-    /// #![feature(vec_push_within_capacity)]
-    ///
-    /// use std::collections::TryReserveError;
-    /// fn from_iter_fallible<T>(iter: impl Iterator<Item=T>) -> Result<Vec<T>, TryReserveError> {
-    ///     let mut vec = Vec::new();
-    ///     for value in iter {
-    ///         if let Err(value) = vec.push_within_capacity(value) {
-    ///             vec.try_reserve(1)?;
-    ///             // this cannot fail, the previous line either returned or added at least 1 free slot
-    ///             let _ = vec.push_within_capacity(value);
-    ///         }
-    ///     }
-    ///     Ok(vec)
-    /// }
-    /// assert_eq!(from_iter_fallible(0..100), Ok(Vec::from_iter(0..100)));
-    /// ```
-    #[inline]
-    #[unstable(feature = "vec_push_within_capacity", issue = "100486")]
-    pub fn push_within_capacity(&mut self, value: T) -> Result<(), T> {
-        if self.len == self.buf.capacity() {
-            return Err(value);
-        }
-        unsafe {
-            let end = self.as_mut_ptr().add(self.len);
-            ptr::write(end, value);
-            self.len += 1;
-        }
-        Ok(())
-    }
-
-    /// Removes the last element from a vector and returns it, or [`None`] if it
-    /// is empty.
-    ///
-    /// If you'd like to pop the first element, consider using
-    /// [`VecDeque::pop_front`] instead.
-    ///
-    /// [`VecDeque::pop_front`]: crate::collections::VecDeque::pop_front
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1, 2, 3];
-    /// assert_eq!(vec.pop(), Some(3));
-    /// assert_eq!(vec, [1, 2]);
-    /// ```
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn pop(&mut self) -> Option<T> {
-        if self.len == 0 {
-            None
-        } else {
-            unsafe {
-                self.len -= 1;
-                core::intrinsics::assume(self.len < self.capacity());
-                Some(ptr::read(self.as_ptr().add(self.len())))
-            }
-        }
-    }
-
-    /// Moves all the elements of `other` into `self`, leaving `other` empty.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the new capacity exceeds `isize::MAX` bytes.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1, 2, 3];
-    /// let mut vec2 = vec![4, 5, 6];
-    /// vec.append(&mut vec2);
-    /// assert_eq!(vec, [1, 2, 3, 4, 5, 6]);
-    /// assert_eq!(vec2, []);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[inline]
-    #[stable(feature = "append", since = "1.4.0")]
-    pub fn append(&mut self, other: &mut Self) {
-        unsafe {
-            self.append_elements(other.as_slice() as _);
-            other.set_len(0);
-        }
-    }
-
-    /// Appends elements to `self` from other buffer.
-    #[cfg(not(no_global_oom_handling))]
-    #[inline]
-    unsafe fn append_elements(&mut self, other: *const [T]) {
-        let count = unsafe { (*other).len() };
-        self.reserve(count);
-        let len = self.len();
-        unsafe { ptr::copy_nonoverlapping(other as *const T, self.as_mut_ptr().add(len), count) };
-        self.len += count;
-    }
-
-    /// Tries to append elements to `self` from other buffer.
-    #[inline]
-    unsafe fn try_append_elements(&mut self, other: *const [T]) -> Result<(), TryReserveError> {
-        let count = unsafe { (*other).len() };
-        self.try_reserve(count)?;
-        let len = self.len();
-        unsafe { ptr::copy_nonoverlapping(other as *const T, self.as_mut_ptr().add(len), count) };
-        self.len += count;
-        Ok(())
-    }
-
-    /// Removes the specified range from the vector in bulk, returning all
-    /// removed elements as an iterator. If the iterator is dropped before
-    /// being fully consumed, it drops the remaining removed elements.
-    ///
-    /// The returned iterator keeps a mutable borrow on the vector to optimize
-    /// its implementation.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the starting point is greater than the end point or if
-    /// the end point is greater than the length of the vector.
-    ///
-    /// # Leaking
-    ///
-    /// If the returned iterator goes out of scope without being dropped (due to
-    /// [`mem::forget`], for example), the vector may have lost and leaked
-    /// elements arbitrarily, including elements outside the range.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut v = vec![1, 2, 3];
-    /// let u: Vec<_> = v.drain(1..).collect();
-    /// assert_eq!(v, &[1]);
-    /// assert_eq!(u, &[2, 3]);
-    ///
-    /// // A full range clears the vector, like `clear()` does
-    /// v.drain(..);
-    /// assert_eq!(v, &[]);
-    /// ```
-    #[stable(feature = "drain", since = "1.6.0")]
-    pub fn drain<R>(&mut self, range: R) -> Drain<'_, T, A>
-    where
-        R: RangeBounds<usize>,
-    {
-        // Memory safety
-        //
-        // When the Drain is first created, it shortens the length of
-        // the source vector to make sure no uninitialized or moved-from elements
-        // are accessible at all if the Drain's destructor never gets to run.
-        //
-        // Drain will ptr::read out the values to remove.
-        // When finished, remaining tail of the vec is copied back to cover
-        // the hole, and the vector length is restored to the new length.
-        //
-        let len = self.len();
-        let Range { start, end } = slice::range(range, ..len);
-
-        unsafe {
-            // set self.vec length's to start, to be safe in case Drain is leaked
-            self.set_len(start);
-            let range_slice = slice::from_raw_parts(self.as_ptr().add(start), end - start);
-            Drain {
-                tail_start: end,
-                tail_len: len - end,
-                iter: range_slice.iter(),
-                vec: NonNull::from(self),
-            }
-        }
-    }
-
-    /// Clears the vector, removing all values.
-    ///
-    /// Note that this method has no effect on the allocated capacity
-    /// of the vector.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut v = vec![1, 2, 3];
-    ///
-    /// v.clear();
-    ///
-    /// assert!(v.is_empty());
-    /// ```
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn clear(&mut self) {
-        let elems: *mut [T] = self.as_mut_slice();
-
-        // SAFETY:
-        // - `elems` comes directly from `as_mut_slice` and is therefore valid.
-        // - Setting `self.len` before calling `drop_in_place` means that,
-        //   if an element's `Drop` impl panics, the vector's `Drop` impl will
-        //   do nothing (leaking the rest of the elements) instead of dropping
-        //   some twice.
-        unsafe {
-            self.len = 0;
-            ptr::drop_in_place(elems);
-        }
-    }
-
-    /// Returns the number of elements in the vector, also referred to
-    /// as its 'length'.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let a = vec![1, 2, 3];
-    /// assert_eq!(a.len(), 3);
-    /// ```
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn len(&self) -> usize {
-        self.len
-    }
-
-    /// Returns `true` if the vector contains no elements.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut v = Vec::new();
-    /// assert!(v.is_empty());
-    ///
-    /// v.push(1);
-    /// assert!(!v.is_empty());
-    /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn is_empty(&self) -> bool {
-        self.len() == 0
-    }
-
-    /// Splits the collection into two at the given index.
-    ///
-    /// Returns a newly allocated vector containing the elements in the range
-    /// `[at, len)`. After the call, the original vector will be left containing
-    /// the elements `[0, at)` with its previous capacity unchanged.
-    ///
-    /// # Panics
-    ///
-    /// Panics if `at > len`.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1, 2, 3];
-    /// let vec2 = vec.split_off(1);
-    /// assert_eq!(vec, [1]);
-    /// assert_eq!(vec2, [2, 3]);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[inline]
-    #[must_use = "use `.truncate()` if you don't need the other half"]
-    #[stable(feature = "split_off", since = "1.4.0")]
-    pub fn split_off(&mut self, at: usize) -> Self
-    where
-        A: Clone,
-    {
-        #[cold]
-        #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
-        #[track_caller]
-        fn assert_failed(at: usize, len: usize) -> ! {
-            panic!("`at` split index (is {at}) should be <= len (is {len})");
-        }
-
-        if at > self.len() {
-            assert_failed(at, self.len());
-        }
-
-        if at == 0 {
-            // the new vector can take over the original buffer and avoid the copy
-            return mem::replace(
-                self,
-                Vec::with_capacity_in(self.capacity(), self.allocator().clone()),
-            );
-        }
-
-        let other_len = self.len - at;
-        let mut other = Vec::with_capacity_in(other_len, self.allocator().clone());
-
-        // Unsafely `set_len` and copy items to `other`.
-        unsafe {
-            self.set_len(at);
-            other.set_len(other_len);
-
-            ptr::copy_nonoverlapping(self.as_ptr().add(at), other.as_mut_ptr(), other.len());
-        }
-        other
-    }
-
-    /// Resizes the `Vec` in-place so that `len` is equal to `new_len`.
-    ///
-    /// If `new_len` is greater than `len`, the `Vec` is extended by the
-    /// difference, with each additional slot filled with the result of
-    /// calling the closure `f`. The return values from `f` will end up
-    /// in the `Vec` in the order they have been generated.
-    ///
-    /// If `new_len` is less than `len`, the `Vec` is simply truncated.
-    ///
-    /// This method uses a closure to create new values on every push. If
-    /// you'd rather [`Clone`] a given value, use [`Vec::resize`]. If you
-    /// want to use the [`Default`] trait to generate values, you can
-    /// pass [`Default::default`] as the second argument.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1, 2, 3];
-    /// vec.resize_with(5, Default::default);
-    /// assert_eq!(vec, [1, 2, 3, 0, 0]);
-    ///
-    /// let mut vec = vec![];
-    /// let mut p = 1;
-    /// vec.resize_with(4, || { p *= 2; p });
-    /// assert_eq!(vec, [2, 4, 8, 16]);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[stable(feature = "vec_resize_with", since = "1.33.0")]
-    pub fn resize_with<F>(&mut self, new_len: usize, f: F)
-    where
-        F: FnMut() -> T,
-    {
-        let len = self.len();
-        if new_len > len {
-            self.extend_trusted(iter::repeat_with(f).take(new_len - len));
-        } else {
-            self.truncate(new_len);
-        }
-    }
-
-    /// Consumes and leaks the `Vec`, returning a mutable reference to the contents,
-    /// `&'a mut [T]`. Note that the type `T` must outlive the chosen lifetime
-    /// `'a`. If the type has only static references, or none at all, then this
-    /// may be chosen to be `'static`.
-    ///
-    /// As of Rust 1.57, this method does not reallocate or shrink the `Vec`,
-    /// so the leaked allocation may include unused capacity that is not part
-    /// of the returned slice.
-    ///
-    /// This function is mainly useful for data that lives for the remainder of
-    /// the program's life. Dropping the returned reference will cause a memory
-    /// leak.
-    ///
-    /// # Examples
-    ///
-    /// Simple usage:
-    ///
-    /// ```
-    /// let x = vec![1, 2, 3];
-    /// let static_ref: &'static mut [usize] = x.leak();
-    /// static_ref[0] += 1;
-    /// assert_eq!(static_ref, &[2, 2, 3]);
-    /// ```
-    #[stable(feature = "vec_leak", since = "1.47.0")]
-    #[inline]
-    pub fn leak<'a>(self) -> &'a mut [T]
-    where
-        A: 'a,
-    {
-        let mut me = ManuallyDrop::new(self);
-        unsafe { slice::from_raw_parts_mut(me.as_mut_ptr(), me.len) }
-    }
-
-    /// Returns the remaining spare capacity of the vector as a slice of
-    /// `MaybeUninit<T>`.
-    ///
-    /// The returned slice can be used to fill the vector with data (e.g. by
-    /// reading from a file) before marking the data as initialized using the
-    /// [`set_len`] method.
-    ///
-    /// [`set_len`]: Vec::set_len
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// // Allocate vector big enough for 10 elements.
-    /// let mut v = Vec::with_capacity(10);
-    ///
-    /// // Fill in the first 3 elements.
-    /// let uninit = v.spare_capacity_mut();
-    /// uninit[0].write(0);
-    /// uninit[1].write(1);
-    /// uninit[2].write(2);
-    ///
-    /// // Mark the first 3 elements of the vector as being initialized.
-    /// unsafe {
-    ///     v.set_len(3);
-    /// }
-    ///
-    /// assert_eq!(&v, &[0, 1, 2]);
-    /// ```
-    #[stable(feature = "vec_spare_capacity", since = "1.60.0")]
-    #[inline]
-    pub fn spare_capacity_mut(&mut self) -> &mut [MaybeUninit<T>] {
-        // Note:
-        // This method is not implemented in terms of `split_at_spare_mut`,
-        // to prevent invalidation of pointers to the buffer.
-        unsafe {
-            slice::from_raw_parts_mut(
-                self.as_mut_ptr().add(self.len) as *mut MaybeUninit<T>,
-                self.buf.capacity() - self.len,
-            )
-        }
-    }
-
-    /// Returns vector content as a slice of `T`, along with the remaining spare
-    /// capacity of the vector as a slice of `MaybeUninit<T>`.
-    ///
-    /// The returned spare capacity slice can be used to fill the vector with data
-    /// (e.g. by reading from a file) before marking the data as initialized using
-    /// the [`set_len`] method.
-    ///
-    /// [`set_len`]: Vec::set_len
-    ///
-    /// Note that this is a low-level API, which should be used with care for
-    /// optimization purposes. If you need to append data to a `Vec`
-    /// you can use [`push`], [`extend`], [`extend_from_slice`],
-    /// [`extend_from_within`], [`insert`], [`append`], [`resize`] or
-    /// [`resize_with`], depending on your exact needs.
-    ///
-    /// [`push`]: Vec::push
-    /// [`extend`]: Vec::extend
-    /// [`extend_from_slice`]: Vec::extend_from_slice
-    /// [`extend_from_within`]: Vec::extend_from_within
-    /// [`insert`]: Vec::insert
-    /// [`append`]: Vec::append
-    /// [`resize`]: Vec::resize
-    /// [`resize_with`]: Vec::resize_with
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(vec_split_at_spare)]
-    ///
-    /// let mut v = vec![1, 1, 2];
-    ///
-    /// // Reserve additional space big enough for 10 elements.
-    /// v.reserve(10);
-    ///
-    /// let (init, uninit) = v.split_at_spare_mut();
-    /// let sum = init.iter().copied().sum::<u32>();
-    ///
-    /// // Fill in the next 4 elements.
-    /// uninit[0].write(sum);
-    /// uninit[1].write(sum * 2);
-    /// uninit[2].write(sum * 3);
-    /// uninit[3].write(sum * 4);
-    ///
-    /// // Mark the 4 elements of the vector as being initialized.
-    /// unsafe {
-    ///     let len = v.len();
-    ///     v.set_len(len + 4);
-    /// }
-    ///
-    /// assert_eq!(&v, &[1, 1, 2, 4, 8, 12, 16]);
-    /// ```
-    #[unstable(feature = "vec_split_at_spare", issue = "81944")]
-    #[inline]
-    pub fn split_at_spare_mut(&mut self) -> (&mut [T], &mut [MaybeUninit<T>]) {
-        // SAFETY:
-        // - len is ignored and so never changed
-        let (init, spare, _) = unsafe { self.split_at_spare_mut_with_len() };
-        (init, spare)
-    }
-
-    /// Safety: changing returned .2 (&mut usize) is considered the same as calling `.set_len(_)`.
-    ///
-    /// This method provides unique access to all vec parts at once in `extend_from_within`.
-    unsafe fn split_at_spare_mut_with_len(
-        &mut self,
-    ) -> (&mut [T], &mut [MaybeUninit<T>], &mut usize) {
-        let ptr = self.as_mut_ptr();
-        // SAFETY:
-        // - `ptr` is guaranteed to be valid for `self.len` elements
-        // - but the allocation extends out to `self.buf.capacity()` elements, possibly
-        // uninitialized
-        let spare_ptr = unsafe { ptr.add(self.len) };
-        let spare_ptr = spare_ptr.cast::<MaybeUninit<T>>();
-        let spare_len = self.buf.capacity() - self.len;
-
-        // SAFETY:
-        // - `ptr` is guaranteed to be valid for `self.len` elements
-        // - `spare_ptr` is pointing one element past the buffer, so it doesn't overlap with `initialized`
-        unsafe {
-            let initialized = slice::from_raw_parts_mut(ptr, self.len);
-            let spare = slice::from_raw_parts_mut(spare_ptr, spare_len);
-
-            (initialized, spare, &mut self.len)
-        }
-    }
-}
-
-impl<T: Clone, A: Allocator> Vec<T, A> {
-    /// Resizes the `Vec` in-place so that `len` is equal to `new_len`.
-    ///
-    /// If `new_len` is greater than `len`, the `Vec` is extended by the
-    /// difference, with each additional slot filled with `value`.
-    /// If `new_len` is less than `len`, the `Vec` is simply truncated.
-    ///
-    /// This method requires `T` to implement [`Clone`],
-    /// in order to be able to clone the passed value.
-    /// If you need more flexibility (or want to rely on [`Default`] instead of
-    /// [`Clone`]), use [`Vec::resize_with`].
-    /// If you only need to resize to a smaller size, use [`Vec::truncate`].
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec!["hello"];
-    /// vec.resize(3, "world");
-    /// assert_eq!(vec, ["hello", "world", "world"]);
-    ///
-    /// let mut vec = vec![1, 2, 3, 4];
-    /// vec.resize(2, 0);
-    /// assert_eq!(vec, [1, 2]);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[stable(feature = "vec_resize", since = "1.5.0")]
-    pub fn resize(&mut self, new_len: usize, value: T) {
-        let len = self.len();
-
-        if new_len > len {
-            self.extend_with(new_len - len, value)
-        } else {
-            self.truncate(new_len);
-        }
-    }
-
-    /// Tries to resize the `Vec` in-place so that `len` is equal to `new_len`.
-    ///
-    /// If `new_len` is greater than `len`, the `Vec` is extended by the
-    /// difference, with each additional slot filled with `value`.
-    /// If `new_len` is less than `len`, the `Vec` is simply truncated.
-    ///
-    /// This method requires `T` to implement [`Clone`],
-    /// in order to be able to clone the passed value.
-    /// If you need more flexibility (or want to rely on [`Default`] instead of
-    /// [`Clone`]), use [`Vec::resize_with`].
-    /// If you only need to resize to a smaller size, use [`Vec::truncate`].
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec!["hello"];
-    /// vec.try_resize(3, "world").unwrap();
-    /// assert_eq!(vec, ["hello", "world", "world"]);
-    ///
-    /// let mut vec = vec![1, 2, 3, 4];
-    /// vec.try_resize(2, 0).unwrap();
-    /// assert_eq!(vec, [1, 2]);
-    ///
-    /// let mut vec = vec![42];
-    /// let result = vec.try_resize(usize::MAX, 0);
-    /// assert!(result.is_err());
-    /// ```
-    #[stable(feature = "kernel", since = "1.0.0")]
-    pub fn try_resize(&mut self, new_len: usize, value: T) -> Result<(), TryReserveError> {
-        let len = self.len();
-
-        if new_len > len {
-            self.try_extend_with(new_len - len, value)
-        } else {
-            self.truncate(new_len);
-            Ok(())
-        }
-    }
-
-    /// Clones and appends all elements in a slice to the `Vec`.
-    ///
-    /// Iterates over the slice `other`, clones each element, and then appends
-    /// it to this `Vec`. The `other` slice is traversed in-order.
-    ///
-    /// Note that this function is same as [`extend`] except that it is
-    /// specialized to work with slices instead. If and when Rust gets
-    /// specialization this function will likely be deprecated (but still
-    /// available).
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1];
-    /// vec.extend_from_slice(&[2, 3, 4]);
-    /// assert_eq!(vec, [1, 2, 3, 4]);
-    /// ```
-    ///
-    /// [`extend`]: Vec::extend
-    #[cfg(not(no_global_oom_handling))]
-    #[stable(feature = "vec_extend_from_slice", since = "1.6.0")]
-    pub fn extend_from_slice(&mut self, other: &[T]) {
-        self.spec_extend(other.iter())
-    }
-
-    /// Tries to clone and append all elements in a slice to the `Vec`.
-    ///
-    /// Iterates over the slice `other`, clones each element, and then appends
-    /// it to this `Vec`. The `other` slice is traversed in-order.
-    ///
-    /// Note that this function is same as [`extend`] except that it is
-    /// specialized to work with slices instead. If and when Rust gets
-    /// specialization this function will likely be deprecated (but still
-    /// available).
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1];
-    /// vec.try_extend_from_slice(&[2, 3, 4]).unwrap();
-    /// assert_eq!(vec, [1, 2, 3, 4]);
-    /// ```
-    ///
-    /// [`extend`]: Vec::extend
-    #[stable(feature = "kernel", since = "1.0.0")]
-    pub fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError> {
-        self.try_spec_extend(other.iter())
-    }
-
-    /// Copies elements from `src` range to the end of the vector.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the starting point is greater than the end point or if
-    /// the end point is greater than the length of the vector.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![0, 1, 2, 3, 4];
-    ///
-    /// vec.extend_from_within(2..);
-    /// assert_eq!(vec, [0, 1, 2, 3, 4, 2, 3, 4]);
-    ///
-    /// vec.extend_from_within(..2);
-    /// assert_eq!(vec, [0, 1, 2, 3, 4, 2, 3, 4, 0, 1]);
-    ///
-    /// vec.extend_from_within(4..8);
-    /// assert_eq!(vec, [0, 1, 2, 3, 4, 2, 3, 4, 0, 1, 4, 2, 3, 4]);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[stable(feature = "vec_extend_from_within", since = "1.53.0")]
-    pub fn extend_from_within<R>(&mut self, src: R)
-    where
-        R: RangeBounds<usize>,
-    {
-        let range = slice::range(src, ..self.len());
-        self.reserve(range.len());
-
-        // SAFETY:
-        // - `slice::range` guarantees that the given range is valid for indexing self
-        unsafe {
-            self.spec_extend_from_within(range);
-        }
-    }
-}
-
-impl<T, A: Allocator, const N: usize> Vec<[T; N], A> {
-    /// Takes a `Vec<[T; N]>` and flattens it into a `Vec<T>`.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the length of the resulting vector would overflow a `usize`.
-    ///
-    /// This is only possible when flattening a vector of arrays of zero-sized
-    /// types, and thus tends to be irrelevant in practice. If
-    /// `size_of::<T>() > 0`, this will never panic.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(slice_flatten)]
-    ///
-    /// let mut vec = vec![[1, 2, 3], [4, 5, 6], [7, 8, 9]];
-    /// assert_eq!(vec.pop(), Some([7, 8, 9]));
-    ///
-    /// let mut flattened = vec.into_flattened();
-    /// assert_eq!(flattened.pop(), Some(6));
-    /// ```
-    #[unstable(feature = "slice_flatten", issue = "95629")]
-    pub fn into_flattened(self) -> Vec<T, A> {
-        let (ptr, len, cap, alloc) = self.into_raw_parts_with_alloc();
-        let (new_len, new_cap) = if T::IS_ZST {
-            (len.checked_mul(N).expect("vec len overflow"), usize::MAX)
-        } else {
-            // SAFETY:
-            // - `cap * N` cannot overflow because the allocation is already in
-            // the address space.
-            // - Each `[T; N]` has `N` valid elements, so there are `len * N`
-            // valid elements in the allocation.
-            unsafe { (len.unchecked_mul(N), cap.unchecked_mul(N)) }
-        };
-        // SAFETY:
-        // - `ptr` was allocated by `self`
-        // - `ptr` is well-aligned because `[T; N]` has the same alignment as `T`.
-        // - `new_cap` refers to the same sized allocation as `cap` because
-        // `new_cap * size_of::<T>()` == `cap * size_of::<[T; N]>()`
-        // - `len` <= `cap`, so `len * N` <= `cap * N`.
-        unsafe { Vec::<T, A>::from_raw_parts_in(ptr.cast(), new_len, new_cap, alloc) }
-    }
-}
-
-impl<T: Clone, A: Allocator> Vec<T, A> {
-    #[cfg(not(no_global_oom_handling))]
-    /// Extend the vector by `n` clones of value.
-    fn extend_with(&mut self, n: usize, value: T) {
-        self.reserve(n);
-
-        unsafe {
-            let mut ptr = self.as_mut_ptr().add(self.len());
-            // Use SetLenOnDrop to work around bug where compiler
-            // might not realize the store through `ptr` through self.set_len()
-            // don't alias.
-            let mut local_len = SetLenOnDrop::new(&mut self.len);
-
-            // Write all elements except the last one
-            for _ in 1..n {
-                ptr::write(ptr, value.clone());
-                ptr = ptr.add(1);
-                // Increment the length in every step in case clone() panics
-                local_len.increment_len(1);
-            }
-
-            if n > 0 {
-                // We can write the last element directly without cloning needlessly
-                ptr::write(ptr, value);
-                local_len.increment_len(1);
-            }
-
-            // len set by scope guard
-        }
-    }
-
-    /// Try to extend the vector by `n` clones of value.
-    fn try_extend_with(&mut self, n: usize, value: T) -> Result<(), TryReserveError> {
-        self.try_reserve(n)?;
-
-        unsafe {
-            let mut ptr = self.as_mut_ptr().add(self.len());
-            // Use SetLenOnDrop to work around bug where compiler
-            // might not realize the store through `ptr` through self.set_len()
-            // don't alias.
-            let mut local_len = SetLenOnDrop::new(&mut self.len);
-
-            // Write all elements except the last one
-            for _ in 1..n {
-                ptr::write(ptr, value.clone());
-                ptr = ptr.add(1);
-                // Increment the length in every step in case clone() panics
-                local_len.increment_len(1);
-            }
-
-            if n > 0 {
-                // We can write the last element directly without cloning needlessly
-                ptr::write(ptr, value);
-                local_len.increment_len(1);
-            }
-
-            // len set by scope guard
-            Ok(())
-        }
-    }
-}
-
-impl<T: PartialEq, A: Allocator> Vec<T, A> {
-    /// Removes consecutive repeated elements in the vector according to the
-    /// [`PartialEq`] trait implementation.
-    ///
-    /// If the vector is sorted, this removes all duplicates.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1, 2, 2, 3, 2];
-    ///
-    /// vec.dedup();
-    ///
-    /// assert_eq!(vec, [1, 2, 3, 2]);
-    /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
-    #[inline]
-    pub fn dedup(&mut self) {
-        self.dedup_by(|a, b| a == b)
-    }
-}
-
-////////////////////////////////////////////////////////////////////////////////
-// Internal methods and functions
-////////////////////////////////////////////////////////////////////////////////
-
-#[doc(hidden)]
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-pub fn from_elem<T: Clone>(elem: T, n: usize) -> Vec<T> {
-    <T as SpecFromElem>::from_elem(elem, n, Global)
-}
-
-#[doc(hidden)]
-#[cfg(not(no_global_oom_handling))]
-#[unstable(feature = "allocator_api", issue = "32838")]
-pub fn from_elem_in<T: Clone, A: Allocator>(elem: T, n: usize, alloc: A) -> Vec<T, A> {
-    <T as SpecFromElem>::from_elem(elem, n, alloc)
-}
-
-#[cfg(not(no_global_oom_handling))]
-trait ExtendFromWithinSpec {
-    /// # Safety
-    ///
-    /// - `src` needs to be valid index
-    /// - `self.capacity() - self.len()` must be `>= src.len()`
-    unsafe fn spec_extend_from_within(&mut self, src: Range<usize>);
-}
-
-#[cfg(not(no_global_oom_handling))]
-impl<T: Clone, A: Allocator> ExtendFromWithinSpec for Vec<T, A> {
-    default unsafe fn spec_extend_from_within(&mut self, src: Range<usize>) {
-        // SAFETY:
-        // - len is increased only after initializing elements
-        let (this, spare, len) = unsafe { self.split_at_spare_mut_with_len() };
-
-        // SAFETY:
-        // - caller guarantees that src is a valid index
-        let to_clone = unsafe { this.get_unchecked(src) };
-
-        iter::zip(to_clone, spare)
-            .map(|(src, dst)| dst.write(src.clone()))
-            // Note:
-            // - Element was just initialized with `MaybeUninit::write`, so it's ok to increase len
-            // - len is increased after each element to prevent leaks (see issue #82533)
-            .for_each(|_| *len += 1);
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-impl<T: Copy, A: Allocator> ExtendFromWithinSpec for Vec<T, A> {
-    unsafe fn spec_extend_from_within(&mut self, src: Range<usize>) {
-        let count = src.len();
-        {
-            let (init, spare) = self.split_at_spare_mut();
-
-            // SAFETY:
-            // - caller guarantees that `src` is a valid index
-            let source = unsafe { init.get_unchecked(src) };
-
-            // SAFETY:
-            // - Both pointers are created from unique slice references (`&mut [_]`)
-            //   so they are valid and do not overlap.
-            // - Elements are :Copy so it's OK to copy them, without doing
-            //   anything with the original values
-            // - `count` is equal to the len of `source`, so source is valid for
-            //   `count` reads
-            // - `.reserve(count)` guarantees that `spare.len() >= count` so spare
-            //   is valid for `count` writes
-            unsafe { ptr::copy_nonoverlapping(source.as_ptr(), spare.as_mut_ptr() as _, count) };
-        }
-
-        // SAFETY:
-        // - The elements were just initialized by `copy_nonoverlapping`
-        self.len += count;
-    }
-}
-
-////////////////////////////////////////////////////////////////////////////////
-// Common trait implementations for Vec
-////////////////////////////////////////////////////////////////////////////////
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, A: Allocator> ops::Deref for Vec<T, A> {
-    type Target = [T];
-
-    #[inline]
-    fn deref(&self) -> &[T] {
-        unsafe { slice::from_raw_parts(self.as_ptr(), self.len) }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, A: Allocator> ops::DerefMut for Vec<T, A> {
-    #[inline]
-    fn deref_mut(&mut self) -> &mut [T] {
-        unsafe { slice::from_raw_parts_mut(self.as_mut_ptr(), self.len) }
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Clone, A: Allocator + Clone> Clone for Vec<T, A> {
-    #[cfg(not(test))]
-    fn clone(&self) -> Self {
-        let alloc = self.allocator().clone();
-        <[T]>::to_vec_in(&**self, alloc)
-    }
-
-    // HACK(japaric): with cfg(test) the inherent `[T]::to_vec` method, which is
-    // required for this method definition, is not available. Instead use the
-    // `slice::to_vec` function which is only available with cfg(test)
-    // NB see the slice::hack module in slice.rs for more information
-    #[cfg(test)]
-    fn clone(&self) -> Self {
-        let alloc = self.allocator().clone();
-        crate::slice::to_vec(&**self, alloc)
-    }
-
-    fn clone_from(&mut self, other: &Self) {
-        crate::slice::SpecCloneIntoVec::clone_into(other.as_slice(), self);
-    }
-}
-
-/// The hash of a vector is the same as that of the corresponding slice,
-/// as required by the `core::borrow::Borrow` implementation.
-///
-/// ```
-/// use std::hash::BuildHasher;
-///
-/// let b = std::hash::RandomState::new();
-/// let v: Vec<u8> = vec![0xa8, 0x3c, 0x09];
-/// let s: &[u8] = &[0xa8, 0x3c, 0x09];
-/// assert_eq!(b.hash_one(v), b.hash_one(s));
-/// ```
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Hash, A: Allocator> Hash for Vec<T, A> {
-    #[inline]
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        Hash::hash(&**self, state)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_on_unimplemented(
-    message = "vector indices are of type `usize` or ranges of `usize`",
-    label = "vector indices are of type `usize` or ranges of `usize`"
-)]
-impl<T, I: SliceIndex<[T]>, A: Allocator> Index<I> for Vec<T, A> {
-    type Output = I::Output;
-
-    #[inline]
-    fn index(&self, index: I) -> &Self::Output {
-        Index::index(&**self, index)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_on_unimplemented(
-    message = "vector indices are of type `usize` or ranges of `usize`",
-    label = "vector indices are of type `usize` or ranges of `usize`"
-)]
-impl<T, I: SliceIndex<[T]>, A: Allocator> IndexMut<I> for Vec<T, A> {
-    #[inline]
-    fn index_mut(&mut self, index: I) -> &mut Self::Output {
-        IndexMut::index_mut(&mut **self, index)
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T> FromIterator<T> for Vec<T> {
-    #[inline]
-    fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Vec<T> {
-        <Self as SpecFromIter<T, I::IntoIter>>::from_iter(iter.into_iter())
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, A: Allocator> IntoIterator for Vec<T, A> {
-    type Item = T;
-    type IntoIter = IntoIter<T, A>;
-
-    /// Creates a consuming iterator, that is, one that moves each value out of
-    /// the vector (from start to end). The vector cannot be used after calling
-    /// this.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let v = vec!["a".to_string(), "b".to_string()];
-    /// let mut v_iter = v.into_iter();
-    ///
-    /// let first_element: Option<String> = v_iter.next();
-    ///
-    /// assert_eq!(first_element, Some("a".to_string()));
-    /// assert_eq!(v_iter.next(), Some("b".to_string()));
-    /// assert_eq!(v_iter.next(), None);
-    /// ```
-    #[inline]
-    fn into_iter(self) -> Self::IntoIter {
-        unsafe {
-            let mut me = ManuallyDrop::new(self);
-            let alloc = ManuallyDrop::new(ptr::read(me.allocator()));
-            let begin = me.as_mut_ptr();
-            let end = if T::IS_ZST {
-                begin.wrapping_byte_add(me.len())
-            } else {
-                begin.add(me.len()) as *const T
-            };
-            let cap = me.buf.capacity();
-            IntoIter {
-                buf: NonNull::new_unchecked(begin),
-                phantom: PhantomData,
-                cap,
-                alloc,
-                ptr: begin,
-                end,
-            }
-        }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T, A: Allocator> IntoIterator for &'a Vec<T, A> {
-    type Item = &'a T;
-    type IntoIter = slice::Iter<'a, T>;
-
-    fn into_iter(self) -> Self::IntoIter {
-        self.iter()
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T, A: Allocator> IntoIterator for &'a mut Vec<T, A> {
-    type Item = &'a mut T;
-    type IntoIter = slice::IterMut<'a, T>;
-
-    fn into_iter(self) -> Self::IntoIter {
-        self.iter_mut()
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, A: Allocator> Extend<T> for Vec<T, A> {
-    #[inline]
-    fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
-        <Self as SpecExtend<T, I::IntoIter>>::spec_extend(self, iter.into_iter())
-    }
-
-    #[inline]
-    fn extend_one(&mut self, item: T) {
-        self.push(item);
-    }
-
-    #[inline]
-    fn extend_reserve(&mut self, additional: usize) {
-        self.reserve(additional);
-    }
-}
-
-impl<T, A: Allocator> Vec<T, A> {
-    // leaf method to which various SpecFrom/SpecExtend implementations delegate when
-    // they have no further optimizations to apply
-    #[cfg(not(no_global_oom_handling))]
-    fn extend_desugared<I: Iterator<Item = T>>(&mut self, mut iterator: I) {
-        // This is the case for a general iterator.
-        //
-        // This function should be the moral equivalent of:
-        //
-        //      for item in iterator {
-        //          self.push(item);
-        //      }
-        while let Some(element) = iterator.next() {
-            let len = self.len();
-            if len == self.capacity() {
-                let (lower, _) = iterator.size_hint();
-                self.reserve(lower.saturating_add(1));
-            }
-            unsafe {
-                ptr::write(self.as_mut_ptr().add(len), element);
-                // Since next() executes user code which can panic we have to bump the length
-                // after each step.
-                // NB can't overflow since we would have had to alloc the address space
-                self.set_len(len + 1);
-            }
-        }
-    }
-
-    // leaf method to which various SpecFrom/SpecExtend implementations delegate when
-    // they have no further optimizations to apply
-    fn try_extend_desugared<I: Iterator<Item = T>>(&mut self, mut iterator: I) -> Result<(), TryReserveError> {
-        // This is the case for a general iterator.
-        //
-        // This function should be the moral equivalent of:
-        //
-        //      for item in iterator {
-        //          self.push(item);
-        //      }
-        while let Some(element) = iterator.next() {
-            let len = self.len();
-            if len == self.capacity() {
-                let (lower, _) = iterator.size_hint();
-                self.try_reserve(lower.saturating_add(1))?;
-            }
-            unsafe {
-                ptr::write(self.as_mut_ptr().add(len), element);
-                // Since next() executes user code which can panic we have to bump the length
-                // after each step.
-                // NB can't overflow since we would have had to alloc the address space
-                self.set_len(len + 1);
-            }
-        }
-
-        Ok(())
-    }
-
-    // specific extend for `TrustedLen` iterators, called both by the specializations
-    // and internal places where resolving specialization makes compilation slower
-    #[cfg(not(no_global_oom_handling))]
-    fn extend_trusted(&mut self, iterator: impl iter::TrustedLen<Item = T>) {
-        let (low, high) = iterator.size_hint();
-        if let Some(additional) = high {
-            debug_assert_eq!(
-                low,
-                additional,
-                "TrustedLen iterator's size hint is not exact: {:?}",
-                (low, high)
-            );
-            self.reserve(additional);
-            unsafe {
-                let ptr = self.as_mut_ptr();
-                let mut local_len = SetLenOnDrop::new(&mut self.len);
-                iterator.for_each(move |element| {
-                    ptr::write(ptr.add(local_len.current_len()), element);
-                    // Since the loop executes user code which can panic we have to update
-                    // the length every step to correctly drop what we've written.
-                    // NB can't overflow since we would have had to alloc the address space
-                    local_len.increment_len(1);
-                });
-            }
-        } else {
-            // Per TrustedLen contract a `None` upper bound means that the iterator length
-            // truly exceeds usize::MAX, which would eventually lead to a capacity overflow anyway.
-            // Since the other branch already panics eagerly (via `reserve()`) we do the same here.
-            // This avoids additional codegen for a fallback code path which would eventually
-            // panic anyway.
-            panic!("capacity overflow");
-        }
-    }
-
-    // specific extend for `TrustedLen` iterators, called both by the specializations
-    // and internal places where resolving specialization makes compilation slower
-    fn try_extend_trusted(&mut self, iterator: impl iter::TrustedLen<Item = T>) -> Result<(), TryReserveError> {
-        let (low, high) = iterator.size_hint();
-        if let Some(additional) = high {
-            debug_assert_eq!(
-                low,
-                additional,
-                "TrustedLen iterator's size hint is not exact: {:?}",
-                (low, high)
-            );
-            self.try_reserve(additional)?;
-            unsafe {
-                let ptr = self.as_mut_ptr();
-                let mut local_len = SetLenOnDrop::new(&mut self.len);
-                iterator.for_each(move |element| {
-                    ptr::write(ptr.add(local_len.current_len()), element);
-                    // Since the loop executes user code which can panic we have to update
-                    // the length every step to correctly drop what we've written.
-                    // NB can't overflow since we would have had to alloc the address space
-                    local_len.increment_len(1);
-                });
-            }
-            Ok(())
-        } else {
-            Err(TryReserveErrorKind::CapacityOverflow.into())
-        }
-    }
-
-    /// Creates a splicing iterator that replaces the specified range in the vector
-    /// with the given `replace_with` iterator and yields the removed items.
-    /// `replace_with` does not need to be the same length as `range`.
-    ///
-    /// `range` is removed even if the iterator is not consumed until the end.
-    ///
-    /// It is unspecified how many elements are removed from the vector
-    /// if the `Splice` value is leaked.
-    ///
-    /// The input iterator `replace_with` is only consumed when the `Splice` value is dropped.
-    ///
-    /// This is optimal if:
-    ///
-    /// * The tail (elements in the vector after `range`) is empty,
-    /// * or `replace_with` yields fewer or equal elements than `range`’s length
-    /// * or the lower bound of its `size_hint()` is exact.
-    ///
-    /// Otherwise, a temporary vector is allocated and the tail is moved twice.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the starting point is greater than the end point or if
-    /// the end point is greater than the length of the vector.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut v = vec![1, 2, 3, 4];
-    /// let new = [7, 8, 9];
-    /// let u: Vec<_> = v.splice(1..3, new).collect();
-    /// assert_eq!(v, &[1, 7, 8, 9, 4]);
-    /// assert_eq!(u, &[2, 3]);
-    /// ```
-    #[cfg(not(no_global_oom_handling))]
-    #[inline]
-    #[stable(feature = "vec_splice", since = "1.21.0")]
-    pub fn splice<R, I>(&mut self, range: R, replace_with: I) -> Splice<'_, I::IntoIter, A>
-    where
-        R: RangeBounds<usize>,
-        I: IntoIterator<Item = T>,
-    {
-        Splice { drain: self.drain(range), replace_with: replace_with.into_iter() }
-    }
-
-    /// Creates an iterator which uses a closure to determine if an element should be removed.
-    ///
-    /// If the closure returns true, then the element is removed and yielded.
-    /// If the closure returns false, the element will remain in the vector and will not be yielded
-    /// by the iterator.
-    ///
-    /// If the returned `ExtractIf` is not exhausted, e.g. because it is dropped without iterating
-    /// or the iteration short-circuits, then the remaining elements will be retained.
-    /// Use [`retain`] with a negated predicate if you do not need the returned iterator.
-    ///
-    /// [`retain`]: Vec::retain
-    ///
-    /// Using this method is equivalent to the following code:
-    ///
-    /// ```
-    /// # let some_predicate = |x: &mut i32| { *x == 2 || *x == 3 || *x == 6 };
-    /// # let mut vec = vec![1, 2, 3, 4, 5, 6];
-    /// let mut i = 0;
-    /// while i < vec.len() {
-    ///     if some_predicate(&mut vec[i]) {
-    ///         let val = vec.remove(i);
-    ///         // your code here
-    ///     } else {
-    ///         i += 1;
-    ///     }
-    /// }
-    ///
-    /// # assert_eq!(vec, vec![1, 4, 5]);
-    /// ```
-    ///
-    /// But `extract_if` is easier to use. `extract_if` is also more efficient,
-    /// because it can backshift the elements of the array in bulk.
-    ///
-    /// Note that `extract_if` also lets you mutate every element in the filter closure,
-    /// regardless of whether you choose to keep or remove it.
-    ///
-    /// # Examples
-    ///
-    /// Splitting an array into evens and odds, reusing the original allocation:
-    ///
-    /// ```
-    /// #![feature(extract_if)]
-    /// let mut numbers = vec![1, 2, 3, 4, 5, 6, 8, 9, 11, 13, 14, 15];
-    ///
-    /// let evens = numbers.extract_if(|x| *x % 2 == 0).collect::<Vec<_>>();
-    /// let odds = numbers;
-    ///
-    /// assert_eq!(evens, vec![2, 4, 6, 8, 14]);
-    /// assert_eq!(odds, vec![1, 3, 5, 9, 11, 13, 15]);
-    /// ```
-    #[unstable(feature = "extract_if", reason = "recently added", issue = "43244")]
-    pub fn extract_if<F>(&mut self, filter: F) -> ExtractIf<'_, T, F, A>
-    where
-        F: FnMut(&mut T) -> bool,
-    {
-        let old_len = self.len();
-
-        // Guard against us getting leaked (leak amplification)
-        unsafe {
-            self.set_len(0);
-        }
-
-        ExtractIf { vec: self, idx: 0, del: 0, old_len, pred: filter }
-    }
-}
-
-/// Extend implementation that copies elements out of references before pushing them onto the Vec.
-///
-/// This implementation is specialized for slice iterators, where it uses [`copy_from_slice`] to
-/// append the entire slice at once.
-///
-/// [`copy_from_slice`]: slice::copy_from_slice
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "extend_ref", since = "1.2.0")]
-impl<'a, T: Copy + 'a, A: Allocator> Extend<&'a T> for Vec<T, A> {
-    fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) {
-        self.spec_extend(iter.into_iter())
-    }
-
-    #[inline]
-    fn extend_one(&mut self, &item: &'a T) {
-        self.push(item);
-    }
-
-    #[inline]
-    fn extend_reserve(&mut self, additional: usize) {
-        self.reserve(additional);
-    }
-}
-
-/// Implements comparison of vectors, [lexicographically](Ord#lexicographical-comparison).
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, A1, A2> PartialOrd<Vec<T, A2>> for Vec<T, A1>
-where
-    T: PartialOrd,
-    A1: Allocator,
-    A2: Allocator,
-{
-    #[inline]
-    fn partial_cmp(&self, other: &Vec<T, A2>) -> Option<Ordering> {
-        PartialOrd::partial_cmp(&**self, &**other)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Eq, A: Allocator> Eq for Vec<T, A> {}
-
-/// Implements ordering of vectors, [lexicographically](Ord#lexicographical-comparison).
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Ord, A: Allocator> Ord for Vec<T, A> {
-    #[inline]
-    fn cmp(&self, other: &Self) -> Ordering {
-        Ord::cmp(&**self, &**other)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-unsafe impl<#[may_dangle] T, A: Allocator> Drop for Vec<T, A> {
-    fn drop(&mut self) {
-        unsafe {
-            // use drop for [T]
-            // use a raw slice to refer to the elements of the vector as weakest necessary type;
-            // could avoid questions of validity in certain cases
-            ptr::drop_in_place(ptr::slice_from_raw_parts_mut(self.as_mut_ptr(), self.len))
-        }
-        // RawVec handles deallocation
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T> Default for Vec<T> {
-    /// Creates an empty `Vec<T>`.
-    ///
-    /// The vector will not allocate until elements are pushed onto it.
-    fn default() -> Vec<T> {
-        Vec::new()
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: fmt::Debug, A: Allocator> fmt::Debug for Vec<T, A> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Debug::fmt(&**self, f)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, A: Allocator> AsRef<Vec<T, A>> for Vec<T, A> {
-    fn as_ref(&self) -> &Vec<T, A> {
-        self
-    }
-}
-
-#[stable(feature = "vec_as_mut", since = "1.5.0")]
-impl<T, A: Allocator> AsMut<Vec<T, A>> for Vec<T, A> {
-    fn as_mut(&mut self) -> &mut Vec<T, A> {
-        self
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, A: Allocator> AsRef<[T]> for Vec<T, A> {
-    fn as_ref(&self) -> &[T] {
-        self
-    }
-}
-
-#[stable(feature = "vec_as_mut", since = "1.5.0")]
-impl<T, A: Allocator> AsMut<[T]> for Vec<T, A> {
-    fn as_mut(&mut self) -> &mut [T] {
-        self
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Clone> From<&[T]> for Vec<T> {
-    /// Allocate a `Vec<T>` and fill it by cloning `s`'s items.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// assert_eq!(Vec::from(&[1, 2, 3][..]), vec![1, 2, 3]);
-    /// ```
-    #[cfg(not(test))]
-    fn from(s: &[T]) -> Vec<T> {
-        s.to_vec()
-    }
-    #[cfg(test)]
-    fn from(s: &[T]) -> Vec<T> {
-        crate::slice::to_vec(s, Global)
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "vec_from_mut", since = "1.19.0")]
-impl<T: Clone> From<&mut [T]> for Vec<T> {
-    /// Allocate a `Vec<T>` and fill it by cloning `s`'s items.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// assert_eq!(Vec::from(&mut [1, 2, 3][..]), vec![1, 2, 3]);
-    /// ```
-    #[cfg(not(test))]
-    fn from(s: &mut [T]) -> Vec<T> {
-        s.to_vec()
-    }
-    #[cfg(test)]
-    fn from(s: &mut [T]) -> Vec<T> {
-        crate::slice::to_vec(s, Global)
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "vec_from_array_ref", since = "1.74.0")]
-impl<T: Clone, const N: usize> From<&[T; N]> for Vec<T> {
-    /// Allocate a `Vec<T>` and fill it by cloning `s`'s items.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// assert_eq!(Vec::from(&[1, 2, 3]), vec![1, 2, 3]);
-    /// ```
-    fn from(s: &[T; N]) -> Vec<T> {
-        Self::from(s.as_slice())
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "vec_from_array_ref", since = "1.74.0")]
-impl<T: Clone, const N: usize> From<&mut [T; N]> for Vec<T> {
-    /// Allocate a `Vec<T>` and fill it by cloning `s`'s items.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// assert_eq!(Vec::from(&mut [1, 2, 3]), vec![1, 2, 3]);
-    /// ```
-    fn from(s: &mut [T; N]) -> Vec<T> {
-        Self::from(s.as_mut_slice())
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "vec_from_array", since = "1.44.0")]
-impl<T, const N: usize> From<[T; N]> for Vec<T> {
-    /// Allocate a `Vec<T>` and move `s`'s items into it.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// assert_eq!(Vec::from([1, 2, 3]), vec![1, 2, 3]);
-    /// ```
-    #[cfg(not(test))]
-    fn from(s: [T; N]) -> Vec<T> {
-        <[T]>::into_vec(Box::new(s))
-    }
-
-    #[cfg(test)]
-    fn from(s: [T; N]) -> Vec<T> {
-        crate::slice::into_vec(Box::new(s))
-    }
-}
-
-#[cfg(not(no_borrow))]
-#[stable(feature = "vec_from_cow_slice", since = "1.14.0")]
-impl<'a, T> From<Cow<'a, [T]>> for Vec<T>
-where
-    [T]: ToOwned<Owned = Vec<T>>,
-{
-    /// Convert a clone-on-write slice into a vector.
-    ///
-    /// If `s` already owns a `Vec<T>`, it will be returned directly.
-    /// If `s` is borrowing a slice, a new `Vec<T>` will be allocated and
-    /// filled by cloning `s`'s items into it.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// # use std::borrow::Cow;
-    /// let o: Cow<'_, [i32]> = Cow::Owned(vec![1, 2, 3]);
-    /// let b: Cow<'_, [i32]> = Cow::Borrowed(&[1, 2, 3]);
-    /// assert_eq!(Vec::from(o), Vec::from(b));
-    /// ```
-    fn from(s: Cow<'a, [T]>) -> Vec<T> {
-        s.into_owned()
-    }
-}
-
-// note: test pulls in std, which causes errors here
-#[cfg(not(test))]
-#[stable(feature = "vec_from_box", since = "1.18.0")]
-impl<T, A: Allocator> From<Box<[T], A>> for Vec<T, A> {
-    /// Convert a boxed slice into a vector by transferring ownership of
-    /// the existing heap allocation.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let b: Box<[i32]> = vec![1, 2, 3].into_boxed_slice();
-    /// assert_eq!(Vec::from(b), vec![1, 2, 3]);
-    /// ```
-    fn from(s: Box<[T], A>) -> Self {
-        s.into_vec()
-    }
-}
-
-// note: test pulls in std, which causes errors here
-#[cfg(not(no_global_oom_handling))]
-#[cfg(not(test))]
-#[stable(feature = "box_from_vec", since = "1.20.0")]
-impl<T, A: Allocator> From<Vec<T, A>> for Box<[T], A> {
-    /// Convert a vector into a boxed slice.
-    ///
-    /// If `v` has excess capacity, its items will be moved into a
-    /// newly-allocated buffer with exactly the right capacity.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// assert_eq!(Box::from(vec![1, 2, 3]), vec![1, 2, 3].into_boxed_slice());
-    /// ```
-    ///
-    /// Any excess capacity is removed:
-    /// ```
-    /// let mut vec = Vec::with_capacity(10);
-    /// vec.extend([1, 2, 3]);
-    ///
-    /// assert_eq!(Box::from(vec), vec![1, 2, 3].into_boxed_slice());
-    /// ```
-    fn from(v: Vec<T, A>) -> Self {
-        v.into_boxed_slice()
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl From<&str> for Vec<u8> {
-    /// Allocate a `Vec<u8>` and fill it with a UTF-8 string.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// assert_eq!(Vec::from("123"), vec![b'1', b'2', b'3']);
-    /// ```
-    fn from(s: &str) -> Vec<u8> {
-        From::from(s.as_bytes())
-    }
-}
-
-#[stable(feature = "array_try_from_vec", since = "1.48.0")]
-impl<T, A: Allocator, const N: usize> TryFrom<Vec<T, A>> for [T; N] {
-    type Error = Vec<T, A>;
-
-    /// Gets the entire contents of the `Vec<T>` as an array,
-    /// if its size exactly matches that of the requested array.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// assert_eq!(vec![1, 2, 3].try_into(), Ok([1, 2, 3]));
-    /// assert_eq!(<Vec<i32>>::new().try_into(), Ok([]));
-    /// ```
-    ///
-    /// If the length doesn't match, the input comes back in `Err`:
-    /// ```
-    /// let r: Result<[i32; 4], _> = (0..10).collect::<Vec<_>>().try_into();
-    /// assert_eq!(r, Err(vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9]));
-    /// ```
-    ///
-    /// If you're fine with just getting a prefix of the `Vec<T>`,
-    /// you can call [`.truncate(N)`](Vec::truncate) first.
-    /// ```
-    /// let mut v = String::from("hello world").into_bytes();
-    /// v.sort();
-    /// v.truncate(2);
-    /// let [a, b]: [_; 2] = v.try_into().unwrap();
-    /// assert_eq!(a, b' ');
-    /// assert_eq!(b, b'd');
-    /// ```
-    fn try_from(mut vec: Vec<T, A>) -> Result<[T; N], Vec<T, A>> {
-        if vec.len() != N {
-            return Err(vec);
-        }
-
-        // SAFETY: `.set_len(0)` is always sound.
-        unsafe { vec.set_len(0) };
-
-        // SAFETY: A `Vec`'s pointer is always aligned properly, and
-        // the alignment the array needs is the same as the items.
-        // We checked earlier that we have sufficient items.
-        // The items will not double-drop as the `set_len`
-        // tells the `Vec` not to also drop them.
-        let array = unsafe { ptr::read(vec.as_ptr() as *const [T; N]) };
-        Ok(array)
-    }
-}
diff --git a/rust/alloc/vec/partial_eq.rs b/rust/alloc/vec/partial_eq.rs
deleted file mode 100644
index 10ad4e492287..000000000000
--- a/rust/alloc/vec/partial_eq.rs
+++ /dev/null
@@ -1,49 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-use crate::alloc::Allocator;
-#[cfg(not(no_global_oom_handling))]
-use crate::borrow::Cow;
-
-use super::Vec;
-
-macro_rules! __impl_slice_eq1 {
-    ([$($vars:tt)*] $lhs:ty, $rhs:ty $(where $ty:ty: $bound:ident)?, #[$stability:meta]) => {
-        #[$stability]
-        impl<T, U, $($vars)*> PartialEq<$rhs> for $lhs
-        where
-            T: PartialEq<U>,
-            $($ty: $bound)?
-        {
-            #[inline]
-            fn eq(&self, other: &$rhs) -> bool { self[..] == other[..] }
-            #[inline]
-            fn ne(&self, other: &$rhs) -> bool { self[..] != other[..] }
-        }
-    }
-}
-
-__impl_slice_eq1! { [A1: Allocator, A2: Allocator] Vec<T, A1>, Vec<U, A2>, #[stable(feature = "rust1", since = "1.0.0")] }
-__impl_slice_eq1! { [A: Allocator] Vec<T, A>, &[U], #[stable(feature = "rust1", since = "1.0.0")] }
-__impl_slice_eq1! { [A: Allocator] Vec<T, A>, &mut [U], #[stable(feature = "rust1", since = "1.0.0")] }
-__impl_slice_eq1! { [A: Allocator] &[T], Vec<U, A>, #[stable(feature = "partialeq_vec_for_ref_slice", since = "1.46.0")] }
-__impl_slice_eq1! { [A: Allocator] &mut [T], Vec<U, A>, #[stable(feature = "partialeq_vec_for_ref_slice", since = "1.46.0")] }
-__impl_slice_eq1! { [A: Allocator] Vec<T, A>, [U], #[stable(feature = "partialeq_vec_for_slice", since = "1.48.0")]  }
-__impl_slice_eq1! { [A: Allocator] [T], Vec<U, A>, #[stable(feature = "partialeq_vec_for_slice", since = "1.48.0")]  }
-#[cfg(not(no_global_oom_handling))]
-__impl_slice_eq1! { [A: Allocator] Cow<'_, [T]>, Vec<U, A> where T: Clone, #[stable(feature = "rust1", since = "1.0.0")] }
-#[cfg(not(no_global_oom_handling))]
-__impl_slice_eq1! { [] Cow<'_, [T]>, &[U] where T: Clone, #[stable(feature = "rust1", since = "1.0.0")] }
-#[cfg(not(no_global_oom_handling))]
-__impl_slice_eq1! { [] Cow<'_, [T]>, &mut [U] where T: Clone, #[stable(feature = "rust1", since = "1.0.0")] }
-__impl_slice_eq1! { [A: Allocator, const N: usize] Vec<T, A>, [U; N], #[stable(feature = "rust1", since = "1.0.0")] }
-__impl_slice_eq1! { [A: Allocator, const N: usize] Vec<T, A>, &[U; N], #[stable(feature = "rust1", since = "1.0.0")] }
-
-// NOTE: some less important impls are omitted to reduce code bloat
-// FIXME(Centril): Reconsider this?
-//__impl_slice_eq1! { [const N: usize] Vec<A>, &mut [B; N], }
-//__impl_slice_eq1! { [const N: usize] [A; N], Vec<B>, }
-//__impl_slice_eq1! { [const N: usize] &[A; N], Vec<B>, }
-//__impl_slice_eq1! { [const N: usize] &mut [A; N], Vec<B>, }
-//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, [B; N], }
-//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, &[B; N], }
-//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, &mut [B; N], }
diff --git a/rust/alloc/vec/set_len_on_drop.rs b/rust/alloc/vec/set_len_on_drop.rs
deleted file mode 100644
index d3c7297b80ec..000000000000
--- a/rust/alloc/vec/set_len_on_drop.rs
+++ /dev/null
@@ -1,35 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-// Set the length of the vec when the `SetLenOnDrop` value goes out of scope.
-//
-// The idea is: The length field in SetLenOnDrop is a local variable
-// that the optimizer will see does not alias with any stores through the Vec's data
-// pointer. This is a workaround for alias analysis issue #32155
-pub(super) struct SetLenOnDrop<'a> {
-    len: &'a mut usize,
-    local_len: usize,
-}
-
-impl<'a> SetLenOnDrop<'a> {
-    #[inline]
-    pub(super) fn new(len: &'a mut usize) -> Self {
-        SetLenOnDrop { local_len: *len, len }
-    }
-
-    #[inline]
-    pub(super) fn increment_len(&mut self, increment: usize) {
-        self.local_len += increment;
-    }
-
-    #[inline]
-    pub(super) fn current_len(&self) -> usize {
-        self.local_len
-    }
-}
-
-impl Drop for SetLenOnDrop<'_> {
-    #[inline]
-    fn drop(&mut self) {
-        *self.len = self.local_len;
-    }
-}
diff --git a/rust/alloc/vec/spec_extend.rs b/rust/alloc/vec/spec_extend.rs
deleted file mode 100644
index ada919537446..000000000000
--- a/rust/alloc/vec/spec_extend.rs
+++ /dev/null
@@ -1,119 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-use crate::alloc::Allocator;
-use crate::collections::TryReserveError;
-use core::iter::TrustedLen;
-use core::slice::{self};
-
-use super::{IntoIter, Vec};
-
-// Specialization trait used for Vec::extend
-#[cfg(not(no_global_oom_handling))]
-pub(super) trait SpecExtend<T, I> {
-    fn spec_extend(&mut self, iter: I);
-}
-
-// Specialization trait used for Vec::try_extend
-pub(super) trait TrySpecExtend<T, I> {
-    fn try_spec_extend(&mut self, iter: I) -> Result<(), TryReserveError>;
-}
-
-#[cfg(not(no_global_oom_handling))]
-impl<T, I, A: Allocator> SpecExtend<T, I> for Vec<T, A>
-where
-    I: Iterator<Item = T>,
-{
-    default fn spec_extend(&mut self, iter: I) {
-        self.extend_desugared(iter)
-    }
-}
-
-impl<T, I, A: Allocator> TrySpecExtend<T, I> for Vec<T, A>
-where
-    I: Iterator<Item = T>,
-{
-    default fn try_spec_extend(&mut self, iter: I) -> Result<(), TryReserveError> {
-        self.try_extend_desugared(iter)
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-impl<T, I, A: Allocator> SpecExtend<T, I> for Vec<T, A>
-where
-    I: TrustedLen<Item = T>,
-{
-    default fn spec_extend(&mut self, iterator: I) {
-        self.extend_trusted(iterator)
-    }
-}
-
-impl<T, I, A: Allocator> TrySpecExtend<T, I> for Vec<T, A>
-where
-    I: TrustedLen<Item = T>,
-{
-    default fn try_spec_extend(&mut self, iterator: I) -> Result<(), TryReserveError> {
-        self.try_extend_trusted(iterator)
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-impl<T, A: Allocator> SpecExtend<T, IntoIter<T>> for Vec<T, A> {
-    fn spec_extend(&mut self, mut iterator: IntoIter<T>) {
-        unsafe {
-            self.append_elements(iterator.as_slice() as _);
-        }
-        iterator.forget_remaining_elements();
-    }
-}
-
-impl<T, A: Allocator> TrySpecExtend<T, IntoIter<T>> for Vec<T, A> {
-    fn try_spec_extend(&mut self, mut iterator: IntoIter<T>) -> Result<(), TryReserveError> {
-        unsafe {
-            self.try_append_elements(iterator.as_slice() as _)?;
-        }
-        iterator.forget_remaining_elements();
-        Ok(())
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-impl<'a, T: 'a, I, A: Allocator> SpecExtend<&'a T, I> for Vec<T, A>
-where
-    I: Iterator<Item = &'a T>,
-    T: Clone,
-{
-    default fn spec_extend(&mut self, iterator: I) {
-        self.spec_extend(iterator.cloned())
-    }
-}
-
-impl<'a, T: 'a, I, A: Allocator> TrySpecExtend<&'a T, I> for Vec<T, A>
-where
-    I: Iterator<Item = &'a T>,
-    T: Clone,
-{
-    default fn try_spec_extend(&mut self, iterator: I) -> Result<(), TryReserveError> {
-        self.try_spec_extend(iterator.cloned())
-    }
-}
-
-#[cfg(not(no_global_oom_handling))]
-impl<'a, T: 'a, A: Allocator> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T, A>
-where
-    T: Copy,
-{
-    fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) {
-        let slice = iterator.as_slice();
-        unsafe { self.append_elements(slice) };
-    }
-}
-
-impl<'a, T: 'a, A: Allocator> TrySpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T, A>
-where
-    T: Copy,
-{
-    fn try_spec_extend(&mut self, iterator: slice::Iter<'a, T>) -> Result<(), TryReserveError> {
-        let slice = iterator.as_slice();
-        unsafe { self.try_append_elements(slice) }
-    }
-}
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread

* [PATCH 05/10] rust: alloc: introduce allocation flags
  2024-03-25 19:54 [PATCH 00/10] Allocation APIs Wedson Almeida Filho
                   ` (3 preceding siblings ...)
  2024-03-25 19:54 ` [PATCH 04/10] rust: alloc: remove our fork of the " Wedson Almeida Filho
@ 2024-03-25 19:54 ` Wedson Almeida Filho
  2024-03-25 22:26   ` Benno Lossin
  2024-03-25 19:54 ` [PATCH 06/10] rust: alloc: introduce the `BoxExt` trait Wedson Almeida Filho
                   ` (4 subsequent siblings)
  9 siblings, 1 reply; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-25 19:54 UTC (permalink / raw)
  To: rust-for-linux
  Cc: Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
	linux-kernel, Wedson Almeida Filho

From: Wedson Almeida Filho <walmeida@microsoft.com>

We'll use them when allocating `Box`, `Arc`, and `UniqueArc` instances,
as well as when allocating memory for `Vec` elements. These changes will
come in subsequent patches.

Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
---
 rust/bindings/bindings_helper.h |  3 ++
 rust/kernel/alloc.rs            | 56 +++++++++++++++++++++++++++++++++
 rust/kernel/prelude.rs          |  2 +-
 3 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 65b98831b975..ddb5644d4fd9 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -20,5 +20,8 @@
 
 /* `bindgen` gets confused at certain things. */
 const size_t RUST_CONST_HELPER_ARCH_SLAB_MINALIGN = ARCH_SLAB_MINALIGN;
+const gfp_t RUST_CONST_HELPER_GFP_ATOMIC = GFP_ATOMIC;
 const gfp_t RUST_CONST_HELPER_GFP_KERNEL = GFP_KERNEL;
+const gfp_t RUST_CONST_HELPER_GFP_KERNEL_ACCOUNT = GFP_KERNEL_ACCOUNT;
+const gfp_t RUST_CONST_HELPER_GFP_NOWAIT = GFP_NOWAIT;
 const gfp_t RUST_CONST_HELPER___GFP_ZERO = __GFP_ZERO;
diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
index 8ad57a2e693e..ad48ac8dc13d 100644
--- a/rust/kernel/alloc.rs
+++ b/rust/kernel/alloc.rs
@@ -6,3 +6,59 @@
 #[cfg(not(testlib))]
 mod allocator;
 pub mod vecext;
+
+/// Flags to be used when allocating memory.
+///
+/// They can be combined with the operators `|`, `&`, and `!`.
+///
+/// Values can be used from the [`flags`] module.
+#[derive(Clone, Copy)]
+pub struct Flags(u32);
+
+impl core::ops::BitOr for Flags {
+    type Output = Self;
+    fn bitor(self, rhs: Self) -> Self::Output {
+        Self(self.0 | rhs.0)
+    }
+}
+
+impl core::ops::BitAnd for Flags {
+    type Output = Self;
+    fn bitand(self, rhs: Self) -> Self::Output {
+        Self(self.0 & rhs.0)
+    }
+}
+
+impl core::ops::Not for Flags {
+    type Output = Self;
+    fn not(self) -> Self::Output {
+        Self(!self.0)
+    }
+}
+
+/// Allocation flags.
+///
+/// These are meant to be used in functions that can allocate memory.
+pub mod flags {
+    use super::Flags;
+    use crate::bindings;
+
+    /// Users can not sleep and need the allocation to succeed.
+    ///
+    /// A lower watermark is applied to allow access to "atomic reserves". The current
+    /// implementation doesn't support NMI and few other strict non-preemptive contexts (e.g.
+    /// raw_spin_lock). The same applies to [`GFP_NOWAIT`].
+    pub const GFP_ATOMIC: Flags = Flags(bindings::GFP_ATOMIC);
+
+    /// Typical for kernel-internal allocations. The caller requires ZONE_NORMAL or a lower zone
+    /// for direct access but can direct reclaim.
+    pub const GFP_KERNEL: Flags = Flags(bindings::GFP_KERNEL);
+
+    /// The same as [`GFP_KERNEL`], except the allocation is accounted to kmemcg.
+    pub const GFP_KERNEL_ACCOUNT: Flags = Flags(bindings::GFP_KERNEL_ACCOUNT);
+
+    /// Ror kernel allocations that should not stall for direct reclaim, start physical IO or
+    /// use any filesystem callback.  It is very likely to fail to allocate memory, even for very
+    /// small allocations.
+    pub const GFP_NOWAIT: Flags = Flags(bindings::GFP_NOWAIT);
+}
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index a0177f195dec..a7b203f87aa1 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -14,7 +14,7 @@
 #[doc(no_inline)]
 pub use core::pin::Pin;
 
-pub use crate::alloc::vecext::VecExt;
+pub use crate::alloc::{flags::*, vecext::VecExt};
 
 #[doc(no_inline)]
 pub use alloc::{boxed::Box, vec::Vec};
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread

* [PATCH 06/10] rust: alloc: introduce the `BoxExt` trait
  2024-03-25 19:54 [PATCH 00/10] Allocation APIs Wedson Almeida Filho
                   ` (4 preceding siblings ...)
  2024-03-25 19:54 ` [PATCH 05/10] rust: alloc: introduce allocation flags Wedson Almeida Filho
@ 2024-03-25 19:54 ` Wedson Almeida Filho
  2024-03-25 22:37   ` Benno Lossin
  2024-03-25 19:54 ` [PATCH 07/10] rust: alloc: update `VecExt` to take allocation flags Wedson Almeida Filho
                   ` (3 subsequent siblings)
  9 siblings, 1 reply; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-25 19:54 UTC (permalink / raw)
  To: rust-for-linux
  Cc: Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
	linux-kernel, Wedson Almeida Filho

From: Wedson Almeida Filho <walmeida@microsoft.com>

Make fallible versions of `new` and `new_uninit` methods available in
`Box` even though it doesn't implement them because we build `alloc`
with the `no_global_oom_handling` config.

They also have an extra `flags` parameter that allows callers to pass
flags to the allocator.

Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
---
 rust/kernel/alloc.rs           |  1 +
 rust/kernel/alloc/allocator.rs |  6 +++-
 rust/kernel/alloc/boxext.rs    | 61 ++++++++++++++++++++++++++++++++++
 rust/kernel/init.rs            | 13 ++++----
 rust/kernel/prelude.rs         |  2 +-
 rust/kernel/sync/arc.rs        |  3 +-
 6 files changed, 77 insertions(+), 9 deletions(-)
 create mode 100644 rust/kernel/alloc/boxext.rs

diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
index ad48ac8dc13d..5712c81b1308 100644
--- a/rust/kernel/alloc.rs
+++ b/rust/kernel/alloc.rs
@@ -5,6 +5,7 @@
 #[cfg(not(test))]
 #[cfg(not(testlib))]
 mod allocator;
+pub mod boxext;
 pub mod vecext;
 
 /// Flags to be used when allocating memory.
diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
index 01ad139e19bc..fc0439455faa 100644
--- a/rust/kernel/alloc/allocator.rs
+++ b/rust/kernel/alloc/allocator.rs
@@ -15,7 +15,11 @@
 ///
 /// - `ptr` can be either null or a pointer which has been allocated by this allocator.
 /// - `new_layout` must have a non-zero size.
-unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gfp_t) -> *mut u8 {
+pub(crate) unsafe fn krealloc_aligned(
+    ptr: *mut u8,
+    new_layout: Layout,
+    flags: bindings::gfp_t,
+) -> *mut u8 {
     // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
     let layout = new_layout.pad_to_align();
 
diff --git a/rust/kernel/alloc/boxext.rs b/rust/kernel/alloc/boxext.rs
new file mode 100644
index 000000000000..26a918df7acf
--- /dev/null
+++ b/rust/kernel/alloc/boxext.rs
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Extensions to [`Box`] for fallible allocations.
+
+use super::Flags;
+use alloc::boxed::Box;
+use core::alloc::AllocError;
+use core::mem::MaybeUninit;
+use core::result::Result;
+
+/// Extensions to [`Box`].
+pub trait BoxExt<T>: Sized {
+    /// Allocates a new box.
+    ///
+    /// The allocation may fail, in which case an error is returned.
+    fn new(x: T, flags: Flags) -> Result<Self, AllocError>;
+
+    /// Allocates a new uninitialised box.
+    ///
+    /// The allocation may fail, in which case an error is returned.
+    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError>;
+}
+
+impl<T> BoxExt<T> for Box<T> {
+    #[cfg(any(test, testlib))]
+    fn new(x: T, _flags: Flags) -> Result<Self, AllocError> {
+        Ok(Box::new(x))
+    }
+
+    #[cfg(not(any(test, testlib)))]
+    fn new(x: T, flags: Flags) -> Result<Self, AllocError> {
+        let ptr = if core::mem::size_of::<T>() == 0 {
+            core::ptr::NonNull::<T>::dangling().as_ptr()
+        } else {
+            let layout = core::alloc::Layout::new::<T>();
+
+            // SAFETY: Memory is being allocated (first arg is null). The only other source of
+            // safety issues is sleeping on atomic context, which is addressed by klint.
+            let ptr = unsafe {
+                super::allocator::krealloc_aligned(core::ptr::null_mut(), layout, flags.0)
+            };
+            if ptr.is_null() {
+                return Err(AllocError);
+            }
+
+            let ptr = ptr.cast::<T>();
+
+            // SAFETY: We just allocated the memory above, it is valid for write.
+            unsafe { ptr.write(x) };
+            ptr
+        };
+
+        // SAFETY: For non-zero-sized types, we allocate above using the global allocator. For
+        // zero-sized types, we use `NonNull::dangling`.
+        Ok(unsafe { Box::from_raw(ptr) })
+    }
+
+    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
+        <Box<_> as BoxExt<_>>::new(MaybeUninit::<T>::uninit(), flags)
+    }
+}
diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs
index 424257284d16..0d956934eaa4 100644
--- a/rust/kernel/init.rs
+++ b/rust/kernel/init.rs
@@ -210,6 +210,7 @@
 //! [`pin_init!`]: crate::pin_init!
 
 use crate::{
+    alloc::{boxext::BoxExt, flags::*},
     error::{self, Error},
     sync::UniqueArc,
     types::{Opaque, ScopeGuard},
@@ -305,9 +306,9 @@ macro_rules! stack_pin_init {
 ///
 /// stack_try_pin_init!(let foo: Result<Pin<&mut Foo>, AllocError> = pin_init!(Foo {
 ///     a <- new_mutex!(42),
-///     b: Box::try_new(Bar {
+///     b: Box::new(Bar {
 ///         x: 64,
-///     })?,
+///     }, GFP_KERNEL)?,
 /// }));
 /// let foo = foo.unwrap();
 /// pr_info!("a: {}", &*foo.a.lock());
@@ -331,9 +332,9 @@ macro_rules! stack_pin_init {
 ///
 /// stack_try_pin_init!(let foo: Pin<&mut Foo> =? pin_init!(Foo {
 ///     a <- new_mutex!(42),
-///     b: Box::try_new(Bar {
+///     b: Box::new(Bar {
 ///         x: 64,
-///     })?,
+///     }, GFP_KERNEL)?,
 /// }));
 /// pr_info!("a: {}", &*foo.a.lock());
 /// # Ok::<_, AllocError>(())
@@ -1158,7 +1159,7 @@ fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
     where
         E: From<AllocError>,
     {
-        let mut this = Box::try_new_uninit()?;
+        let mut this = <Box<_> as BoxExt<_>>::new_uninit(GFP_KERNEL)?;
         let slot = this.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
         // slot is valid and will not be moved, because we pin it later.
@@ -1172,7 +1173,7 @@ fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
     where
         E: From<AllocError>,
     {
-        let mut this = Box::try_new_uninit()?;
+        let mut this = <Box<_> as BoxExt<_>>::new_uninit(GFP_KERNEL)?;
         let slot = this.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
         // slot is valid.
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index a7b203f87aa1..f73b4285168c 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -14,7 +14,7 @@
 #[doc(no_inline)]
 pub use core::pin::Pin;
 
-pub use crate::alloc::{flags::*, vecext::VecExt};
+pub use crate::alloc::{boxext::BoxExt, flags::*, vecext::VecExt};
 
 #[doc(no_inline)]
 pub use alloc::{boxed::Box, vec::Vec};
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index 7d4c4bf58388..f0a5aed69693 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -16,6 +16,7 @@
 //! [`Arc`]: https://doc.rust-lang.org/std/sync/struct.Arc.html
 
 use crate::{
+    alloc::{boxext::BoxExt, flags::*},
     bindings,
     error::{self, Error},
     init::{self, InPlaceInit, Init, PinInit},
@@ -170,7 +171,7 @@ pub fn try_new(contents: T) -> Result<Self, AllocError> {
             data: contents,
         };
 
-        let inner = Box::try_new(value)?;
+        let inner = <Box<_> as BoxExt<_>>::new(value, GFP_KERNEL)?;
 
         // SAFETY: We just created `inner` with a reference count of 1, which is owned by the new
         // `Arc` object.
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread

* [PATCH 07/10] rust: alloc: update `VecExt` to take allocation flags
  2024-03-25 19:54 [PATCH 00/10] Allocation APIs Wedson Almeida Filho
                   ` (5 preceding siblings ...)
  2024-03-25 19:54 ` [PATCH 06/10] rust: alloc: introduce the `BoxExt` trait Wedson Almeida Filho
@ 2024-03-25 19:54 ` Wedson Almeida Filho
  2024-03-25 20:44   ` Boqun Feng
  2024-03-25 19:54 ` [PATCH 08/10] rust: sync: update `Arc` and `UniqueArc` " Wedson Almeida Filho
                   ` (2 subsequent siblings)
  9 siblings, 1 reply; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-25 19:54 UTC (permalink / raw)
  To: rust-for-linux
  Cc: Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
	linux-kernel, Wedson Almeida Filho

From: Wedson Almeida Filho <walmeida@microsoft.com>

We also rename the methods by removing the `try_` prefix since the names
are available due to our usage of the `no_global_oom_handling` config
when building the `alloc` crate.

Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
---
 rust/kernel/alloc/vecext.rs  | 106 ++++++++++++++++++++++++++++-------
 rust/kernel/lib.rs           |   1 -
 rust/kernel/str.rs           |   6 +-
 rust/kernel/types.rs         |   4 +-
 samples/rust/rust_minimal.rs |   6 +-
 5 files changed, 95 insertions(+), 28 deletions(-)

diff --git a/rust/kernel/alloc/vecext.rs b/rust/kernel/alloc/vecext.rs
index 59e92bab534e..1d4d51b45a49 100644
--- a/rust/kernel/alloc/vecext.rs
+++ b/rust/kernel/alloc/vecext.rs
@@ -2,51 +2,119 @@
 
 //! Extensions to [`Vec`] for fallible allocations.
 
-use alloc::{collections::TryReserveError, vec::Vec};
-use core::result::Result;
+use super::Flags;
+use alloc::{alloc::AllocError, vec::Vec};
+use core::{mem::ManuallyDrop, result::Result};
 
 /// Extensions to [`Vec`].
 pub trait VecExt<T>: Sized {
     /// Creates a new [`Vec`] instance with at least the given capacity.
-    fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError>;
+    fn with_capacity(capacity: usize, flags: Flags) -> Result<Self, AllocError>;
 
     /// Appends an element to the back of the [`Vec`] instance.
-    fn try_push(&mut self, v: T) -> Result<(), TryReserveError>;
+    fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError>;
 
     /// Pushes clones of the elements of slice into the [`Vec`] instance.
-    fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError>
+    fn extend_from_slice(&mut self, other: &[T], flags: Flags) -> Result<(), AllocError>
     where
         T: Clone;
+
+    /// Ensures that the capacity exceeds the length by at least `additional` elements.
+    fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocError>;
 }
 
 impl<T> VecExt<T> for Vec<T> {
-    fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError> {
+    fn with_capacity(capacity: usize, flags: Flags) -> Result<Self, AllocError> {
         let mut v = Vec::new();
-        v.try_reserve(capacity)?;
+        <Self as VecExt<_>>::reserve(&mut v, capacity, flags)?;
         Ok(v)
     }
 
-    fn try_push(&mut self, v: T) -> Result<(), TryReserveError> {
-        if let Err(retry) = self.push_within_capacity(v) {
-            self.try_reserve(1)?;
-            let _ = self.push_within_capacity(retry);
-        }
+    fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError> {
+        <Self as VecExt<_>>::reserve(self, 1, flags)?;
+        let (ptr, len, cap) = destructure(self);
+        // SAFETY: ptr is valid for `cap` elements. And `cap` is greater (by at least 1) than
+        // `len` because of the call to `reserve` above. So the pointer after offsetting by `len`
+        // elements is valid for write.
+        unsafe { ptr.wrapping_add(len).write(v) };
+
+        // SAFETY: The only difference from the values returned by `destructure` is that `length`
+        // is incremented by 1, which is fine because we have just initialised the element at
+        // offset `length`.
+        unsafe { rebuild(self, ptr, len + 1, cap) };
         Ok(())
     }
 
-    fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError>
+    fn extend_from_slice(&mut self, other: &[T], flags: Flags) -> Result<(), AllocError>
     where
         T: Clone,
     {
-        let extra_cap = self.capacity() - self.len();
-        if extra_cap > 0 {
-            self.try_reserve(extra_cap)?;
-        }
-
+        <Self as VecExt<_>>::reserve(self, other.len(), flags)?;
         for item in other {
-            self.try_push(item.clone())?;
+            <Self as VecExt<_>>::push(self, item.clone(), flags)?;
         }
+        Ok(())
+    }
 
+    #[cfg(any(test, testlib))]
+    fn reserve(&mut self, additional: usize, _flags: Flags) -> Result<(), AllocError> {
+        Vec::reserve(self, additional);
         Ok(())
     }
+
+    #[cfg(not(any(test, testlib)))]
+    fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocError> {
+        let len = self.len();
+        let cap = self.capacity();
+
+        if cap - len >= additional {
+            return Ok(());
+        }
+
+        if core::mem::size_of::<T>() == 0 {
+            // The capacity is already `usize::MAX` for SZTs, we can't go higher.
+            return Err(AllocError);
+        }
+
+        // We know cap is <= `isize::MAX` because `Layout::array` fails if the resulting byte size
+        // is greater than `isize::MAX`. So the multiplication by two won't overflow.
+        let new_cap = core::cmp::max(cap * 2, len.checked_add(additional).ok_or(AllocError)?);
+        let layout = core::alloc::Layout::array::<T>(new_cap).map_err(|_| AllocError)?;
+
+        let (ptr, len, cap) = destructure(self);
+
+        // SAFETY: `ptr` is valid because it's either NULL or comes from a previous call to
+        // `krealloc_aligned`. We also verified that the type is not a ZST.
+        let new_ptr = unsafe { super::allocator::krealloc_aligned(ptr.cast(), layout, flags.0) };
+        if new_ptr.is_null() {
+            // SAFETY: We are just rebuilding the existing `Vec` with no changes.
+            unsafe { rebuild(self, ptr, len, cap) };
+            Err(AllocError)
+        } else {
+            // SAFETY: `ptr` has been reallocated with the layout for `new_cap` elements. New cap
+            // is greater than `cap`, so it continues to be >= `len`.
+            unsafe { rebuild(self, new_ptr.cast::<T>(), len, new_cap) };
+            Ok(())
+        }
+    }
+}
+
+fn destructure<T>(v: &mut Vec<T>) -> (*mut T, usize, usize) {
+    let mut tmp = Vec::new();
+    core::mem::swap(&mut tmp, v);
+    let mut tmp = ManuallyDrop::new(tmp);
+    let len = tmp.len();
+    let cap = tmp.capacity();
+    (tmp.as_mut_ptr(), len, cap)
+}
+
+/// Rebuilds a `Vec` from a pointer, length, and capacity.
+///
+/// # Safety
+///
+/// The same as [`Vec::from_raw_parts`].
+unsafe fn rebuild<T>(v: &mut Vec<T>, ptr: *mut T, len: usize, cap: usize) {
+    // SAFETY: The safety requirements from this function satisfy those of `from_raw_parts`.
+    let mut tmp = unsafe { Vec::from_raw_parts(ptr, len, cap) };
+    core::mem::swap(&mut tmp, v);
 }
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 7f2841a18d05..51f30e55bd00 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -19,7 +19,6 @@
 #![feature(offset_of)]
 #![feature(receiver_trait)]
 #![feature(unsize)]
-#![feature(vec_push_within_capacity)]
 
 // Ensure conditional compilation based on the kernel configuration works;
 // otherwise we may silently break things like initcall handling.
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 183748328d43..34dbc85b5220 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -2,7 +2,7 @@
 
 //! String representations.
 
-use crate::alloc::vecext::VecExt;
+use crate::alloc::{flags::*, vecext::VecExt};
 use alloc::alloc::AllocError;
 use alloc::vec::Vec;
 use core::fmt::{self, Write};
@@ -730,7 +730,7 @@ pub fn try_from_fmt(args: fmt::Arguments<'_>) -> Result<Self, Error> {
         let size = f.bytes_written();
 
         // Allocate a vector with the required number of bytes, and write to it.
-        let mut buf = Vec::try_with_capacity(size)?;
+        let mut buf = <Vec<_> as VecExt<_>>::with_capacity(size, GFP_KERNEL)?;
         // SAFETY: The buffer stored in `buf` is at least of size `size` and is valid for writes.
         let mut f = unsafe { Formatter::from_buffer(buf.as_mut_ptr(), size) };
         f.write_fmt(args)?;
@@ -771,7 +771,7 @@ impl<'a> TryFrom<&'a CStr> for CString {
     fn try_from(cstr: &'a CStr) -> Result<CString, AllocError> {
         let mut buf = Vec::new();
 
-        buf.try_extend_from_slice(cstr.as_bytes_with_nul())
+        <Vec<_> as VecExt<_>>::extend_from_slice(&mut buf, cstr.as_bytes_with_nul(), GFP_KERNEL)
             .map_err(|_| AllocError)?;
 
         // INVARIANT: The `CStr` and `CString` types have the same invariants for
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index aa77bad9bce4..8fad61268465 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -157,11 +157,11 @@ unsafe fn from_foreign(_: *const core::ffi::c_void) -> Self {}
 ///     let mut vec =
 ///         ScopeGuard::new_with_data(Vec::new(), |v| pr_info!("vec had {} elements\n", v.len()));
 ///
-///     vec.try_push(10u8)?;
+///     vec.push(10u8, GFP_KERNEL)?;
 ///     if arg {
 ///         return Ok(());
 ///     }
-///     vec.try_push(20u8)?;
+///     vec.push(20u8, GFP_KERNEL)?;
 ///     Ok(())
 /// }
 ///
diff --git a/samples/rust/rust_minimal.rs b/samples/rust/rust_minimal.rs
index dc05f4bbe27e..2a9eaab62d1c 100644
--- a/samples/rust/rust_minimal.rs
+++ b/samples/rust/rust_minimal.rs
@@ -22,9 +22,9 @@ fn init(_module: &'static ThisModule) -> Result<Self> {
         pr_info!("Am I built-in? {}\n", !cfg!(MODULE));
 
         let mut numbers = Vec::new();
-        numbers.try_push(72)?;
-        numbers.try_push(108)?;
-        numbers.try_push(200)?;
+        numbers.push(72, GFP_KERNEL)?;
+        numbers.push(108, GFP_KERNEL)?;
+        numbers.push(200, GFP_KERNEL)?;
 
         Ok(RustMinimal { numbers })
     }
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread

* [PATCH 08/10] rust: sync: update `Arc` and `UniqueArc` to take allocation flags
  2024-03-25 19:54 [PATCH 00/10] Allocation APIs Wedson Almeida Filho
                   ` (6 preceding siblings ...)
  2024-03-25 19:54 ` [PATCH 07/10] rust: alloc: update `VecExt` to take allocation flags Wedson Almeida Filho
@ 2024-03-25 19:54 ` Wedson Almeida Filho
  2024-03-26 14:01   ` Benno Lossin
  2024-03-25 19:54 ` [PATCH 09/10] rust: init: update `init` module " Wedson Almeida Filho
  2024-03-25 19:54 ` [PATCH 10/10] rust: kernel: remove usage of `allocator_api` unstable feature Wedson Almeida Filho
  9 siblings, 1 reply; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-25 19:54 UTC (permalink / raw)
  To: rust-for-linux
  Cc: Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
	linux-kernel, Wedson Almeida Filho

From: Wedson Almeida Filho <walmeida@microsoft.com>

We also remove the `try_` prefix to align with how `Box` and `Vec` are
providing methods now.

`init` is temporarily updated with uses of GFP_KERNEL. These will be
updated in a subsequent patch to take flags as well.

Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
---
 rust/kernel/init.rs        |  4 ++--
 rust/kernel/sync/arc.rs    | 28 ++++++++++++++--------------
 samples/rust/rust_print.rs |  4 ++--
 3 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs
index 0d956934eaa4..c8b2f9774a39 100644
--- a/rust/kernel/init.rs
+++ b/rust/kernel/init.rs
@@ -1189,7 +1189,7 @@ fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
     where
         E: From<AllocError>,
     {
-        let mut this = UniqueArc::try_new_uninit()?;
+        let mut this = UniqueArc::new_uninit(GFP_KERNEL)?;
         let slot = this.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
         // slot is valid and will not be moved, because we pin it later.
@@ -1203,7 +1203,7 @@ fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
     where
         E: From<AllocError>,
     {
-        let mut this = UniqueArc::try_new_uninit()?;
+        let mut this = UniqueArc::new_uninit(GFP_KERNEL)?;
         let slot = this.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
         // slot is valid.
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index f0a5aed69693..077200f5350b 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -16,7 +16,7 @@
 //! [`Arc`]: https://doc.rust-lang.org/std/sync/struct.Arc.html
 
 use crate::{
-    alloc::{boxext::BoxExt, flags::*},
+    alloc::{boxext::BoxExt, Flags},
     bindings,
     error::{self, Error},
     init::{self, InPlaceInit, Init, PinInit},
@@ -58,7 +58,7 @@
 /// }
 ///
 /// // Create a refcounted instance of `Example`.
-/// let obj = Arc::try_new(Example { a: 10, b: 20 })?;
+/// let obj = Arc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?;
 ///
 /// // Get a new pointer to `obj` and increment the refcount.
 /// let cloned = obj.clone();
@@ -97,7 +97,7 @@
 ///     }
 /// }
 ///
-/// let obj = Arc::try_new(Example { a: 10, b: 20 })?;
+/// let obj = Arc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?;
 /// obj.use_reference();
 /// obj.take_over();
 /// # Ok::<(), Error>(())
@@ -120,7 +120,7 @@
 /// impl MyTrait for Example {}
 ///
 /// // `obj` has type `Arc<Example>`.
-/// let obj: Arc<Example> = Arc::try_new(Example)?;
+/// let obj: Arc<Example> = Arc::new(Example, GFP_KERNEL)?;
 ///
 /// // `coerced` has type `Arc<dyn MyTrait>`.
 /// let coerced: Arc<dyn MyTrait> = obj;
@@ -163,7 +163,7 @@ unsafe impl<T: ?Sized + Sync + Send> Sync for Arc<T> {}
 
 impl<T> Arc<T> {
     /// Constructs a new reference counted instance of `T`.
-    pub fn try_new(contents: T) -> Result<Self, AllocError> {
+    pub fn new(contents: T, flags: Flags) -> Result<Self, AllocError> {
         // INVARIANT: The refcount is initialised to a non-zero value.
         let value = ArcInner {
             // SAFETY: There are no safety requirements for this FFI call.
@@ -171,7 +171,7 @@ pub fn try_new(contents: T) -> Result<Self, AllocError> {
             data: contents,
         };
 
-        let inner = <Box<_> as BoxExt<_>>::new(value, GFP_KERNEL)?;
+        let inner = <Box<_> as BoxExt<_>>::new(value, flags)?;
 
         // SAFETY: We just created `inner` with a reference count of 1, which is owned by the new
         // `Arc` object.
@@ -388,7 +388,7 @@ fn from(item: Pin<UniqueArc<T>>) -> Self {
 ///     e.into()
 /// }
 ///
-/// let obj = Arc::try_new(Example)?;
+/// let obj = Arc::new(Example, GFP_KERNEL)?;
 /// let cloned = do_something(obj.as_arc_borrow());
 ///
 /// // Assert that both `obj` and `cloned` point to the same underlying object.
@@ -412,7 +412,7 @@ fn from(item: Pin<UniqueArc<T>>) -> Self {
 ///     }
 /// }
 ///
-/// let obj = Arc::try_new(Example { a: 10, b: 20 })?;
+/// let obj = Arc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?;
 /// obj.as_arc_borrow().use_reference();
 /// # Ok::<(), Error>(())
 /// ```
@@ -500,7 +500,7 @@ fn deref(&self) -> &Self::Target {
 /// }
 ///
 /// fn test() -> Result<Arc<Example>> {
-///     let mut x = UniqueArc::try_new(Example { a: 10, b: 20 })?;
+///     let mut x = UniqueArc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?;
 ///     x.a += 1;
 ///     x.b += 1;
 ///     Ok(x.into())
@@ -523,7 +523,7 @@ fn deref(&self) -> &Self::Target {
 /// }
 ///
 /// fn test() -> Result<Arc<Example>> {
-///     let x = UniqueArc::try_new_uninit()?;
+///     let x = UniqueArc::new_uninit(GFP_KERNEL)?;
 ///     Ok(x.write(Example { a: 10, b: 20 }).into())
 /// }
 ///
@@ -543,7 +543,7 @@ fn deref(&self) -> &Self::Target {
 /// }
 ///
 /// fn test() -> Result<Arc<Example>> {
-///     let mut pinned = Pin::from(UniqueArc::try_new(Example { a: 10, b: 20 })?);
+///     let mut pinned = Pin::from(UniqueArc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?);
 ///     // We can modify `pinned` because it is `Unpin`.
 ///     pinned.as_mut().a += 1;
 ///     Ok(pinned.into())
@@ -557,15 +557,15 @@ pub struct UniqueArc<T: ?Sized> {
 
 impl<T> UniqueArc<T> {
     /// Tries to allocate a new [`UniqueArc`] instance.
-    pub fn try_new(value: T) -> Result<Self, AllocError> {
+    pub fn new(value: T, flags: Flags) -> Result<Self, AllocError> {
         Ok(Self {
             // INVARIANT: The newly-created object has a refcount of 1.
-            inner: Arc::try_new(value)?,
+            inner: Arc::new(value, flags)?,
         })
     }
 
     /// Tries to allocate a new [`UniqueArc`] instance whose contents are not initialised yet.
-    pub fn try_new_uninit() -> Result<UniqueArc<MaybeUninit<T>>, AllocError> {
+    pub fn new_uninit(_flags: Flags) -> Result<UniqueArc<MaybeUninit<T>>, AllocError> {
         // INVARIANT: The refcount is initialised to a non-zero value.
         let inner = Box::try_init::<AllocError>(try_init!(ArcInner {
             // SAFETY: There are no safety requirements for this FFI call.
diff --git a/samples/rust/rust_print.rs b/samples/rust/rust_print.rs
index 67ed8ebf8e8e..6eabb0d79ea3 100644
--- a/samples/rust/rust_print.rs
+++ b/samples/rust/rust_print.rs
@@ -18,8 +18,8 @@
 fn arc_print() -> Result {
     use kernel::sync::*;
 
-    let a = Arc::try_new(1)?;
-    let b = UniqueArc::try_new("hello, world")?;
+    let a = Arc::new(1, GFP_KERNEL)?;
+    let b = UniqueArc::new("hello, world", GFP_KERNEL)?;
 
     // Prints the value of data in `a`.
     pr_info!("{}", a);
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread

* [PATCH 09/10] rust: init: update `init` module to take allocation flags
  2024-03-25 19:54 [PATCH 00/10] Allocation APIs Wedson Almeida Filho
                   ` (7 preceding siblings ...)
  2024-03-25 19:54 ` [PATCH 08/10] rust: sync: update `Arc` and `UniqueArc` " Wedson Almeida Filho
@ 2024-03-25 19:54 ` Wedson Almeida Filho
  2024-03-26 14:08   ` Benno Lossin
  2024-03-25 19:54 ` [PATCH 10/10] rust: kernel: remove usage of `allocator_api` unstable feature Wedson Almeida Filho
  9 siblings, 1 reply; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-25 19:54 UTC (permalink / raw)
  To: rust-for-linux
  Cc: Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
	linux-kernel, Wedson Almeida Filho

From: Wedson Almeida Filho <walmeida@microsoft.com>

This is the last component in the conversion for allocators to take
allocation flags as parameters.

Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
---
 rust/kernel/init.rs               | 49 ++++++++++++++++---------------
 rust/kernel/sync/arc.rs           | 17 ++++++-----
 rust/kernel/sync/condvar.rs       |  2 +-
 rust/kernel/sync/lock/mutex.rs    |  2 +-
 rust/kernel/sync/lock/spinlock.rs |  2 +-
 rust/kernel/workqueue.rs          | 13 +++++---
 6 files changed, 47 insertions(+), 38 deletions(-)

diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs
index c8b2f9774a39..1a8b0464db0c 100644
--- a/rust/kernel/init.rs
+++ b/rust/kernel/init.rs
@@ -68,7 +68,7 @@
 //! #     a <- new_mutex!(42, "Foo::a"),
 //! #     b: 24,
 //! # });
-//! let foo: Result<Pin<Box<Foo>>> = Box::pin_init(foo);
+//! let foo: Result<Pin<Box<Foo>>> = Box::pin_init(foo, GFP_KERNEL);
 //! ```
 //!
 //! For more information see the [`pin_init!`] macro.
@@ -80,7 +80,8 @@
 //!
 //! ```rust
 //! # use kernel::sync::{new_mutex, Arc, Mutex};
-//! let mtx: Result<Arc<Mutex<usize>>> = Arc::pin_init(new_mutex!(42, "example::mtx"));
+//! let mtx: Result<Arc<Mutex<usize>>> =
+//!     Arc::pin_init(new_mutex!(42, "example::mtx"), GFP_KERNEL);
 //! ```
 //!
 //! To declare an init macro/function you just return an [`impl PinInit<T, E>`]:
@@ -99,7 +100,7 @@
 //!     fn new() -> impl PinInit<Self, Error> {
 //!         try_pin_init!(Self {
 //!             status <- new_mutex!(0, "DriverData::status"),
-//!             buffer: Box::init(kernel::init::zeroed())?,
+//!             buffer: Box::init(kernel::init::zeroed(), GFP_KERNEL)?,
 //!         })
 //!     }
 //! }
@@ -210,7 +211,7 @@
 //! [`pin_init!`]: crate::pin_init!
 
 use crate::{
-    alloc::{boxext::BoxExt, flags::*},
+    alloc::{boxext::BoxExt, Flags},
     error::{self, Error},
     sync::UniqueArc,
     types::{Opaque, ScopeGuard},
@@ -391,7 +392,7 @@ macro_rules! stack_try_pin_init {
 ///     },
 /// });
 /// # initializer }
-/// # Box::pin_init(demo()).unwrap();
+/// # Box::pin_init(demo(), GFP_KERNEL).unwrap();
 /// ```
 ///
 /// Arbitrary Rust expressions can be used to set the value of a variable.
@@ -461,7 +462,7 @@ macro_rules! stack_try_pin_init {
 /// #         })
 /// #     }
 /// # }
-/// let foo = Box::pin_init(Foo::new());
+/// let foo = Box::pin_init(Foo::new(), GFP_KERNEL);
 /// ```
 ///
 /// They can also easily embed it into their own `struct`s:
@@ -601,7 +602,7 @@ macro_rules! pin_init {
 /// impl BigBuf {
 ///     fn new() -> impl PinInit<Self, Error> {
 ///         try_pin_init!(Self {
-///             big: Box::init(init::zeroed())?,
+///             big: Box::init(init::zeroed(), GFP_KERNEL)?,
 ///             small: [0; 1024 * 1024],
 ///             ptr: core::ptr::null_mut(),
 ///         }? Error)
@@ -702,7 +703,7 @@ macro_rules! init {
 /// impl BigBuf {
 ///     fn new() -> impl Init<Self, Error> {
 ///         try_init!(Self {
-///             big: Box::init(zeroed())?,
+///             big: Box::init(zeroed(), GFP_KERNEL)?,
 ///             small: [0; 1024 * 1024],
 ///         }? Error)
 ///     }
@@ -1014,7 +1015,7 @@ pub fn uninit<T, E>() -> impl Init<MaybeUninit<T>, E> {
 ///
 /// ```rust
 /// use kernel::{error::Error, init::init_array_from_fn};
-/// let array: Box<[usize; 1_000]> = Box::init::<Error>(init_array_from_fn(|i| i)).unwrap();
+/// let array: Box<[usize; 1_000]> = Box::init::<Error>(init_array_from_fn(|i| i), GFP_KERNEL).unwrap();
 /// assert_eq!(array.len(), 1_000);
 /// ```
 pub fn init_array_from_fn<I, const N: usize, T, E>(
@@ -1058,7 +1059,7 @@ pub fn init_array_from_fn<I, const N: usize, T, E>(
 /// ```rust
 /// use kernel::{sync::{Arc, Mutex}, init::pin_init_array_from_fn, new_mutex};
 /// let array: Arc<[Mutex<usize>; 1_000]> =
-///     Arc::pin_init(pin_init_array_from_fn(|i| new_mutex!(i))).unwrap();
+///     Arc::pin_init(pin_init_array_from_fn(|i| new_mutex!(i)), GFP_KERNEL).unwrap();
 /// assert_eq!(array.len(), 1_000);
 /// ```
 pub fn pin_init_array_from_fn<I, const N: usize, T, E>(
@@ -1116,7 +1117,7 @@ pub trait InPlaceInit<T>: Sized {
     /// type.
     ///
     /// If `T: !Unpin` it will not be able to move afterwards.
-    fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
+    fn try_pin_init<E>(init: impl PinInit<T, E>, flags: Flags) -> Result<Pin<Self>, E>
     where
         E: From<AllocError>;
 
@@ -1124,7 +1125,7 @@ fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
     /// type.
     ///
     /// If `T: !Unpin` it will not be able to move afterwards.
-    fn pin_init<E>(init: impl PinInit<T, E>) -> error::Result<Pin<Self>>
+    fn pin_init<E>(init: impl PinInit<T, E>, flags: Flags) -> error::Result<Pin<Self>>
     where
         Error: From<E>,
     {
@@ -1132,16 +1133,16 @@ fn pin_init<E>(init: impl PinInit<T, E>) -> error::Result<Pin<Self>>
         let init = unsafe {
             pin_init_from_closure(|slot| init.__pinned_init(slot).map_err(|e| Error::from(e)))
         };
-        Self::try_pin_init(init)
+        Self::try_pin_init(init, flags)
     }
 
     /// Use the given initializer to in-place initialize a `T`.
-    fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
+    fn try_init<E>(init: impl Init<T, E>, flags: Flags) -> Result<Self, E>
     where
         E: From<AllocError>;
 
     /// Use the given initializer to in-place initialize a `T`.
-    fn init<E>(init: impl Init<T, E>) -> error::Result<Self>
+    fn init<E>(init: impl Init<T, E>, flags: Flags) -> error::Result<Self>
     where
         Error: From<E>,
     {
@@ -1149,17 +1150,17 @@ fn init<E>(init: impl Init<T, E>) -> error::Result<Self>
         let init = unsafe {
             init_from_closure(|slot| init.__pinned_init(slot).map_err(|e| Error::from(e)))
         };
-        Self::try_init(init)
+        Self::try_init(init, flags)
     }
 }
 
 impl<T> InPlaceInit<T> for Box<T> {
     #[inline]
-    fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
+    fn try_pin_init<E>(init: impl PinInit<T, E>, flags: Flags) -> Result<Pin<Self>, E>
     where
         E: From<AllocError>,
     {
-        let mut this = <Box<_> as BoxExt<_>>::new_uninit(GFP_KERNEL)?;
+        let mut this = <Box<_> as BoxExt<_>>::new_uninit(flags)?;
         let slot = this.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
         // slot is valid and will not be moved, because we pin it later.
@@ -1169,11 +1170,11 @@ fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
     }
 
     #[inline]
-    fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
+    fn try_init<E>(init: impl Init<T, E>, flags: Flags) -> Result<Self, E>
     where
         E: From<AllocError>,
     {
-        let mut this = <Box<_> as BoxExt<_>>::new_uninit(GFP_KERNEL)?;
+        let mut this = <Box<_> as BoxExt<_>>::new_uninit(flags)?;
         let slot = this.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
         // slot is valid.
@@ -1185,11 +1186,11 @@ fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
 
 impl<T> InPlaceInit<T> for UniqueArc<T> {
     #[inline]
-    fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
+    fn try_pin_init<E>(init: impl PinInit<T, E>, flags: Flags) -> Result<Pin<Self>, E>
     where
         E: From<AllocError>,
     {
-        let mut this = UniqueArc::new_uninit(GFP_KERNEL)?;
+        let mut this = UniqueArc::new_uninit(flags)?;
         let slot = this.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
         // slot is valid and will not be moved, because we pin it later.
@@ -1199,11 +1200,11 @@ fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
     }
 
     #[inline]
-    fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
+    fn try_init<E>(init: impl Init<T, E>, flags: Flags) -> Result<Self, E>
     where
         E: From<AllocError>,
     {
-        let mut this = UniqueArc::new_uninit(GFP_KERNEL)?;
+        let mut this = UniqueArc::new_uninit(flags)?;
         let slot = this.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
         // slot is valid.
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index 077200f5350b..af539c5eb4bc 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -182,22 +182,22 @@ pub fn new(contents: T, flags: Flags) -> Result<Self, AllocError> {
     ///
     /// If `T: !Unpin` it will not be able to move afterwards.
     #[inline]
-    pub fn pin_init<E>(init: impl PinInit<T, E>) -> error::Result<Self>
+    pub fn pin_init<E>(init: impl PinInit<T, E>, flags: Flags) -> error::Result<Self>
     where
         Error: From<E>,
     {
-        UniqueArc::pin_init(init).map(|u| u.into())
+        UniqueArc::pin_init(init, flags).map(|u| u.into())
     }
 
     /// Use the given initializer to in-place initialize a `T`.
     ///
     /// This is equivalent to [`Arc<T>::pin_init`], since an [`Arc`] is always pinned.
     #[inline]
-    pub fn init<E>(init: impl Init<T, E>) -> error::Result<Self>
+    pub fn init<E>(init: impl Init<T, E>, flags: Flags) -> error::Result<Self>
     where
         Error: From<E>,
     {
-        UniqueArc::init(init).map(|u| u.into())
+        UniqueArc::init(init, flags).map(|u| u.into())
     }
 }
 
@@ -565,13 +565,16 @@ pub fn new(value: T, flags: Flags) -> Result<Self, AllocError> {
     }
 
     /// Tries to allocate a new [`UniqueArc`] instance whose contents are not initialised yet.
-    pub fn new_uninit(_flags: Flags) -> Result<UniqueArc<MaybeUninit<T>>, AllocError> {
+    pub fn new_uninit(flags: Flags) -> Result<UniqueArc<MaybeUninit<T>>, AllocError> {
         // INVARIANT: The refcount is initialised to a non-zero value.
-        let inner = Box::try_init::<AllocError>(try_init!(ArcInner {
+        let inner = Box::try_init::<AllocError>(
+            try_init!(ArcInner {
             // SAFETY: There are no safety requirements for this FFI call.
             refcount: Opaque::new(unsafe { bindings::REFCOUNT_INIT(1) }),
             data <- init::uninit::<T, AllocError>(),
-        }? AllocError))?;
+        }? AllocError),
+            flags,
+        )?;
         Ok(UniqueArc {
             // INVARIANT: The newly-created object has a refcount of 1.
             // SAFETY: The pointer from the `Box` is valid.
diff --git a/rust/kernel/sync/condvar.rs b/rust/kernel/sync/condvar.rs
index 0c3671caffeb..ef6ffef0aa88 100644
--- a/rust/kernel/sync/condvar.rs
+++ b/rust/kernel/sync/condvar.rs
@@ -75,7 +75,7 @@ macro_rules! new_condvar {
 ///     Box::pin_init(pin_init!(Example {
 ///         value <- new_mutex!(0),
 ///         value_changed <- new_condvar!(),
-///     }))
+///     }), GFP_KERNEL)
 /// }
 /// ```
 ///
diff --git a/rust/kernel/sync/lock/mutex.rs b/rust/kernel/sync/lock/mutex.rs
index ef4c4634d294..93e1c982facf 100644
--- a/rust/kernel/sync/lock/mutex.rs
+++ b/rust/kernel/sync/lock/mutex.rs
@@ -60,7 +60,7 @@ macro_rules! new_mutex {
 /// }
 ///
 /// // Allocate a boxed `Example`.
-/// let e = Box::pin_init(Example::new())?;
+/// let e = Box::pin_init(Example::new(), GFP_KERNEL)?;
 /// assert_eq!(e.c, 10);
 /// assert_eq!(e.d.lock().a, 20);
 /// assert_eq!(e.d.lock().b, 30);
diff --git a/rust/kernel/sync/lock/spinlock.rs b/rust/kernel/sync/lock/spinlock.rs
index 0b22c635634f..6e900807d3b7 100644
--- a/rust/kernel/sync/lock/spinlock.rs
+++ b/rust/kernel/sync/lock/spinlock.rs
@@ -58,7 +58,7 @@ macro_rules! new_spinlock {
 /// }
 ///
 /// // Allocate a boxed `Example`.
-/// let e = Box::pin_init(Example::new())?;
+/// let e = Box::pin_init(Example::new(), GFP_KERNEL)?;
 /// assert_eq!(e.c, 10);
 /// assert_eq!(e.d.lock().a, 20);
 /// assert_eq!(e.d.lock().b, 30);
diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index 544f0c51f1b7..09a0f158ff1b 100644
--- a/rust/kernel/workqueue.rs
+++ b/rust/kernel/workqueue.rs
@@ -53,7 +53,7 @@
 //!         Arc::pin_init(pin_init!(MyStruct {
 //!             value,
 //!             work <- new_work!("MyStruct::work"),
-//!         }))
+//!         }), GFP_KERNEL)
 //!     }
 //! }
 //!
@@ -101,7 +101,7 @@
 //!             value_2,
 //!             work_1 <- new_work!("MyStruct::work_1"),
 //!             work_2 <- new_work!("MyStruct::work_2"),
-//!         }))
+//!         }), GFP_KERNEL)
 //!     }
 //! }
 //!
@@ -132,6 +132,7 @@
 //!
 //! C header: [`include/linux/workqueue.h`](srctree/include/linux/workqueue.h)
 
+use crate::alloc::Flags;
 use crate::{bindings, prelude::*, sync::Arc, sync::LockClassKey, types::Opaque};
 use alloc::alloc::AllocError;
 use alloc::boxed::Box;
@@ -206,13 +207,17 @@ pub fn enqueue<W, const ID: u64>(&self, w: W) -> W::EnqueueOutput
     /// Tries to spawn the given function or closure as a work item.
     ///
     /// This method can fail because it allocates memory to store the work item.
-    pub fn try_spawn<T: 'static + Send + FnOnce()>(&self, func: T) -> Result<(), AllocError> {
+    pub fn try_spawn<T: 'static + Send + FnOnce()>(
+        &self,
+        flags: Flags,
+        func: T,
+    ) -> Result<(), AllocError> {
         let init = pin_init!(ClosureWork {
             work <- new_work!("Queue::try_spawn"),
             func: Some(func),
         });
 
-        self.enqueue(Box::pin_init(init).map_err(|_| AllocError)?);
+        self.enqueue(Box::pin_init(init, flags).map_err(|_| AllocError)?);
         Ok(())
     }
 }
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread

* [PATCH 10/10] rust: kernel: remove usage of `allocator_api` unstable feature
  2024-03-25 19:54 [PATCH 00/10] Allocation APIs Wedson Almeida Filho
                   ` (8 preceding siblings ...)
  2024-03-25 19:54 ` [PATCH 09/10] rust: init: update `init` module " Wedson Almeida Filho
@ 2024-03-25 19:54 ` Wedson Almeida Filho
  2024-03-26 15:27   ` Benno Lossin
  9 siblings, 1 reply; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-25 19:54 UTC (permalink / raw)
  To: rust-for-linux
  Cc: Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
	linux-kernel, Wedson Almeida Filho

From: Wedson Almeida Filho <walmeida@microsoft.com>

With the adoption of `BoxExt` and `VecExt`, we don't need the functions
provided by this feature (namely the methods prefixed with `try_` and
different allocator per collection instance).

We do need `AllocError`, but we define our own as it is a trivial empty
struct.

Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
---
 rust/kernel/alloc.rs        |  3 +++
 rust/kernel/alloc/boxext.rs |  3 +--
 rust/kernel/alloc/vecext.rs |  4 ++--
 rust/kernel/error.rs        | 13 ++-----------
 rust/kernel/init.rs         |  3 +--
 rust/kernel/lib.rs          |  1 -
 rust/kernel/str.rs          |  3 +--
 rust/kernel/sync/arc.rs     |  4 ++--
 rust/kernel/workqueue.rs    |  3 +--
 9 files changed, 13 insertions(+), 24 deletions(-)

diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
index 5712c81b1308..f17f48130f13 100644
--- a/rust/kernel/alloc.rs
+++ b/rust/kernel/alloc.rs
@@ -8,6 +8,9 @@
 pub mod boxext;
 pub mod vecext;
 
+/// Indicates an allocation error.
+pub struct AllocError;
+
 /// Flags to be used when allocating memory.
 ///
 /// They can be combined with the operators `|`, `&`, and `!`.
diff --git a/rust/kernel/alloc/boxext.rs b/rust/kernel/alloc/boxext.rs
index 26a918df7acf..3cdda0f635a3 100644
--- a/rust/kernel/alloc/boxext.rs
+++ b/rust/kernel/alloc/boxext.rs
@@ -2,9 +2,8 @@
 
 //! Extensions to [`Box`] for fallible allocations.
 
-use super::Flags;
+use super::{AllocError, Flags};
 use alloc::boxed::Box;
-use core::alloc::AllocError;
 use core::mem::MaybeUninit;
 use core::result::Result;
 
diff --git a/rust/kernel/alloc/vecext.rs b/rust/kernel/alloc/vecext.rs
index 1d4d51b45a49..85ca6a6db6de 100644
--- a/rust/kernel/alloc/vecext.rs
+++ b/rust/kernel/alloc/vecext.rs
@@ -2,8 +2,8 @@
 
 //! Extensions to [`Vec`] for fallible allocations.
 
-use super::Flags;
-use alloc::{alloc::AllocError, vec::Vec};
+use super::{AllocError, Flags};
+use alloc::vec::Vec;
 use core::{mem::ManuallyDrop, result::Result};
 
 /// Extensions to [`Vec`].
diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
index 4786d3ee1e92..fc986bc24c6d 100644
--- a/rust/kernel/error.rs
+++ b/rust/kernel/error.rs
@@ -4,12 +4,9 @@
 //!
 //! C header: [`include/uapi/asm-generic/errno-base.h`](srctree/include/uapi/asm-generic/errno-base.h)
 
-use crate::str::CStr;
+use crate::{alloc::AllocError, str::CStr};
 
-use alloc::{
-    alloc::{AllocError, LayoutError},
-    collections::TryReserveError,
-};
+use alloc::alloc::LayoutError;
 
 use core::convert::From;
 use core::fmt;
@@ -192,12 +189,6 @@ fn from(_: Utf8Error) -> Error {
     }
 }
 
-impl From<TryReserveError> for Error {
-    fn from(_: TryReserveError) -> Error {
-        code::ENOMEM
-    }
-}
-
 impl From<LayoutError> for Error {
     fn from(_: LayoutError) -> Error {
         code::ENOMEM
diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs
index 1a8b0464db0c..1f7a6b5892ac 100644
--- a/rust/kernel/init.rs
+++ b/rust/kernel/init.rs
@@ -211,14 +211,13 @@
 //! [`pin_init!`]: crate::pin_init!
 
 use crate::{
-    alloc::{boxext::BoxExt, Flags},
+    alloc::{boxext::BoxExt, AllocError, Flags},
     error::{self, Error},
     sync::UniqueArc,
     types::{Opaque, ScopeGuard},
 };
 use alloc::boxed::Box;
 use core::{
-    alloc::AllocError,
     cell::UnsafeCell,
     convert::Infallible,
     marker::PhantomData,
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 51f30e55bd00..5c641233e26d 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -12,7 +12,6 @@
 //! do so first instead of bypassing this crate.
 
 #![no_std]
-#![feature(allocator_api)]
 #![feature(coerce_unsized)]
 #![feature(dispatch_from_dyn)]
 #![feature(new_uninit)]
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 34dbc85b5220..5206b18f882b 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -2,8 +2,7 @@
 
 //! String representations.
 
-use crate::alloc::{flags::*, vecext::VecExt};
-use alloc::alloc::AllocError;
+use crate::alloc::{flags::*, vecext::VecExt, AllocError};
 use alloc::vec::Vec;
 use core::fmt::{self, Write};
 use core::ops::{self, Deref, Index};
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index af539c5eb4bc..8db25f73b37f 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -16,7 +16,7 @@
 //! [`Arc`]: https://doc.rust-lang.org/std/sync/struct.Arc.html
 
 use crate::{
-    alloc::{boxext::BoxExt, Flags},
+    alloc::{boxext::BoxExt, AllocError, Flags},
     bindings,
     error::{self, Error},
     init::{self, InPlaceInit, Init, PinInit},
@@ -25,7 +25,7 @@
 };
 use alloc::boxed::Box;
 use core::{
-    alloc::{AllocError, Layout},
+    alloc::Layout,
     fmt,
     marker::{PhantomData, Unsize},
     mem::{ManuallyDrop, MaybeUninit},
diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index 09a0f158ff1b..50837e56efc7 100644
--- a/rust/kernel/workqueue.rs
+++ b/rust/kernel/workqueue.rs
@@ -132,9 +132,8 @@
 //!
 //! C header: [`include/linux/workqueue.h`](srctree/include/linux/workqueue.h)
 
-use crate::alloc::Flags;
+use crate::alloc::{AllocError, Flags};
 use crate::{bindings, prelude::*, sync::Arc, sync::LockClassKey, types::Opaque};
-use alloc::alloc::AllocError;
 use alloc::boxed::Box;
 use core::marker::PhantomData;
 use core::pin::Pin;
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread

* Re: [PATCH 07/10] rust: alloc: update `VecExt` to take allocation flags
  2024-03-25 19:54 ` [PATCH 07/10] rust: alloc: update `VecExt` to take allocation flags Wedson Almeida Filho
@ 2024-03-25 20:44   ` Boqun Feng
  2024-03-26  0:03     ` Wedson Almeida Filho
  0 siblings, 1 reply; 30+ messages in thread
From: Boqun Feng @ 2024-03-25 20:44 UTC (permalink / raw)
  To: Wedson Almeida Filho
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Gary Guo,
	Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
	linux-kernel, Wedson Almeida Filho

On Mon, Mar 25, 2024 at 04:54:15PM -0300, Wedson Almeida Filho wrote:
[...]
> +    fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError> {
> +        <Self as VecExt<_>>::reserve(self, 1, flags)?;
> +        let (ptr, len, cap) = destructure(self);
> +        // SAFETY: ptr is valid for `cap` elements. And `cap` is greater (by at least 1) than
> +        // `len` because of the call to `reserve` above. So the pointer after offsetting by `len`
> +        // elements is valid for write.
> +        unsafe { ptr.wrapping_add(len).write(v) };
> +
> +        // SAFETY: The only difference from the values returned by `destructure` is that `length`
> +        // is incremented by 1, which is fine because we have just initialised the element at
> +        // offset `length`.
> +        unsafe { rebuild(self, ptr, len + 1, cap) };

probably use spare_capacity_mut() here to avoid `destructure` and
`rebuild`?
	
	https://doc.rust-lang.org/std/vec/struct.Vec.html#method.spare_capacity_mut

	// .. after reserve succeed.
	// there must be room for adding one more.
	self.spare_capacity_mut()[0].write(v);
	// or unsafe { self.spare_capacity_mut().as_mut_ptr().cast().write(v); }

	unsafe {
		self.set_len(self.len() + 1);
	}

Thoughts?

Regards,
Boqun

>          Ok(())
>      }
>  
[...]

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 01/10] rust: kernel: move `allocator` module under `alloc`
  2024-03-25 19:54 ` [PATCH 01/10] rust: kernel: move `allocator` module under `alloc` Wedson Almeida Filho
@ 2024-03-25 21:56   ` Benno Lossin
  2024-03-26  0:04     ` Wedson Almeida Filho
  0 siblings, 1 reply; 30+ messages in thread
From: Benno Lossin @ 2024-03-25 21:56 UTC (permalink / raw)
  To: Wedson Almeida Filho
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On 25.03.24 20:54, Wedson Almeida Filho wrote:> From: Wedson Almeida Filho <walmeida@microsoft.com>
> 
> We will add more to the `alloc` module in subsequent patches (e.g.,
> allocation flags and extension traits).
> 
> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

One nit below, but feel free to add:

Reviewed-by: Benno Lossin <benno.lossin@proton.me>

> ---
>   rust/kernel/alloc.rs                 | 7 +++++++
>   rust/kernel/{ => alloc}/allocator.rs | 0
>   rust/kernel/lib.rs                   | 4 +---
>   3 files changed, 8 insertions(+), 3 deletions(-)
>   create mode 100644 rust/kernel/alloc.rs
>   rename rust/kernel/{ => alloc}/allocator.rs (100%)
> 
> diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> new file mode 100644
> index 000000000000..ccd4149932c3
> --- /dev/null
> +++ b/rust/kernel/alloc.rs
> @@ -0,0 +1,7 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +//! Allocation support.

I think 'Extensions to the `alloc` crate.' fits better.

-- 
Cheers,
Benno

> +
> +#[cfg(not(test))]
> +#[cfg(not(testlib))]
> +mod allocator;
> diff --git a/rust/kernel/allocator.rs b/rust/kernel/alloc/allocator.rs
> similarity index 100%
> rename from rust/kernel/allocator.rs
> rename to rust/kernel/alloc/allocator.rs
> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> index be68d5e567b1..51f30e55bd00 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -28,9 +28,7 @@
>   // Allow proc-macros to refer to `::kernel` inside the `kernel` crate (this crate).
>   extern crate self as kernel;
> 
> -#[cfg(not(test))]
> -#[cfg(not(testlib))]
> -mod allocator;
> +pub mod alloc;
>   mod build_assert;
>   pub mod error;
>   pub mod init;
> --
> 2.34.1
>

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 02/10] rust: alloc: introduce the `VecExt` trait
  2024-03-25 19:54 ` [PATCH 02/10] rust: alloc: introduce the `VecExt` trait Wedson Almeida Filho
@ 2024-03-25 22:05   ` Benno Lossin
  2024-03-26  0:02     ` Wedson Almeida Filho
  0 siblings, 1 reply; 30+ messages in thread
From: Benno Lossin @ 2024-03-25 22:05 UTC (permalink / raw)
  To: Wedson Almeida Filho
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On 25.03.24 20:54, Wedson Almeida Filho wrote:> From: Wedson Almeida Filho <walmeida@microsoft.com>
> 
> Make `try_with_capacity`, `try_push`, and `try_extend_from_slice`
> methods available in `Vec` even though it doesn't implement them. It is
> implemented with `try_reserve` and `push_within_capacity`.
> 
> This is in preparation for switching to the upstream `alloc` crate.
> 
> Suggested-by: Gary Guo <gary@garyguo.net>
> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
> ---
>   rust/kernel/alloc.rs        |  1 +
>   rust/kernel/alloc/vecext.rs | 52 +++++++++++++++++++++++++++++++++++++
>   rust/kernel/lib.rs          |  1 +
>   rust/kernel/prelude.rs      |  2 ++
>   4 files changed, 56 insertions(+)
>   create mode 100644 rust/kernel/alloc/vecext.rs
> 
> diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> index ccd4149932c3..8ad57a2e693e 100644
> --- a/rust/kernel/alloc.rs
> +++ b/rust/kernel/alloc.rs
> @@ -5,3 +5,4 @@
>   #[cfg(not(test))]
>   #[cfg(not(testlib))]
>   mod allocator;
> +pub mod vecext;
> diff --git a/rust/kernel/alloc/vecext.rs b/rust/kernel/alloc/vecext.rs
> new file mode 100644
> index 000000000000..59e92bab534e
> --- /dev/null
> +++ b/rust/kernel/alloc/vecext.rs
> @@ -0,0 +1,52 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +//! Extensions to [`Vec`] for fallible allocations.
> +
> +use alloc::{collections::TryReserveError, vec::Vec};
> +use core::result::Result;
> +
> +/// Extensions to [`Vec`].
> +pub trait VecExt<T>: Sized {
> +    /// Creates a new [`Vec`] instance with at least the given capacity.
> +    fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError>;
> +
> +    /// Appends an element to the back of the [`Vec`] instance.
> +    fn try_push(&mut self, v: T) -> Result<(), TryReserveError>;
> +
> +    /// Pushes clones of the elements of slice into the [`Vec`] instance.
> +    fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError>
> +    where
> +        T: Clone;

All of the non `try_` prefix functions require 
`not(no_global_oom_handling)`, so we could also drop the `try_` prefix
here.
What do you think?

> +}
> +
> +impl<T> VecExt<T> for Vec<T> {
> +    fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError> {
> +        let mut v = Vec::new();
> +        v.try_reserve(capacity)?;
> +        Ok(v)
> +    }
> +
> +    fn try_push(&mut self, v: T) -> Result<(), TryReserveError> {
> +        if let Err(retry) = self.push_within_capacity(v) {
> +            self.try_reserve(1)?;
> +            let _ = self.push_within_capacity(retry);
> +        }
> +        Ok(())
> +    }
> +
> +    fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError>
> +    where
> +        T: Clone,
> +    {
> +        let extra_cap = self.capacity() - self.len();
> +        if extra_cap > 0 {
> +            self.try_reserve(extra_cap)?;
> +        }

I am confused, why are you doing this? Did you mean to do this?:
    let extra_cap = self.capacity() - self.len() - other.len();

-- 
Cheers,
Benno

> +
> +        for item in other {
> +            self.try_push(item.clone())?;
> +        }
> +
> +        Ok(())
> +    }
> +}
> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> index 51f30e55bd00..7f2841a18d05 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -19,6 +19,7 @@
>   #![feature(offset_of)]
>   #![feature(receiver_trait)]
>   #![feature(unsize)]
> +#![feature(vec_push_within_capacity)]
> 
>   // Ensure conditional compilation based on the kernel configuration works;
>   // otherwise we may silently break things like initcall handling.
> diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
> index ae21600970b3..a0177f195dec 100644
> --- a/rust/kernel/prelude.rs
> +++ b/rust/kernel/prelude.rs
> @@ -14,6 +14,8 @@
>   #[doc(no_inline)]
>   pub use core::pin::Pin;
> 
> +pub use crate::alloc::vecext::VecExt;
> +
>   #[doc(no_inline)]
>   pub use alloc::{boxed::Box, vec::Vec};
> 
> --
> 2.34.1
>

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 04/10] rust: alloc: remove our fork of the `alloc` crate
  2024-03-25 19:54 ` [PATCH 04/10] rust: alloc: remove our fork of the " Wedson Almeida Filho
@ 2024-03-25 22:24   ` Benno Lossin
  0 siblings, 0 replies; 30+ messages in thread
From: Benno Lossin @ 2024-03-25 22:24 UTC (permalink / raw)
  To: Wedson Almeida Filho
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On 25.03.24 20:54, Wedson Almeida Filho wrote:
> From: Wedson Almeida Filho <walmeida@microsoft.com>
> 
> It is not used anymore as `VecExt` now provides the functionality we
> depend on.
> 
> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
> ---
>   rust/alloc/README.md              |   36 -
>   rust/alloc/alloc.rs               |  452 ----
>   rust/alloc/boxed.rs               | 2463 -------------------
>   rust/alloc/collections/mod.rs     |  160 --
>   rust/alloc/lib.rs                 |  288 ---
>   rust/alloc/raw_vec.rs             |  611 -----
>   rust/alloc/slice.rs               |  890 -------
>   rust/alloc/vec/drain.rs           |  255 --
>   rust/alloc/vec/extract_if.rs      |  115 -
>   rust/alloc/vec/into_iter.rs       |  454 ----
>   rust/alloc/vec/is_zero.rs         |  204 --
>   rust/alloc/vec/mod.rs             | 3683 -----------------------------
>   rust/alloc/vec/partial_eq.rs      |   49 -
>   rust/alloc/vec/set_len_on_drop.rs |   35 -
>   rust/alloc/vec/spec_extend.rs     |  119 -
>   15 files changed, 9814 deletions(-)

Reviewed-by: Benno Lossin <benno.lossin@proton.me>

-- 
Cheers,
Benno

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 05/10] rust: alloc: introduce allocation flags
  2024-03-25 19:54 ` [PATCH 05/10] rust: alloc: introduce allocation flags Wedson Almeida Filho
@ 2024-03-25 22:26   ` Benno Lossin
  0 siblings, 0 replies; 30+ messages in thread
From: Benno Lossin @ 2024-03-25 22:26 UTC (permalink / raw)
  To: Wedson Almeida Filho
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On 25.03.24 20:54, Wedson Almeida Filho wrote:
> From: Wedson Almeida Filho <walmeida@microsoft.com>
> 
> We'll use them when allocating `Box`, `Arc`, and `UniqueArc` instances,
> as well as when allocating memory for `Vec` elements. These changes will
> come in subsequent patches.
> 
> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>

-- 
Cheers,
Benno

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 06/10] rust: alloc: introduce the `BoxExt` trait
  2024-03-25 19:54 ` [PATCH 06/10] rust: alloc: introduce the `BoxExt` trait Wedson Almeida Filho
@ 2024-03-25 22:37   ` Benno Lossin
  2024-03-26  0:17     ` Wedson Almeida Filho
  0 siblings, 1 reply; 30+ messages in thread
From: Benno Lossin @ 2024-03-25 22:37 UTC (permalink / raw)
  To: Wedson Almeida Filho
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On 25.03.24 20:54, Wedson Almeida Filho wrote:
> From: Wedson Almeida Filho <walmeida@microsoft.com>
> 
> Make fallible versions of `new` and `new_uninit` methods available in
> `Box` even though it doesn't implement them because we build `alloc`
> with the `no_global_oom_handling` config.
> 
> They also have an extra `flags` parameter that allows callers to pass
> flags to the allocator.
> 
> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
> ---
>   rust/kernel/alloc.rs           |  1 +
>   rust/kernel/alloc/allocator.rs |  6 +++-
>   rust/kernel/alloc/boxext.rs    | 61 ++++++++++++++++++++++++++++++++++
>   rust/kernel/init.rs            | 13 ++++----
>   rust/kernel/prelude.rs         |  2 +-
>   rust/kernel/sync/arc.rs        |  3 +-
>   6 files changed, 77 insertions(+), 9 deletions(-)
>   create mode 100644 rust/kernel/alloc/boxext.rs
> 
> diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> index ad48ac8dc13d..5712c81b1308 100644
> --- a/rust/kernel/alloc.rs
> +++ b/rust/kernel/alloc.rs
> @@ -5,6 +5,7 @@
>   #[cfg(not(test))]
>   #[cfg(not(testlib))]
>   mod allocator;
> +pub mod boxext;
>   pub mod vecext;
> 
>   /// Flags to be used when allocating memory.
> diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
> index 01ad139e19bc..fc0439455faa 100644
> --- a/rust/kernel/alloc/allocator.rs
> +++ b/rust/kernel/alloc/allocator.rs
> @@ -15,7 +15,11 @@
>   ///
>   /// - `ptr` can be either null or a pointer which has been allocated by this allocator.
>   /// - `new_layout` must have a non-zero size.
> -unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gfp_t) -> *mut u8 {
> +pub(crate) unsafe fn krealloc_aligned(
> +    ptr: *mut u8,
> +    new_layout: Layout,
> +    flags: bindings::gfp_t,
> +) -> *mut u8 {
>       // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
>       let layout = new_layout.pad_to_align();
> 
> diff --git a/rust/kernel/alloc/boxext.rs b/rust/kernel/alloc/boxext.rs
> new file mode 100644
> index 000000000000..26a918df7acf
> --- /dev/null
> +++ b/rust/kernel/alloc/boxext.rs
> @@ -0,0 +1,61 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +//! Extensions to [`Box`] for fallible allocations.
> +
> +use super::Flags;
> +use alloc::boxed::Box;
> +use core::alloc::AllocError;
> +use core::mem::MaybeUninit;
> +use core::result::Result;
> +
> +/// Extensions to [`Box`].
> +pub trait BoxExt<T>: Sized {
> +    /// Allocates a new box.
> +    ///
> +    /// The allocation may fail, in which case an error is returned.
> +    fn new(x: T, flags: Flags) -> Result<Self, AllocError>;
> +
> +    /// Allocates a new uninitialised box.
> +    ///
> +    /// The allocation may fail, in which case an error is returned.
> +    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError>;
> +}
> +
> +impl<T> BoxExt<T> for Box<T> {
> +    #[cfg(any(test, testlib))]
> +    fn new(x: T, _flags: Flags) -> Result<Self, AllocError> {
> +        Ok(Box::new(x))
> +    }

When running under `cfg(test)`, are we using the normal standard
library? Or why is this needed?

> +
> +    #[cfg(not(any(test, testlib)))]
> +    fn new(x: T, flags: Flags) -> Result<Self, AllocError> {
> +        let ptr = if core::mem::size_of::<T>() == 0 {
> +            core::ptr::NonNull::<T>::dangling().as_ptr()
> +        } else {
> +            let layout = core::alloc::Layout::new::<T>();
> +
> +            // SAFETY: Memory is being allocated (first arg is null). The only other source of
> +            // safety issues is sleeping on atomic context, which is addressed by klint.

The `krealloc_aligned` function states:

/// # Safety
///
/// - `ptr` can be either null or a pointer which has been allocated by this allocator.
/// - `new_layout` must have a non-zero size.

So it should also mention that you checked for `layout.size() > 0`
above.

> +            let ptr = unsafe {
> +                super::allocator::krealloc_aligned(core::ptr::null_mut(), layout, flags.0)
> +            };
> +            if ptr.is_null() {
> +                return Err(AllocError);
> +            }
> +
> +            let ptr = ptr.cast::<T>();
> +
> +            // SAFETY: We just allocated the memory above, it is valid for write.
> +            unsafe { ptr.write(x) };
> +            ptr
> +        };
> +
> +        // SAFETY: For non-zero-sized types, we allocate above using the global allocator. For
> +        // zero-sized types, we use `NonNull::dangling`.
> +        Ok(unsafe { Box::from_raw(ptr) })
> +    }
> +
> +    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
> +        <Box<_> as BoxExt<_>>::new(MaybeUninit::<T>::uninit(), flags)

Why do you use the extended syntax? I tried to use `Box::new` and it
compiled.

-- 
Cheers,
Benno

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 02/10] rust: alloc: introduce the `VecExt` trait
  2024-03-25 22:05   ` Benno Lossin
@ 2024-03-26  0:02     ` Wedson Almeida Filho
  0 siblings, 0 replies; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-26  0:02 UTC (permalink / raw)
  To: Benno Lossin
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On Mon, 25 Mar 2024 at 19:05, Benno Lossin <benno.lossin@proton.me> wrote:
>
> On 25.03.24 20:54, Wedson Almeida Filho wrote:> From: Wedson Almeida Filho <walmeida@microsoft.com>
> >
> > Make `try_with_capacity`, `try_push`, and `try_extend_from_slice`
> > methods available in `Vec` even though it doesn't implement them. It is
> > implemented with `try_reserve` and `push_within_capacity`.
> >
> > This is in preparation for switching to the upstream `alloc` crate.
> >
> > Suggested-by: Gary Guo <gary@garyguo.net>
> > Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
> > ---
> >   rust/kernel/alloc.rs        |  1 +
> >   rust/kernel/alloc/vecext.rs | 52 +++++++++++++++++++++++++++++++++++++
> >   rust/kernel/lib.rs          |  1 +
> >   rust/kernel/prelude.rs      |  2 ++
> >   4 files changed, 56 insertions(+)
> >   create mode 100644 rust/kernel/alloc/vecext.rs
> >
> > diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> > index ccd4149932c3..8ad57a2e693e 100644
> > --- a/rust/kernel/alloc.rs
> > +++ b/rust/kernel/alloc.rs
> > @@ -5,3 +5,4 @@
> >   #[cfg(not(test))]
> >   #[cfg(not(testlib))]
> >   mod allocator;
> > +pub mod vecext;
> > diff --git a/rust/kernel/alloc/vecext.rs b/rust/kernel/alloc/vecext.rs
> > new file mode 100644
> > index 000000000000..59e92bab534e
> > --- /dev/null
> > +++ b/rust/kernel/alloc/vecext.rs
> > @@ -0,0 +1,52 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +
> > +//! Extensions to [`Vec`] for fallible allocations.
> > +
> > +use alloc::{collections::TryReserveError, vec::Vec};
> > +use core::result::Result;
> > +
> > +/// Extensions to [`Vec`].
> > +pub trait VecExt<T>: Sized {
> > +    /// Creates a new [`Vec`] instance with at least the given capacity.
> > +    fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError>;
> > +
> > +    /// Appends an element to the back of the [`Vec`] instance.
> > +    fn try_push(&mut self, v: T) -> Result<(), TryReserveError>;
> > +
> > +    /// Pushes clones of the elements of slice into the [`Vec`] instance.
> > +    fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError>
> > +    where
> > +        T: Clone;
>
> All of the non `try_` prefix functions require
> `not(no_global_oom_handling)`, so we could also drop the `try_` prefix
> here.
> What do you think?

Yes, I do drop the `try_` prefixes in patch 7.

Patches 1 through 4 remove the fork with minimal changes. Patches 5 to
10 introduce new functions with flags and drop `allocator_api`.

> > +}
> > +
> > +impl<T> VecExt<T> for Vec<T> {
> > +    fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError> {
> > +        let mut v = Vec::new();
> > +        v.try_reserve(capacity)?;
> > +        Ok(v)
> > +    }
> > +
> > +    fn try_push(&mut self, v: T) -> Result<(), TryReserveError> {
> > +        if let Err(retry) = self.push_within_capacity(v) {
> > +            self.try_reserve(1)?;
> > +            let _ = self.push_within_capacity(retry);
> > +        }
> > +        Ok(())
> > +    }
> > +
> > +    fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError>
> > +    where
> > +        T: Clone,
> > +    {
> > +        let extra_cap = self.capacity() - self.len();
> > +        if extra_cap > 0 {
> > +            self.try_reserve(extra_cap)?;
> > +        }
>
> I am confused, why are you doing this? Did you mean to do this?:
>     let extra_cap = self.capacity() - self.len() - other.len();

I originally meant `extracap = other.len() - self.capacity() +
self.len()` because originally I thought `additional` meant additional
capacity (so the final capacity would be original capacity plus
`additional`). But after I looked at the code I learned that
`additional` is really the minimum capacity.

Then I decided that we don't need this check at all in
`try_extend_from_slice`, which I removed in patch 7, I just call
`reserve` directly with `other.len()`.

The code happens to work now because the `try_push` calls below ensure
the capacity gets expanded. In any case, I'll fix this in v2.

> --
> Cheers,
> Benno
>
> > +
> > +        for item in other {
> > +            self.try_push(item.clone())?;
> > +        }
> > +
> > +        Ok(())
> > +    }
> > +}
> > diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> > index 51f30e55bd00..7f2841a18d05 100644
> > --- a/rust/kernel/lib.rs
> > +++ b/rust/kernel/lib.rs
> > @@ -19,6 +19,7 @@
> >   #![feature(offset_of)]
> >   #![feature(receiver_trait)]
> >   #![feature(unsize)]
> > +#![feature(vec_push_within_capacity)]
> >
> >   // Ensure conditional compilation based on the kernel configuration works;
> >   // otherwise we may silently break things like initcall handling.
> > diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
> > index ae21600970b3..a0177f195dec 100644
> > --- a/rust/kernel/prelude.rs
> > +++ b/rust/kernel/prelude.rs
> > @@ -14,6 +14,8 @@
> >   #[doc(no_inline)]
> >   pub use core::pin::Pin;
> >
> > +pub use crate::alloc::vecext::VecExt;
> > +
> >   #[doc(no_inline)]
> >   pub use alloc::{boxed::Box, vec::Vec};
> >
> > --
> > 2.34.1
> >

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 07/10] rust: alloc: update `VecExt` to take allocation flags
  2024-03-25 20:44   ` Boqun Feng
@ 2024-03-26  0:03     ` Wedson Almeida Filho
  2024-03-26 13:58       ` Benno Lossin
  0 siblings, 1 reply; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-26  0:03 UTC (permalink / raw)
  To: Boqun Feng
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Gary Guo,
	Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
	linux-kernel, Wedson Almeida Filho

On Mon, 25 Mar 2024 at 17:44, Boqun Feng <boqun.feng@gmail.com> wrote:
>
> On Mon, Mar 25, 2024 at 04:54:15PM -0300, Wedson Almeida Filho wrote:
> [...]
> > +    fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError> {
> > +        <Self as VecExt<_>>::reserve(self, 1, flags)?;
> > +        let (ptr, len, cap) = destructure(self);
> > +        // SAFETY: ptr is valid for `cap` elements. And `cap` is greater (by at least 1) than
> > +        // `len` because of the call to `reserve` above. So the pointer after offsetting by `len`
> > +        // elements is valid for write.
> > +        unsafe { ptr.wrapping_add(len).write(v) };
> > +
> > +        // SAFETY: The only difference from the values returned by `destructure` is that `length`
> > +        // is incremented by 1, which is fine because we have just initialised the element at
> > +        // offset `length`.
> > +        unsafe { rebuild(self, ptr, len + 1, cap) };
>
> probably use spare_capacity_mut() here to avoid `destructure` and
> `rebuild`?

Ah, yes, this sounds like a better approach. I will use this in v2.

>
>         https://doc.rust-lang.org/std/vec/struct.Vec.html#method.spare_capacity_mut
>
>         // .. after reserve succeed.
>         // there must be room for adding one more.
>         self.spare_capacity_mut()[0].write(v);
>         // or unsafe { self.spare_capacity_mut().as_mut_ptr().cast().write(v); }
>
>         unsafe {
>                 self.set_len(self.len() + 1);
>         }
>
> Thoughts?
>
> Regards,
> Boqun
>
> >          Ok(())
> >      }
> >
> [...]

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 01/10] rust: kernel: move `allocator` module under `alloc`
  2024-03-25 21:56   ` Benno Lossin
@ 2024-03-26  0:04     ` Wedson Almeida Filho
  0 siblings, 0 replies; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-26  0:04 UTC (permalink / raw)
  To: Benno Lossin
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On Mon, 25 Mar 2024 at 18:56, Benno Lossin <benno.lossin@proton.me> wrote:
>
> On 25.03.24 20:54, Wedson Almeida Filho wrote:> From: Wedson Almeida Filho <walmeida@microsoft.com>
> >
> > We will add more to the `alloc` module in subsequent patches (e.g.,
> > allocation flags and extension traits).
> >
> > Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
>
> One nit below, but feel free to add:
>
> Reviewed-by: Benno Lossin <benno.lossin@proton.me>
>
> > ---
> >   rust/kernel/alloc.rs                 | 7 +++++++
> >   rust/kernel/{ => alloc}/allocator.rs | 0
> >   rust/kernel/lib.rs                   | 4 +---
> >   3 files changed, 8 insertions(+), 3 deletions(-)
> >   create mode 100644 rust/kernel/alloc.rs
> >   rename rust/kernel/{ => alloc}/allocator.rs (100%)
> >
> > diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> > new file mode 100644
> > index 000000000000..ccd4149932c3
> > --- /dev/null
> > +++ b/rust/kernel/alloc.rs
> > @@ -0,0 +1,7 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +
> > +//! Allocation support.
>
> I think 'Extensions to the `alloc` crate.' fits better.

SGTM. I will update for v2.

>
> --
> Cheers,
> Benno
>
> > +
> > +#[cfg(not(test))]
> > +#[cfg(not(testlib))]
> > +mod allocator;
> > diff --git a/rust/kernel/allocator.rs b/rust/kernel/alloc/allocator.rs
> > similarity index 100%
> > rename from rust/kernel/allocator.rs
> > rename to rust/kernel/alloc/allocator.rs
> > diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> > index be68d5e567b1..51f30e55bd00 100644
> > --- a/rust/kernel/lib.rs
> > +++ b/rust/kernel/lib.rs
> > @@ -28,9 +28,7 @@
> >   // Allow proc-macros to refer to `::kernel` inside the `kernel` crate (this crate).
> >   extern crate self as kernel;
> >
> > -#[cfg(not(test))]
> > -#[cfg(not(testlib))]
> > -mod allocator;
> > +pub mod alloc;
> >   mod build_assert;
> >   pub mod error;
> >   pub mod init;
> > --
> > 2.34.1
> >

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 06/10] rust: alloc: introduce the `BoxExt` trait
  2024-03-25 22:37   ` Benno Lossin
@ 2024-03-26  0:17     ` Wedson Almeida Filho
  2024-03-26 13:30       ` Benno Lossin
  0 siblings, 1 reply; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-26  0:17 UTC (permalink / raw)
  To: Benno Lossin
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On Mon, 25 Mar 2024 at 19:37, Benno Lossin <benno.lossin@proton.me> wrote:
>
> On 25.03.24 20:54, Wedson Almeida Filho wrote:
> > From: Wedson Almeida Filho <walmeida@microsoft.com>
> >
> > Make fallible versions of `new` and `new_uninit` methods available in
> > `Box` even though it doesn't implement them because we build `alloc`
> > with the `no_global_oom_handling` config.
> >
> > They also have an extra `flags` parameter that allows callers to pass
> > flags to the allocator.
> >
> > Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
> > ---
> >   rust/kernel/alloc.rs           |  1 +
> >   rust/kernel/alloc/allocator.rs |  6 +++-
> >   rust/kernel/alloc/boxext.rs    | 61 ++++++++++++++++++++++++++++++++++
> >   rust/kernel/init.rs            | 13 ++++----
> >   rust/kernel/prelude.rs         |  2 +-
> >   rust/kernel/sync/arc.rs        |  3 +-
> >   6 files changed, 77 insertions(+), 9 deletions(-)
> >   create mode 100644 rust/kernel/alloc/boxext.rs
> >
> > diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> > index ad48ac8dc13d..5712c81b1308 100644
> > --- a/rust/kernel/alloc.rs
> > +++ b/rust/kernel/alloc.rs
> > @@ -5,6 +5,7 @@
> >   #[cfg(not(test))]
> >   #[cfg(not(testlib))]
> >   mod allocator;
> > +pub mod boxext;
> >   pub mod vecext;
> >
> >   /// Flags to be used when allocating memory.
> > diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
> > index 01ad139e19bc..fc0439455faa 100644
> > --- a/rust/kernel/alloc/allocator.rs
> > +++ b/rust/kernel/alloc/allocator.rs
> > @@ -15,7 +15,11 @@
> >   ///
> >   /// - `ptr` can be either null or a pointer which has been allocated by this allocator.
> >   /// - `new_layout` must have a non-zero size.
> > -unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gfp_t) -> *mut u8 {
> > +pub(crate) unsafe fn krealloc_aligned(
> > +    ptr: *mut u8,
> > +    new_layout: Layout,
> > +    flags: bindings::gfp_t,
> > +) -> *mut u8 {
> >       // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
> >       let layout = new_layout.pad_to_align();
> >
> > diff --git a/rust/kernel/alloc/boxext.rs b/rust/kernel/alloc/boxext.rs
> > new file mode 100644
> > index 000000000000..26a918df7acf
> > --- /dev/null
> > +++ b/rust/kernel/alloc/boxext.rs
> > @@ -0,0 +1,61 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +
> > +//! Extensions to [`Box`] for fallible allocations.
> > +
> > +use super::Flags;
> > +use alloc::boxed::Box;
> > +use core::alloc::AllocError;
> > +use core::mem::MaybeUninit;
> > +use core::result::Result;
> > +
> > +/// Extensions to [`Box`].
> > +pub trait BoxExt<T>: Sized {
> > +    /// Allocates a new box.
> > +    ///
> > +    /// The allocation may fail, in which case an error is returned.
> > +    fn new(x: T, flags: Flags) -> Result<Self, AllocError>;
> > +
> > +    /// Allocates a new uninitialised box.
> > +    ///
> > +    /// The allocation may fail, in which case an error is returned.
> > +    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError>;
> > +}
> > +
> > +impl<T> BoxExt<T> for Box<T> {
> > +    #[cfg(any(test, testlib))]
> > +    fn new(x: T, _flags: Flags) -> Result<Self, AllocError> {
> > +        Ok(Box::new(x))
> > +    }
>
> When running under `cfg(test)`, are we using the normal standard
> library? Or why is this needed?

Because it uses 34 other crates that rely on `Box::new` and friends.

I discussed this with Miguel recently and once he's done with the
build system changes, he will think about what to do with tests. It
may be that we abandon the current method of running standalone tests
and run everything in kunit, or perhaps we'll find a way to exclude
code that won't run in standalone tests anyway...

> > +
> > +    #[cfg(not(any(test, testlib)))]
> > +    fn new(x: T, flags: Flags) -> Result<Self, AllocError> {
> > +        let ptr = if core::mem::size_of::<T>() == 0 {
> > +            core::ptr::NonNull::<T>::dangling().as_ptr()
> > +        } else {
> > +            let layout = core::alloc::Layout::new::<T>();
> > +
> > +            // SAFETY: Memory is being allocated (first arg is null). The only other source of
> > +            // safety issues is sleeping on atomic context, which is addressed by klint.
>
> The `krealloc_aligned` function states:
>
> /// # Safety
> ///
> /// - `ptr` can be either null or a pointer which has been allocated by this allocator.
> /// - `new_layout` must have a non-zero size.
>
> So it should also mention that you checked for `layout.size() > 0`
> above.

Good point. I mentioned this in the VecExt version but not here. I
will update this for v2.

> > +            let ptr = unsafe {
> > +                super::allocator::krealloc_aligned(core::ptr::null_mut(), layout, flags.0)
> > +            };
> > +            if ptr.is_null() {
> > +                return Err(AllocError);
> > +            }
> > +
> > +            let ptr = ptr.cast::<T>();
> > +
> > +            // SAFETY: We just allocated the memory above, it is valid for write.
> > +            unsafe { ptr.write(x) };
> > +            ptr
> > +        };
> > +
> > +        // SAFETY: For non-zero-sized types, we allocate above using the global allocator. For
> > +        // zero-sized types, we use `NonNull::dangling`.
> > +        Ok(unsafe { Box::from_raw(ptr) })
> > +    }
> > +
> > +    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
> > +        <Box<_> as BoxExt<_>>::new(MaybeUninit::<T>::uninit(), flags)
>
> Why do you use the extended syntax? I tried to use `Box::new` and it
> compiled.

It works when compiling the kernel but fails when compiling for
userspace with regular (no_global_oom_handling disabled) `alloc` when
running `make rusttest`. In the latter case, it chooses the inherent
version of `Box::new` which is infallible and doesn't take flags so it
fails to compile.

Using the extended syntax allows it always pick the right version,
regardless of how `alloc` is compiled.

There are 5 places in existing code that required this change and this
is limited to the kernel crate (e.g., drivers, samples and
documentation examples can continue to use `Box::new`). So we thought
it was ok until Miguel figures out what we want to do with tests.

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 06/10] rust: alloc: introduce the `BoxExt` trait
  2024-03-26  0:17     ` Wedson Almeida Filho
@ 2024-03-26 13:30       ` Benno Lossin
  2024-03-27  1:54         ` Wedson Almeida Filho
  2024-03-27  1:55         ` Wedson Almeida Filho
  0 siblings, 2 replies; 30+ messages in thread
From: Benno Lossin @ 2024-03-26 13:30 UTC (permalink / raw)
  To: Wedson Almeida Filho
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On 26.03.24 01:17, Wedson Almeida Filho wrote:
> On Mon, 25 Mar 2024 at 19:37, Benno Lossin <benno.lossin@proton.me> wrote:
>>
>> On 25.03.24 20:54, Wedson Almeida Filho wrote:
>>> From: Wedson Almeida Filho <walmeida@microsoft.com>
>>>
>>> Make fallible versions of `new` and `new_uninit` methods available in
>>> `Box` even though it doesn't implement them because we build `alloc`
>>> with the `no_global_oom_handling` config.
>>>
>>> They also have an extra `flags` parameter that allows callers to pass
>>> flags to the allocator.
>>>
>>> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
>>> ---
>>>    rust/kernel/alloc.rs           |  1 +
>>>    rust/kernel/alloc/allocator.rs |  6 +++-
>>>    rust/kernel/alloc/boxext.rs    | 61 ++++++++++++++++++++++++++++++++++
>>>    rust/kernel/init.rs            | 13 ++++----
>>>    rust/kernel/prelude.rs         |  2 +-
>>>    rust/kernel/sync/arc.rs        |  3 +-
>>>    6 files changed, 77 insertions(+), 9 deletions(-)
>>>    create mode 100644 rust/kernel/alloc/boxext.rs
>>>
>>> diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
>>> index ad48ac8dc13d..5712c81b1308 100644
>>> --- a/rust/kernel/alloc.rs
>>> +++ b/rust/kernel/alloc.rs
>>> @@ -5,6 +5,7 @@
>>>    #[cfg(not(test))]
>>>    #[cfg(not(testlib))]
>>>    mod allocator;
>>> +pub mod boxext;
>>>    pub mod vecext;

One thing I forgot to say: I think these modules should be named
`box_ext` and `vec_ext`. It fits better with the usual style.

>>>
>>>    /// Flags to be used when allocating memory.
>>> diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
>>> index 01ad139e19bc..fc0439455faa 100644
>>> --- a/rust/kernel/alloc/allocator.rs
>>> +++ b/rust/kernel/alloc/allocator.rs
>>> @@ -15,7 +15,11 @@
>>>    ///
>>>    /// - `ptr` can be either null or a pointer which has been allocated by this allocator.
>>>    /// - `new_layout` must have a non-zero size.
>>> -unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gfp_t) -> *mut u8 {
>>> +pub(crate) unsafe fn krealloc_aligned(
>>> +    ptr: *mut u8,
>>> +    new_layout: Layout,
>>> +    flags: bindings::gfp_t,
>>> +) -> *mut u8 {
>>>        // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
>>>        let layout = new_layout.pad_to_align();
>>>
>>> diff --git a/rust/kernel/alloc/boxext.rs b/rust/kernel/alloc/boxext.rs
>>> new file mode 100644
>>> index 000000000000..26a918df7acf
>>> --- /dev/null
>>> +++ b/rust/kernel/alloc/boxext.rs
>>> @@ -0,0 +1,61 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +
>>> +//! Extensions to [`Box`] for fallible allocations.
>>> +
>>> +use super::Flags;
>>> +use alloc::boxed::Box;
>>> +use core::alloc::AllocError;
>>> +use core::mem::MaybeUninit;
>>> +use core::result::Result;
>>> +
>>> +/// Extensions to [`Box`].
>>> +pub trait BoxExt<T>: Sized {
>>> +    /// Allocates a new box.
>>> +    ///
>>> +    /// The allocation may fail, in which case an error is returned.
>>> +    fn new(x: T, flags: Flags) -> Result<Self, AllocError>;
>>> +
>>> +    /// Allocates a new uninitialised box.
>>> +    ///
>>> +    /// The allocation may fail, in which case an error is returned.
>>> +    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError>;
>>> +}
>>> +
>>> +impl<T> BoxExt<T> for Box<T> {
>>> +    #[cfg(any(test, testlib))]
>>> +    fn new(x: T, _flags: Flags) -> Result<Self, AllocError> {
>>> +        Ok(Box::new(x))
>>> +    }
>>
>> When running under `cfg(test)`, are we using the normal standard
>> library? Or why is this needed?
> 
> Because it uses 34 other crates that rely on `Box::new` and friends.
> 
> I discussed this with Miguel recently and once he's done with the
> build system changes, he will think about what to do with tests. It
> may be that we abandon the current method of running standalone tests
> and run everything in kunit, or perhaps we'll find a way to exclude
> code that won't run in standalone tests anyway...

Ah I see, I think it would be nice to not need this. Let's see what the
new build system can do here.

> 
>>> +
>>> +    #[cfg(not(any(test, testlib)))]
>>> +    fn new(x: T, flags: Flags) -> Result<Self, AllocError> {
>>> +        let ptr = if core::mem::size_of::<T>() == 0 {
>>> +            core::ptr::NonNull::<T>::dangling().as_ptr()
>>> +        } else {
>>> +            let layout = core::alloc::Layout::new::<T>();
>>> +
>>> +            // SAFETY: Memory is being allocated (first arg is null). The only other source of
>>> +            // safety issues is sleeping on atomic context, which is addressed by klint.
>>
>> The `krealloc_aligned` function states:
>>
>> /// # Safety
>> ///
>> /// - `ptr` can be either null or a pointer which has been allocated by this allocator.
>> /// - `new_layout` must have a non-zero size.
>>
>> So it should also mention that you checked for `layout.size() > 0`
>> above.
> 
> Good point. I mentioned this in the VecExt version but not here. I
> will update this for v2.
> 
>>> +            let ptr = unsafe {
>>> +                super::allocator::krealloc_aligned(core::ptr::null_mut(), layout, flags.0)
>>> +            };
>>> +            if ptr.is_null() {
>>> +                return Err(AllocError);
>>> +            }
>>> +
>>> +            let ptr = ptr.cast::<T>();
>>> +
>>> +            // SAFETY: We just allocated the memory above, it is valid for write.
>>> +            unsafe { ptr.write(x) };
>>> +            ptr
>>> +        };
>>> +
>>> +        // SAFETY: For non-zero-sized types, we allocate above using the global allocator. For
>>> +        // zero-sized types, we use `NonNull::dangling`.
>>> +        Ok(unsafe { Box::from_raw(ptr) })
>>> +    }
>>> +
>>> +    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
>>> +        <Box<_> as BoxExt<_>>::new(MaybeUninit::<T>::uninit(), flags)
>>
>> Why do you use the extended syntax? I tried to use `Box::new` and it
>> compiled.
> 
> It works when compiling the kernel but fails when compiling for
> userspace with regular (no_global_oom_handling disabled) `alloc` when
> running `make rusttest`. In the latter case, it chooses the inherent
> version of `Box::new` which is infallible and doesn't take flags so it
> fails to compile.
> 
> Using the extended syntax allows it always pick the right version,
> regardless of how `alloc` is compiled.
> 
> There are 5 places in existing code that required this change and this
> is limited to the kernel crate (e.g., drivers, samples and
> documentation examples can continue to use `Box::new`). So we thought
> it was ok until Miguel figures out what we want to do with tests.

Thanks for the explanation, again it would be nice to be able to just
write `Box::new`.

-- 
Cheers,
Benno


^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 07/10] rust: alloc: update `VecExt` to take allocation flags
  2024-03-26  0:03     ` Wedson Almeida Filho
@ 2024-03-26 13:58       ` Benno Lossin
  0 siblings, 0 replies; 30+ messages in thread
From: Benno Lossin @ 2024-03-26 13:58 UTC (permalink / raw)
  To: Wedson Almeida Filho
  Cc: Boqun Feng, rust-for-linux, Miguel Ojeda, Alex Gaynor, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On 25.03.24 20:54, Wedson Almeida Filho wrote:
> From: Wedson Almeida Filho <walmeida@microsoft.com>
> 
> We also rename the methods by removing the `try_` prefix since the names
> are available due to our usage of the `no_global_oom_handling` config
> when building the `alloc` crate.
> 
> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
> ---
>   rust/kernel/alloc/vecext.rs  | 106 ++++++++++++++++++++++++++++-------
>   rust/kernel/lib.rs           |   1 -
>   rust/kernel/str.rs           |   6 +-
>   rust/kernel/types.rs         |   4 +-
>   samples/rust/rust_minimal.rs |   6 +-
>   5 files changed, 95 insertions(+), 28 deletions(-)

With Boqun's change:

Reviewed-by: Benno Lossin <benno.lossin@proton.me>

One thing that we might consider in the future would be to create
our own `Extend` trait to allow extending a Vec with any iterator.

-- 
Cheers,
Benno

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 08/10] rust: sync: update `Arc` and `UniqueArc` to take allocation flags
  2024-03-25 19:54 ` [PATCH 08/10] rust: sync: update `Arc` and `UniqueArc` " Wedson Almeida Filho
@ 2024-03-26 14:01   ` Benno Lossin
  0 siblings, 0 replies; 30+ messages in thread
From: Benno Lossin @ 2024-03-26 14:01 UTC (permalink / raw)
  To: Wedson Almeida Filho
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On 25.03.24 20:54, Wedson Almeida Filho wrote:
> From: Wedson Almeida Filho <walmeida@microsoft.com>
> 
> We also remove the `try_` prefix to align with how `Box` and `Vec` are
> providing methods now.
> 
> `init` is temporarily updated with uses of GFP_KERNEL. These will be
> updated in a subsequent patch to take flags as well.
> 
> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
> ---
>   rust/kernel/init.rs        |  4 ++--
>   rust/kernel/sync/arc.rs    | 28 ++++++++++++++--------------
>   samples/rust/rust_print.rs |  4 ++--
>   3 files changed, 18 insertions(+), 18 deletions(-)

Reviewed-by: Benno Lossin <benno.lossin@proton.me>

-- 
Cheers,
Benno

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 09/10] rust: init: update `init` module to take allocation flags
  2024-03-25 19:54 ` [PATCH 09/10] rust: init: update `init` module " Wedson Almeida Filho
@ 2024-03-26 14:08   ` Benno Lossin
  2024-03-27  2:17     ` Wedson Almeida Filho
  0 siblings, 1 reply; 30+ messages in thread
From: Benno Lossin @ 2024-03-26 14:08 UTC (permalink / raw)
  To: Wedson Almeida Filho
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On 25.03.24 20:54, Wedson Almeida Filho wrote:
> From: Wedson Almeida Filho <walmeida@microsoft.com>
> 
> This is the last component in the conversion for allocators to take
> allocation flags as parameters.
> 
> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
> ---
>   rust/kernel/init.rs               | 49 ++++++++++++++++---------------
>   rust/kernel/sync/arc.rs           | 17 ++++++-----
>   rust/kernel/sync/condvar.rs       |  2 +-
>   rust/kernel/sync/lock/mutex.rs    |  2 +-
>   rust/kernel/sync/lock/spinlock.rs |  2 +-
>   rust/kernel/workqueue.rs          | 13 +++++---
>   6 files changed, 47 insertions(+), 38 deletions(-)

One formatting issue below, with that fixed:

Reviewed-by: Benno Lossin <benno.lossin@proton.me>

> diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
> index 077200f5350b..af539c5eb4bc 100644
> --- a/rust/kernel/sync/arc.rs
> +++ b/rust/kernel/sync/arc.rs
> @@ -565,13 +565,16 @@ pub fn new(value: T, flags: Flags) -> Result<Self, AllocError> {
>       }
> 
>       /// Tries to allocate a new [`UniqueArc`] instance whose contents are not initialised yet.
> -    pub fn new_uninit(_flags: Flags) -> Result<UniqueArc<MaybeUninit<T>>, AllocError> {
> +    pub fn new_uninit(flags: Flags) -> Result<UniqueArc<MaybeUninit<T>>, AllocError> {
>           // INVARIANT: The refcount is initialised to a non-zero value.
> -        let inner = Box::try_init::<AllocError>(try_init!(ArcInner {
> +        let inner = Box::try_init::<AllocError>(
> +            try_init!(ArcInner {
>               // SAFETY: There are no safety requirements for this FFI call.
>               refcount: Opaque::new(unsafe { bindings::REFCOUNT_INIT(1) }),
>               data <- init::uninit::<T, AllocError>(),
> -        }? AllocError))?;
> +        }? AllocError),
> +            flags,
> +        )?;

The indentation looks wrong, rustfmt sadly cannot handle the pin-init
macros. This looks better to me:

        let inner = Box::try_init::<AllocError>(
            try_init!(ArcInner {
                // SAFETY: There are no safety requirements for this FFI call.
                refcount: Opaque::new(unsafe { bindings::REFCOUNT_INIT(1) }),
                data <- init::uninit::<T, AllocError>(),
            }? AllocError),
            flags,
        )?;

-- 
Cheers,
Benno

>           Ok(UniqueArc {
>               // INVARIANT: The newly-created object has a refcount of 1.
>               // SAFETY: The pointer from the `Box` is valid.

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 10/10] rust: kernel: remove usage of `allocator_api` unstable feature
  2024-03-25 19:54 ` [PATCH 10/10] rust: kernel: remove usage of `allocator_api` unstable feature Wedson Almeida Filho
@ 2024-03-26 15:27   ` Benno Lossin
  2024-03-27  2:13     ` Wedson Almeida Filho
  0 siblings, 1 reply; 30+ messages in thread
From: Benno Lossin @ 2024-03-26 15:27 UTC (permalink / raw)
  To: Wedson Almeida Filho
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On 25.03.24 20:54, Wedson Almeida Filho wrote:
> From: Wedson Almeida Filho <walmeida@microsoft.com>
> 
> With the adoption of `BoxExt` and `VecExt`, we don't need the functions
> provided by this feature (namely the methods prefixed with `try_` and
> different allocator per collection instance).
> 
> We do need `AllocError`, but we define our own as it is a trivial empty
> struct.
> 
> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
> ---
>  rust/kernel/alloc.rs        |  3 +++
>  rust/kernel/alloc/boxext.rs |  3 +--
>  rust/kernel/alloc/vecext.rs |  4 ++--
>  rust/kernel/error.rs        | 13 ++-----------
>  rust/kernel/init.rs         |  3 +--
>  rust/kernel/lib.rs          |  1 -
>  rust/kernel/str.rs          |  3 +--
>  rust/kernel/sync/arc.rs     |  4 ++--
>  rust/kernel/workqueue.rs    |  3 +--
>  9 files changed, 13 insertions(+), 24 deletions(-)
> 
> diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> index 5712c81b1308..f17f48130f13 100644
> --- a/rust/kernel/alloc.rs
> +++ b/rust/kernel/alloc.rs
> @@ -8,6 +8,9 @@
>  pub mod boxext;
>  pub mod vecext;
> 
> +/// Indicates an allocation error.
> +pub struct AllocError;

I think it would be sensible to add this now:
    #[derive(Copy, Clone, PartialEq, Eq, Debug)]

> +
>  /// Flags to be used when allocating memory.
>  ///
>  /// They can be combined with the operators `|`, `&`, and `!`.
> diff --git a/rust/kernel/alloc/boxext.rs b/rust/kernel/alloc/boxext.rs
> index 26a918df7acf..3cdda0f635a3 100644
> --- a/rust/kernel/alloc/boxext.rs
> +++ b/rust/kernel/alloc/boxext.rs
> @@ -2,9 +2,8 @@
> 
>  //! Extensions to [`Box`] for fallible allocations.
> 
> -use super::Flags;
> +use super::{AllocError, Flags};
>  use alloc::boxed::Box;
> -use core::alloc::AllocError;
>  use core::mem::MaybeUninit;
>  use core::result::Result;
> 
> diff --git a/rust/kernel/alloc/vecext.rs b/rust/kernel/alloc/vecext.rs
> index 1d4d51b45a49..85ca6a6db6de 100644
> --- a/rust/kernel/alloc/vecext.rs
> +++ b/rust/kernel/alloc/vecext.rs
> @@ -2,8 +2,8 @@
> 
>  //! Extensions to [`Vec`] for fallible allocations.
> 
> -use super::Flags;
> -use alloc::{alloc::AllocError, vec::Vec};
> +use super::{AllocError, Flags};
> +use alloc::vec::Vec;
>  use core::{mem::ManuallyDrop, result::Result};
> 
>  /// Extensions to [`Vec`].
> diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
> index 4786d3ee1e92..fc986bc24c6d 100644
> --- a/rust/kernel/error.rs
> +++ b/rust/kernel/error.rs
> @@ -4,12 +4,9 @@
>  //!
>  //! C header: [`include/uapi/asm-generic/errno-base.h`](srctree/include/uapi/asm-generic/errno-base.h)
> 
> -use crate::str::CStr;
> +use crate::{alloc::AllocError, str::CStr};
> 
> -use alloc::{
> -    alloc::{AllocError, LayoutError},
> -    collections::TryReserveError,
> -};
> +use alloc::alloc::LayoutError;
> 
>  use core::convert::From;
>  use core::fmt;
> @@ -192,12 +189,6 @@ fn from(_: Utf8Error) -> Error {
>      }
>  }
> 
> -impl From<TryReserveError> for Error {
> -    fn from(_: TryReserveError) -> Error {
> -        code::ENOMEM
> -    }
> -}
> -

Why are you removing this?

-- 
Cheers,
Benno

>  impl From<LayoutError> for Error {
>      fn from(_: LayoutError) -> Error {
>          code::ENOMEM
> diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs
> index 1a8b0464db0c..1f7a6b5892ac 100644
> --- a/rust/kernel/init.rs
> +++ b/rust/kernel/init.rs
> @@ -211,14 +211,13 @@
>  //! [`pin_init!`]: crate::pin_init!
> 
>  use crate::{
> -    alloc::{boxext::BoxExt, Flags},
> +    alloc::{boxext::BoxExt, AllocError, Flags},
>      error::{self, Error},
>      sync::UniqueArc,
>      types::{Opaque, ScopeGuard},
>  };
>  use alloc::boxed::Box;
>  use core::{
> -    alloc::AllocError,
>      cell::UnsafeCell,
>      convert::Infallible,
>      marker::PhantomData,
> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> index 51f30e55bd00..5c641233e26d 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -12,7 +12,6 @@
>  //! do so first instead of bypassing this crate.
> 
>  #![no_std]
> -#![feature(allocator_api)]
>  #![feature(coerce_unsized)]
>  #![feature(dispatch_from_dyn)]
>  #![feature(new_uninit)]
> diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
> index 34dbc85b5220..5206b18f882b 100644
> --- a/rust/kernel/str.rs
> +++ b/rust/kernel/str.rs
> @@ -2,8 +2,7 @@
> 
>  //! String representations.
> 
> -use crate::alloc::{flags::*, vecext::VecExt};
> -use alloc::alloc::AllocError;
> +use crate::alloc::{flags::*, vecext::VecExt, AllocError};
>  use alloc::vec::Vec;
>  use core::fmt::{self, Write};
>  use core::ops::{self, Deref, Index};
> diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
> index af539c5eb4bc..8db25f73b37f 100644
> --- a/rust/kernel/sync/arc.rs
> +++ b/rust/kernel/sync/arc.rs
> @@ -16,7 +16,7 @@
>  //! [`Arc`]: https://doc.rust-lang.org/std/sync/struct.Arc.html
> 
>  use crate::{
> -    alloc::{boxext::BoxExt, Flags},
> +    alloc::{boxext::BoxExt, AllocError, Flags},
>      bindings,
>      error::{self, Error},
>      init::{self, InPlaceInit, Init, PinInit},
> @@ -25,7 +25,7 @@
>  };
>  use alloc::boxed::Box;
>  use core::{
> -    alloc::{AllocError, Layout},
> +    alloc::Layout,
>      fmt,
>      marker::{PhantomData, Unsize},
>      mem::{ManuallyDrop, MaybeUninit},
> diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
> index 09a0f158ff1b..50837e56efc7 100644
> --- a/rust/kernel/workqueue.rs
> +++ b/rust/kernel/workqueue.rs
> @@ -132,9 +132,8 @@
>  //!
>  //! C header: [`include/linux/workqueue.h`](srctree/include/linux/workqueue.h)
> 
> -use crate::alloc::Flags;
> +use crate::alloc::{AllocError, Flags};
>  use crate::{bindings, prelude::*, sync::Arc, sync::LockClassKey, types::Opaque};
> -use alloc::alloc::AllocError;
>  use alloc::boxed::Box;
>  use core::marker::PhantomData;
>  use core::pin::Pin;
> --
> 2.34.1
>

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 06/10] rust: alloc: introduce the `BoxExt` trait
  2024-03-26 13:30       ` Benno Lossin
@ 2024-03-27  1:54         ` Wedson Almeida Filho
  2024-03-27  1:55         ` Wedson Almeida Filho
  1 sibling, 0 replies; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-27  1:54 UTC (permalink / raw)
  To: Benno Lossin
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On Tue, 26 Mar 2024 at 10:30, Benno Lossin <benno.lossin@proton.me> wrote:
>
> On 26.03.24 01:17, Wedson Almeida Filho wrote:
> > On Mon, 25 Mar 2024 at 19:37, Benno Lossin <benno.lossin@proton.me> wrote:
> >>
> >> On 25.03.24 20:54, Wedson Almeida Filho wrote:
> >>> From: Wedson Almeida Filho <walmeida@microsoft.com>
> >>>
> >>> Make fallible versions of `new` and `new_uninit` methods available in
> >>> `Box` even though it doesn't implement them because we build `alloc`
> >>> with the `no_global_oom_handling` config.
> >>>
> >>> They also have an extra `flags` parameter that allows callers to pass
> >>> flags to the allocator.
> >>>
> >>> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
> >>> ---
> >>>    rust/kernel/alloc.rs           |  1 +
> >>>    rust/kernel/alloc/allocator.rs |  6 +++-
> >>>    rust/kernel/alloc/boxext.rs    | 61 ++++++++++++++++++++++++++++++++++
> >>>    rust/kernel/init.rs            | 13 ++++----
> >>>    rust/kernel/prelude.rs         |  2 +-
> >>>    rust/kernel/sync/arc.rs        |  3 +-
> >>>    6 files changed, 77 insertions(+), 9 deletions(-)
> >>>    create mode 100644 rust/kernel/alloc/boxext.rs
> >>>
> >>> diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> >>> index ad48ac8dc13d..5712c81b1308 100644
> >>> --- a/rust/kernel/alloc.rs
> >>> +++ b/rust/kernel/alloc.rs
> >>> @@ -5,6 +5,7 @@
> >>>    #[cfg(not(test))]
> >>>    #[cfg(not(testlib))]
> >>>    mod allocator;
> >>> +pub mod boxext;
> >>>    pub mod vecext;
>
> One thing I forgot to say: I think these modules should be named
> `box_ext` and `vec_ext`. It fits better with the usual style.

Yeah, looking at std for precedents, I see one module called
`backtrace` but also `assert_matches` and `async_iter`.

Snake case is the standard anyway, so I'll make the change for v2.

>
> >>>
> >>>    /// Flags to be used when allocating memory.
> >>> diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
> >>> index 01ad139e19bc..fc0439455faa 100644
> >>> --- a/rust/kernel/alloc/allocator.rs
> >>> +++ b/rust/kernel/alloc/allocator.rs
> >>> @@ -15,7 +15,11 @@
> >>>    ///
> >>>    /// - `ptr` can be either null or a pointer which has been allocated by this allocator.
> >>>    /// - `new_layout` must have a non-zero size.
> >>> -unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gfp_t) -> *mut u8 {
> >>> +pub(crate) unsafe fn krealloc_aligned(
> >>> +    ptr: *mut u8,
> >>> +    new_layout: Layout,
> >>> +    flags: bindings::gfp_t,
> >>> +) -> *mut u8 {
> >>>        // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
> >>>        let layout = new_layout.pad_to_align();
> >>>
> >>> diff --git a/rust/kernel/alloc/boxext.rs b/rust/kernel/alloc/boxext.rs
> >>> new file mode 100644
> >>> index 000000000000..26a918df7acf
> >>> --- /dev/null
> >>> +++ b/rust/kernel/alloc/boxext.rs
> >>> @@ -0,0 +1,61 @@
> >>> +// SPDX-License-Identifier: GPL-2.0
> >>> +
> >>> +//! Extensions to [`Box`] for fallible allocations.
> >>> +
> >>> +use super::Flags;
> >>> +use alloc::boxed::Box;
> >>> +use core::alloc::AllocError;
> >>> +use core::mem::MaybeUninit;
> >>> +use core::result::Result;
> >>> +
> >>> +/// Extensions to [`Box`].
> >>> +pub trait BoxExt<T>: Sized {
> >>> +    /// Allocates a new box.
> >>> +    ///
> >>> +    /// The allocation may fail, in which case an error is returned.
> >>> +    fn new(x: T, flags: Flags) -> Result<Self, AllocError>;
> >>> +
> >>> +    /// Allocates a new uninitialised box.
> >>> +    ///
> >>> +    /// The allocation may fail, in which case an error is returned.
> >>> +    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError>;
> >>> +}
> >>> +
> >>> +impl<T> BoxExt<T> for Box<T> {
> >>> +    #[cfg(any(test, testlib))]
> >>> +    fn new(x: T, _flags: Flags) -> Result<Self, AllocError> {
> >>> +        Ok(Box::new(x))
> >>> +    }
> >>
> >> When running under `cfg(test)`, are we using the normal standard
> >> library? Or why is this needed?
> >
> > Because it uses 34 other crates that rely on `Box::new` and friends.
> >
> > I discussed this with Miguel recently and once he's done with the
> > build system changes, he will think about what to do with tests. It
> > may be that we abandon the current method of running standalone tests
> > and run everything in kunit, or perhaps we'll find a way to exclude
> > code that won't run in standalone tests anyway...
>
> Ah I see, I think it would be nice to not need this. Let's see what the
> new build system can do here.
>
> >
> >>> +
> >>> +    #[cfg(not(any(test, testlib)))]
> >>> +    fn new(x: T, flags: Flags) -> Result<Self, AllocError> {
> >>> +        let ptr = if core::mem::size_of::<T>() == 0 {
> >>> +            core::ptr::NonNull::<T>::dangling().as_ptr()
> >>> +        } else {
> >>> +            let layout = core::alloc::Layout::new::<T>();
> >>> +
> >>> +            // SAFETY: Memory is being allocated (first arg is null). The only other source of
> >>> +            // safety issues is sleeping on atomic context, which is addressed by klint.
> >>
> >> The `krealloc_aligned` function states:
> >>
> >> /// # Safety
> >> ///
> >> /// - `ptr` can be either null or a pointer which has been allocated by this allocator.
> >> /// - `new_layout` must have a non-zero size.
> >>
> >> So it should also mention that you checked for `layout.size() > 0`
> >> above.
> >
> > Good point. I mentioned this in the VecExt version but not here. I
> > will update this for v2.
> >
> >>> +            let ptr = unsafe {
> >>> +                super::allocator::krealloc_aligned(core::ptr::null_mut(), layout, flags.0)
> >>> +            };
> >>> +            if ptr.is_null() {
> >>> +                return Err(AllocError);
> >>> +            }
> >>> +
> >>> +            let ptr = ptr.cast::<T>();
> >>> +
> >>> +            // SAFETY: We just allocated the memory above, it is valid for write.
> >>> +            unsafe { ptr.write(x) };
> >>> +            ptr
> >>> +        };
> >>> +
> >>> +        // SAFETY: For non-zero-sized types, we allocate above using the global allocator. For
> >>> +        // zero-sized types, we use `NonNull::dangling`.
> >>> +        Ok(unsafe { Box::from_raw(ptr) })
> >>> +    }
> >>> +
> >>> +    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
> >>> +        <Box<_> as BoxExt<_>>::new(MaybeUninit::<T>::uninit(), flags)
> >>
> >> Why do you use the extended syntax? I tried to use `Box::new` and it
> >> compiled.
> >
> > It works when compiling the kernel but fails when compiling for
> > userspace with regular (no_global_oom_handling disabled) `alloc` when
> > running `make rusttest`. In the latter case, it chooses the inherent
> > version of `Box::new` which is infallible and doesn't take flags so it
> > fails to compile.
> >
> > Using the extended syntax allows it always pick the right version,
> > regardless of how `alloc` is compiled.
> >
> > There are 5 places in existing code that required this change and this
> > is limited to the kernel crate (e.g., drivers, samples and
> > documentation examples can continue to use `Box::new`). So we thought
> > it was ok until Miguel figures out what we want to do with tests.
>
> Thanks for the explanation, again it would be nice to be able to just
> write `Box::new`.
>
> --
> Cheers,
> Benno
>

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 06/10] rust: alloc: introduce the `BoxExt` trait
  2024-03-26 13:30       ` Benno Lossin
  2024-03-27  1:54         ` Wedson Almeida Filho
@ 2024-03-27  1:55         ` Wedson Almeida Filho
  1 sibling, 0 replies; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-27  1:55 UTC (permalink / raw)
  To: Benno Lossin
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On Tue, 26 Mar 2024 at 10:30, Benno Lossin <benno.lossin@proton.me> wrote:
>
> On 26.03.24 01:17, Wedson Almeida Filho wrote:
> > On Mon, 25 Mar 2024 at 19:37, Benno Lossin <benno.lossin@proton.me> wrote:
> >>
> >> On 25.03.24 20:54, Wedson Almeida Filho wrote:
> >>> From: Wedson Almeida Filho <walmeida@microsoft.com>
> >>>
> >>> Make fallible versions of `new` and `new_uninit` methods available in
> >>> `Box` even though it doesn't implement them because we build `alloc`
> >>> with the `no_global_oom_handling` config.
> >>>
> >>> They also have an extra `flags` parameter that allows callers to pass
> >>> flags to the allocator.
> >>>
> >>> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
> >>> ---
> >>>    rust/kernel/alloc.rs           |  1 +
> >>>    rust/kernel/alloc/allocator.rs |  6 +++-
> >>>    rust/kernel/alloc/boxext.rs    | 61 ++++++++++++++++++++++++++++++++++
> >>>    rust/kernel/init.rs            | 13 ++++----
> >>>    rust/kernel/prelude.rs         |  2 +-
> >>>    rust/kernel/sync/arc.rs        |  3 +-
> >>>    6 files changed, 77 insertions(+), 9 deletions(-)
> >>>    create mode 100644 rust/kernel/alloc/boxext.rs
> >>>
> >>> diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> >>> index ad48ac8dc13d..5712c81b1308 100644
> >>> --- a/rust/kernel/alloc.rs
> >>> +++ b/rust/kernel/alloc.rs
> >>> @@ -5,6 +5,7 @@
> >>>    #[cfg(not(test))]
> >>>    #[cfg(not(testlib))]
> >>>    mod allocator;
> >>> +pub mod boxext;
> >>>    pub mod vecext;
>
> One thing I forgot to say: I think these modules should be named
> `box_ext` and `vec_ext`. It fits better with the usual style.
>
> >>>
> >>>    /// Flags to be used when allocating memory.
> >>> diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
> >>> index 01ad139e19bc..fc0439455faa 100644
> >>> --- a/rust/kernel/alloc/allocator.rs
> >>> +++ b/rust/kernel/alloc/allocator.rs
> >>> @@ -15,7 +15,11 @@
> >>>    ///
> >>>    /// - `ptr` can be either null or a pointer which has been allocated by this allocator.
> >>>    /// - `new_layout` must have a non-zero size.
> >>> -unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gfp_t) -> *mut u8 {
> >>> +pub(crate) unsafe fn krealloc_aligned(
> >>> +    ptr: *mut u8,
> >>> +    new_layout: Layout,
> >>> +    flags: bindings::gfp_t,
> >>> +) -> *mut u8 {
> >>>        // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
> >>>        let layout = new_layout.pad_to_align();
> >>>
> >>> diff --git a/rust/kernel/alloc/boxext.rs b/rust/kernel/alloc/boxext.rs
> >>> new file mode 100644
> >>> index 000000000000..26a918df7acf
> >>> --- /dev/null
> >>> +++ b/rust/kernel/alloc/boxext.rs
> >>> @@ -0,0 +1,61 @@
> >>> +// SPDX-License-Identifier: GPL-2.0
> >>> +
> >>> +//! Extensions to [`Box`] for fallible allocations.
> >>> +
> >>> +use super::Flags;
> >>> +use alloc::boxed::Box;
> >>> +use core::alloc::AllocError;
> >>> +use core::mem::MaybeUninit;
> >>> +use core::result::Result;
> >>> +
> >>> +/// Extensions to [`Box`].
> >>> +pub trait BoxExt<T>: Sized {
> >>> +    /// Allocates a new box.
> >>> +    ///
> >>> +    /// The allocation may fail, in which case an error is returned.
> >>> +    fn new(x: T, flags: Flags) -> Result<Self, AllocError>;
> >>> +
> >>> +    /// Allocates a new uninitialised box.
> >>> +    ///
> >>> +    /// The allocation may fail, in which case an error is returned.
> >>> +    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError>;
> >>> +}
> >>> +
> >>> +impl<T> BoxExt<T> for Box<T> {
> >>> +    #[cfg(any(test, testlib))]
> >>> +    fn new(x: T, _flags: Flags) -> Result<Self, AllocError> {
> >>> +        Ok(Box::new(x))
> >>> +    }
> >>
> >> When running under `cfg(test)`, are we using the normal standard
> >> library? Or why is this needed?
> >
> > Because it uses 34 other crates that rely on `Box::new` and friends.
> >
> > I discussed this with Miguel recently and once he's done with the
> > build system changes, he will think about what to do with tests. It
> > may be that we abandon the current method of running standalone tests
> > and run everything in kunit, or perhaps we'll find a way to exclude
> > code that won't run in standalone tests anyway...
>
> Ah I see, I think it would be nice to not need this. Let's see what the
> new build system can do here.
>
> >
> >>> +
> >>> +    #[cfg(not(any(test, testlib)))]
> >>> +    fn new(x: T, flags: Flags) -> Result<Self, AllocError> {
> >>> +        let ptr = if core::mem::size_of::<T>() == 0 {
> >>> +            core::ptr::NonNull::<T>::dangling().as_ptr()
> >>> +        } else {
> >>> +            let layout = core::alloc::Layout::new::<T>();
> >>> +
> >>> +            // SAFETY: Memory is being allocated (first arg is null). The only other source of
> >>> +            // safety issues is sleeping on atomic context, which is addressed by klint.
> >>
> >> The `krealloc_aligned` function states:
> >>
> >> /// # Safety
> >> ///
> >> /// - `ptr` can be either null or a pointer which has been allocated by this allocator.
> >> /// - `new_layout` must have a non-zero size.
> >>
> >> So it should also mention that you checked for `layout.size() > 0`
> >> above.
> >
> > Good point. I mentioned this in the VecExt version but not here. I
> > will update this for v2.
> >
> >>> +            let ptr = unsafe {
> >>> +                super::allocator::krealloc_aligned(core::ptr::null_mut(), layout, flags.0)
> >>> +            };
> >>> +            if ptr.is_null() {
> >>> +                return Err(AllocError);
> >>> +            }
> >>> +
> >>> +            let ptr = ptr.cast::<T>();
> >>> +
> >>> +            // SAFETY: We just allocated the memory above, it is valid for write.
> >>> +            unsafe { ptr.write(x) };
> >>> +            ptr
> >>> +        };
> >>> +
> >>> +        // SAFETY: For non-zero-sized types, we allocate above using the global allocator. For
> >>> +        // zero-sized types, we use `NonNull::dangling`.
> >>> +        Ok(unsafe { Box::from_raw(ptr) })
> >>> +    }
> >>> +
> >>> +    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
> >>> +        <Box<_> as BoxExt<_>>::new(MaybeUninit::<T>::uninit(), flags)
> >>
> >> Why do you use the extended syntax? I tried to use `Box::new` and it
> >> compiled.
> >
> > It works when compiling the kernel but fails when compiling for
> > userspace with regular (no_global_oom_handling disabled) `alloc` when
> > running `make rusttest`. In the latter case, it chooses the inherent
> > version of `Box::new` which is infallible and doesn't take flags so it
> > fails to compile.
> >
> > Using the extended syntax allows it always pick the right version,
> > regardless of how `alloc` is compiled.
> >
> > There are 5 places in existing code that required this change and this
> > is limited to the kernel crate (e.g., drivers, samples and
> > documentation examples can continue to use `Box::new`). So we thought
> > it was ok until Miguel figures out what we want to do with tests.
>
> Thanks for the explanation, again it would be nice to be able to just
> write `Box::new`.

Indeed, that's what I had originally but we don't want to break rusttest.

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 10/10] rust: kernel: remove usage of `allocator_api` unstable feature
  2024-03-26 15:27   ` Benno Lossin
@ 2024-03-27  2:13     ` Wedson Almeida Filho
  0 siblings, 0 replies; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-27  2:13 UTC (permalink / raw)
  To: Benno Lossin
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On Tue, 26 Mar 2024 at 12:27, Benno Lossin <benno.lossin@proton.me> wrote:
>
> On 25.03.24 20:54, Wedson Almeida Filho wrote:
> > From: Wedson Almeida Filho <walmeida@microsoft.com>
> >
> > With the adoption of `BoxExt` and `VecExt`, we don't need the functions
> > provided by this feature (namely the methods prefixed with `try_` and
> > different allocator per collection instance).
> >
> > We do need `AllocError`, but we define our own as it is a trivial empty
> > struct.
> >
> > Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
> > ---
> >  rust/kernel/alloc.rs        |  3 +++
> >  rust/kernel/alloc/boxext.rs |  3 +--
> >  rust/kernel/alloc/vecext.rs |  4 ++--
> >  rust/kernel/error.rs        | 13 ++-----------
> >  rust/kernel/init.rs         |  3 +--
> >  rust/kernel/lib.rs          |  1 -
> >  rust/kernel/str.rs          |  3 +--
> >  rust/kernel/sync/arc.rs     |  4 ++--
> >  rust/kernel/workqueue.rs    |  3 +--
> >  9 files changed, 13 insertions(+), 24 deletions(-)
> >
> > diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> > index 5712c81b1308..f17f48130f13 100644
> > --- a/rust/kernel/alloc.rs
> > +++ b/rust/kernel/alloc.rs
> > @@ -8,6 +8,9 @@
> >  pub mod boxext;
> >  pub mod vecext;
> >
> > +/// Indicates an allocation error.
> > +pub struct AllocError;
>
> I think it would be sensible to add this now:
>     #[derive(Copy, Clone, PartialEq, Eq, Debug)]

Agreed. Will add in v2.

> > +
> >  /// Flags to be used when allocating memory.
> >  ///
> >  /// They can be combined with the operators `|`, `&`, and `!`.
> > diff --git a/rust/kernel/alloc/boxext.rs b/rust/kernel/alloc/boxext.rs
> > index 26a918df7acf..3cdda0f635a3 100644
> > --- a/rust/kernel/alloc/boxext.rs
> > +++ b/rust/kernel/alloc/boxext.rs
> > @@ -2,9 +2,8 @@
> >
> >  //! Extensions to [`Box`] for fallible allocations.
> >
> > -use super::Flags;
> > +use super::{AllocError, Flags};
> >  use alloc::boxed::Box;
> > -use core::alloc::AllocError;
> >  use core::mem::MaybeUninit;
> >  use core::result::Result;
> >
> > diff --git a/rust/kernel/alloc/vecext.rs b/rust/kernel/alloc/vecext.rs
> > index 1d4d51b45a49..85ca6a6db6de 100644
> > --- a/rust/kernel/alloc/vecext.rs
> > +++ b/rust/kernel/alloc/vecext.rs
> > @@ -2,8 +2,8 @@
> >
> >  //! Extensions to [`Vec`] for fallible allocations.
> >
> > -use super::Flags;
> > -use alloc::{alloc::AllocError, vec::Vec};
> > +use super::{AllocError, Flags};
> > +use alloc::vec::Vec;
> >  use core::{mem::ManuallyDrop, result::Result};
> >
> >  /// Extensions to [`Vec`].
> > diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
> > index 4786d3ee1e92..fc986bc24c6d 100644
> > --- a/rust/kernel/error.rs
> > +++ b/rust/kernel/error.rs
> > @@ -4,12 +4,9 @@
> >  //!
> >  //! C header: [`include/uapi/asm-generic/errno-base.h`](srctree/include/uapi/asm-generic/errno-base.h)
> >
> > -use crate::str::CStr;
> > +use crate::{alloc::AllocError, str::CStr};
> >
> > -use alloc::{
> > -    alloc::{AllocError, LayoutError},
> > -    collections::TryReserveError,
> > -};
> > +use alloc::alloc::LayoutError;
> >
> >  use core::convert::From;
> >  use core::fmt;
> > @@ -192,12 +189,6 @@ fn from(_: Utf8Error) -> Error {
> >      }
> >  }
> >
> > -impl From<TryReserveError> for Error {
> > -    fn from(_: TryReserveError) -> Error {
> > -        code::ENOMEM
> > -    }
> > -}
> > -
>
> Why are you removing this?

We don't use `TryReserveError` anymore. I'll move this chunk to the
patch 7 in v2, which is where we remove the use of this error.

>
> --
> Cheers,
> Benno
>
> >  impl From<LayoutError> for Error {
> >      fn from(_: LayoutError) -> Error {
> >          code::ENOMEM
> > diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs
> > index 1a8b0464db0c..1f7a6b5892ac 100644
> > --- a/rust/kernel/init.rs
> > +++ b/rust/kernel/init.rs
> > @@ -211,14 +211,13 @@
> >  //! [`pin_init!`]: crate::pin_init!
> >
> >  use crate::{
> > -    alloc::{boxext::BoxExt, Flags},
> > +    alloc::{boxext::BoxExt, AllocError, Flags},
> >      error::{self, Error},
> >      sync::UniqueArc,
> >      types::{Opaque, ScopeGuard},
> >  };
> >  use alloc::boxed::Box;
> >  use core::{
> > -    alloc::AllocError,
> >      cell::UnsafeCell,
> >      convert::Infallible,
> >      marker::PhantomData,
> > diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> > index 51f30e55bd00..5c641233e26d 100644
> > --- a/rust/kernel/lib.rs
> > +++ b/rust/kernel/lib.rs
> > @@ -12,7 +12,6 @@
> >  //! do so first instead of bypassing this crate.
> >
> >  #![no_std]
> > -#![feature(allocator_api)]
> >  #![feature(coerce_unsized)]
> >  #![feature(dispatch_from_dyn)]
> >  #![feature(new_uninit)]
> > diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
> > index 34dbc85b5220..5206b18f882b 100644
> > --- a/rust/kernel/str.rs
> > +++ b/rust/kernel/str.rs
> > @@ -2,8 +2,7 @@
> >
> >  //! String representations.
> >
> > -use crate::alloc::{flags::*, vecext::VecExt};
> > -use alloc::alloc::AllocError;
> > +use crate::alloc::{flags::*, vecext::VecExt, AllocError};
> >  use alloc::vec::Vec;
> >  use core::fmt::{self, Write};
> >  use core::ops::{self, Deref, Index};
> > diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
> > index af539c5eb4bc..8db25f73b37f 100644
> > --- a/rust/kernel/sync/arc.rs
> > +++ b/rust/kernel/sync/arc.rs
> > @@ -16,7 +16,7 @@
> >  //! [`Arc`]: https://doc.rust-lang.org/std/sync/struct.Arc.html
> >
> >  use crate::{
> > -    alloc::{boxext::BoxExt, Flags},
> > +    alloc::{boxext::BoxExt, AllocError, Flags},
> >      bindings,
> >      error::{self, Error},
> >      init::{self, InPlaceInit, Init, PinInit},
> > @@ -25,7 +25,7 @@
> >  };
> >  use alloc::boxed::Box;
> >  use core::{
> > -    alloc::{AllocError, Layout},
> > +    alloc::Layout,
> >      fmt,
> >      marker::{PhantomData, Unsize},
> >      mem::{ManuallyDrop, MaybeUninit},
> > diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
> > index 09a0f158ff1b..50837e56efc7 100644
> > --- a/rust/kernel/workqueue.rs
> > +++ b/rust/kernel/workqueue.rs
> > @@ -132,9 +132,8 @@
> >  //!
> >  //! C header: [`include/linux/workqueue.h`](srctree/include/linux/workqueue.h)
> >
> > -use crate::alloc::Flags;
> > +use crate::alloc::{AllocError, Flags};
> >  use crate::{bindings, prelude::*, sync::Arc, sync::LockClassKey, types::Opaque};
> > -use alloc::alloc::AllocError;
> >  use alloc::boxed::Box;
> >  use core::marker::PhantomData;
> >  use core::pin::Pin;
> > --
> > 2.34.1
> >

^ permalink raw reply	[flat|nested] 30+ messages in thread

* Re: [PATCH 09/10] rust: init: update `init` module to take allocation flags
  2024-03-26 14:08   ` Benno Lossin
@ 2024-03-27  2:17     ` Wedson Almeida Filho
  0 siblings, 0 replies; 30+ messages in thread
From: Wedson Almeida Filho @ 2024-03-27  2:17 UTC (permalink / raw)
  To: Benno Lossin
  Cc: rust-for-linux, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Andreas Hindborg, Alice Ryhl, linux-kernel,
	Wedson Almeida Filho

On Tue, 26 Mar 2024 at 11:08, Benno Lossin <benno.lossin@proton.me> wrote:
>
> On 25.03.24 20:54, Wedson Almeida Filho wrote:
> > From: Wedson Almeida Filho <walmeida@microsoft.com>
> >
> > This is the last component in the conversion for allocators to take
> > allocation flags as parameters.
> >
> > Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
> > ---
> >   rust/kernel/init.rs               | 49 ++++++++++++++++---------------
> >   rust/kernel/sync/arc.rs           | 17 ++++++-----
> >   rust/kernel/sync/condvar.rs       |  2 +-
> >   rust/kernel/sync/lock/mutex.rs    |  2 +-
> >   rust/kernel/sync/lock/spinlock.rs |  2 +-
> >   rust/kernel/workqueue.rs          | 13 +++++---
> >   6 files changed, 47 insertions(+), 38 deletions(-)
>
> One formatting issue below, with that fixed:
>
> Reviewed-by: Benno Lossin <benno.lossin@proton.me>
>
> > diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
> > index 077200f5350b..af539c5eb4bc 100644
> > --- a/rust/kernel/sync/arc.rs
> > +++ b/rust/kernel/sync/arc.rs
> > @@ -565,13 +565,16 @@ pub fn new(value: T, flags: Flags) -> Result<Self, AllocError> {
> >       }
> >
> >       /// Tries to allocate a new [`UniqueArc`] instance whose contents are not initialised yet.
> > -    pub fn new_uninit(_flags: Flags) -> Result<UniqueArc<MaybeUninit<T>>, AllocError> {
> > +    pub fn new_uninit(flags: Flags) -> Result<UniqueArc<MaybeUninit<T>>, AllocError> {
> >           // INVARIANT: The refcount is initialised to a non-zero value.
> > -        let inner = Box::try_init::<AllocError>(try_init!(ArcInner {
> > +        let inner = Box::try_init::<AllocError>(
> > +            try_init!(ArcInner {
> >               // SAFETY: There are no safety requirements for this FFI call.
> >               refcount: Opaque::new(unsafe { bindings::REFCOUNT_INIT(1) }),
> >               data <- init::uninit::<T, AllocError>(),
> > -        }? AllocError))?;
> > +        }? AllocError),
> > +            flags,
> > +        )?;
>
> The indentation looks wrong, rustfmt sadly cannot handle the pin-init
> macros. This looks better to me:
>
>         let inner = Box::try_init::<AllocError>(
>             try_init!(ArcInner {
>                 // SAFETY: There are no safety requirements for this FFI call.
>                 refcount: Opaque::new(unsafe { bindings::REFCOUNT_INIT(1) }),
>                 data <- init::uninit::<T, AllocError>(),
>             }? AllocError),
>             flags,
>         )?;

I remember trying to rearrange this and `rustfmtcheck` not liking it
but it seems to be happy with your suggestion.

Applying it in v2.

> --
> Cheers,
> Benno
>
> >           Ok(UniqueArc {
> >               // INVARIANT: The newly-created object has a refcount of 1.
> >               // SAFETY: The pointer from the `Box` is valid.

^ permalink raw reply	[flat|nested] 30+ messages in thread

end of thread, other threads:[~2024-03-27  2:17 UTC | newest]

Thread overview: 30+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-03-25 19:54 [PATCH 00/10] Allocation APIs Wedson Almeida Filho
2024-03-25 19:54 ` [PATCH 01/10] rust: kernel: move `allocator` module under `alloc` Wedson Almeida Filho
2024-03-25 21:56   ` Benno Lossin
2024-03-26  0:04     ` Wedson Almeida Filho
2024-03-25 19:54 ` [PATCH 02/10] rust: alloc: introduce the `VecExt` trait Wedson Almeida Filho
2024-03-25 22:05   ` Benno Lossin
2024-03-26  0:02     ` Wedson Almeida Filho
2024-03-25 19:54 ` [PATCH 03/10] kbuild: use the upstream `alloc` crate Wedson Almeida Filho
2024-03-25 19:54 ` [PATCH 04/10] rust: alloc: remove our fork of the " Wedson Almeida Filho
2024-03-25 22:24   ` Benno Lossin
2024-03-25 19:54 ` [PATCH 05/10] rust: alloc: introduce allocation flags Wedson Almeida Filho
2024-03-25 22:26   ` Benno Lossin
2024-03-25 19:54 ` [PATCH 06/10] rust: alloc: introduce the `BoxExt` trait Wedson Almeida Filho
2024-03-25 22:37   ` Benno Lossin
2024-03-26  0:17     ` Wedson Almeida Filho
2024-03-26 13:30       ` Benno Lossin
2024-03-27  1:54         ` Wedson Almeida Filho
2024-03-27  1:55         ` Wedson Almeida Filho
2024-03-25 19:54 ` [PATCH 07/10] rust: alloc: update `VecExt` to take allocation flags Wedson Almeida Filho
2024-03-25 20:44   ` Boqun Feng
2024-03-26  0:03     ` Wedson Almeida Filho
2024-03-26 13:58       ` Benno Lossin
2024-03-25 19:54 ` [PATCH 08/10] rust: sync: update `Arc` and `UniqueArc` " Wedson Almeida Filho
2024-03-26 14:01   ` Benno Lossin
2024-03-25 19:54 ` [PATCH 09/10] rust: init: update `init` module " Wedson Almeida Filho
2024-03-26 14:08   ` Benno Lossin
2024-03-27  2:17     ` Wedson Almeida Filho
2024-03-25 19:54 ` [PATCH 10/10] rust: kernel: remove usage of `allocator_api` unstable feature Wedson Almeida Filho
2024-03-26 15:27   ` Benno Lossin
2024-03-27  2:13     ` Wedson Almeida Filho

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