Hi Nick,

On Wed, 11 Aug 2021 10:04:36 -0700 Nick Desaulniers <ndesaulniers@google.com> wrote:
>
> Thanks Stephen for taking the time to resolve this and send a patch.
> We owe you one. We knew this conflict was coming.
> 
> Miguel, would you mind rolling this patch into your tree, then
> crediting Stephen if possible (on the patch that adds
> TENTATIVE_CLANG_FLAGS)?
> 
> I think the above `ifneq ($(findstring clang,$(CC_VERSION_TEXT)),)`
> should stay in the top level Makefile though. It does look nicer to
> bury it in scripts/Makefile.clang, but I worry that someone doing a
> GCC build might trip the $(error) in that file (if CROSS_COMPILE was
> set and we're building a non-llvm-supported target).

OK, I have changed the patch today to be this:

From: Stephen Rothwell <sfr@canb.auug.org.au>
Date: Wed, 11 Aug 2021 17:18:36 +1000
Subject: [PATCH] fixup for rust integration with Makefile.clang creation

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---
 Makefile               | 17 -----------------
 scripts/Makefile.clang | 19 +++++++++++++------
 2 files changed, 13 insertions(+), 23 deletions(-)

diff --git a/Makefile b/Makefile
index 5d504a1dcb06..3638ce07f208 100644
--- a/Makefile
+++ b/Makefile
@@ -625,22 +625,7 @@ endif
 # and from include/config/auto.conf.cmd to detect the compiler upgrade.
 CC_VERSION_TEXT = $(subst $(pound),,$(shell LC_ALL=C $(CC) --version 2>/dev/null | head -n 1))
 
-TENTATIVE_CLANG_FLAGS := -Werror=unknown-warning-option
-
-ifneq ($(CROSS_COMPILE),)
-TENTATIVE_CLANG_FLAGS	+= --target=$(notdir $(CROSS_COMPILE:%-=%))
-endif
-ifeq ($(LLVM_IAS),1)
-TENTATIVE_CLANG_FLAGS	+= -integrated-as
-else
-TENTATIVE_CLANG_FLAGS	+= -no-integrated-as
-GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))
-TENTATIVE_CLANG_FLAGS	+= --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
-endif
-
-export TENTATIVE_CLANG_FLAGS
-
 ifneq ($(findstring clang,$(CC_VERSION_TEXT)),)
 include $(srctree)/scripts/Makefile.clang
 endif
 
diff --git a/scripts/Makefile.clang b/scripts/Makefile.clang
index 3ae63bd35582..555b5255d9b3 100644
--- a/scripts/Makefile.clang
+++ b/scripts/Makefile.clang
@@ -12,24 +12,29 @@ CLANG_TARGET_FLAGS_s390		:= s390x-linux-gnu
 CLANG_TARGET_FLAGS_x86		:= x86_64-linux-gnu
 CLANG_TARGET_FLAGS		:= $(CLANG_TARGET_FLAGS_$(SRCARCH))
 
+TENTATIVE_CLANG_FLAGS := -Werror=unknown-warning-option
+
 ifeq ($(CROSS_COMPILE),)
 ifeq ($(CLANG_TARGET_FLAGS),)
 $(error Specify CROSS_COMPILE or add '--target=' option to scripts/Makefile.clang)
 else
-CLANG_FLAGS	+= --target=$(CLANG_TARGET_FLAGS)
+TENTATIVE_CLANG_FLAGS	+= --target=$(CLANG_TARGET_FLAGS)
 endif # CLANG_TARGET_FLAGS
 else
-CLANG_FLAGS	+= --target=$(notdir $(CROSS_COMPILE:%-=%))
+TENTATIVE_CLANG_FLAGS	+= --target=$(notdir $(CROSS_COMPILE:%-=%))
 endif # CROSS_COMPILE
 
 ifeq ($(LLVM_IAS),0)
-CLANG_FLAGS	+= -no-integrated-as
+TENTATIVE_CLANG_FLAGS	+= -no-integrated-as
 GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))
-CLANG_FLAGS	+= --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
+TENTATIVE_CLANG_FLAGS	+= --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
 else
-CLANG_FLAGS	+= -integrated-as
+TENTATIVE_CLANG_FLAGS	+= -integrated-as
 endif
-CLANG_FLAGS	+= -Werror=unknown-warning-option
+
+export TENTATIVE_CLANG_FLAGS
+
+CLANG_FLAGS	+= $(TENTATIVE_CLANG_FLAGS)
 KBUILD_CFLAGS	+= $(CLANG_FLAGS)
 KBUILD_AFLAGS	+= $(CLANG_FLAGS)
 export CLANG_FLAGS
-- 
2.30.2

Please give it a spin when linux-next has been released.

-- 
Cheers,
Stephen Rothwell