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From: Nathan Chancellor <natechancellor@gmail.com>
To: Masahiro Yamada <masahiroy@kernel.org>,
	Michal Marek <michal.lkml@markovi.net>,
	Arnd Bergmann <arnd@arndb.de>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>, Jason Baron <jbaron@akamai.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
	linux-arch@vger.kernel.org, linux-mm@kvack.org,
	clang-built-linux@googlegroups.com,
	Nathan Chancellor <natechancellor@gmail.com>
Subject: [PATCH 6/6] kbuild: Enable -Wtautological-compare
Date: Tue, 18 Feb 2020 21:54:23 -0700
Message-ID: <20200219045423.54190-7-natechancellor@gmail.com> (raw)
In-Reply-To: <20200219045423.54190-1-natechancellor@gmail.com>

Currently, we disable -Wtautological-compare, which in turn disables a
bunch of more specific tautological comparison warnings that are useful
for the kernel (see clang's documentation below). Now that all of the
major/noisy warnings have been fixed, enable -Wtautological-compare so
that more issues can be caught at build time.

-Wtautological-constant-out-of-range-compare is kept disabled because
there are places in the kernel where a constant or variable size can
change based on the kernel configuration; these are not fixed in a
clean/concise way and they are almost always harmless so this one
subwarning is kept disabled.

Link: https://github.com/ClangBuiltLinux/linux/issues/488
Link: http://releases.llvm.org/9.0.0/tools/clang/docs/DiagnosticsReference.html#wtautological-compare
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
 Makefile | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index b954c304c479..99080c57a1cb 100644
--- a/Makefile
+++ b/Makefile
@@ -742,8 +742,7 @@ ifdef CONFIG_CC_IS_CLANG
 KBUILD_CPPFLAGS += -Qunused-arguments
 KBUILD_CFLAGS += -Wno-format-invalid-specifier
 KBUILD_CFLAGS += -Wno-gnu
-# Quiet clang warning: comparison of unsigned expression < 0 is always false
-KBUILD_CFLAGS += -Wno-tautological-compare
+KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
 # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the
 # source of a reference will be _MergedGlobals and not on of the whitelisted names.
 # See modpost pattern 2
-- 
2.25.1


  parent reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-19  4:54 [PATCH 0/6] Silence some instances of -Wtautological-compare and enable globally Nathan Chancellor
2020-02-19  4:54 ` [PATCH 1/6] asm/sections: Add COMPARE_SECTIONS macro Nathan Chancellor
2020-02-19  4:54 ` [PATCH 2/6] kernel/extable: Wrap section comparison in sort_main_extable with COMPARE_SECTIONS Nathan Chancellor
2020-02-19  4:54 ` [PATCH 3/6] tracing: Wrap section comparison in tracer_alloc_buffers " Nathan Chancellor
2020-02-19 14:34   ` Steven Rostedt
2020-02-19 17:44     ` Nick Desaulniers
2020-02-19 18:16       ` Jason Gunthorpe
2020-02-19 19:09         ` Steven Rostedt
2020-02-19 19:11         ` Nick Desaulniers
2020-02-19 19:22           ` Nathan Chancellor
2020-02-19 19:43             ` Steven Rostedt
2020-02-19 19:54           ` Jason Gunthorpe
2020-02-19 21:32             ` Nick Desaulniers
2020-02-19  4:54 ` [PATCH 4/6] dynamic_debug: Wrap section comparison in dynamic_debug_init " Nathan Chancellor
2020-02-19  4:54 ` [PATCH 5/6] mm: kmemleak: Wrap section comparison in kmemleak_init " Nathan Chancellor
2020-02-19  4:54 ` Nathan Chancellor [this message]
2020-04-21  4:03 ` [PATCH 0/6] Silence some instances of -Wtautological-compare and enable globally Andrew Morton
2020-04-21  4:32   ` Nathan Chancellor

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