From 1c8b6e9b55209fd47b79feb92ddcf9d14ce1a449 Mon Sep 17 00:00:00 2001
From: Nathan Chancellor <nathan@kernel.org>
Date: Thu, 17 Oct 2024 10:09:22 -0700
Subject: [PATCH] kbuild: Move -Wenum-enum-conversion to W=2
commit 8f6629c004b193d23612641c3607e785819e97ab upstream.
-Wenum-enum-conversion was strengthened in clang-19 to warn for C, which
caused the kernel to move it to W=1 in commit 75b5ab134bb5 ("kbuild:
Move -Wenum-{compare-conditional,enum-conversion} into W=1") because
there were numerous instances that would break builds with -Werror.
Unfortunately, this is not a full solution, as more and more developers,
subsystems, and distributors are building with W=1 as well, so they
continue to see the numerous instances of this warning.
Since the move to W=1, there have not been many new instances that have
appeared through various build reports and the ones that have appeared
seem to be following similar existing patterns, suggesting that most
instances of this warning will not be real issues. The only alternatives
for silencing this warning are adding casts (which is generally seen as
an ugly practice) or refactoring the enums to macro defines or a unified
enum (which may be undesirable because of type safety in other parts of
the code).
Move the warning to W=2, where warnings that occur frequently but may be
relevant should reside.
Cc: stable@vger.kernel.org
Fixes: 75b5ab134bb5 ("kbuild: Move -Wenum-{compare-conditional,enum-conversion} into W=1")
Link: https://lore.kernel.org/ZwRA9SOcOjjLJcpi@google.com/
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
scripts/Makefile.extrawarn | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index fa5ef41806882..0971b1222e47d 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -38,6 +38,10 @@ KBUILD_CFLAGS += -Wno-sign-compare
KBUILD_CFLAGS += -Wno-type-limits
KBUILD_CFLAGS += -Wno-shift-negative-value
+ifdef CONFIG_CC_IS_CLANG
+KBUILD_CFLAGS += -Wno-enum-enum-conversion
+endif
+
KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
else
@@ -66,7 +70,6 @@ KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
KBUILD_CFLAGS += $(call cc-disable-warning, unaligned-access)
KBUILD_CFLAGS += $(call cc-disable-warning, cast-function-type-strict)
KBUILD_CFLAGS += -Wno-enum-compare-conditional
-KBUILD_CFLAGS += -Wno-enum-enum-conversion
endif
endif
--
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