-Wenum-enum-conversion and -Wenum-compare-conditional were strengthened in clang-19 to warn in C mode, which caused the kernel to move them to W=1 in commit 75b5ab134bb5 ("kbuild: Move -Wenum-{compare-conditional,enum-conversion} into W=1") because there were numerous instances of each 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 these warnings.
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 these warnings will not be real issues. The only alternatives for silencing these warnings 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).
Disable the warnings altogether so that W=1 users do not see them.
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 --- I am open to discussion around whether or not to disable this entirely but I think it needs to be out of W=1. --- scripts/Makefile.extrawarn | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn index 1d13cecc7cc7808610e635ddc03476cf92b3a8c1..3f124c80bee5133899047c07bc05e3173ee4c7f0 100644 --- a/scripts/Makefile.extrawarn +++ b/scripts/Makefile.extrawarn @@ -31,6 +31,8 @@ KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds ifdef CONFIG_CC_IS_CLANG # The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable. KBUILD_CFLAGS += -Wno-gnu +KBUILD_CFLAGS += -Wno-enum-compare-conditional +KBUILD_CFLAGS += -Wno-enum-enum-conversion else
# gcc inanely warns about local variables called 'main' @@ -129,8 +131,6 @@ endif KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast) KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare KBUILD_CFLAGS += $(call cc-disable-warning, unaligned-access) -KBUILD_CFLAGS += -Wno-enum-compare-conditional -KBUILD_CFLAGS += -Wno-enum-enum-conversion endif
endif
--- base-commit: 8e929cb546ee42c9a61d24fae60605e9e3192354 change-id: 20241016-disable-two-clang-enum-warnings-e7994d44f948
Best regards,