| Message ID | 20241017-disable-two-clang-enum-warnings-v2-1-163ac04346ae@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] kbuild: Move -Wenum-enum-conversion to W=2 | expand |
On Thu, Oct 17, 2024, at 17:09, Nathan Chancellor wrote: > -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>
Masahiro, could you please pick this up? The lore link is below in case it is no longer in your inbox (or I can resend). https://lore.kernel.org/20241017-disable-two-clang-enum-warnings-v2-1-163ac04346ae@kernel.org/ On Thu, Oct 17, 2024 at 10:09:22AM -0700, Nathan Chancellor wrote: > -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> > --- > Changes in v2: > - Move -Wenum-enum-conversion to W=2, instead of disabling it > outright (Arnd) > - Leave -Wenum-compare-conditional in W=1, as there are not that > many instances, so it can be turned on fully at some point (Arnd) > - Link to v1: https://lore.kernel.org/r/20241016-disable-two-clang-enum-warnings-v1-1-ae886d7a0269@kernel.org > --- > scripts/Makefile.extrawarn | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn > index 1d13cecc7cc7808610e635ddc03476cf92b3a8c1..04faf15ed316a9c291dc952b6cc40fb6c8c330cf 100644 > --- a/scripts/Makefile.extrawarn > +++ b/scripts/Makefile.extrawarn > @@ -130,7 +130,6 @@ 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 > @@ -154,6 +153,10 @@ KBUILD_CFLAGS += -Wno-missing-field-initializers > KBUILD_CFLAGS += -Wno-type-limits > KBUILD_CFLAGS += -Wno-shift-negative-value > > +ifdef CONFIG_CC_IS_CLANG > +KBUILD_CFLAGS += -Wno-enum-enum-conversion > +endif > + > ifdef CONFIG_CC_IS_GCC > KBUILD_CFLAGS += -Wno-maybe-uninitialized > endif > > --- > base-commit: 8e929cb546ee42c9a61d24fae60605e9e3192354 > change-id: 20241016-disable-two-clang-enum-warnings-e7994d44f948 > > Best regards, > -- > Nathan Chancellor <nathan@kernel.org> >
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn index 1d13cecc7cc7808610e635ddc03476cf92b3a8c1..04faf15ed316a9c291dc952b6cc40fb6c8c330cf 100644 --- a/scripts/Makefile.extrawarn +++ b/scripts/Makefile.extrawarn @@ -130,7 +130,6 @@ 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 @@ -154,6 +153,10 @@ KBUILD_CFLAGS += -Wno-missing-field-initializers KBUILD_CFLAGS += -Wno-type-limits KBUILD_CFLAGS += -Wno-shift-negative-value +ifdef CONFIG_CC_IS_CLANG +KBUILD_CFLAGS += -Wno-enum-enum-conversion +endif + ifdef CONFIG_CC_IS_GCC KBUILD_CFLAGS += -Wno-maybe-uninitialized endif
-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> --- Changes in v2: - Move -Wenum-enum-conversion to W=2, instead of disabling it outright (Arnd) - Leave -Wenum-compare-conditional in W=1, as there are not that many instances, so it can be turned on fully at some point (Arnd) - Link to v1: https://lore.kernel.org/r/20241016-disable-two-clang-enum-warnings-v1-1-ae886d7a0269@kernel.org --- scripts/Makefile.extrawarn | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- base-commit: 8e929cb546ee42c9a61d24fae60605e9e3192354 change-id: 20241016-disable-two-clang-enum-warnings-e7994d44f948 Best regards,