diff options
| author | Rasmus Villemoes <linux@rasmusvillemoes.dk> | 2025-10-20 16:22:27 +0200 |
|---|---|---|
| committer | Nathan Chancellor <nathan@kernel.org> | 2025-10-29 16:23:47 -0700 |
| commit | c4781dc3d1cf0e017e1f290607ddc56cfe187afc (patch) | |
| tree | ad82d50ab8aacf0474c81c04197257ad08abc31c | |
| parent | a6773e6932cbfbc0e123bc0529ea27f2a8abb833 (diff) | |
Kbuild: enable -fms-extensions
Once in a while, it turns out that enabling -fms-extensions could
allow some slightly prettier code. But every time it has come up, the
code that had to be used instead has been deemed "not too awful" and
not worth introducing another compiler flag for.
That's probably true for each individual case, but then it's somewhat
of a chicken/egg situation.
If we just "bite the bullet" as Linus says and enable it once and for
all, it is available whenever a use case turns up, and no individual
case has to justify it.
A lore.kernel.org search provides these examples:
- https://lore.kernel.org/lkml/200706301813.58435.agruen@suse.de/
- https://lore.kernel.org/lkml/20180419152817.GD25406@bombadil.infradead.org/
- https://lore.kernel.org/lkml/170622208395.21664.2510213291504081000@noble.neil.brown.name/
- https://lore.kernel.org/lkml/87h6475w9q.fsf@prevas.dk/
- https://lore.kernel.org/lkml/CAHk-=wjeZwww6Zswn6F_iZTpUihTSNKYppLqj36iQDDhfntuEw@mail.gmail.com/
Undoubtedly, there are more places in the code where this could also
be used but where -fms-extensions just didn't come up in any
discussion.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: David Sterba <dsterba@suse.com>
Link: https://patch.msgid.link/20251020142228.1819871-2-linux@rasmusvillemoes.dk
[nathan: Move disabled clang warning to scripts/Makefile.extrawarn and
adjust comment]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
| -rw-r--r-- | Makefile | 3 | ||||
| -rw-r--r-- | scripts/Makefile.extrawarn | 4 |
2 files changed, 6 insertions, 1 deletions
@@ -1061,6 +1061,9 @@ NOSTDINC_FLAGS += -nostdinc # perform bounds checking. KBUILD_CFLAGS += $(call cc-option, -fstrict-flex-arrays=3) +# Allow including a tagged struct or union anonymously in another struct/union. +KBUILD_CFLAGS += -fms-extensions + # disable invalid "can't wrap" optimizations for signed / pointers KBUILD_CFLAGS += -fno-strict-overflow diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn index 6af392f9cd02..68e6fafcb80c 100644 --- a/scripts/Makefile.extrawarn +++ b/scripts/Makefile.extrawarn @@ -28,8 +28,10 @@ endif KBUILD_CFLAGS-$(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. +# The kernel builds with '-std=gnu11' and '-fms-extensions' so use of GNU and +# Microsoft extensions is acceptable. KBUILD_CFLAGS += -Wno-gnu +KBUILD_CFLAGS += -Wno-microsoft-anon-tag # Clang checks for overflow/truncation with '%p', while GCC does not: # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111219 |