Merge patch "kbuild: Add '-fms-extensions' to areas with dedicated CFLAGS"

Nathan Chancellor <nathan@kernel.org> says:

Shared branch between Kbuild and other trees for enabling
'-fms-extensions' for 6.19.

* tag 'kbuild-ms-extensions-6.19' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/kbuild/linux:
  kbuild: Add '-fms-extensions' to areas with dedicated CFLAGS
  Kbuild: enable -fms-extensions
  jfs: Rename _inline to avoid conflict with clang's '-fms-extensions'

Link: https://patch.msgid.link/20251101-kbuild-ms-extensions-dedicated-cflags-v1-1-38004aba524b@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

12 files changed, 29 insertions, 15 deletions

diff --git a/Makefile b/Makefile
index b34a1f4c0396..de6c1d8d7ad7 100644
--- a/Makefile
+++ b/Makefile
@@ -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/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
index ffa3536581f6..9d0efed91414 100644
--- a/arch/arm64/kernel/vdso32/Makefile
+++ b/arch/arm64/kernel/vdso32/Makefile
@@ -63,7 +63,7 @@ VDSO_CFLAGS += -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
                $(filter -Werror,$(KBUILD_CPPFLAGS)) \
                -Werror-implicit-function-declaration \
                -Wno-format-security \
-               -std=gnu11
+               -std=gnu11 -fms-extensions
 VDSO_CFLAGS  += -O2
 # Some useful compiler-dependent flags from top-level Makefile
 VDSO_CFLAGS += $(call cc32-option,-Wno-pointer-sign)
@@ -71,6 +71,7 @@ VDSO_CFLAGS += -fno-strict-overflow
 VDSO_CFLAGS += $(call cc32-option,-Werror=strict-prototypes)
 VDSO_CFLAGS += -Werror=date-time
 VDSO_CFLAGS += $(call cc32-option,-Werror=incompatible-pointer-types)
+VDSO_CFLAGS += $(if $(CONFIG_CC_IS_CLANG),-Wno-microsoft-anon-tag)
 
 # Compile as THUMB2 or ARM. Unwinding via frame-pointers in THUMB2 is
 # unreliable.
diff --git a/arch/loongarch/vdso/Makefile b/arch/loongarch/vdso/Makefile
index d8316f993482..c0cc3ca5da9f 100644
--- a/arch/loongarch/vdso/Makefile
+++ b/arch/loongarch/vdso/Makefile
@@ -19,7 +19,7 @@ ccflags-vdso := \
 cflags-vdso := $(ccflags-vdso) \
 	-isystem $(shell $(CC) -print-file-name=include) \
 	$(filter -W%,$(filter-out -Wa$(comma)%,$(KBUILD_CFLAGS))) \
-	-std=gnu11 -O2 -g -fno-strict-aliasing -fno-common -fno-builtin \
+	-std=gnu11 -fms-extensions -O2 -g -fno-strict-aliasing -fno-common -fno-builtin \
 	-fno-stack-protector -fno-jump-tables -DDISABLE_BRANCH_PROFILING \
 	$(call cc-option, -fno-asynchronous-unwind-tables) \
 	$(call cc-option, -fno-stack-protector)
diff --git a/arch/parisc/boot/compressed/Makefile b/arch/parisc/boot/compressed/Makefile
index 17c42d718eb3..f8481e4e9d21 100644
--- a/arch/parisc/boot/compressed/Makefile
+++ b/arch/parisc/boot/compressed/Makefile
@@ -18,7 +18,7 @@ KBUILD_CFLAGS += -fno-PIE -mno-space-regs -mdisable-fpregs -Os
 ifndef CONFIG_64BIT
 KBUILD_CFLAGS += -mfast-indirect-calls
 endif
-KBUILD_CFLAGS += -std=gnu11
+KBUILD_CFLAGS += -std=gnu11 -fms-extensions
 
 LDFLAGS_vmlinux := -X -e startup --as-needed -T
 $(obj)/vmlinux: $(obj)/vmlinux.lds $(addprefix $(obj)/, $(OBJECTS)) $(LIBGCC) FORCE
diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
index c47b78c1d3e7..f1a4761ebd44 100644
--- a/arch/powerpc/boot/Makefile
+++ b/arch/powerpc/boot/Makefile
@@ -70,7 +70,7 @@ BOOTCPPFLAGS	:= -nostdinc $(LINUXINCLUDE)
 BOOTCPPFLAGS	+= -isystem $(shell $(BOOTCC) -print-file-name=include)
 
 BOOTCFLAGS	:= $(BOOTTARGETFLAGS) \
-		   -std=gnu11 \
+		   -std=gnu11 -fms-extensions \
 		   -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
 		   -fno-strict-aliasing -O2 \
 		   -msoft-float -mno-altivec -mno-vsx \
@@ -86,6 +86,7 @@ BOOTARFLAGS	:= -crD
 
 ifdef CONFIG_CC_IS_CLANG
 BOOTCFLAGS += $(CLANG_FLAGS)
+BOOTCFLAGS += -Wno-microsoft-anon-tag
 BOOTAFLAGS += $(CLANG_FLAGS)
 endif
 
diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index b4769241332b..8578361133a4 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -22,7 +22,7 @@ KBUILD_AFLAGS_DECOMPRESSOR := $(CLANG_FLAGS) -m64 -D__ASSEMBLY__
 ifndef CONFIG_AS_IS_LLVM
 KBUILD_AFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO),$(aflags_dwarf))
 endif
-KBUILD_CFLAGS_DECOMPRESSOR := $(CLANG_FLAGS) -m64 -O2 -mpacked-stack -std=gnu11
+KBUILD_CFLAGS_DECOMPRESSOR := $(CLANG_FLAGS) -m64 -O2 -mpacked-stack -std=gnu11 -fms-extensions
 KBUILD_CFLAGS_DECOMPRESSOR += -DDISABLE_BRANCH_PROFILING -D__NO_FORTIFY
 KBUILD_CFLAGS_DECOMPRESSOR += -D__DECOMPRESSOR
 KBUILD_CFLAGS_DECOMPRESSOR += -Wno-pointer-sign
@@ -35,6 +35,7 @@ KBUILD_CFLAGS_DECOMPRESSOR += $(call cc-disable-warning, address-of-packed-membe
 KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO),-g)
 KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO_DWARF4), $(call cc-option, -gdwarf-4,))
 KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_CC_NO_ARRAY_BOUNDS),-Wno-array-bounds)
+KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_CC_IS_CLANG),-Wno-microsoft-anon-tag)
 
 UTS_MACHINE	:= s390x
 STACK_SIZE	:= $(if $(CONFIG_KASAN),65536,$(if $(CONFIG_KMSAN),65536,16384))
diff --git a/arch/s390/purgatory/Makefile b/arch/s390/purgatory/Makefile
index bd39b36e7bd6..0c196a5b194a 100644
--- a/arch/s390/purgatory/Makefile
+++ b/arch/s390/purgatory/Makefile
@@ -13,7 +13,7 @@ CFLAGS_sha256.o := -D__NO_FORTIFY
 $(obj)/mem.o: $(srctree)/arch/s390/lib/mem.S FORCE
 	$(call if_changed_rule,as_o_S)
 
-KBUILD_CFLAGS := -std=gnu11 -fno-strict-aliasing -Wall -Wstrict-prototypes
+KBUILD_CFLAGS := -std=gnu11 -fms-extensions -fno-strict-aliasing -Wall -Wstrict-prototypes
 KBUILD_CFLAGS += -Wno-pointer-sign -Wno-sign-compare
 KBUILD_CFLAGS += -fno-zero-initialized-in-bss -fno-builtin -ffreestanding
 KBUILD_CFLAGS += -Os -m64 -msoft-float -fno-common
@@ -21,6 +21,7 @@ KBUILD_CFLAGS += -fno-stack-protector
 KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
 KBUILD_CFLAGS += -D__DISABLE_EXPORTS
 KBUILD_CFLAGS += $(CLANG_FLAGS)
+KBUILD_CFLAGS += $(if $(CONFIG_CC_IS_CLANG),-Wno-microsoft-anon-tag)
 KBUILD_CFLAGS += $(call cc-option,-fno-PIE)
 KBUILD_AFLAGS := $(filter-out -DCC_USING_EXPOLINE,$(KBUILD_AFLAGS))
 KBUILD_AFLAGS += -D__DISABLE_EXPORTS
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 4db7e4bf69f5..e20e25b8b16c 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -48,7 +48,8 @@ endif
 
 # How to compile the 16-bit code.  Note we always compile for -march=i386;
 # that way we can complain to the user if the CPU is insufficient.
-REALMODE_CFLAGS	:= -std=gnu11 -m16 -g -Os -DDISABLE_BRANCH_PROFILING -D__DISABLE_EXPORTS \
+REALMODE_CFLAGS	:= -std=gnu11 -fms-extensions -m16 -g -Os \
+		   -DDISABLE_BRANCH_PROFILING -D__DISABLE_EXPORTS \
 		   -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
 		   -fno-strict-aliasing -fomit-frame-pointer -fno-pic \
 		   -mno-mmx -mno-sse $(call cc-option,-fcf-protection=none)
@@ -60,6 +61,7 @@ REALMODE_CFLAGS += $(cc_stack_align4)
 REALMODE_CFLAGS += $(CLANG_FLAGS)
 ifdef CONFIG_CC_IS_CLANG
 REALMODE_CFLAGS += -Wno-gnu
+REALMODE_CFLAGS += -Wno-microsoft-anon-tag
 endif
 export REALMODE_CFLAGS
 
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 74657589264d..68f9d7a1683b 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -25,7 +25,7 @@ targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma \
 # avoid errors with '-march=i386', and future flags may depend on the target to
 # be valid.
 KBUILD_CFLAGS := -m$(BITS) -O2 $(CLANG_FLAGS)
-KBUILD_CFLAGS += -std=gnu11
+KBUILD_CFLAGS += -std=gnu11 -fms-extensions
 KBUILD_CFLAGS += -fno-strict-aliasing -fPIE
 KBUILD_CFLAGS += -Wundef
 KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
@@ -36,7 +36,10 @@ KBUILD_CFLAGS += -mno-mmx -mno-sse
 KBUILD_CFLAGS += -ffreestanding -fshort-wchar
 KBUILD_CFLAGS += -fno-stack-protector
 KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
-KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
+ifdef CONFIG_CC_IS_CLANG
+KBUILD_CFLAGS += -Wno-gnu
+KBUILD_CFLAGS += -Wno-microsoft-anon-tag
+endif
 KBUILD_CFLAGS += -Wno-pointer-sign
 KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
 KBUILD_CFLAGS += -D__DISABLE_EXPORTS
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 94b05e4451dd..7d15a85d579f 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -11,12 +11,12 @@ cflags-y			:= $(KBUILD_CFLAGS)
 
 cflags-$(CONFIG_X86_32)		:= -march=i386
 cflags-$(CONFIG_X86_64)		:= -mcmodel=small
-cflags-$(CONFIG_X86)		+= -m$(BITS) -D__KERNEL__ -std=gnu11 \
+cflags-$(CONFIG_X86)		+= -m$(BITS) -D__KERNEL__ -std=gnu11 -fms-extensions \
 				   -fPIC -fno-strict-aliasing -mno-red-zone \
 				   -mno-mmx -mno-sse -fshort-wchar \
 				   -Wno-pointer-sign \
 				   $(call cc-disable-warning, address-of-packed-member) \
-				   $(call cc-disable-warning, gnu) \
+				   $(if $(CONFIG_CC_IS_CLANG),-Wno-gnu -Wno-microsoft-anon-tag) \
 				   -fno-asynchronous-unwind-tables \
 				   $(CLANG_FLAGS)
 
diff --git a/fs/jfs/jfs_incore.h b/fs/jfs/jfs_incore.h
index 10934f9a11be..5aaafedb8fbc 100644
--- a/fs/jfs/jfs_incore.h
+++ b/fs/jfs/jfs_incore.h
@@ -76,14 +76,14 @@ struct jfs_inode_info {
 		struct {
 			unchar _unused[16];	/* 16: */
 			dxd_t _dxd;		/* 16: */
-			/* _inline may overflow into _inline_ea when needed */
+			/* _inline_sym may overflow into _inline_ea when needed */
 			/* _inline_ea may overlay the last part of
 			 * file._xtroot if maxentry = XTROOTINITSLOT
 			 */
 			union {
 				struct {
 					/* 128: inline symlink */
-					unchar _inline[128];
+					unchar _inline_sym[128];
 					/* 128: inline extended attr */
 					unchar _inline_ea[128];
 				};
@@ -101,7 +101,7 @@ struct jfs_inode_info {
 #define i_imap u.file._imap
 #define i_dirtable u.dir._table
 #define i_dtroot u.dir._dtroot
-#define i_inline u.link._inline
+#define i_inline u.link._inline_sym
 #define i_inline_ea u.link._inline_ea
 #define i_inline_all u.link._inline_all
 
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