mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-05-15 23:41:35 -04:00
Code Issues Packages Projects Releases Wiki Activity

kbuild: Use '-fms-anonymous-structs' if it is available

Browse Source 
Clang recently added '-fms-anonymous-structs' [1] to specifically enable
the Microsoft tagged anonymous structure / union extension, for which
the kernel added '-fms-extensions' in commit c4781dc3d1 ("Kbuild:
enable -fms-extensions"). Switch to this more narrow option if it is
available, which would have helped avoid the issue addressed by
commit a6773e6932 ("jfs: Rename _inline to avoid conflict with clang's
'-fms-extensions'"). GCC has talked about adding a similar flag [2] as
well but potentially naming it differently.

Move the selection of the flag to Kconfig to make it easier to use
cc-option (as CC_FLAGS_DIALECT may be used in arch Makefiles, which may
be too early for cc-option in Kbuild) and customize based on compiler
flag names.

Link: c391efe6fb [1]
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123623 [2]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Helge Deller <deller@gmx.de>  # parisc
Link: https://patch.msgid.link/20260223-fms-anonymous-structs-v1-2-8ee406d3c36c@kernel.org
Signed-off-by: Nicolas Schier <nsc@kernel.org>
This commit is contained in:
Nathan Chancellor
2026-02-23 12:10:29 -07:00
committed by Nicolas Schier
parent ec4c28276c
commit 0d3fccf68d
2 changed files with 6 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
Makefile
View File

@@ -791,7 +791,7 @@ endif
CC_FLAGS_DIALECT := -std=gnu11
# Allow including a tagged struct or union anonymously in another struct/union.
CC_FLAGS_DIALECT += -fms-extensions
CC_FLAGS_DIALECT += $(CONFIG_CC_MS_EXTENSIONS)
# Clang enables warnings about GNU and Microsoft extensions by default, disable
# them because this is expected with the above options.
ifdef CONFIG_CC_IS_CLANG

5
init/Kconfig
View File

@@ -960,6 +960,11 @@ config CC_IMPLICIT_FALLTHROUGH
default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
config CC_MS_EXTENSIONS
string
default "-fms-anonymous-structs" if $(cc-option,-fms-anonymous-structs)
default "-fms-extensions"
# Currently, disable gcc-10+ array-bounds globally.
# It's still broken in gcc-13, so no upper bound yet.
config GCC10_NO_ARRAY_BOUNDS