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| author | Nathan Chancellor <nathan@kernel.org> | 2026-02-23 22:10:29 +0300 |
|---|---|---|
| committer | Nicolas Schier <nsc@kernel.org> | 2026-03-12 14:52:37 +0300 |
| commit | 0d3fccf68d9873a3c824fb70be0dbb2c4642aa90 (patch) | |
| tree | 160d12c130d3e5b805de6b9e5c4cb46f17661692 | |
| parent | ec4c28276c140a9338700041112f64f8d7ccc3e9 (diff) | |
| download | linux-0d3fccf68d9873a3c824fb70be0dbb2c4642aa90.tar.xz | |
kbuild: Use '-fms-anonymous-structs' if it is available
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 c4781dc3d1cf ("Kbuild:
enable -fms-extensions"). Switch to this more narrow option if it is
available, which would have helped avoid the issue addressed by
commit a6773e6932cb ("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: https://github.com/llvm/llvm-project/commit/c391efe6fb67329d8e2fd231692cc6b0ea902956 [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>
| -rw-r--r-- | Makefile | 2 | ||||
| -rw-r--r-- | init/Kconfig | 5 |
2 files changed, 6 insertions, 1 deletions
@@ -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 diff --git a/init/Kconfig b/init/Kconfig index c25869cf59c1..c4282d049463 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -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 |