6.14-stable review patch. If anyone has any objections, please let me know.
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From: Nathan Chancellor nathan@kernel.org
commit 4f79eaa2ceac86a0e0f304b0bab556cca5bf4f30 upstream.
Clang and GCC have different behaviors around disabling warnings included in -Wall and -Wextra and the order in which flags are specified, which is exposed by clang's new support for -Wunterminated-string-initialization.
$ cat test.c const char foo[3] = "FOO"; const char bar[3] __attribute__((__nonstring__)) = "BAR";
$ clang -fsyntax-only -Wextra test.c test.c:1:21: warning: initializer-string for character array is too long, array size is 3 but initializer has size 4 (including the null terminating character); did you mean to use the 'nonstring' attribute? [-Wunterminated-string-initialization] 1 | const char foo[3] = "FOO"; | ^~~~~ $ clang -fsyntax-only -Wextra -Wno-unterminated-string-initialization test.c $ clang -fsyntax-only -Wno-unterminated-string-initialization -Wextra test.c test.c:1:21: warning: initializer-string for character array is too long, array size is 3 but initializer has size 4 (including the null terminating character); did you mean to use the 'nonstring' attribute? [-Wunterminated-string-initialization] 1 | const char foo[3] = "FOO"; | ^~~~~
$ gcc -fsyntax-only -Wextra test.c test.c:1:21: warning: initializer-string for array of ‘char’ truncates NUL terminator but destination lacks ‘nonstring’ attribute (4 chars into 3 available) [-Wunterminated-string-initialization] 1 | const char foo[3] = "FOO"; | ^~~~~ $ gcc -fsyntax-only -Wextra -Wno-unterminated-string-initialization test.c $ gcc -fsyntax-only -Wno-unterminated-string-initialization -Wextra test.c
Move -Wextra up right below -Wall in Makefile.extrawarn to ensure these flags are at the beginning of the warning options list. Move the couple of warning options that have been added to the main Makefile since commit e88ca24319e4 ("kbuild: consolidate warning flags in scripts/Makefile.extrawarn") to scripts/Makefile.extrawarn after -Wall / -Wextra to ensure they get properly disabled for all compilers.
Fixes: 9d7a0577c9db ("gcc-15: disable '-Wunterminated-string-initialization' entirely for now") Link: https://github.com/llvm/llvm-project/issues/10359 Signed-off-by: Nathan Chancellor nathan@kernel.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Nathan Chancellor nathan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- Makefile | 7 ------- scripts/Makefile.extrawarn | 9 ++++++++- 2 files changed, 8 insertions(+), 8 deletions(-)
--- a/Makefile +++ b/Makefile @@ -1049,13 +1049,6 @@ NOSTDINC_FLAGS += -nostdinc # perform bounds checking. KBUILD_CFLAGS += $(call cc-option, -fstrict-flex-arrays=3)
-#Currently, disable -Wstringop-overflow for GCC 11, globally. -KBUILD_CFLAGS-$(CONFIG_CC_NO_STRINGOP_OVERFLOW) += $(call cc-disable-warning, stringop-overflow) -KBUILD_CFLAGS-$(CONFIG_CC_STRINGOP_OVERFLOW) += $(call cc-option, -Wstringop-overflow) - -#Currently, disable -Wunterminated-string-initialization as broken -KBUILD_CFLAGS += $(call cc-disable-warning, unterminated-string-initialization) - # disable invalid "can't wrap" optimizations for signed / pointers KBUILD_CFLAGS += -fno-strict-overflow
--- a/scripts/Makefile.extrawarn +++ b/scripts/Makefile.extrawarn @@ -8,6 +8,7 @@
# Default set of warnings, always enabled KBUILD_CFLAGS += -Wall +KBUILD_CFLAGS += -Wextra KBUILD_CFLAGS += -Wundef KBUILD_CFLAGS += -Werror=implicit-function-declaration KBUILD_CFLAGS += -Werror=implicit-int @@ -68,6 +69,13 @@ KBUILD_CFLAGS += -Wno-pointer-sign # globally built with -Wcast-function-type. KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type)
+# Currently, disable -Wstringop-overflow for GCC 11, globally. +KBUILD_CFLAGS-$(CONFIG_CC_NO_STRINGOP_OVERFLOW) += $(call cc-disable-warning, stringop-overflow) +KBUILD_CFLAGS-$(CONFIG_CC_STRINGOP_OVERFLOW) += $(call cc-option, -Wstringop-overflow) + +# Currently, disable -Wunterminated-string-initialization as broken +KBUILD_CFLAGS += $(call cc-disable-warning, unterminated-string-initialization) + # The allocators already balk at large sizes, so silence the compiler # warnings for bounds checks involving those possible values. While # -Wno-alloc-size-larger-than would normally be used here, earlier versions @@ -97,7 +105,6 @@ KBUILD_CFLAGS += $(call cc-option,-Wenum # Explicitly clear padding bits during variable initialization KBUILD_CFLAGS += $(call cc-option,-fzero-init-padding-bits=all)
-KBUILD_CFLAGS += -Wextra KBUILD_CFLAGS += -Wunused
#