The common error type found in forward-ported/backported patches is missing headers. One recent example (files and function names are mangled): void foo(){} EXPORT_SYMBOL(foo); gave only warning foo.c:12345678:5: warning: function declaration isn't a prototype [-Wstrict-prototypes] void foo(){} ^ foo.c:12345679:5: warning: data definition has no type or storage class [enabled by default] EXPORT_SYMBOL(foo); foo.c:12345679:5: warning: type defaults to 'int' in declaration of 'EXORT_SYMBOL' [-Werror=implicit-int] Now it's a fata error. Tested on x86_64 allyesconfig. Signed-off-by: Sergei Trofimovich <slyfox@xxxxxxxxxx> Cc: Michal Marek <mmarek@xxxxxxx> Cc: linux-kbuild@xxxxxxxxxxxxxxx Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Makefile | 5 +++++ 1 file changed, 5 insertions(+) Change since v1: - use 'cc-option' to respect old gccs - fix typos. Thanks to Oleg Verych diff --git a/Makefile b/Makefile index 6e48848..53f4776 100644 --- a/Makefile +++ b/Makefile @@ -374,6 +374,11 @@ KBUILD_CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ -Werror-implicit-function-declaration \ -Wno-format-security \ -fno-delete-null-pointer-checks + +# not universally available, but nice to have ones +KBUILD_CFLAGS += $(call cc-option,-Werror=implicit-int) \ + $(call cc-option,-Werror=strict-prototypes) + KBUILD_AFLAGS_KERNEL := KBUILD_CFLAGS_KERNEL := KBUILD_AFLAGS := -D__ASSEMBLY__ -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html