GCC 4.10 and newer, and Sparse, supports __attribute__((designated_init)), which marks a structure as requiring a designated initializer rather than a positional one. This helps reduce churn and errors when used with _ops structures and similar structures designed for future extension. Add a wrapper __designated_init, which turns into __attribute__((designated_init)) for Sparse or sufficiently new GCC. Enable the corresponding warning as an error. The following semantic patch can help mark structures containing function pointers as requiring designated initializers: @@ identifier I, f; type T; @@ struct I { ... T (*f)(...); ... } + __designated_init ; Signed-off-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx> --- Makefile | 3 +++ include/linux/compiler-gcc4.h | 4 ++++ include/linux/compiler.h | 5 +++++ 3 files changed, 12 insertions(+) diff --git a/Makefile b/Makefile index f6a7794..83773c2 100644 --- a/Makefile +++ b/Makefile @@ -744,6 +744,9 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=strict-prototypes) # Prohibit date/time macros, which would make the build non-deterministic KBUILD_CFLAGS += $(call cc-option,-Werror=date-time) +# Disallow positional initialization of designated structs +KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init) + # use the deterministic mode of AR if available KBUILD_ARFLAGS := $(call ar-option,D) diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h index 2507fd2..5cd3c26 100644 --- a/include/linux/compiler-gcc4.h +++ b/include/linux/compiler-gcc4.h @@ -85,4 +85,8 @@ #if GCC_VERSION >= 40800 || (defined(__powerpc__) && GCC_VERSION >= 40600) #define __HAVE_BUILTIN_BSWAP16__ #endif + +#if GCC_VERSION >= 41000 || defined(__CHECKER__) +#define __designated_init __attribute__((designated_init)) +#endif #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */ diff --git a/include/linux/compiler.h b/include/linux/compiler.h index d5ad7b1..c2334b2 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -266,6 +266,11 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); #define __always_inline inline #endif +/* Marks a struct as requiring designated initializers, never positional. */ +#ifndef __designated_init +#define __designated_init +#endif + #endif /* __KERNEL__ */ /* -- 2.0.1 -- 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