From 87fe5df3653cf20b6bf9854bea42e4016c7d4688 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Tue, 6 May 2014 11:14:42 -0400 Subject: inline constant return from error() function Commit e208f9c introduced a macro to turn error() calls into: (error(), -1) to make the constant return value more visible to the calling code (and thus let the compiler make better decisions about the code). This works well for code like: return error(...); but the "-1" is superfluous in code that just calls error() without caring about the return value. In older versions of gcc, that was fine, but gcc 4.9 complains with -Wunused-value. We can work around this by encapsulating the constant return value in a static inline function, as gcc specifically avoids complaining about unused function returns unless the function has been specifically marked with the warn_unused_result attribute. We also use the same trick for config_error_nonbool and opterror, which learned the same error technique in a469a10. Reported-by: Felipe Contreras Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- parse-options.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'parse-options.h') diff --git a/parse-options.h b/parse-options.h index d670cb9669..1ef8da1f3e 100644 --- a/parse-options.h +++ b/parse-options.h @@ -180,7 +180,7 @@ extern NORETURN void usage_msg_opt(const char *msg, extern int optbug(const struct option *opt, const char *reason); extern int opterror(const struct option *opt, const char *reason, int flags); #if defined(__GNUC__) && ! defined(__clang__) -#define opterror(o,r,f) (opterror((o),(r),(f)), -1) +#define opterror(o,r,f) (opterror((o),(r),(f)), const_error()) #endif /*----- incremental advanced APIs -----*/ -- cgit v1.2.3 From ff0a80af724e81dbad6a269847523e39c2e7e479 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Tue, 6 May 2014 11:17:50 -0400 Subject: let clang use the constant-return error() macro Commit e208f9c converted error() into a macro to make its constant return value more apparent to calling code. Commit 5ded807 prevents us using this macro with clang, since clang's -Wunused-value is smart enough to realize that the constant "-1" is useless in some contexts. However, since the last commit puts the constant behind an inline function call, this is enough to prevent the -Wunused-value warning on both modern gcc and clang. So we can now re-enable the macro when compiling with clang. Tested with clang 3.3, 3.4, and 3.5. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- parse-options.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'parse-options.h') diff --git a/parse-options.h b/parse-options.h index 1ef8da1f3e..0a2b2e19a5 100644 --- a/parse-options.h +++ b/parse-options.h @@ -179,7 +179,7 @@ extern NORETURN void usage_msg_opt(const char *msg, extern int optbug(const struct option *opt, const char *reason); extern int opterror(const struct option *opt, const char *reason, int flags); -#if defined(__GNUC__) && ! defined(__clang__) +#if defined(__GNUC__) #define opterror(o,r,f) (opterror((o),(r),(f)), const_error()) #endif -- cgit v1.2.3