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 <felipe.contreras@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
pull/97/head
Jeff King 9 years ago committed by Junio C Hamano
parent 0bc85abb7a
commit 87fe5df365
  1. 2
      cache.h
  2. 6
      git-compat-util.h
  3. 2
      parse-options.h

@ -1184,7 +1184,7 @@ extern int git_env_bool(const char *, int);
extern int git_config_system(void);
extern int config_error_nonbool(const char *);
#if defined(__GNUC__) && ! defined(__clang__)
#define config_error_nonbool(s) (config_error_nonbool(s), -1)
#define config_error_nonbool(s) (config_error_nonbool(s), const_error())
#endif
extern const char *get_log_output_encoding(void);
extern const char *get_commit_output_encoding(void);

@ -343,7 +343,11 @@ extern void warning(const char *err, ...) __attribute__((format (printf, 1, 2)))
* using the function as usual.
*/
#if defined(__GNUC__) && ! defined(__clang__)
#define error(...) (error(__VA_ARGS__), -1)
static inline int const_error(void)
{
return -1;
}
#define error(...) (error(__VA_ARGS__), const_error())
#endif
extern void set_die_routine(NORETURN_PTR void (*routine)(const char *err, va_list params));

@ -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 -----*/

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