[PATCH 2/2] silence some -Wuninitialized false positives
- From
Jeff King <peff@peff.net>
- Date
- Dec 15, 2012, 17:42 UTC
- Message-ID
- <20121215174210.GB22069@sigill.intra.peff.net>
- In-Reply-To
- <20121215173621.GA21011@sigill.intra.peff.net>
There are a few error functions that simply wrap error() and provide a standardized message text. Like error(), they always return -1; knowing that can help the compiler silence some false positive -Wuninitialized warnings.
One strategy would be to just declare these as inline in the header file so that the compiler can see that they always return -1. However, gcc does not always inline them (e.g., it will not inline opterror, even with -O3), which renders our change pointless.
Instead, let's follow the same route we did with error() in the last patch, and define a macro that makes the constant return value obvious to the compiler.
Signed-off-by: Jeff King <peff@peff.net> --- Another option would be to force inlining with __attribute(always_inline)__. But I don't like that, as we are affecting the generated code in that case (and any time we are overriding gcc's decision, I have to assume that it is smarter about when to inline than we are).
Other variants include:
1. Inline functions, but keep them as one-liners. E.g.:
int opterror(...)
{
real_opterror(...);
return -1;
} 2. Using these macros even when __GNUC__ isn't set. Unlike the
variadic error() macro, these do not use any special features.
If we used them everywhere, the functions themselves could be
converted to a void return. That would make it less likely that
somebody modifying the function in the future would fail to realize
that the error return must always be -1.I dunno. All the solutions are a bit ugly. I really do like being -Wall clean, but I wonder if this is spending too much effort to work around the compiler (we could also just mark these few cases as "int foo = foo" to say we have manually verified that they're OK).
cache.h | 3 +++ config.c | 1 + parse-options.c | 18 +++++++++--------- parse-options.h | 4 ++++ 4 files changed, 17 insertions(+), 9 deletions(-)
diff --git a/cache.h b/cache.h index 18fdd18..0e8e5d8 100644 --- a/cache.h +++ b/cache.h @@ -1136,6 +1136,9 @@ extern int config_error_nonbool(const char *); extern int git_env_bool(const char *, int); extern int git_config_system(void); extern int config_error_nonbool(const char *); +#ifdef __GNUC__ +#define config_error_nonbool(s) (config_error_nonbool(s), -1) +#endif extern const char *get_log_output_encoding(void); extern const char *get_commit_output_encoding(void); diff --git a/config.c b/config.c index fb3f868..526f682 100644 --- a/config.c +++ b/config.c @@ -1660,6 +1660,7 @@ int git_config_rename_section(const char *old_name, const char *new_name) * Call this to report error for your variable that should not * get a boolean value (i.e. "[my] var" means "true"). */ +#undef config_error_nonbool int config_error_nonbool(const char *var) { return error("Missing value for '%s'", var); diff --git a/parse-options.c b/parse-options.c index c1c66bd..67e98a6 100644 --- a/parse-options.c +++ b/parse-options.c @@ -18,15 +18,6 @@ int optbug(const struct option *opt, const char *reason) return error("BUG: switch '%c' %s", opt->short_name, reason); } -int opterror(const struct option *opt, const char *reason, int flags) -{ - if (flags & OPT_SHORT) - return error("switch `%c' %s", opt->short_name, reason); - if (flags & OPT_UNSET) - return error("option `no-%s' %s", opt->long_name, reason); - return error("option `%s' %s", opt->long_name, reason); -} - static int get_arg(struct parse_opt_ctx_t *p, const struct option *opt, int flags, const char **arg) { @@ -594,3 +585,12 @@ static int parse_options_usage(struct parse_opt_ctx_t *ctx, return usage_with_options_internal(ctx, usagestr, opts, 0, err); } +#undef opterror +int opterror(const struct option *opt, const char *reason, int flags) +{ + if (flags & OPT_SHORT) + return error("switch `%c' %s", opt->short_name, reason); + if (flags & OPT_UNSET) + return error("option `no-%s' %s", opt->long_name, reason); + return error("option `%s' %s", opt->long_name, reason); +} diff --git a/parse-options.h b/parse-options.h index 71a39c6..e703853 100644 --- a/parse-options.h +++ b/parse-options.h @@ -177,6 +177,10 @@ extern int opterror(const struct option *opt, const char *reason, int flags); extern int optbug(const struct option *opt, const char *reason); extern int opterror(const struct option *opt, const char *reason, int flags); +#ifdef __GNUC__ +#define opterror(o,r,f) (opterror((o),(r),(f)), -1) +#endif + /*----- incremental advanced APIs -----*/ enum {
-- 1.8.0.2.4.g59402aa