git-compat-util.h: clarify GCC v.s. C99-specific in comment

Change a comment added in e208f9c (make error()'s constant return
value more visible, 2012-12-15). It's not correct that this is GCC-ism
anymore, it's code that uses standard C99 features.

The comment being changed here pre-dates the HAVE_VARIADIC_MACROS
define, which we got in e05bed9 (trace: add 'file:line' to all
trace output, 2014-07-12).

The original implementation of an error() macro) in e208f9c used a
GCC-ism with the paste operator (see the commit message for mention of
it), but that was dropped later by 9798f7e (Use __VA_ARGS__ for all
of error's arguments, 2013-02-08), giving us the C99-portable version
we have now.

While we could remove the __GNUC__ define here, it might cause issues
for other compilers or static analysis systems, so let's not. See
87fe5df (inline constant return from error() function, 2014-05-06)
for one such issue.

See also e05bed9 (trace: add 'file:line' to all trace output,
2014-07-12) for another comment about GNUC's handling of __VA_ARGS__.

Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: avar

git-compat-util.h

@@ -534,9 +534,7 @@ void warning_errno(const char *err, ...) __attribute__((format (printf, 1, 2)));
 /*
  * Let callers be aware of the constant return value; this can help
  * gcc with -Wuninitialized analysis. We restrict this trick to gcc, though,
- * because some compilers may not support variadic macros. Since we're only
- * trying to help gcc, anyway, it's OK; other compilers will fall back to
- * using the function as usual.
+ * because other compilers may be confused by this.
  */
 #if defined(__GNUC__)
 static inline int const_error(void)