[PATCH] avoid GCC 10 test suite warnings (BZ #25219)

[DJ Delorie]

Martin Sebor <msebor@gmail.com> writes:
> +#if __GNUC_PREREQ (7, 0)
> +  DIAG_PUSH_NEEDS_COMMENT;
> +  /* Avoid warnings about the second (size) argument being negative.  */
> +  DIAG_IGNORE_NEEDS_COMMENT (10.1, "-Wstringop-overflow");

This means "for gcc 7.0 or higher, ignore -Wstringop-overflow, and
remember that gcc 10.1 was the last version we saw that needed this."

I'm not sure that's what you intended ;-)

(also DIAG_IGNORE_NEEDS_COMMENT's comment says major version only,
although it totally ignores the version argument)

 - - - - -

/* Convenience macro to test the version of gcc.
   Use like this:
   #if __GNUC_PREREQ (2,8)
   ... code requiring gcc 2.8 or later ...
   #endif
   Note: only works for GCC 2.0 and later, because __GNUC_MINOR__ was
   added in 2.0.  */
#if defined __GNUC__ && defined __GNUC_MINOR__
# define __GNUC_PREREQ(maj, min) \
 . . .

/* Ignore the diagnostic OPTION.  VERSION is the most recent GCC
   version for which the diagnostic has been confirmed to appear in
   the absence of the pragma (in the form MAJOR.MINOR for GCC 4.x,
   just MAJOR for GCC 5 and later).  Uses of this pragma should be
   reviewed when the GCC version given is no longer supported for
   building glibc; the version number should always be on the same
   source line as the macro name, so such uses can be found with grep.
   Uses should come with a comment giving more details of the
   diagnostic, and an architecture on which it is seen if possibly
   optimization-related and not in architecture-specific code.  This
   macro should only be used if the diagnostic seems hard to fix (for
   example, optimization-related false positives).  */
#define DIAG_IGNORE_NEEDS_COMMENT(version, option)     \
  _Pragma (_DIAG_STR (GCC diagnostic ignored option))