[Bug preprocessor/22428] New: __extension__ won't silence pedwarns about hex float constants

["bje at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

The __extension__ keyword does not silence pedwarns about hexadecimal floating
point constants.  This is used by GNU libc, for example in the definition of
INFINITY:

#  define HUGE_VALF (__extension__ 0x1.0p255f)
#  define HUGE_VALL (__extension__ 0x1.0p32767L)

These macros produce warnings that cannot be silenced.  This appears not to work
because the pedwarn is generated by the preprocessor.

-- 
           Summary: __extension__ won't silence pedwarns about hex float
                    constants
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: preprocessor
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: bje at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org
  GCC host triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22428