test for visibility

[James K. Lowden]

I would like to be able to test whether or not the preprocessor
supports the visibility pragma.   My program today says:

#if defined(__GNUC__) && __GNUC__ >= 4 && !defined(__MINGW32__)
#pragma GCC visibility push(hidden)
#endif

which cries out for a feature test

#if HAVE_PRAGMA_VISIBILITY
#pragma GCC visibility push(hidden)
#endif

because e.g. clang defines GCC. 

My search of the docs and the m4 macro archive didn't turn up anything,
so I thought maybe I'd contribute one.  The macro below almost works,
but for the fact that clang only warns about the construct.  (It is
the warnings I would like to squelch.)  

How do I tell the compiler to use -Werror within an m4 macro?  I see
AC_LANG_WERROR and AC_PROG_CPP_WERROR, but afaict they aren't available
within m4.  Alternatively, how can I construct a macro that returns
"no" if the compiler issues a diagnostic?  

Text of the macro follows.  Many thanks for your advice.  

--jkl

dnl Test whether or not the compiler supports visibility
AC_DEFUN([AC_HAVE_PRAGMA_VISIBILITY],
 [AC_CACHE_CHECK([whether the compiler supports visibility],
   ac_cv_have_pragma_visibility,
   [AC_LINK_IFELSE([AC_LANG_PROGRAM([
#pragma GCC visibility push(hidden)
      ],[
int i;
      ])],
     ac_cv_have_pragma_visibility=yes,
     ac_cv_have_pragma_visibility=no)])
  if test $ac_cv_have_pragma_visibility = yes; then
   AC_DEFINE(HAVE_PRAGMA_VISIBILITY, 1, 
        [Define to 1 if your system supports pragma GCC visibility.])
  fi])