# visibility.m4 serial 1 (gettext-0.15)dnl Copyright (C) 2005 Free Software Foundation, Inc.dnl This file is free software; the Free Software Foundationdnl gives unlimited permission to copy and/or distribute it,dnl with or without modifications, as long as this notice is preserved.dnl From Bruno Haible.dnl Tests whether the compiler supports the command-line optiondnl -fvisibility=hidden and the function and variable attributesdnl __attribute__((__visibility__("hidden"))) anddnl __attribute__((__visibility__("default"))).dnl Does *not* test for __visibility__("protected") - which has trickydnl semantics (see the 'vismain' test in glibc) and does not exist e.g. ondnl MacOS X.dnl Does *not* test for __visibility__("internal") - which has processordnl dependent semantics.dnl Does *not* test for #pragma GCC visibility push(hidden) - which isdnl "really only recommended for legacy code".dnl Set the variable CFLAG_VISIBILITY.dnl Defines and sets the variable HAVE_VISIBILITY.AC_DEFUN([gl_VISIBILITY],[  AC_REQUIRE([AC_PROG_CC])  CFLAG_VISIBILITY=  HAVE_VISIBILITY=0  if test -n "$GCC"; then    AC_MSG_CHECKING([for simple visibility declarations])    AC_CACHE_VAL(gl_cv_cc_visibility, [      gl_save_CFLAGS="$CFLAGS"      CFLAGS="$CFLAGS -fvisibility=hidden"      AC_TRY_COMPILE(        [extern __attribute__((__visibility__("hidden"))) int hiddenvar;         extern __attribute__((__visibility__("default"))) int exportedvar;         extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void);         extern __attribute__((__visibility__("default"))) int exportedfunc (void);],        [],        gl_cv_cc_visibility=yes,        gl_cv_cc_visibility=no)      CFLAGS="$gl_save_CFLAGS"])    AC_MSG_RESULT([$gl_cv_cc_visibility])    if test $gl_cv_cc_visibility = yes; then      CFLAG_VISIBILITY="-fvisibility=hidden"      HAVE_VISIBILITY=1    fi  fi  AC_SUBST([CFLAG_VISIBILITY])  AC_SUBST([HAVE_VISIBILITY])  AC_DEFINE_UNQUOTED([HAVE_VISIBILITY], [$HAVE_VISIBILITY],    [Define to 1 or 0, depending whether the compiler supports simple visibility declarations.])])