build/aclocal/visibility.m4

   1 dnl visibility.m4 serial 1 (gettext-0.15)
   2 dnl Copyright (C) 2005 Free Software Foundation, Inc.
   3 dnl This file is free software; the Free Software Foundation
   4 dnl gives unlimited permission to copy and/or distribute it,
   5 dnl with or without modifications, as long as this notice is preserved.
   6
   7 dnl From Bruno Haible.
   8
   9 dnl Modified for use in wxWidgets by Vaclav Slavik:
  10 dnl    - don't define HAVE_VISIBILITY (=0) if not supported
  11 dnl    - use -fvisibility-inlines-hidden too
  12 dnl    - test in C++ mode
  13
  14 dnl Tests whether the compiler supports the command-line option
  15 dnl -fvisibility=hidden and the function and variable attributes
  16 dnl __attribute__((__visibility__("hidden"))) and
  17 dnl __attribute__((__visibility__("default"))).
  18 dnl Does *not* test for __visibility__("protected") - which has tricky
  19 dnl semantics (see the 'vismain' test in glibc) and does not exist e.g. on
  20 dnl MacOS X.
  21 dnl Does *not* test for __visibility__("internal") - which has processor
  22 dnl dependent semantics.
  23 dnl Does *not* test for #pragma GCC visibility push(hidden) - which is
  24 dnl "really only recommended for legacy code".
  25 dnl Set the variable CFLAG_VISIBILITY.
  26 dnl Defines and sets the variable HAVE_VISIBILITY.
  27
  28 AC_DEFUN([WX_VISIBILITY],
  29 [
  30   AC_REQUIRE([AC_PROG_CC])
  31   if test -n "$GCC"; then
  32     CFLAGS_VISIBILITY="-fvisibility=hidden"
  33     CXXFLAGS_VISIBILITY="-fvisibility=hidden -fvisibility-inlines-hidden"
  34     AC_MSG_CHECKING([for symbols visibility support])
  35     AC_CACHE_VAL(wx_cv_cc_visibility, [
  36       wx_save_CXXFLAGS="$CXXFLAGS"
  37       CXXFLAGS="$CXXFLAGS $CXXFLAGS_VISIBILITY"
  38       AC_LANG_PUSH(C++)
  39       AC_TRY_COMPILE(
  40         [
  41          /* we need gcc >= 4.0, older versions with visibility support
  42             didn't have class visibility: */
  43          #if defined(__GNUC__) && __GNUC__ < 4
  44          error this gcc is too old;
  45          #endif
  46
  47          extern __attribute__((__visibility__("hidden"))) int hiddenvar;
  48          extern __attribute__((__visibility__("default"))) int exportedvar;
  49          extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void);
  50          extern __attribute__((__visibility__("default"))) int exportedfunc (void);
  51          class __attribute__((__visibility__("default"))) Foo {
  52            Foo() {}
  53          };
  54         ],
  55         [],
  56         wx_cv_cc_visibility=yes,
  57         wx_cv_cc_visibility=no)
  58       AC_LANG_POP()
  59       CXXFLAGS="$wx_save_CXXFLAGS"])
  60     AC_MSG_RESULT([$wx_cv_cc_visibility])
  61     if test $wx_cv_cc_visibility = yes; then
  62       AC_DEFINE([HAVE_VISIBILITY])
  63     else
  64       CFLAGS_VISIBILITY=""
  65       CXXFLAGS_VISIBILITY=""
  66     fi
  67     AC_SUBST([CFLAGS_VISIBILITY])
  68     AC_SUBST([CXXFLAGS_VISIBILITY])
  69   fi
  70 ])