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 $CXXFLAGS_VISIBILITY"
  38       AC_LANG_PUSH(C++)
  39       AC_TRY_COMPILE(
  40         [
  41          /* we need gcc >= 4.0, older versions with visibility support
  42             didn't have class visibility: */
  43          #if defined(__GNUC__) && __GNUC__ < 4
  44          error this gcc is too old;
  45          #endif
  46
  47          /* visibility only makes sense for ELF shared libs: */
  48          #if !defined(__ELF__) && !defined(__APPLE__)
  49          error this platform has no visibility;
  50          #endif
  51
  52          /* at the time of Xcode 4.1 / Clang 3, Clang++ still didn't have the bugs sorted out: */
  53          #if defined(__clang__)
  54          clang compiler is still broken w.r.t. visibility;
  55          #endif
  56
  57          extern __attribute__((__visibility__("hidden"))) int hiddenvar;
  58          extern __attribute__((__visibility__("default"))) int exportedvar;
  59          extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void);
  60          extern __attribute__((__visibility__("default"))) int exportedfunc (void);
  61          class __attribute__((__visibility__("default"))) Foo {
  62            Foo() {}
  63          };
  64         ],
  65         [],
  66         wx_cv_cc_visibility=yes,
  67         wx_cv_cc_visibility=no)
  68       AC_LANG_POP()
  69       CXXFLAGS="$wx_save_CXXFLAGS"])
  70     AC_MSG_RESULT([$wx_cv_cc_visibility])
  71     if test $wx_cv_cc_visibility = yes; then
  72       dnl we do have basic visibility support, now check if we can use it:
  73       dnl
  74       dnl Debian/Ubuntu's gcc 4.1 is affected:
  75       dnl https://bugs.launchpad.net/ubuntu/+source/gcc-4.1/+bug/109262
  76       AC_MSG_CHECKING([for broken libstdc++ visibility])
  77       AC_CACHE_VAL(wx_cv_cc_broken_libstdcxx_visibility, [
  78         wx_save_CXXFLAGS="$CXXFLAGS"
  79         wx_save_LDFLAGS="$LDFLAGS"
  80         CXXFLAGS="$CXXFLAGS $CXXFLAGS_VISIBILITY"
  81         LDFLAGS="$LDFLAGS -shared -fPIC"
  82         AC_LANG_PUSH(C++)
  83         AC_TRY_LINK(
  84           [
  85             #include <string>
  86           ],
  87           [
  88             std::string s("hello");
  89             return s.length();
  90           ],
  91           wx_cv_cc_broken_libstdcxx_visibility=no,
  92           wx_cv_cc_broken_libstdcxx_visibility=yes)
  93         AC_LANG_POP()
  94         CXXFLAGS="$wx_save_CXXFLAGS"
  95         LDFLAGS="$wx_save_LDFLAGS"])
  96       AC_MSG_RESULT([$wx_cv_cc_broken_libstdcxx_visibility])
  97
  98       if test $wx_cv_cc_broken_libstdcxx_visibility = yes; then
  99         AC_MSG_CHECKING([whether we can work around it])
 100         AC_CACHE_VAL(wx_cv_cc_visibility_workaround, [
 101           AC_LANG_PUSH(C++)
 102           AC_TRY_LINK(
 103             [
 104               #pragma GCC visibility push(default)
 105               #include <string>
 106               #pragma GCC visibility pop
 107             ],
 108             [
 109               std::string s("hello");
 110               return s.length();
 111             ],
 112             wx_cv_cc_visibility_workaround=no,
 113             wx_cv_cc_visibility_workaround=yes)
 114           AC_LANG_POP()
 115         ])
 116         AC_MSG_RESULT([$wx_cv_cc_visibility_workaround])
 117
 118         if test $wx_cv_cc_visibility_workaround = no; then
 119           dnl we can't use visibility at all then
 120           wx_cv_cc_visibility=no
 121         fi
 122       fi
 123     fi
 124
 125     if test $wx_cv_cc_visibility = yes; then
 126       AC_DEFINE([HAVE_VISIBILITY])
 127       if test $wx_cv_cc_broken_libstdcxx_visibility = yes; then
 128         AC_DEFINE([HAVE_BROKEN_LIBSTDCXX_VISIBILITY])
 129       fi
 130     else
 131       CFLAGS_VISIBILITY=""
 132       CXXFLAGS_VISIBILITY=""
 133     fi
 134     AC_SUBST([CFLAGS_VISIBILITY])
 135     AC_SUBST([CXXFLAGS_VISIBILITY])
 136   fi
 137 ])