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dnl visibility.m4 serial 1 (gettext-0.15)
dnl Copyright (C) 2005 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl 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 Modified for use in wxWidgets by Vaclav Slavik:
dnl - don't define HAVE_VISIBILITY (=0) if not supported
dnl - use -fvisibility-inlines-hidden too
dnl - test in C++ mode
dnl Tests whether the compiler supports the command-line option
dnl -fvisibility=hidden and the function and variable attributes
dnl __attribute__((__visibility__("hidden"))) and
dnl __attribute__((__visibility__("default"))).
dnl Does *not* test for __visibility__("protected") - which has tricky
dnl semantics (see the 'vismain' test in glibc) and does not exist e.g. on
dnl MacOS X.
dnl Does *not* test for __visibility__("internal") - which has processor
dnl dependent semantics.
dnl Does *not* test for #pragma GCC visibility push(hidden) - which is
dnl "really only recommended for legacy code".
dnl Set the variable CFLAG_VISIBILITY.
dnl Defines and sets the variable HAVE_VISIBILITY.
AC_DEFUN([WX_VISIBILITY],
[
AC_REQUIRE([AC_PROG_CC])
if test -n "$GCC"; then
CFLAGS_VISIBILITY="-fvisibility=hidden"
CXXFLAGS_VISIBILITY="-fvisibility=hidden -fvisibility-inlines-hidden"
AC_MSG_CHECKING([for symbols visibility support])
AC_CACHE_VAL(wx_cv_cc_visibility, [
wx_save_CXXFLAGS="$CXXFLAGS"
CXXFLAGS="$CXXFLAGS $CXXFLAGS_VISIBILITY"
AC_LANG_PUSH(C++)
AC_TRY_COMPILE(
[
/* we need gcc >= 4.0, older versions with visibility support
didn't have class visibility: */
#if defined(__GNUC__) && __GNUC__ < 4
error this gcc is too old;
#endif
/* visibility only makes sense for ELF shared libs: */
#if !defined(__ELF__) && !defined(__APPLE__)
error this platform has no visibility;
#endif
/* At the time of Xcode 4.1 / Clang 3, Clang++ still didn't
have the bugs sorted out. These were fixed starting with
Xcode 4.6.0 / Apple Clang 4.2 (which is based on Clang 3.2 so
check for that version too). */
#ifdef __clang__
#ifdef __APPLE__
#if __clang_major__ < 4 \
|| (__clang_major__ == 4 && __clang_minor__ < 2)
error Clang compiler version < 4.2 is broken w.r.t. visibility;
#endif
#else
#if __clang_major__ < 3 \
|| (__clang_major__ == 3 && __clang_minor__ < 2)
error Clang compiler version < 3.2 is broken w.r.t. visibility;
#endif
#endif
#endif
extern __attribute__((__visibility__("hidden"))) int hiddenvar;
extern __attribute__((__visibility__("default"))) int exportedvar;
extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void);
extern __attribute__((__visibility__("default"))) int exportedfunc (void);
class __attribute__((__visibility__("default"))) Foo {
Foo() {}
};
],
[],
wx_cv_cc_visibility=yes,
wx_cv_cc_visibility=no)
AC_LANG_POP()
CXXFLAGS="$wx_save_CXXFLAGS"])
AC_MSG_RESULT([$wx_cv_cc_visibility])
if test $wx_cv_cc_visibility = yes; then
dnl we do have basic visibility support, now check if we can use it:
dnl
dnl Debian/Ubuntu's gcc 4.1 is affected:
dnl https://bugs.launchpad.net/ubuntu/+source/gcc-4.1/+bug/109262
AC_MSG_CHECKING([for broken libstdc++ visibility])
AC_CACHE_VAL(wx_cv_cc_broken_libstdcxx_visibility, [
wx_save_CXXFLAGS="$CXXFLAGS"
wx_save_LDFLAGS="$LDFLAGS"
CXXFLAGS="$CXXFLAGS $CXXFLAGS_VISIBILITY"
LDFLAGS="$LDFLAGS -shared -fPIC"
AC_LANG_PUSH(C++)
AC_TRY_LINK(
[
#include <string>
],
[
std::string s("hello");
return s.length();
],
wx_cv_cc_broken_libstdcxx_visibility=no,
wx_cv_cc_broken_libstdcxx_visibility=yes)
AC_LANG_POP()
CXXFLAGS="$wx_save_CXXFLAGS"
LDFLAGS="$wx_save_LDFLAGS"])
AC_MSG_RESULT([$wx_cv_cc_broken_libstdcxx_visibility])
if test $wx_cv_cc_broken_libstdcxx_visibility = yes; then
AC_MSG_CHECKING([whether we can work around it])
AC_CACHE_VAL(wx_cv_cc_visibility_workaround, [
AC_LANG_PUSH(C++)
AC_TRY_LINK(
[
#pragma GCC visibility push(default)
#include <string>
#pragma GCC visibility pop
],
[
std::string s("hello");
return s.length();
],
wx_cv_cc_visibility_workaround=no,
wx_cv_cc_visibility_workaround=yes)
AC_LANG_POP()
])
AC_MSG_RESULT([$wx_cv_cc_visibility_workaround])
if test $wx_cv_cc_visibility_workaround = no; then
dnl we can't use visibility at all then
wx_cv_cc_visibility=no
fi
fi
fi
if test $wx_cv_cc_visibility = yes; then
AC_DEFINE([HAVE_VISIBILITY])
if test $wx_cv_cc_broken_libstdcxx_visibility = yes; then
AC_DEFINE([HAVE_BROKEN_LIBSTDCXX_VISIBILITY])
fi
else
CFLAGS_VISIBILITY=""
CXXFLAGS_VISIBILITY=""
fi
AC_SUBST([CFLAGS_VISIBILITY])
AC_SUBST([CXXFLAGS_VISIBILITY])
fi
])
|
