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configure.ac: change our visibility policy

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Check for -fvisibility=hidden as a supported CFLAG.

If it is supported, use it and emit an AC_DEFINE to change the meaning
of _GLIB_EXTERN to include the GNU attribute for marking symbols as
public: __attribute((visibility("default"))).

This will override the public definition of _GLIB_EXTERN for any file
which does #include "config.h" (forcing all our .c files to do so, as a
side effect).

If we're on mingw, assume that -fvisibility will work and also throw in
a __declspec(dllexport) for good measure.  This will allow us to move
away from using a .def file to create the the various DLLs.

It's possible that there may be compilers that accept
-fvisibility=hidden but don't accept the GNU attribute for making
symbols public again -- we will hopefully receive bugs if any of those
exist.

https://bugzilla.gnome.org/show_bug.cgi?id=688681
This commit is contained in:
Ryan Lortie 2012-12-06 13:42:06 -05:00
parent f13d3c075f
commit 2e7669f5cc
1 changed files with 31 additions and 0 deletions
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31
configure.ac
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@ -3566,6 +3566,37 @@ fi
AC_SUBST(GLIB_LINK_FLAGS)
dnl
dnl Check for -fvisibility=hidden to determine if we can do GNU-style
dnl visibility attributes for symbol export control
dnl
case "$host" in
*-*-mingw*)
dnl on mingw32 we do -fvisibility=hidden and __declspec(dllexport)
AC_DEFINE([_GLIB_EXTERN], [__attribute__((visibility("default"))) __declspec(dllexport) extern],
[defines how to decorate public symbols while building])
CFLAGS="${CFLAGS} -fvisibility=hidden"
;;
*)
dnl on other compilers, check if we can do -fvisibility=hidden
SAVED_CFLAGS="${CFLAGS}"
CFLAGS="-fvisibility=hidden"
AC_MSG_CHECKING([for -fvisibility=hidden compiler flag])
AC_TRY_COMPILE([], [int main (void) { return 0; }],
AC_MSG_RESULT(yes)
enable_fvisibility_hidden=yes,
AC_MSG_RESULT(no)
enable_fvisibility_hidden=no)
CFLAGS="${SAVED_CFLAGS}"
AS_IF([test "${enable_fvisibility_hidden}" = "yes"], [
AC_DEFINE([_GLIB_EXTERN], [__attribute__((visibility("default"))) extern],
[defines how to decorate public symbols while building])
CFLAGS="${CFLAGS} -fvisibility=hidden"
])
;;
esac
dnl Compiler flags; macro originates from systemd
dnl See https://bugzilla.gnome.org/show_bug.cgi?id=608953
CC_CHECK_FLAGS_APPEND([with_cflags], [CFLAGS], [\