[glib] Use a real test for G_HAVE_GNUC_VISIBILITY

[LRN <ruslanizhb src gnome org>]

commit a9c65317d30dc1acacdcf4846b4d61e93ccf5e25
Author: Руслан Ижбулатов <lrn1986 gmail com>
Date:   Fri Mar 23 18:26:01 2018 +0000

    Use a real test for G_HAVE_GNUC_VISIBILITY
    
    Accurate G_HAVE_GNUC_VISIBILITY is needed to correctly
    define G_GNUC_INTERNAL later on. Autotools did that,
    meson currently doesn't and opts to just set
    G_HAVE_GNUC_VISIBILITY to 1 for all compilers except MSVC.
    This leads to MinGW GCC having G_HAVE_GNUC_VISIBILITY=1,
    which results in G_GNUC_INTERNAL being defined to
    __attribute__((visibility("hidden"))), which is not supported.
    
    Because cc.compiles() does not support override_options or
    anything like that, we just feed it '-Werror' as-is, since
    MSVC is known as not supporting visibility attributes anyway.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=794636

 glib/glibconfig.h.in |  2 +-
 meson.build          | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)
---
diff --git a/glib/glibconfig.h.in b/glib/glibconfig.h.in
index fb456a972..2bf6c43c1 100644
--- a/glib/glibconfig.h.in
+++ b/glib/glibconfig.h.in
@@ -133,10 +133,10 @@ typedef unsigned @glib_intptr_type_define@ guintptr;
 #endif
 
 #mesondefine G_HAVE_GROWING_STACK
+#mesondefine G_HAVE_GNUC_VISIBILITY
 
 #ifndef _MSC_VER
 # define G_HAVE_GNUC_VARARGS 1
-# define G_HAVE_GNUC_VISIBILITY 1
 #endif
 
 #if defined(__SUNPRO_C) && (__SUNPRO_C >= 0x590)
diff --git a/meson.build b/meson.build
index 9f08db92b..26689a6e4 100644
--- a/meson.build
+++ b/meson.build
@@ -112,6 +112,47 @@ if host_system == 'windows'
   glib_conf.set('BROKEN_POLL', true)
 endif
 
+# Check for GNU visibility attributes
+g_have_gnuc_visibility = cc.compiles('''
+  void
+  __attribute__ ((visibility ("hidden")))
+       f_hidden (void)
+  {
+  }
+  void
+  __attribute__ ((visibility ("internal")))
+       f_internal (void)
+  {
+  }
+  void
+  __attribute__ ((visibility ("protected")))
+       f_protected (void)
+  {
+  }
+  void
+  __attribute__ ((visibility ("default")))
+       f_default (void)
+  {
+  }
+  int main (void)
+  {
+    f_hidden();
+    f_internal();
+    f_protected();
+    f_default();
+    return 0;
+  }
+  ''',
+  # Not supported by MSVC, but MSVC also won't support visibility,
+  # so it's OK to pass -Werror explicitly. Replace with
+  # override_options : 'werror=true' once that is supported
+  args: ['-Werror'],
+  name : 'GNU C visibility attributes test')
+
+if g_have_gnuc_visibility
+  glibconfig_conf.set('G_HAVE_GNUC_VISIBILITY', '1')
+endif
+
 # Detect and set symbol visibility
 glib_hidden_visibility_args = []
 if get_option('default_library') != 'static'