Detect GDate autoptr when available.

The GDate autoptr cleanup was finally officially added in
GLib 2.63.3--which is now available in Fedora Rawhide--so stop
defining it ourselves.

https://gitlab.gnome.org/GNOME/glib/merge_requests/1256

Fixes: #414

Signed-off-by: Stephen Gallagher <sgallagh@redhat.com>

meson.build

@@ -59,7 +59,8 @@ with_libmagic = get_option('libmagic')
 rpm = dependency('rpm', required : with_rpmio)
 magic = cc.find_library('magic', required : with_libmagic)
 
-glib_prefix = dependency('glib-2.0').get_pkgconfig_variable('prefix')
+glib = dependency('glib-2.0')
+glib_prefix = glib.get_pkgconfig_variable('prefix')
 
 sh = find_program('sh')
 sed = find_program('sed')
@@ -81,6 +82,20 @@ if with_docs
   endif
 endif
 
+
+# Check whether this version of glib has the GDate autoptr defined
+gdate_check = '''#include <glib.h>
+int main (int argc, char **argv)
+{
+  g_autoptr(GDate) date = NULL;
+  return 0;
+}
+'''
+has_gdate_autoptr = cc.compiles(
+    gdate_check,
+    dependencies : [ glib ],
+    name : 'g_autoptr(GDate)')
+
 python_name = get_option('python_name')
 
 if python_name != ''

modulemd/include/private/glib-extensions.h

@@ -11,6 +11,13 @@
  * For more information on free software, see <https://www.gnu.org/philosophy/free-sw.en.html>.
  */
 
+#pragma once
+
 #include <glib.h>
 
-G_DEFINE_AUTOPTR_CLEANUP_FUNC (GDate, g_date_free);
+#include "config.h"
+
+/* GDate autoptr cleanup was finally added in GLib 2.63.3. */
+#ifndef HAVE_GDATE_AUTOPTR
+G_DEFINE_AUTOPTR_CLEANUP_FUNC (GDate, g_date_free)
+#endif

modulemd/meson.build

@@ -229,6 +229,7 @@ cdata = configuration_data()
 cdata.set_quoted('LIBMODULEMD_VERSION', libmodulemd_version)
 cdata.set('HAVE_RPMIO', rpm.found())
 cdata.set('HAVE_LIBMAGIC', magic.found())
+cdata.set('HAVE_GDATE_AUTOPTR', has_gdate_autoptr)
 configure_file(
   output : 'config.h',
   configuration : cdata