Fix OpenSUSE Leap build

lib/App.vala

@@ -158,8 +158,13 @@ public class Gala.App : GLib.Object {
         return windows.data;
     }
 
+#if VALA_0_56_17
     public GLib.SList<pid_t?> get_pids () {
         var results = new GLib.SList<pid_t?> ();
+#else
+    public GLib.SList<int?> get_pids () {
+        var results = new GLib.SList<int?> ();
+#endif
         foreach (unowned var window in windows) {
             var pid = window.get_pid ();
             if (pid < 1) {

meson.build

@@ -11,14 +11,7 @@ gnome = import('gnome')
 i18n = import('i18n')
 pkg = import('pkgconfig')
 cc = meson.get_compiler('c')
-
-gala_version = meson.project_version()
-
-vala_version_required = '0.46.0'
 vala = meson.get_compiler('vala')
-if not vala.version().version_compare('>= @0@'.format(vala_version_required))
-    error('Valac >= @0@ required!'.format(vala_version_required))
-endif
 
 vapi_dir = meson.current_source_dir() / 'vapi'
 
@@ -35,7 +28,7 @@ conf.set_quoted('DATADIR', data_dir)
 conf.set_quoted('PKGDATADIR', pkgdata_dir)
 conf.set_quoted('PLUGINDIR', plugins_dir)
 conf.set_quoted('RESOURCEPATH', '/org/pantheon/desktop/gala')
-conf.set_quoted('VERSION', gala_version)
+conf.set_quoted('VERSION', meson.project_version())
 config_h = configure_file(
     output: 'config.h',
     configuration: conf
@@ -158,6 +151,10 @@ if get_option('systemd')
     vala_flags += ['--define', 'WITH_SYSTEMD']
 endif
 
+if vala.version().version_compare('>= 0.56.17')
+    vala_flags += ['--define', 'VALA_0_56_17']
+endif
+
 add_project_arguments(vala_flags, language: 'vala')
 add_project_link_arguments(['-Wl,-rpath,@0@'.format(mutter_typelib_dir)], language: 'c')
 

src/Gestures/ActorTarget.vala

@@ -30,7 +30,11 @@ public class Gala.ActorTarget : Clutter.Actor, GestureTarget {
         current_commit = new double[GestureAction.N_ACTIONS];
         targets = new Gee.ArrayList<GestureTarget> ();
 
+#if HAS_MUTTER46
         child_added.connect (on_child_added);
+#else
+        actor_added.connect (on_child_added);
+#endif
     }
 
     private void sync_target (GestureTarget target) {

src/WindowTracker.vala

@@ -52,7 +52,11 @@ public class Gala.WindowTracker : GLib.Object {
         return get_app_from_id (id);
     }
 
+#if VALA_0_56_17
     private static unowned Gala.App? get_app_from_pid (pid_t pid) {
+#else
+    private static unowned Gala.App? get_app_from_pid (int pid) {
+#endif
         var running_apps = Gala.AppSystem.get_default ().get_running_apps ();
         foreach (unowned Gala.App app in running_apps) {
             var app_pids = app.get_pids ();

vapi/libmutter.vapi

@@ -968,7 +968,11 @@ namespace Meta {
 		public Meta.MaximizeFlags get_maximized ();
 		public int get_monitor ();
 		public unowned string? get_mutter_hints ();
+#if VALA_0_56_17
 		public pid_t get_pid ();
+#else
+		public int get_pid ();
+#endif
 		public unowned string get_role ();
 		public unowned string? get_sandboxed_app_id ();
 		public uint get_stable_sequence ();