compositor: Enable introspection

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2718>

src/compositor/compositor.c

@@ -1655,11 +1655,19 @@ meta_compositor_is_switching_workspace (MetaCompositor *compositor)
   return priv->switch_workspace_in_progress > 0;
 }
 
+/**
+ * meta_compositor_get_laters:
+ * @compositor: a #MetaCompositor
+ *
+ * Returns: (transfer none): a #MetaLaters
+ */
 MetaLaters *
 meta_compositor_get_laters (MetaCompositor *compositor)
 {
-  MetaCompositorPrivate *priv =
-    meta_compositor_get_instance_private (compositor);
+  MetaCompositorPrivate *priv;
 
+  g_return_val_if_fail (META_IS_COMPOSITOR (compositor), NULL);
+
+  priv = meta_compositor_get_instance_private (compositor);
   return priv->laters;
 }

src/core/display.c

@@ -2859,9 +2859,10 @@ meta_display_get_context (MetaDisplay *display)
 }
 
 /**
- * meta_display_get_compositor: (skip)
+ * meta_display_get_compositor:
  * @display: a #MetaDisplay
  *
+ * Returns: (transfer none): the #MetaCompositor
  */
 MetaCompositor *
 meta_display_get_compositor (MetaDisplay *display)

src/meta/types.h

@@ -20,10 +20,6 @@
 #ifndef META_TYPES_H
 #define META_TYPES_H
 
-/**
- * MetaCompositor: (skip)
- *
- */
 typedef struct _MetaBackend     MetaBackend;
 typedef struct _MetaContext     MetaContext;
 typedef struct _MetaCompositor  MetaCompositor;