[gtk+] csspathnode: Handle context going away

[Benjamin Otte <otte src gnome org>]

commit ec57c6c10b3a0774a27e11a9279a25b90ce76ed4
Author: Benjamin Otte <otte redhat com>
Date:   Wed Mar 18 18:22:17 2015 +0100

    csspathnode: Handle context going away
    
    Sometimes path nodes can survive longer than the style context that
    created them. Don't crash in those cases.
    
    Fixes startup of mutter.
    
    Testcase included.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=746407

 gtk/gtkcsspathnode.c         |   11 +++++++++++
 gtk/gtkcsspathnodeprivate.h  |    2 ++
 gtk/gtkstylecontext.c        |    7 +++++--
 testsuite/gtk/stylecontext.c |   15 +++++++++++++++
 4 files changed, 33 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkcsspathnode.c b/gtk/gtkcsspathnode.c
index e9b5298..fecb455 100644
--- a/gtk/gtkcsspathnode.c
+++ b/gtk/gtkcsspathnode.c
@@ -157,6 +157,17 @@ gtk_css_path_node_new (GtkStyleContext *context)
 }
 
 void
+gtk_css_path_node_unset_context (GtkCssPathNode *node)
+{
+  gtk_internal_return_if_fail (GTK_IS_CSS_PATH_NODE (node));
+  gtk_internal_return_if_fail (node->context != NULL);
+
+  node->context = NULL;
+
+  gtk_css_node_invalidate_style_provider (GTK_CSS_NODE (node));
+}
+
+void
 gtk_css_path_node_set_widget_path (GtkCssPathNode *node,
                                    GtkWidgetPath  *path)
 {
diff --git a/gtk/gtkcsspathnodeprivate.h b/gtk/gtkcsspathnodeprivate.h
index dd3831c..4c7d60e 100644
--- a/gtk/gtkcsspathnodeprivate.h
+++ b/gtk/gtkcsspathnodeprivate.h
@@ -50,6 +50,8 @@ GType                   gtk_css_path_node_get_type         (void) G_GNUC_CONST;
 
 GtkCssNode *            gtk_css_path_node_new              (GtkStyleContext *context);
 
+void                    gtk_css_path_node_unset_context    (GtkCssPathNode *node);
+
 void                    gtk_css_path_node_set_widget_path  (GtkCssPathNode *node,
                                                             GtkWidgetPath  *path);
 GtkWidgetPath *         gtk_css_path_node_get_widget_path  (GtkCssPathNode *node);
diff --git a/gtk/gtkstylecontext.c b/gtk/gtkstylecontext.c
index bbf629a..3786e35 100644
--- a/gtk/gtkstylecontext.c
+++ b/gtk/gtkstylecontext.c
@@ -365,12 +365,15 @@ gtk_style_context_finalize (GObject *object)
   style_context = GTK_STYLE_CONTEXT (object);
   priv = style_context->priv;
 
+  while (priv->saved_nodes)
+    gtk_style_context_pop_style_node (style_context);
+  if (GTK_IS_CSS_PATH_NODE (priv->cssnode))
+    gtk_css_path_node_unset_context (GTK_CSS_PATH_NODE (priv->cssnode));
+
   gtk_style_context_clear_parent (style_context);
 
   gtk_style_context_set_cascade (style_context, NULL);
 
-  while (priv->saved_nodes)
-    gtk_style_context_pop_style_node (style_context);
   g_object_unref (priv->cssnode);
 
   gtk_style_context_clear_property_cache (style_context);
diff --git a/testsuite/gtk/stylecontext.c b/testsuite/gtk/stylecontext.c
index fcbc0a1..4d6438c 100644
--- a/testsuite/gtk/stylecontext.c
+++ b/testsuite/gtk/stylecontext.c
@@ -352,6 +352,20 @@ test_set_widget_path_saved (void)
   g_object_unref (context);
 }
 
+void
+test_widget_path_parent (void)
+{
+  GtkStyleContext *parent, *context;
+
+  parent = gtk_style_context_new ();
+  context = gtk_style_context_new ();
+
+  gtk_style_context_set_parent (context, parent);
+
+  g_object_unref (parent);
+  g_object_unref (context);
+}
+
 int
 main (int argc, char *argv[])
 {
@@ -364,6 +378,7 @@ main (int argc, char *argv[])
   g_test_add_func ("/style/basic", test_basic_properties);
   g_test_add_func ("/style/invalidate-saved", test_invalidate_saved);
   g_test_add_func ("/style/set-widget-path-saved", test_set_widget_path_saved);
+  g_test_add_func ("/style/widget-path-parent", test_widget_path_parent);
 
   return g_test_run ();
 }