Fix T44439: outliner's treestore could keep invalid ID pointers, could crash on undo due to invalid mem access.

We cannot nuke treestore in readfile's `blo_lib_link_screen_restore()`, because this will
destroy all UI-state data (like opened/closed items, etc.).

Since we cannot know for sure whether an ID pointer from tselem->id is valid here, we
have to ensure they are never invalid, i.e. to always set them to NULL when we delete them.

To do so, this commit uses a similar approach as what already exists for ID references
in WM notifiers - it extends `free_notifier_reference_cb()` to also nullify those IDs in
all outliners.

Note that some ID types are not used(shown) by outliner currently, so `TREESTORE_ID_TYPE` macro
was added, that checks whether an ID is possibly used by outliner. Avoids a few searches
in whole tree whene deleting some IDs.

Reviewers: campbellbarton, sergey

Maniphest Tasks: T44439

Differential Revision: https://developer.blender.org/D1272

1 files changed, 36 insertions, 0 deletions

diff --git a/source/blender/editors/include/ED_outliner.h b/source/blender/editors/include/ED_outliner.h
new file mode 100644
index 00000000000..af4af8e2f5d
--- /dev/null
+++ b/source/blender/editors/include/ED_outliner.h
@@ -0,0 +1,36 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2015, Blender Foundation
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file ED_outliner.h
+ *  \ingroup editors
+ */
+
+#ifndef __ED_OUTLINER_H__
+#define __ED_OUTLINER_H__
+
+struct ID;
+struct SpaceOops;
+
+/* Used to check whether a given texture context is valid in current context. */
+void ED_outliner_id_unref(struct SpaceOops *so, const struct ID *id);
+
+#endif /*  __ED_OUTLINER_H__ */