Fix T75893: Undo causes crash with "Load UI" disabled.

We need to re-generate a new session uuid for the UI-related data-blocks
that are kept across file reading, when load UI is disabled. Otherwise
there will be several IDs with same uuid, which is an ensured way to
crash in new undo code.

1 files changed, 21 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/blendfile.c b/source/blender/blenkernel/intern/blendfile.c
index 2a53a0b69a4..5c000fbcb36 100644
--- a/source/blender/blenkernel/intern/blendfile.c
+++ b/source/blender/blenkernel/intern/blendfile.c
@@ -201,6 +201,27 @@ static void setup_app_data(bContext *C,
     SWAP(ListBase, bmain->workspaces, bfd->main->workspaces);
     SWAP(ListBase, bmain->screens, bfd->main->screens);
 
+    /* In case of actual new file reading without loading UI, we need to regenerate the session
+     * uuid of the UI-related datablocks we are keeping from previous session, otherwise their uuid
+     * will collide with some generated for newly read data. */
+    if (mode != LOAD_UNDO) {
+      ID *id;
+      FOREACH_MAIN_LISTBASE_ID_BEGIN (&bfd->main->wm, id) {
+        BKE_lib_libblock_session_uuid_renew(id);
+      }
+      FOREACH_MAIN_LISTBASE_ID_END;
+
+      FOREACH_MAIN_LISTBASE_ID_BEGIN (&bfd->main->workspaces, id) {
+        BKE_lib_libblock_session_uuid_renew(id);
+      }
+      FOREACH_MAIN_LISTBASE_ID_END;
+
+      FOREACH_MAIN_LISTBASE_ID_BEGIN (&bfd->main->screens, id) {
+        BKE_lib_libblock_session_uuid_renew(id);
+      }
+      FOREACH_MAIN_LISTBASE_ID_END;
+    }
+
     /* we re-use current window and screen */
     win = CTX_wm_window(C);
     curscreen = CTX_wm_screen(C);