[Bf-blender-cvs] [544ddcdaac2] master: Fix (studio-reported) liboverride resync crash after recent changes.

[Bastien Montagne]

Commit: 544ddcdaac20bab7707a49edbd31b8ae38446603
Author: Bastien Montagne
Date:   Wed Jul 28 12:24:07 2021 +0200
Branches: master
https://developer.blender.org/rB544ddcdaac20bab7707a49edbd31b8ae38446603

Fix (studio-reported) liboverride resync crash after recent changes.

Recent own rBabf3ce811f6e prevented any LayerCollection update during
the whole liboverride resync process, for both performances and feature
reasons.

However that means that the various runtime caches like the Base GHash
are not cleared anymore during ID remapping process, so we need to call
`BKE_main_collection_sync_remap` instead of `BKE_main_collection_sync`
when we finally are ready for this update.

Reported by @eyecandy (Andy Goralczyk) from Blender studio, thanks!

===================================================================

M	source/blender/blenkernel/intern/layer.c
M	source/blender/blenkernel/intern/lib_override.c

===================================================================

diff --git a/source/blender/blenkernel/intern/layer.c b/source/blender/blenkernel/intern/layer.c
index 61b031396dd..23ea306c1a8 100644
--- a/source/blender/blenkernel/intern/layer.c
+++ b/source/blender/blenkernel/intern/layer.c
@@ -748,6 +748,11 @@ int BKE_layer_collection_findindex(ViewLayer *view_layer, const LayerCollection
  *
  * WARNING: This is not threadsafe at all, only use from main thread.
  *
+ * NOTE: It is probably needed to use #BKE_main_collection_sync_remap instead
+ *       of just #BKE_main_collection_sync after disabling LayerCollection resync,
+ *       unless it is absolutely certain that no ID remapping (or any other process
+ *       that may invalidate the caches) will happen while it is disabled.
+ *
  * NOTE: This is a quick and safe band-aid around the long-known issue
  *       regarding this resync process.
  *       Proper fix would be to make resync itself lazy, i.e. only happen
diff --git a/source/blender/blenkernel/intern/lib_override.c b/source/blender/blenkernel/intern/lib_override.c
index 8b63594955f..8e67547b719 100644
--- a/source/blender/blenkernel/intern/lib_override.c
+++ b/source/blender/blenkernel/intern/lib_override.c
@@ -772,7 +772,11 @@ static void lib_override_library_create_post_process(Main *bmain,
   /* NOTE: We only care about local IDs here, if a linked object is not instantiated in any way we
    * do not do anything about it. */
 
-  BKE_main_collection_sync(bmain);
+  /* We need to use the `_remap` version here as we prevented any LayerCollection resync during the
+   * whole liboverride resyncing, which involves a lot of ID remapping.
+   *
+   * Otherwise, cached Base GHash e.g. can contain invalid stale data. */
+  BKE_main_collection_sync_remap(bmain);
 
   /* We create a set of all objects referenced into the scene by its hierarchy of collections.
    * NOTE: This is different that the list of bases, since objects in excluded collections etc.