From e0ff032711ec1a8cb85a2a9be9a6b0188d7f9db5 Mon Sep 17 00:00:00 2001
From: Bastien Montagne <bastien@blender.org>
Date: Mon, 25 May 2020 15:11:36 +0200
Subject: Fix T76997: bad handling of embedded IDs in partial append.

Code dealing with embedded data was pre-existing proper generic
handling of those by `BKE_library_foreach_ID_link()` - and was never
updated for scene's master collection it would seem...

Note that such fix/refactor is a bit risky at this point in the release
cycle, but on the other end previous situation was really broken. So
finger crossed. :|
---
 source/blender/blenkernel/intern/lib_id.c | 37 ++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 11 deletions(-)

(limited to 'source/blender/blenkernel')

diff --git a/source/blender/blenkernel/intern/lib_id.c b/source/blender/blenkernel/intern/lib_id.c
index 9ef5c549235..9e8c8c36c63 100644
--- a/source/blender/blenkernel/intern/lib_id.c
+++ b/source/blender/blenkernel/intern/lib_id.c
@@ -128,8 +128,6 @@ static void lib_id_library_local_paths(Main *bmain, Library *lib, ID *id)
  */
 static void lib_id_clear_library_data_ex(Main *bmain, ID *id)
 {
-  bNodeTree *ntree = NULL;
-  Key *key = NULL;
   const bool id_in_mainlist = (id->tag & LIB_TAG_NO_MAIN) == 0 &&
                               (id->flag & LIB_EMBEDDED_DATA) == 0;
 
@@ -146,14 +144,11 @@ static void lib_id_clear_library_data_ex(Main *bmain, ID *id)
     }
   }
 
-  /* Internal bNodeTree blocks inside data-blocks also stores id->lib,
-   * make sure this stays in sync. */
-  if ((ntree = ntreeFromID(id))) {
-    lib_id_clear_library_data_ex(bmain, &ntree->id);
-  }
-
-  /* Same goes for shapekeys. */
-  if ((key = BKE_key_from_id(id))) {
+  /* Internal shape key blocks inside data-blocks also stores id->lib,
+   * make sure this stays in sync (note that we do not need any explicit handling for real EMBEDDED
+   * IDs here, this is down automatically in `lib_id_expand_local_cb()`. */
+  Key *key = BKE_key_from_id(id);
+  if (key != NULL) {
     lib_id_clear_library_data_ex(bmain, &key->id);
   }
 }
@@ -310,10 +305,23 @@ void BKE_id_clear_newpoin(ID *id)
 
 static int lib_id_expand_local_cb(LibraryIDLinkCallbackData *cb_data)
 {
+  Main *bmain = cb_data->user_data;
   ID *id_self = cb_data->id_self;
   ID **id_pointer = cb_data->id_pointer;
   int const cb_flag = cb_data->cb_flag;
+
+  if (cb_flag & IDWALK_CB_LOOPBACK) {
+    /* We should never have anything to do with loopback pointers here. */
+    return IDWALK_RET_NOP;
+  }
+
   if (cb_flag & IDWALK_CB_EMBEDDED) {
+    /* Embedded data-blocks need to be made fully local as well. */
+    if (*id_pointer != NULL) {
+      BLI_assert(*id_pointer != id_self);
+
+      lib_id_clear_library_data_ex(bmain, *id_pointer);
+    }
     return IDWALK_RET_NOP;
   }
 
@@ -335,7 +343,7 @@ static int lib_id_expand_local_cb(LibraryIDLinkCallbackData *cb_data)
  */
 void BKE_lib_id_expand_local(Main *bmain, ID *id)
 {
-  BKE_library_foreach_ID_link(bmain, id, lib_id_expand_local_cb, NULL, IDWALK_READONLY);
+  BKE_library_foreach_ID_link(bmain, id, lib_id_expand_local_cb, bmain, IDWALK_READONLY);
 }
 
 /**
@@ -393,6 +401,13 @@ void BKE_lib_id_make_local_generic(Main *bmain, ID *id, const int flags)
         if (ntree && ntree_new) {
           ID_NEW_SET(ntree, ntree_new);
         }
+        if (GS(id->name) == ID_SCE) {
+          Collection *master_collection = ((Scene *)id)->master_collection,
+                     *master_collection_new = ((Scene *)id_new)->master_collection;
+          if (master_collection && master_collection_new) {
+            ID_NEW_SET(master_collection, master_collection_new);
+          }
+        }
 
         if (!lib_local) {
           BKE_libblock_remap(bmain, id, id_new, ID_REMAP_SKIP_INDIRECT_USAGE);
-- 
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