Fix T83875: Converting Proxy to override crashes blender.

Some weird proxies apparently can have a local collection instancing...
Not sure this is even really valid for proxies, but in any case we
cannot override that, just detect and properly cancel the operation
then.

Should be backported to 2.91.1 should we do it.

2 files changed, 20 insertions, 4 deletions

diff --git a/source/blender/editors/object/object_relations.c b/source/blender/editors/object/object_relations.c
index 8ec9f7af184..5caa7c71e83 100644
--- a/source/blender/editors/object/object_relations.c
+++ b/source/blender/editors/object/object_relations.c
@@ -2527,7 +2527,7 @@ static bool convert_proxy_to_override_poll(bContext *C)
   return obact != NULL && obact->proxy != NULL;
 }
 
-static int convert_proxy_to_override_exec(bContext *C, wmOperator *UNUSED(op))
+static int convert_proxy_to_override_exec(bContext *C, wmOperator *op)
 {
   Main *bmain = CTX_data_main(C);
   Scene *scene = CTX_data_scene(C);
@@ -2541,6 +2541,15 @@ static int convert_proxy_to_override_exec(bContext *C, wmOperator *UNUSED(op))
 
   const bool success = BKE_lib_override_library_proxy_convert(bmain, scene, view_layer, ob_proxy);
 
+  if (!success) {
+    BKE_reportf(
+        op->reports,
+        RPT_ERROR_INVALID_INPUT,
+        "Could not create a library override from proxy '%s' (might use already local data?)",
+        ob_proxy->id.name + 2);
+    return OPERATOR_CANCELLED;
+  }
+
   /* Remove the instance empty from this scene, the items now have an overridden collection
    * instead. */
   if (success && is_override_instancing_object) {
diff --git a/source/blender/editors/space_outliner/outliner_tools.c b/source/blender/editors/space_outliner/outliner_tools.c
index e4c3ebfdff5..492fc5c23bc 100644
--- a/source/blender/editors/space_outliner/outliner_tools.c
+++ b/source/blender/editors/space_outliner/outliner_tools.c
@@ -737,7 +737,7 @@ static void id_local_fn(bContext *C,
 }
 
 static void object_proxy_to_override_convert_fn(bContext *C,
-                                                ReportList *UNUSED(reports),
+                                                ReportList *reports,
                                                 Scene *UNUSED(scene),
                                                 TreeElement *UNUSED(te),
                                                 TreeStoreElem *UNUSED(tsep),
@@ -754,8 +754,15 @@ static void object_proxy_to_override_convert_fn(bContext *C,
     return;
   }
 
-  BKE_lib_override_library_proxy_convert(
-      CTX_data_main(C), scene, CTX_data_view_layer(C), ob_proxy);
+  if (!BKE_lib_override_library_proxy_convert(
+          CTX_data_main(C), scene, CTX_data_view_layer(C), ob_proxy)) {
+    BKE_reportf(
+        reports,
+        RPT_ERROR_INVALID_INPUT,
+        "Could not create a library override from proxy '%s' (might use already local data?)",
+        ob_proxy->id.name + 2);
+    return;
+  }
 
   DEG_id_tag_update(&scene->id, ID_RECALC_BASE_FLAGS | ID_RECALC_COPY_ON_WRITE);
   WM_event_add_notifier(C, NC_WINDOW, NULL);