source/blender/blenkernel/intern/layer.cc

@@ -1317,7 +1317,7 @@ void BKE_layer_collection_sync(const Scene *scene, ViewLayer *view_layer)
 
 #ifndef NDEBUG
   {
-    BLI_assert_msg(BLI_listbase_count_at_most(&view_layer->layer_collections, 2) == 1,
+    BLI_assert_msg(BLI_listbase_is_single(&view_layer->layer_collections),
                    "ViewLayer's first level of children layer collections should always have "
                    "exactly one item");
 

source/blender/blenloader/intern/versioning_280.cc

@@ -1257,7 +1257,7 @@ void do_versions_after_linking_280(FileData *fd, Main *bmain)
 
             space_outliner->outlinevis = SO_VIEW_LAYER;
 
-            if (BLI_listbase_count_at_most(&layer->layer_collections, 2) == 1) {
+            if (BLI_listbase_is_single(&layer->layer_collections)) {
               if (space_outliner->treestore == nullptr) {
                 space_outliner->treestore = BLI_mempool_create(
                     sizeof(TreeStoreElem), 1, 512, BLI_MEMPOOL_ALLOW_ITER);

source/blender/editors/armature/pose_transform.c

@@ -864,7 +864,7 @@ static int pose_paste_exec(bContext *C, wmOperator *op)
     return OPERATOR_CANCELLED;
   }
   /* Make sure data from this file is usable for pose paste. */
-  if (BLI_listbase_count_at_most(&temp_bmain->objects, 2) != 1) {
+  if (!BLI_listbase_is_single(&temp_bmain->objects)) {
     BKE_report(op->reports, RPT_ERROR, "Internal clipboard is not from pose mode");
     BKE_main_free(temp_bmain);
     return OPERATOR_CANCELLED;

source/blender/windowmanager/intern/wm_dragdrop.cc

@@ -832,7 +832,7 @@ const char *WM_drag_get_item_name(wmDrag *drag)
   switch (drag->type) {
     case WM_DRAG_ID: {
       ID *id = WM_drag_get_local_ID(drag, 0);
-      bool single = (BLI_listbase_count_at_most(&drag->ids, 2) == 1);
+      bool single = BLI_listbase_is_single(&drag->ids);
 
       if (single) {
         return id->name + 2;