Tables: Fixed command merging when compiling with VS2013. (#6377)

docs/CHANGELOG.txt

@@ -44,6 +44,8 @@ Other changes:
 
 - Tables: Fixed a small miscalculation in TableHeader() leading to an empty tooltip
   showing when a sorting column has no visible name. (#6342) [@lukaasm]
+- Tables: Fixed command merging when compiling with VS2013 (one array on stack was not
+  initialized on VS2013. Unsure if due to a bug or UB/standard conformance). (#6377)
 - InputText: Avoid setting io.WantTextInputNextFrame during the deactivation frame.
   (#6341) [@lukaasm]
 - Nav: Fixed navigation within tables/columns where item boundaries goes beyond columns limits,

imgui_tables.cpp

@@ -2383,11 +2383,11 @@ void ImGui::TableMergeDrawChannels(ImGuiTable* table)
     struct MergeGroup
     {
         ImRect          ClipRect;
-        int             ChannelsCount;
+        int             ChannelsCount = 0;
-        ImBitArrayPtr   ChannelsMask;
+        ImBitArrayPtr   ChannelsMask = NULL;
     };
     int merge_group_mask = 0x00;
-    MergeGroup merge_groups[4] = {};
+    MergeGroup merge_groups[4];
 
     // Use a reusable temp buffer for the merge masks as they are dynamically sized.
     const int max_draw_channels = (4 + table->ColumnsCount * 2);