Backends: Metal: Fixed null dereference inside command buffer completion handler. (#5363, #5365)

backends/imgui_impl_metal.mm

@@ -12,6 +12,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2022-06-01: Metal: Fixed null dereference on exit inside command buffer completion handler.
 //  2022-04-27: Misc: Store backend data in a per-context struct, allowing to use this backend with multiple contexts.
 //  2022-01-03: Metal: Ignore ImDrawCmd where ElemCount == 0 (very rare but can technically be manufactured by user code).
 //  2021-12-30: Metal: Added Metal C++ support. Enable with '#define IMGUI_IMPL_METAL_CPP' in your imconfig.h file.
@@ -293,8 +294,11 @@ void ImGui_ImplMetal_RenderDrawData(ImDrawData* drawData, id<MTLCommandBuffer> c
     {
         dispatch_async(dispatch_get_main_queue(), ^{
             ImGui_ImplMetal_Data* bd = ImGui_ImplMetal_GetBackendData();
-            [bd->SharedMetalContext.bufferCache addObject:vertexBuffer];
-            [bd->SharedMetalContext.bufferCache addObject:indexBuffer];
+            if (bd != NULL)
+            {
+                [bd->SharedMetalContext.bufferCache addObject:vertexBuffer];
+                [bd->SharedMetalContext.bufferCache addObject:indexBuffer];
+            }
         });
     }];
 }

docs/CHANGELOG.txt

@@ -126,6 +126,7 @@ Other Changes:
 - Backends: OSX: Monitor NSKeyUp events to catch missing keyUp for key when user press Cmd + key (#5128) [@thedmd]
 - Backends: OSX, Metal: Store backend data in a per-context struct, allowing to use these backends with
   multiple contexts. (#5203, #5221, #4141) [@noisewuwei]
+- Backends: Metal: Fixed null dereference on exit inside command buffer completion handler. (#5363, #5365) [@warrenm]
 - Backends: OpenGL3: Partially revert 1.86 change of using glBufferSubData(): now only done on Windows and
   Intel GPU, based on querying glGetString(GL_VENDOR). Essentially we got report of accumulating leaks on Intel
   with multi-viewports when using simple glBufferData() without orphaning, and report of corruptions on other