Merge pull request #2371 from Autodesk/t_bailp/MAYA-123016/clear-stag…

…e-reset-outliner

MAYA-123016 stage clear now resets the outliner

lib/mayaUsd/utils/stageCache.cpp

@@ -25,6 +25,7 @@
 #include <pxr/usd/usdGeom/tokens.h>
 
 #include <maya/MFileIO.h>
+#include <maya/MGlobal.h>
 #include <maya/MSceneMessage.h>
 
 #include <map>
@@ -57,6 +58,22 @@ struct _OnSceneResetListener : public TfWeakBase
     }
 };
 
+void clearMayaAttributeEditor()
+{
+    // When a stage is deleted, the attribute editor could still refer to prims
+    // that were on that stage. If the attribute editor is collapsed, then it
+    // won't refresh itself and could later on try to access the prim.
+    //
+    // This happens when it receives a UFE notification that it thinks is about
+    // the prim it is showing. This only happens if one re-stage the same file,
+    // as the UFE notification will contain the same stage name and the same
+    // prim path.
+    //
+    // To avoid crashes, we refresh the attribute editor templates when the
+    // stages get cleared.
+    MGlobal::executeCommand("refreshEditorTemplates");
+}
+
 } // anonymous namespace
 
 /* static */
@@ -74,6 +91,7 @@ UsdStageCache& UsdMayaStageCache::Get(const bool loadAll)
 /* static */
 void UsdMayaStageCache::Clear()
 {
+    clearMayaAttributeEditor();
     Get(true).Clear();
     Get(false).Clear();
 }
@@ -88,6 +106,8 @@ size_t UsdMayaStageCache::EraseAllStagesWithRootLayerPath(const std::string& lay
         return erasedStages;
     }
 
+    clearMayaAttributeEditor();
+
     erasedStages += Get(true).EraseAll(rootLayer);
     erasedStages += Get(false).EraseAll(rootLayer);