1 files changed, 3 insertions, 0 deletions
diff --git a/lib/CodeGen/CGVtable.cpp b/lib/CodeGen/CGVtable.cpp
index b7f8fe77ea..d5d22154d9 100644
--- a/lib/CodeGen/CGVtable.cpp
+++ b/lib/CodeGen/CGVtable.cpp
@@ -1512,6 +1512,9 @@ VtableBuilder::IsOverriderUsed(BaseSubobject Base,
              "Primary base should always be at offset 0!");
     }
     
+    if (!PrimaryBases.insert(PrimaryBase))
+      assert(false && "Found a duplicate primary base!");
+
     RD = PrimaryBase;
   }