Index: clang/include/clang/AST/ASTUnresolvedSet.h
===================================================================
--- clang/include/clang/AST/ASTUnresolvedSet.h
+++ clang/include/clang/AST/ASTUnresolvedSet.h
@@ -69,7 +69,12 @@
     return false;
   }
 
-  void erase(unsigned I) { Decls[I] = Decls.pop_back_val(); }
+  void erase(unsigned I) {
+    if (I == (Decls.size() - 1))
+      Decls.pop_back_val();
+    else
+      Decls[I] = Decls.pop_back_val();
+  }
 
   void clear() { Decls.clear(); }