Index: utils/TableGen/ClangDiagnosticsEmitter.cpp
===================================================================
--- utils/TableGen/ClangDiagnosticsEmitter.cpp
+++ utils/TableGen/ClangDiagnosticsEmitter.cpp
@@ -950,7 +950,7 @@
         Result += '|';
       }
       if (!P->Options.empty())
-        Result.erase(--Result.end());
+        Result.pop_back();
       Result += '}';
     }
     addInt(mapIndex(P->Index));
@@ -966,7 +966,7 @@
       Result += "|";
     }
     if (!P->Options.empty())
-      Result.erase(--Result.end());
+      Result.pop_back();
     Result += '}';
     addInt(mapIndex(P->Index));
   }