[coroutines] Add overloaded unary 'operator co_await'.

llvm-svn: 250991
diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index 9d6c7dc..c4baed2 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -1046,6 +1046,14 @@
     break;
   }
 
+  case OO_Coawait: {
+    DiagnosticsEngine &Diags = Context.getDiags();
+    unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error,
+      "cannot mangle this operator co_await yet");
+    Diags.Report(Loc, DiagID);
+    break;
+  }
+
   case OO_None:
   case NUM_OVERLOADED_OPERATORS:
     llvm_unreachable("Not an overloaded operator");