Change warning about incomplete parsing of C++ default arg to error and provide a test case; thanks Doug!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@110603 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/DiagnosticParseKinds.td

@@ -271,8 +271,8 @@ def err_destructor_tilde_identifier : Error<
   "expected a class name after '~' to name a destructor">;
 def err_destructor_template_id : Error<
   "destructor name %0 does not refer to a template">;
-def warn_default_arg_unparsed : Warning<
-  "parsing of default argument is incomplete">;
+def err_default_arg_unparsed : Error<
+  "unexpected end of default argument expression">;
 
 // C++ derived classes
 def err_dup_virtual : Error<"duplicate 'virtual' in base specifier">;

lib/Parse/ParseCXXInlineMethods.cpp

@@ -145,12 +145,8 @@ void Parser::ParseLexedMethodDeclarations(ParsingClass &Class) {
         else {
           if (Tok.is(tok::cxx_defaultarg_end))
             ConsumeToken();
-          else {
-            // Warn that there are tokens from the default arg that we left
-            // unparsed. This actually indicates a bug in clang but we avoid
-            // asserting because we want the parser robust.
-            Diag(Tok.getLocation(), diag::warn_default_arg_unparsed);
-          }
+          else
+            Diag(Tok.getLocation(), diag::err_default_arg_unparsed);
           Actions.ActOnParamDefaultArgument(LM.DefaultArgs[I].Param, EqualLoc,
                                             move(DefArgResult));
         }

test/Parser/cxx-default-args.cpp

@@ -10,3 +10,7 @@ class C {
 typedef struct Inst {
   void m(int x=0);
 } *InstPtr;
+
+struct X {
+  void f(int x = 1:); // expected-error {{unexpected end of default argument expression}}
+};