operator<< on a DiagnosticBuilder should *always* output exactly one thing.

Null template arguments are bad, but they're better than crashing with an
argument mismatch.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@110312 91177308-0d34-0410-b5e6-96231b3b80d8

lib/AST/TemplateBase.cpp

@@ -152,7 +152,9 @@ const DiagnosticBuilder &clang::operator<<(const DiagnosticBuilder &DB,
                                            const TemplateArgument &Arg) {
   switch (Arg.getKind()) {
   case TemplateArgument::Null:
-    return DB;
+    // This is bad, but not as bad as crashing because of argument
+    // count mismatches.
+    return DB << "(null template argument)";
       
   case TemplateArgument::Type:
     return DB << Arg.getAsType();