Add a missing ExpressionEvaluationContext for template default arguments. Fixes PR12581.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@155670 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Parse/ParseTemplate.cpp

@@ -652,6 +652,7 @@ Parser::ParseNonTypeTemplateParameter(unsigned Depth, unsigned Position) {
     //   end of the template-parameter-list rather than a greater-than
     //   operator.
     GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
+    EnterExpressionEvaluationContext Unevaluated(Actions, Sema::Unevaluated);
 
     DefaultArg = ParseAssignmentExpression();
     if (DefaultArg.isInvalid())

lib/Sema/SemaTemplate.cpp

@@ -2562,6 +2562,7 @@ SubstDefaultTemplateArgument(Sema &SemaRef,
                                    SourceRange(TemplateLoc, RAngleLoc));
 
   Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
+  EnterExpressionEvaluationContext Unevaluated(SemaRef, Sema::Unevaluated);
   return SemaRef.SubstExpr(Param->getDefaultArgument(), AllTemplateArgs);
 }
 

test/SemaTemplate/default-expr-arguments.cpp

@@ -292,3 +292,14 @@ namespace PR8401 {
     f();
   }
 }
+
+namespace PR12581 {
+  const int a = 0;
+  template < typename > struct A;
+  template < typename MatrixType, int =
+  A < MatrixType >::Flags ? : A < MatrixType >::Flags & a > class B;
+  void
+  fn1 ()
+  {
+  }
+}