[C++ Patch] PR 64970

[Paolo Carlini]

Hi,

this one seems a typical very simple SFINAE issue, where we are not 
correctly forwarding the tsubst_flags_t argument. Not sure if we are 
still in time for 5.0...

Tested x86_64-linux.

Thanks,
Paolo.

///////////////////////
/cp
2015-02-13  Paolo Carlini  <paolo.carl...@oracle.com>

        PR c++/64970
        * decl.c (make_typename_type): Pass tsubst_flags_t argument
        to lookup_template_class.

/testsuite
2015-02-13  Paolo Carlini  <paolo.carl...@oracle.com>

        PR c++/64970
        * testsuite/g++.dg/cpp0x/sfinae55.C: New.
Index: cp/decl.c
===================================================================
--- cp/decl.c   (revision 220679)
+++ cp/decl.c   (working copy)
@@ -3569,7 +3569,7 @@ make_typename_type (tree context, tree name, enum
     return lookup_template_class (t, TREE_OPERAND (fullname, 1),
                                  NULL_TREE, context,
                                  /*entering_scope=*/0,
-                                 tf_warning_or_error | tf_user);
+                                 complain | tf_user);
   
   if (DECL_ARTIFICIAL (t) || !(complain & tf_keep_type_decl))
     t = TREE_TYPE (t);
Index: testsuite/g++.dg/cpp0x/sfinae55.C
===================================================================
--- testsuite/g++.dg/cpp0x/sfinae55.C   (revision 0)
+++ testsuite/g++.dg/cpp0x/sfinae55.C   (working copy)
@@ -0,0 +1,33 @@
+// PR c++/64970
+// { dg-do compile { target c++11 } }
+
+template<typename T>
+T && declval();
+
+template<typename T>
+struct void_ { using type = void; };
+
+template<typename T>
+using void_t = typename void_<T>::type;
+
+template<class A, class B>
+struct Outer
+{
+    template<class C, class D>
+    using Inner = decltype(true ? declval<C>() : declval<D>());
+};
+
+template<class A, class B, typename Enable = void>
+struct S
+{};
+
+template<class A, class B>
+struct S<A, B, void_t<typename Outer<A, B>::template Inner<A, B>>>
+{};
+
+struct A{};
+struct B{};
+int main()
+{
+    S<A, B> s;
+}