Here, the dependent template name in the return type of f() resolves to
an alias of int& after substitution, and we end up complaining about
qualifying this reference type with 'const' from cp_build_qualified_type
rather than just silently dropping the qualification as per [dcl.ref]/1.
The problem is ultimately that make_typename_type ignores the
tf_keep_type_decl flag when the dependent name is a template-id. This
in turn causes the TYPE_DECL check within tsubst <case TYPENAME_TYPE>
to fail, and so we end up not passing tf_ignore_bad_quals to
cp_build_qualified_type. This patch fixes this by making
make_typename_type respect the tf_keep_type_decl flag in this situation.
PR c++/100592
gcc/cp/ChangeLog:
* decl.c (make_typename_type): After calling
lookup_template_class, adjust the result to its TYPE_NAME and
then consider the tf_keep_type_decl flag.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/alias-decl-71.C: New test.
return error_mark_node;
if (want_template)
- return lookup_template_class (t, TREE_OPERAND (fullname, 1),
- NULL_TREE, context,
- /*entering_scope=*/0,
- complain | tf_user);
+ {
+ t = lookup_template_class (t, TREE_OPERAND (fullname, 1),
+ NULL_TREE, context,
+ /*entering_scope=*/0,
+ complain | tf_user);
+ if (t == error_mark_node)
+ return error_mark_node;
+ t = TYPE_NAME (t);
+ }
if (DECL_ARTIFICIAL (t) || !(complain & tf_keep_type_decl))
t = TREE_TYPE (t);
--- /dev/null
+// PR c++/100592
+// { dg-do compile { target c++11 } }
+
+template<bool>
+struct meta {
+ template<class> using if_c = int&;
+};
+
+template<bool B>
+typename meta<B>::template if_c<void> const f();
+
+using type = decltype(f<true>());
+using type = int&;