@@ -25126,6 +25126,14 @@ do_class_deduction (tree ptype, tree tmpl, tree init, int flags,
if (cands == NULL_TREE)
{
+ if (args->length() == 0)
+ {
+ /* Try tmpl<>. */
+ tree t = lookup_template_class (tmpl, NULL_TREE, NULL_TREE,
+ NULL_TREE, false, tf_none);
+ if (t != error_mark_node)
+ return t;
+ }
error ("cannot deduce template arguments for %qT, as it has "
"no deduction guides or user-declared constructors", type);
return error_mark_node;
new file mode 100644
@@ -0,0 +1,6 @@
+// { dg-options -std=c++1z }
+
+template <class T = void> struct A { };
+
+A a{};
+