PR c++/88538 - braced-init-list in template-argument-list.

	* parser.c (cp_parser_template_argument): Handle braced-init-list when
	in C++20.

	* g++.dg/cpp2a/nontype-class11.C: New test.

From-SVN: r267741

gcc/cp/ChangeLog

 2019-01-08  Marek Polacek  <polacek@redhat.com>
 
+	PR c++/88538 - braced-init-list in template-argument-list.
+	* parser.c (cp_parser_template_argument): Handle braced-init-list when
+	in C++20.
+
 	PR c++/88548 - this accepted in static member functions.
 	* parser.c (cp_debug_parser): Adjust printing of
 	local_variables_forbidden_p.

gcc/cp/parser.c

@@ -17026,6 +17026,14 @@ cp_parser_template_argument (cp_parser* parser)
     argument = cp_parser_constant_expression (parser);
   else
     {
+      /* In C++20, we can encounter a braced-init-list.  */
+      if (cxx_dialect >= cxx2a
+	  && cp_lexer_next_token_is (parser->lexer, CPP_OPEN_BRACE))
+	{
+	  bool expr_non_constant_p;
+	  return cp_parser_braced_list (parser, &expr_non_constant_p);
+	}
+
       /* With C++17 generalized non-type template arguments we need to handle
 	 lvalue constant expressions, too.  */
       argument = cp_parser_assignment_expression (parser);

gcc/testsuite/ChangeLog

+2019-01-08  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/88538 - braced-init-list in template-argument-list.
+	* g++.dg/cpp2a/nontype-class11.C: New test.
+
 2019-01-08  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/88457

gcc/testsuite/g++.dg/cpp2a/nontype-class11.C

+// PR c++/88538
+// { dg-do compile { target c++2a } }
+
+struct S {
+  unsigned a;
+  unsigned b;
+  constexpr S(unsigned _a, unsigned _b) noexcept: a{_a}, b{_b} { }
+};
+
+template <S p>
+void fnc()
+{
+}
+
+template<S s> struct X { };
+
+void f()
+{
+  fnc<{10,20}>();
+  X<{1, 2}> x;
+}