P0887R1 The identity metafunction

	* include/std/type_traits (type_identity, type_identity_t): Define
        for C++2a.
	* testsuite/20_util/type_identity/requirements/alias_decl.cc: New.
	* testsuite/20_util/type_identity/requirements/
	explicit_instantiation.cc:New.
	* testsuite/20_util/type_identity/requirements/typedefs.cc: New.

From-SVN: r262319

1 files changed, 35 insertions, 0 deletions

diff --git a/libstdc++-v3/testsuite/20_util/type_identity/requirements/alias_decl.cc b/libstdc++-v3/testsuite/20_util/type_identity/requirements/alias_decl.cc
new file mode 100644
index 00000000000..6729d118273
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/type_identity/requirements/alias_decl.cc
@@ -0,0 +1,35 @@
+// Copyright (C) 2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+//
+#include <type_traits>
+
+using namespace std;
+
+template<typename T, typename = std::type_identity_t<T>>
+  struct test; // undefined
+
+template<typename T>
+  struct test<T, T> : std::true_type { };
+
+static_assert( test<const int>{}, "type_identity_t<const int>" );
+static_assert( test<volatile int>{}, "type_identity_t<volatile int>" );
+static_assert( test<unsigned>{}, "type_identity_t<unsigned>" );
+static_assert( test<char>{}, "type_identity_t<char>" );
+static_assert( test<signed char>{}, "type_identity_t<signed char>" );