libstdc++: Add __cpp_lib_unwrap_ref feature test macro

We already defined the traits in <type_traits> as now required by LWG
3348, but the macro was missing. This adds it.

	* include/std/type_traits (__cpp_lib_unwrap_ref): Define (LWG 3348).
	* include/std/version (__cpp_lib_unwrap_ref): Likewise.
	* testsuite/20_util/unwrap_reference/1.cc: Check macro.
	* testsuite/20_util/unwrap_reference/3.cc: New test.

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 84e5ea98022592c184c8b14dd4ee72f503e78d2d..bc4ce773f1e3af50067bb64583a4fa5085c378de 100644 (file)
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,10 @@
 2020-02-19  Jonathan Wakely  <jwakely@redhat.com>
 
+       * include/std/type_traits (__cpp_lib_unwrap_ref): Define (LWG 3348).
+       * include/std/version (__cpp_lib_unwrap_ref): Likewise.
+       * testsuite/20_util/unwrap_reference/1.cc: Check macro.
+       * testsuite/20_util/unwrap_reference/3.cc: New test.
+
        * include/std/numeric (midpoint(T8, T*)): Do not check for complete
        type during overload resolution, use static assert instead (LWG 3200).
        * testsuite/26_numerics/midpoint/pointer.cc: Do not test with

diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index 684a792d02c19d284b58d6e33149ed93bb090b92..14aa2b37a4f113e60e91c559a00b8ab3d2cfc39f 100644 (file)
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -3242,6 +3242,8 @@ template <typename _From, typename _To>
   template<typename _Tp>
     using type_identity_t = typename type_identity<_Tp>::type;
 
+#define __cpp_lib_unwrap_ref 201811L
+
   /// Unwrap a reference_wrapper
   template<typename _Tp>
     struct unwrap_reference { using type = _Tp; };

diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version
index b36b999cb31333ba2471c1b22371f1171cebce8a..e2ccf619d4abc496d12b7f608851491101d9f826 100644 (file)
--- a/libstdc++-v3/include/std/version
+++ b/libstdc++-v3/include/std/version
@@ -178,6 +178,7 @@
 #ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
 # define __cpp_lib_is_constant_evaluated 201811L
 #endif
+#define __cpp_lib_unwrap_ref 201811L
 
 #if _GLIBCXX_HOSTED
 #define __cpp_lib_bind_front 201907L

diff --git a/libstdc++-v3/testsuite/20_util/unwrap_reference/1.cc b/libstdc++-v3/testsuite/20_util/unwrap_reference/1.cc
index 3a6634339113cace3dc04d3036bb1c5d3694db76..3496204e4d2bbce985ff3b2c3f37f0824f7129eb 100644 (file)
--- a/libstdc++-v3/testsuite/20_util/unwrap_reference/1.cc
+++ b/libstdc++-v3/testsuite/20_util/unwrap_reference/1.cc
@@ -20,6 +20,12 @@
 
 #include <type_traits>
 
+#ifndef __cpp_lib_unwrap_ref
+# error "Feature-test macro for unwrap_reference missing in <type_traits>"
+#elif __cpp_lib_unwrap_ref != 201811L
+# error "Feature-test macro for unwrap_reference has wrong value in <type_traits>"
+#endif
+
 template<typename T, typename U> struct expect_same;
 template<typename T> struct expect_same<T, T> : std::true_type { };
 

diff --git a/libstdc++-v3/testsuite/20_util/unwrap_reference/3.cc b/libstdc++-v3/testsuite/20_util/unwrap_reference/3.cc
new file mode 100644 (file)
index 0000000..3ea9cd1
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/unwrap_reference/3.cc
@@ -0,0 +1,27 @@
+// Copyright (C) 2020 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 <version>
+
+#ifndef __cpp_lib_unwrap_ref
+# error "Feature-test macro for unwrap_reference missing in <version>"
+#elif __cpp_lib_unwrap_ref != 201811L
+# error "Feature-test macro for unwrap_reference has wrong value in <version>"
+#endif