[gcc(refs/vendors/ARM/heads/arm-9-branch)] libstdc++: Add __cpp_lib_unwrap_ref feature test macro

[Vidya Praveen]

https://gcc.gnu.org/g:8079a9ab972b1fc8618a30f0a42a6533810e1c07

commit 8079a9ab972b1fc8618a30f0a42a6533810e1c07
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Feb 19 15:06:24 2020 +0000

    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.
    
    Backport from mainline
    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.

Diff:
---
 libstdc++-v3/ChangeLog                             | 10 ++++++++
 libstdc++-v3/include/std/type_traits               |  2 ++
 libstdc++-v3/include/std/version                   |  1 +
 .../testsuite/20_util/unwrap_reference/1.cc        |  6 +++++
 .../testsuite/20_util/unwrap_reference/3.cc        | 27 ++++++++++++++++++++++
 5 files changed, 46 insertions(+)

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 616b154e866..a5d92e5ae21 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,13 @@
+2020-04-23  Jonathan Wakely  <jwakely@redhat.com>
+
+	Backport from mainline
+	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.
+
 2020-04-22  Jonathan Wakely  <jwakely@redhat.com>
 
 	* doc/Makefile.am (xml_sources_manual): Add missing XML files.
diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index 9bad55829ce..993f7e3153c 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -3044,6 +3044,8 @@ 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 9dc7cbbb184..39b49371370 100644
--- a/libstdc++-v3/include/std/version
+++ b/libstdc++-v3/include/std/version
@@ -161,6 +161,7 @@
 # define __cpp_lib_is_constant_evaluated 201811L
 #endif
 #define __cpp_lib_list_remove_return_type 201806L
+#define __cpp_lib_unwrap_ref 201811L
 #endif // C++2a
 #endif // C++17
 #endif // C++14
diff --git a/libstdc++-v3/testsuite/20_util/unwrap_reference/1.cc b/libstdc++-v3/testsuite/20_util/unwrap_reference/1.cc
index 243526725a0..3c04028bb6e 100644
--- 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
index 00000000000..3ea9cd18a05
--- /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