Constexpr in std::pointer_traits (P1006R1)

	* include/bits/ptr_traits.h [C++20] (pointer_traits<T*>::pointer_to):
	Add constexpr.
	* testsuite/20_util/pointer_traits/pointer_to_constexpr.cc: New test.

From-SVN: r269418

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 44bf6e72c6502ccfdccc5f47bca62ecfb8e82786..053da2c25d8c1b6408c392ae76dbd300d50f92b4 100644 (file)
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,9 @@
+2019-03-06  Jonathan Wakely  <jwakely@redhat.com>
+
+       * include/bits/ptr_traits.h [C++20] (pointer_traits<T*>::pointer_to):
+       Add constexpr.
+       * testsuite/20_util/pointer_traits/pointer_to_constexpr.cc: New test.
+
 2019-03-05  Jonathan Wakely  <jwakely@redhat.com>
 
        * include/c_compatibility/math.h [C++20] (lerp): Add using

diff --git a/libstdc++-v3/include/bits/ptr_traits.h b/libstdc++-v3/include/bits/ptr_traits.h
index 76355863852758ea15896cebcf5feb71579f0b0a..c90a35080f127c93b591b6249f9a11bf51efd72d 100644 (file)
--- a/libstdc++-v3/include/bits/ptr_traits.h
+++ b/libstdc++-v3/include/bits/ptr_traits.h
@@ -137,7 +137,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *  @param  __r  A reference to an object of type @c element_type
        *  @return @c addressof(__r)
       */
-      static pointer
+      static _GLIBCXX20_CONSTEXPR pointer
       pointer_to(__make_not_void<element_type>& __r) noexcept
       { return std::addressof(__r); }
     };

diff --git a/libstdc++-v3/testsuite/20_util/pointer_traits/pointer_to_constexpr.cc b/libstdc++-v3/testsuite/20_util/pointer_traits/pointer_to_constexpr.cc
new file mode 100644 (file)
index 0000000..ed4f215
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/pointer_traits/pointer_to_constexpr.cc
@@ -0,0 +1,27 @@
+// Copyright (C) 2019 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 <memory>
+
+int i = 0;
+static_assert( std::pointer_traits<int*>::pointer_to(i) == &i );
+
+struct X { } x;
+static_assert( std::pointer_traits<X*>::pointer_to(x) == &x );