backport: Make the perfect-forwarding constructor of a two-element tuple sfinae away...

Backport from mainline
2016-12-19  Ville Voutilainen  <ville.voutilainen@gmail.com>

Make the perfect-forwarding constructor of a two-element tuple
sfinae away when the first argument is an allocator_arg.
* include/std/tuple (tuple(_U1&&, _U2&&)): Constrain.
* testsuite/20_util/tuple/cons/allocator_with_any.cc: New.

From-SVN: r243797

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 8dbed86fd64763d8415c66e5df32b305e8c4f638..c56ff11ba5bf9455839e6a4d5e9d03f4a0b73535 100644 (file)
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,13 @@
+2016-12-19  Ville Voutilainen  <ville.voutilainen@gmail.com>
+
+       Backport from mainline
+       2016-12-19  Ville Voutilainen  <ville.voutilainen@gmail.com>
+
+       Make the perfect-forwarding constructor of a two-element tuple
+       sfinae away when the first argument is an allocator_arg.
+       * include/std/tuple (tuple(_U1&&, _U2&&)): Constrain.
+       * testsuite/20_util/tuple/cons/allocator_with_any.cc: New.
+
 2016-12-13  Jonathan Wakely  <jwakely@redhat.com>
 
        Backport from mainline

diff --git a/libstdc++-v3/include/std/tuple b/libstdc++-v3/include/std/tuple
index e500a762d876f6d3c0e9b25c28de4c050caf67cb..90a0d73c58b60e39dbbc1b1a64edbd56e068272d 100644 (file)
--- a/libstdc++-v3/include/std/tuple
+++ b/libstdc++-v3/include/std/tuple
@@ -607,7 +607,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       template<typename _U1, typename _U2, typename = typename
               enable_if<__and_<is_convertible<_U1, _T1>,
-                               is_convertible<_U2, _T2>>::value>::type>
+                               is_convertible<_U2, _T2>,
+                               __not_<is_same<typename decay<_U1>::type,
+                                              allocator_arg_t>>>
+                        ::value>::type>
         explicit
         constexpr tuple(_U1&& __a1, _U2&& __a2)
        : _Inherited(std::forward<_U1>(__a1), std::forward<_U2>(__a2)) { }

diff --git a/libstdc++-v3/testsuite/20_util/tuple/cons/allocator_with_any.cc b/libstdc++-v3/testsuite/20_util/tuple/cons/allocator_with_any.cc
new file mode 100644 (file)
index 0000000..dd9a066
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/tuple/cons/allocator_with_any.cc
@@ -0,0 +1,42 @@
+// { dg-do run }
+// { dg-options "-std=gnu++14" }
+// Copyright (C) 2016 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/>.
+
+
+// NOTE: This makes use of the fact that we know how moveable
+// is implemented on tuple.  If the implementation changed
+// this test may begin to fail.
+
+#include <tuple>
+#include <experimental/any>
+#include <testsuite_hooks.h>
+
+using std::experimental::any;
+
+void test01()
+{
+    std::tuple<any, any> t(std::allocator_arg,
+                          std::allocator<any>{});
+    VERIFY(std::get<0>(t).empty());
+    VERIFY(std::get<1>(t).empty());
+}
+
+int main()
+{
+    test01();
+}