[gcc/devel/omp/gcc-9] PR libstdc++/90700 Fix constructor constraint for std::tuple

[Tobias Burnus]

https://gcc.gnu.org/g:f390c64fac55814e139e4a546c23a0fd44856d5d

commit f390c64fac55814e139e4a546c23a0fd44856d5d
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Jun 3 23:31:45 2019 +0100

    PR libstdc++/90700 Fix constructor constraint for std::tuple
    
    	* include/std/tuple
    	(tuple(allocator_arg_t, const A&, const tuple<UTypes...>&)): Fix
    	value category of template argument to _TC::_NonNestedTuple.
    	* testsuite/20_util/tuple/cons/90700.cc: New test.
    
    From-SVN: r271887

Diff:
---
 libstdc++-v3/ChangeLog                             |  6 ++
 libstdc++-v3/include/std/tuple                     |  4 +-
 libstdc++-v3/testsuite/20_util/tuple/cons/90700.cc | 66 ++++++++++++++++++++++
 3 files changed, 74 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 69888fc..0bc01f8 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,11 @@
 2019-06-03  Jonathan Wakely  <jwakely@redhat.com>
 
+	PR libstdc++/90700
+	* include/std/tuple
+	(tuple(allocator_arg_t, const A&, const tuple<UTypes...>&)): Fix
+	value category of template argument to _TC::_NonNestedTuple.
+	* testsuite/20_util/tuple/cons/90700.cc: New test.
+
 	PR libstdc++/90686
 	* doc/xml/manual/status_cxx2014.xml: Document what's missing from
 	<experimental/memory_resource>.
diff --git a/libstdc++-v3/include/std/tuple b/libstdc++-v3/include/std/tuple
index bc0b1ad..f942109 100644
--- a/libstdc++-v3/include/std/tuple
+++ b/libstdc++-v3/include/std/tuple
@@ -758,7 +758,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                   && _TMCT<_UElements...>::template
                     _ImplicitlyConvertibleTuple<_UElements...>()
                   && _TNTC<_Dummy>::template
-                    _NonNestedTuple<tuple<_UElements...>&&>(),
+                    _NonNestedTuple<const tuple<_UElements...>&>(),
         bool>::type=true>
 	tuple(allocator_arg_t __tag, const _Alloc& __a,
 	      const tuple<_UElements...>& __in)
@@ -773,7 +773,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                   && !_TMCT<_UElements...>::template
                     _ImplicitlyConvertibleTuple<_UElements...>()
                   && _TNTC<_Dummy>::template
-                    _NonNestedTuple<tuple<_UElements...>&&>(),
+                    _NonNestedTuple<const tuple<_UElements...>&>(),
         bool>::type=false>
 	explicit tuple(allocator_arg_t __tag, const _Alloc& __a,
 	      const tuple<_UElements...>& __in)
diff --git a/libstdc++-v3/testsuite/20_util/tuple/cons/90700.cc b/libstdc++-v3/testsuite/20_util/tuple/cons/90700.cc
new file mode 100644
index 0000000..08e7787
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/tuple/cons/90700.cc
@@ -0,0 +1,66 @@
+// 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-do compile { target c++11 } }
+
+#include <tuple>
+#include <memory>
+
+struct X { };
+
+struct Y
+{
+  Y(const std::tuple<X>&) = delete;
+  Y(std::tuple<X>&&) { throw 1; }
+  Y(const X&) { }
+};
+
+struct Z
+{
+  Z(X&&) { }
+  Z(const std::tuple<X>&) { throw 1; }
+  Z(std::tuple<X>&&) = delete;
+};
+
+void
+test01()
+{
+  // PR libstdc++/90700 wrong constraints on constructor
+  const std::allocator<int> a;
+  const std::tuple<X> x;
+
+  static_assert(!std::is_convertible<const std::tuple<X>&, Y>::value, "");
+  static_assert(!std::is_constructible<Y, const std::tuple<X>&>::value, "");
+  static_assert(!std::is_same<Y, X>::value, "");
+  // should use tuple<Y>::tuple<X>(allocator_arg_t, const A&, const tuple<X>&)
+  // and construct Y from X:
+  std::tuple<Y> y(std::allocator_arg, a, x);
+}
+
+void
+test02()
+{
+  const std::allocator<int> a;
+  std::tuple<X> x;
+
+  static_assert(!std::is_convertible<std::tuple<X>, Z>::value, "");
+  static_assert(!std::is_constructible<Z, std::tuple<X>>::value, "");
+  static_assert(!std::is_same<Z, X>::value, "");
+  // should use tuple<Z>::tuple<X>(allocator_arg_t, const A&, tuple<X>&&)
+  // and construct Z from X:
+  std::tuple<Z> z(std::allocator_arg, a, std::move(x));
+}