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PR libstdc++/78939 make tuple_size<cv T> depend on tuple_size<T>

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PR libstdc++/78939
	* include/std/utility (tuple_size<cv T>): Only define partial
	specializations when tuple_size<T>::value is valid.
	* testsuite/20_util/tuple/78939.cc: New.
	* testsuite/20_util/tuple/cv_tuple_size_neg.cc: New.

From-SVN: r247973
This commit is contained in:
Jonathan Wakely 2017-05-12 15:43:11 +01:00 • committed by Jonathan Wakely
parent 48ac9454fa
commit f859f912e4
4 changed files with 107 additions and 13 deletions
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8
libstdc++-v3/ChangeLog
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@ -1,3 +1,11 @@
2017-05-12 Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/78939
* include/std/utility (tuple_size<cv T>): Only define partial
specializations when tuple_size<T>::value is valid.
* testsuite/20_util/tuple/78939.cc: New.
* testsuite/20_util/tuple/cv_tuple_size_neg.cc: New.
2017-05-11 François Dumont <fdumont@gcc.gnu.org>
* include/bits/stl_tree.h [_GLIBCXX_INLINE_VERSION]

28
libstdc++-v3/include/std/utility
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@ -87,25 +87,27 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp>
struct tuple_size;
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2770. tuple_size<const T> specialization is not SFINAE compatible
template<typename _Tp, typename = void>
struct __tuple_size_cv_impl { };
template<typename _Tp>
struct __tuple_size_cv_impl<_Tp, __void_t<decltype(tuple_size<_Tp>::value)>>
: integral_constant<size_t, tuple_size<_Tp>::value> { };
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2313. tuple_size should always derive from integral_constant<size_t, N>
template<typename _Tp>
struct tuple_size<const _Tp> : __tuple_size_cv_impl<_Tp> { };
// 2770. tuple_size<const T> specialization is not SFINAE compatible
template<typename _Tp,
typename _Up = typename remove_cv<_Tp>::type,
typename = typename enable_if<is_same<_Tp, _Up>::value>::type,
size_t = tuple_size<_Tp>::value>
using __enable_if_has_tuple_size = _Tp;
template<typename _Tp>
struct tuple_size<volatile _Tp> : __tuple_size_cv_impl<_Tp> { };
struct tuple_size<const __enable_if_has_tuple_size<_Tp>>
: public tuple_size<_Tp> { };
template<typename _Tp>
struct tuple_size<const volatile _Tp> : __tuple_size_cv_impl<_Tp> { };
struct tuple_size<volatile __enable_if_has_tuple_size<_Tp>>
: public tuple_size<_Tp> { };
template<typename _Tp>
struct tuple_size<const volatile __enable_if_has_tuple_size<_Tp>>
: public tuple_size<_Tp> { };
/// Gives the type of the ith element of a given tuple type.
template<std::size_t __i, typename _Tp>

49
libstdc++-v3/testsuite/20_util/tuple/78939.cc Normal file
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@ -0,0 +1,49 @@
// Copyright (C) 2017 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++17" }
// { dg-do compile { target c++1z } }
// PR libstdc++/78939
#include <utility>
struct A { int i, j; };
int
test01()
{
A a{};
const auto [i, j] = a;
return i + j;
}
int
test02()
{
A a{};
volatile auto [i, j] = a;
return i + j;
}
int
test03()
{
A a{};
const volatile auto [i, j] = a;
return i + j;
}

35
libstdc++-v3/testsuite/20_util/tuple/cv_tuple_size_neg.cc Normal file
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@ -0,0 +1,35 @@
// Copyright (C) 2017 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>
// PR libstdc++/78939
std::tuple_size<const int> ic; // { dg-error "incomplete" }
std::tuple_size<volatile int> iv; // { dg-error "incomplete" }
std::tuple_size<const volatile int> icv; // { dg-error "incomplete" }
struct A { };
std::tuple_size<const A> ac; // { dg-error "incomplete" }
std::tuple_size<volatile A> av; // { dg-error "incomplete" }
std::tuple_size<const volatile A> acv; // { dg-error "incomplete" }
std::tuple_size<const void> vc; // { dg-error "incomplete" }
std::tuple_size<volatile void> vv; // { dg-error "incomplete" }
std::tuple_size<const volatile void> vcv; // { dg-error "incomplete" }