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re PR libstdc++/79141 (std::pair<int,int> p = {}; fails to compile due to ambiguous overload)

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PR libstdc++/79141
* include/bits/stl_pair.h (__nonesuch_no_braces): New.
(operator=(typename conditional<
__and_<is_copy_assignable<_T1>,
is_copy_assignable<_T2>>::value,
const pair&, const __nonesuch&>::type)): Change __nonesuch
to __nonesuch_no_braces.
(operator=(typename conditional<
__not_<__and_<is_copy_assignable<_T1>,
is_copy_assignable<_T2>>>::value,
const pair&, const __nonesuch&>::type)): Likewise.
(operator=(typename conditional<
__and_<is_move_assignable<_T1>,
is_move_assignable<_T2>>::value,
pair&&, __nonesuch&&>::type)): Likewise.
* testsuite/20_util/pair/79141.cc: New.

From-SVN: r246653
This commit is contained in:
Ville Voutilainen 2017-04-03 19:30:58 +03:00 committed by Ville Voutilainen
parent 44bc146fcf
commit c1e2889a32
3 changed files with 54 additions and 3 deletions
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19
libstdc++-v3/ChangeLog
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@ -1,3 +1,22 @@
2017-04-03 Ville Voutilainen <ville.voutilainen@gmail.com>
PR libstdc++/79141
* include/bits/stl_pair.h (__nonesuch_no_braces): New.
(operator=(typename conditional<
__and_<is_copy_assignable<_T1>,
is_copy_assignable<_T2>>::value,
const pair&, const __nonesuch&>::type)): Change __nonesuch
to __nonesuch_no_braces.
(operator=(typename conditional<
__not_<__and_<is_copy_assignable<_T1>,
is_copy_assignable<_T2>>>::value,
const pair&, const __nonesuch&>::type)): Likewise.
(operator=(typename conditional<
__and_<is_move_assignable<_T1>,
is_move_assignable<_T2>>::value,
pair&&, __nonesuch&&>::type)): Likewise.
* testsuite/20_util/pair/79141.cc: New.
2017-04-03 Ville Voutilainen <ville.voutilainen@gmail.com>
Implement std::is_aggregate.

13
libstdc++-v3/include/bits/stl_pair.h
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@ -179,6 +179,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
};
// PR libstdc++/79141, a utility type for preventing
// initialization of an argument of a disabled assignment
// operator from a pair of empty braces.
struct __nonesuch_no_braces : std::__nonesuch {
explicit __nonesuch_no_braces(const __nonesuch&) = delete;
};
#endif
/**
@ -360,7 +367,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
operator=(typename conditional<
__and_<is_copy_assignable<_T1>,
is_copy_assignable<_T2>>::value,
const pair&, const __nonesuch&>::type __p)
const pair&, const __nonesuch_no_braces&>::type __p)
{
first = __p.first;
second = __p.second;
@ -371,13 +378,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
operator=(typename conditional<
__not_<__and_<is_copy_assignable<_T1>,
is_copy_assignable<_T2>>>::value,
const pair&, const __nonesuch&>::type __p) = delete;
const pair&, const __nonesuch_no_braces&>::type __p) = delete;
pair&
operator=(typename conditional<
__and_<is_move_assignable<_T1>,
is_move_assignable<_T2>>::value,
pair&&, __nonesuch&&>::type __p)
pair&&, __nonesuch_no_braces&&>::type __p)
noexcept(__and_<is_nothrow_move_assignable<_T1>,
is_nothrow_move_assignable<_T2>>::value)
{

25
libstdc++-v3/testsuite/20_util/pair/79141.cc Normal file
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@ -0,0 +1,25 @@
// { dg-do compile { target c++11 } }
// 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/>.
#include <utility>
int main() {
std::pair<int,int> p;
p = {};
}