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re PR libstdc++/54388 (std::array.at() const results in undefined behaviour) 

PR libstdc++/54388
	* include/std/array (array::at() const): Ensure lvalue result.
	* testsuite/23_containers/array/element_access/54388.cc: New.

From-SVN: r191117
This commit is contained in:
Jonathan Wakely 2012-09-09 18:40:46 +00:00 committed by Jonathan Wakely
parent b0a95eccae
commit 84dbe9a415
3 changed files with 52 additions and 12 deletions
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6
libstdc++-v3/ChangeLog
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@ -1,3 +1,9 @@
2012-09-09 Jonathan Wakely <jwakely.gcc@gmail.com>
PR libstdc++/54388
* include/std/array (array::at() const): Ensure lvalue result.
* testsuite/23_containers/array/element_access/54388.cc: New.
2012-09-06 Marc Glisse <marc.glisse@inria.fr>
Paolo Carlini <paolo.carlini@oracle.com>

16
libstdc++-v3/include/std/array
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@ -164,22 +164,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return _M_instance[__n];
}
#ifdef __EXCEPTIONS
constexpr const_reference
at(size_type __n) const
{
return __n < _Nm ?
_M_instance[__n] : throw out_of_range(__N("array::at"));
// Result of conditional expression must be an lvalue so use
// boolean ? lvalue : (throw-expr, lvalue)
return __n < _Nm ? _M_instance[__n]
: (std::__throw_out_of_range(__N("array::at")), _M_instance[0]);
}
#else
const_reference
at(size_type __n) const
{
if (__n >= _Nm)
std::__throw_out_of_range(__N("array::at"));
return _M_instance[__n];
}
#endif
reference
front()

42
libstdc++-v3/testsuite/23_containers/array/element_access/54388.cc Normal file
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@ -0,0 +1,42 @@
// { dg-options "-std=gnu++0x" }
//
// Copyright (C) 2012 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 <array>
#include <testsuite_hooks.h>
struct A
{
bool valid = true;
~A() { valid = false; }
};
void
test01()
{
bool test __attribute__((unused)) = true;
const std::array<A, 1> a;
const A& aa = a.at(0);
VERIFY(aa.valid);
}
int main()
{
test01();
}