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PR libstdc++/86734 make reverse_iterator::operator-> more robust

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Implement the proposed resolution from LWG 1052, which also resolves
DR 2118 by avoiding taking the address in the first place.

	PR libstdc++/86734
	* include/bits/stl_iterator.h (reverse_iterator::operator->): Call
	_S_to_pointer (LWG 1052, LWG 2118).
	(reverse_iterator::_S_to_pointer): Define overloaded helper functions.
	* testsuite/24_iterators/reverse_iterator/dr1052.cc: New test.
	* testsuite/24_iterators/reverse_iterator/dr2188.cc: New test.

From-SVN: r263074
This commit is contained in:
Jonathan Wakely 2018-07-30 18:13:05 +01:00 committed by Jonathan Wakely
parent 1b3b888d11
commit a64ede727f
4 changed files with 155 additions and 1 deletions
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7
libstdc++-v3/ChangeLog
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@ -1,5 +1,12 @@
2018-07-30 Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/86734
* include/bits/stl_iterator.h (reverse_iterator::operator->): Call
_S_to_pointer (LWG 1052, LWG 2118).
(reverse_iterator::_S_to_pointer): Define overloaded helper functions.
* testsuite/24_iterators/reverse_iterator/dr1052.cc: New test.
* testsuite/24_iterators/reverse_iterator/dr2188.cc: New test.
* libsupc++/new_opa.cc (operator new(size_t, align_val_t)): Add
workaround for aligned_alloc bug on AIX.
* testsuite/18_support/new_aligned.cc: New test.

20
libstdc++-v3/include/bits/stl_iterator.h
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@ -122,6 +122,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
*/
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 235 No specification of default ctor for reverse_iterator
// 1012. reverse_iterator default ctor should value initialize
_GLIBCXX17_CONSTEXPR
reverse_iterator() : current() { }
@ -182,7 +183,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
*/
_GLIBCXX17_CONSTEXPR pointer
operator->() const
{ return &(operator*()); }
{
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 1052. operator-> should also support smart pointers
_Iterator __tmp = current;
--__tmp;
return _S_to_pointer(__tmp);
}
/**
* @return @c *this
@ -286,6 +293,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_GLIBCXX17_CONSTEXPR reference
operator[](difference_type __n) const
{ return *(*this + __n); }
private:
template<typename _Tp>
static _GLIBCXX17_CONSTEXPR _Tp*
_S_to_pointer(_Tp* __p)
{ return __p; }
template<typename _Tp>
static _GLIBCXX17_CONSTEXPR pointer
_S_to_pointer(_Tp __t)
{ return __t.operator->(); }
};
//@{

82
libstdc++-v3/testsuite/24_iterators/reverse_iterator/dr1052.cc Normal file
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@ -0,0 +1,82 @@
// Copyright (C) 2018 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 run { target c++11 } }
// PR libstdc++/86734
// LWG 1052. reverse_iterator::operator-> should also support smart pointers
// LWG 2775. reverse_iterator is does not compile for fancy pointers
#include <iterator>
#include <testsuite_hooks.h>
void
test01()
{
// Example 1 from LWG 1052
struct X { int m; };
static X x;
struct IterX {
typedef std::bidirectional_iterator_tag iterator_category;
typedef X& reference;
struct pointer
{
pointer(X& v) : value(v) {}
X& value;
X* operator->() const {return &value;}
};
typedef std::ptrdiff_t difference_type;
typedef X value_type;
// additional iterator requirements not important for this issue
reference operator*() const { return x; }
pointer operator->() const { return pointer(x); }
IterX& operator--() {return *this;}
};
std::reverse_iterator<IterX> ix;
VERIFY( &ix->m == &(*ix).m );
}
void
test02()
{
// Example 2 from LWG 1052
struct P {
P() : first(10), second(20.0) { }
int first;
double second;
};
P op;
std::reverse_iterator<P*> ri(&op + 1);
VERIFY( ri->first == 10 );
}
// N.B. Example 3 from LWG 1052 isn't expected to work,
// because a caching iterator like IterX is not a forward iterator.
int
main()
{
test01();
test02();
}

47
libstdc++-v3/testsuite/24_iterators/reverse_iterator/dr2188.cc Normal file
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@ -0,0 +1,47 @@
// Copyright (C) 2018 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 run { target c++11 } }
// PR libstdc++/86734
#include <iterator>
#include <testsuite_hooks.h>
void
test01()
{
// LWG DR 2188
// Reverse iterator does not fully support targets that overload operator&
struct X {
int val;
int* operator&() { return &val; }
const int* operator&() const { return &val; }
};
X x[2] = { {1}, {2} };
std::reverse_iterator<X*> rev(x+2);
VERIFY( rev->val == 2 );
++rev;
VERIFY( rev->val == 1 );
}
int
main()
{
test01();
}