3cb0c7cc16
The body of this function isn't just a return statement, so it can't be constexpr until C++14. PR libstdc++/95289 * include/debug/helper_functions.h (__get_distance): Only declare as a constexpr function for C++14 and up. * testsuite/25_algorithms/copy/debug/95289.cc: New test.
316 lines
9.8 KiB
C++
316 lines
9.8 KiB
C++
// Debugging support implementation -*- C++ -*-
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// Copyright (C) 2003-2020 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file debug/helper_functions.h
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* This file is a GNU debug extension to the Standard C++ Library.
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*/
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#ifndef _GLIBCXX_DEBUG_HELPER_FUNCTIONS_H
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#define _GLIBCXX_DEBUG_HELPER_FUNCTIONS_H 1
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#include <bits/move.h> // for __addressof
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#include <bits/stl_iterator_base_types.h> // for iterator_traits,
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// categories and _Iter_base
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#include <bits/cpp_type_traits.h> // for __is_integer
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#include <bits/stl_pair.h> // for pair
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namespace __gnu_debug
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{
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template<typename _Iterator, typename _Sequence, typename _Category>
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class _Safe_iterator;
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#if __cplusplus >= 201103L
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template<typename _Iterator, typename _Sequence>
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class _Safe_local_iterator;
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#endif
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/** The precision to which we can calculate the distance between
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* two iterators.
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*/
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enum _Distance_precision
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{
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__dp_none, // Not even an iterator type
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__dp_equality, //< Can compare iterator equality, only
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__dp_sign, //< Can determine equality and ordering
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__dp_sign_max_size, //< __dp_sign and gives max range size
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__dp_exact //< Can determine distance precisely
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};
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template<typename _Iterator,
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typename = typename std::__is_integer<_Iterator>::__type>
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struct _Distance_traits
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{
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private:
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typedef
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typename std::iterator_traits<_Iterator>::difference_type _ItDiffType;
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template<typename _DiffType,
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typename = typename std::__is_void<_DiffType>::__type>
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struct _DiffTraits
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{ typedef _DiffType __type; };
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template<typename _DiffType>
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struct _DiffTraits<_DiffType, std::__true_type>
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{ typedef std::ptrdiff_t __type; };
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typedef typename _DiffTraits<_ItDiffType>::__type _DiffType;
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public:
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typedef std::pair<_DiffType, _Distance_precision> __type;
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};
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template<typename _Integral>
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struct _Distance_traits<_Integral, std::__true_type>
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{ typedef std::pair<std::ptrdiff_t, _Distance_precision> __type; };
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/** Determine the distance between two iterators with some known
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* precision.
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*/
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template<typename _Iterator>
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_GLIBCXX_CONSTEXPR
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inline typename _Distance_traits<_Iterator>::__type
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__get_distance(_Iterator __lhs, _Iterator __rhs,
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std::random_access_iterator_tag)
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{ return std::make_pair(__rhs - __lhs, __dp_exact); }
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template<typename _Iterator>
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_GLIBCXX14_CONSTEXPR
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inline typename _Distance_traits<_Iterator>::__type
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__get_distance(_Iterator __lhs, _Iterator __rhs,
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std::input_iterator_tag)
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{
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if (__lhs == __rhs)
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return std::make_pair(0, __dp_exact);
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return std::make_pair(1, __dp_equality);
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}
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template<typename _Iterator>
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_GLIBCXX_CONSTEXPR
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inline typename _Distance_traits<_Iterator>::__type
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__get_distance(_Iterator __lhs, _Iterator __rhs)
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{ return __get_distance(__lhs, __rhs, std::__iterator_category(__lhs)); }
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// An arbitrary iterator pointer is not singular.
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inline bool
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__check_singular_aux(const void*) { return false; }
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// We may have an iterator that derives from _Safe_iterator_base but isn't
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// a _Safe_iterator.
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template<typename _Iterator>
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inline bool
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__check_singular(_Iterator const& __x)
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{ return __check_singular_aux(std::__addressof(__x)); }
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/** Non-NULL pointers are nonsingular. */
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template<typename _Tp>
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inline bool
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__check_singular(_Tp* const& __ptr)
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{ return __ptr == 0; }
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/** We say that integral types for a valid range, and defer to other
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* routines to realize what to do with integral types instead of
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* iterators.
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*/
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template<typename _Integral>
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_GLIBCXX_CONSTEXPR
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inline bool
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__valid_range_aux(_Integral, _Integral, std::__true_type)
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{ return true; }
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template<typename _Integral>
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_GLIBCXX20_CONSTEXPR
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inline bool
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__valid_range_aux(_Integral, _Integral,
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typename _Distance_traits<_Integral>::__type& __dist,
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std::__true_type)
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{
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__dist = std::make_pair(0, __dp_none);
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return true;
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}
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template<typename _InputIterator>
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_GLIBCXX_CONSTEXPR
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inline bool
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__valid_range_aux(_InputIterator __first, _InputIterator __last,
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std::input_iterator_tag)
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{
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return __first == __last
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|| (!__check_singular(__first) && !__check_singular(__last));
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}
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template<typename _InputIterator>
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_GLIBCXX_CONSTEXPR
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inline bool
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__valid_range_aux(_InputIterator __first, _InputIterator __last,
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std::random_access_iterator_tag)
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{
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return
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__valid_range_aux(__first, __last, std::input_iterator_tag())
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&& __first <= __last;
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}
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/** We have iterators, so figure out what kind of iterators they are
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* to see if we can check the range ahead of time.
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*/
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template<typename _InputIterator>
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_GLIBCXX_CONSTEXPR
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inline bool
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__valid_range_aux(_InputIterator __first, _InputIterator __last,
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std::__false_type)
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{
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return __valid_range_aux(__first, __last,
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std::__iterator_category(__first));
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}
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template<typename _InputIterator>
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_GLIBCXX20_CONSTEXPR
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inline bool
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__valid_range_aux(_InputIterator __first, _InputIterator __last,
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typename _Distance_traits<_InputIterator>::__type& __dist,
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std::__false_type)
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{
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if (!__valid_range_aux(__first, __last, std::input_iterator_tag()))
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return false;
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__dist = __get_distance(__first, __last);
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switch (__dist.second)
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{
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case __dp_none:
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break;
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case __dp_equality:
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if (__dist.first == 0)
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return true;
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break;
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case __dp_sign:
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case __dp_sign_max_size:
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case __dp_exact:
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return __dist.first >= 0;
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}
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// Can't tell so assume it is fine.
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return true;
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}
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/** Don't know what these iterators are, or if they are even
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* iterators (we may get an integral type for InputIterator), so
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* see if they are integral and pass them on to the next phase
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* otherwise.
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*/
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template<typename _InputIterator>
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_GLIBCXX20_CONSTEXPR
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inline bool
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__valid_range(_InputIterator __first, _InputIterator __last,
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typename _Distance_traits<_InputIterator>::__type& __dist)
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{
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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// Detected by the compiler directly.
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return true;
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#endif
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typedef typename std::__is_integer<_InputIterator>::__type _Integral;
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return __valid_range_aux(__first, __last, __dist, _Integral());
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}
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template<typename _Iterator, typename _Sequence, typename _Category>
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bool
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__valid_range(const _Safe_iterator<_Iterator, _Sequence, _Category>&,
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const _Safe_iterator<_Iterator, _Sequence, _Category>&,
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typename _Distance_traits<_Iterator>::__type&);
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#if __cplusplus >= 201103L
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template<typename _Iterator,typename _Sequence>
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bool
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__valid_range(const _Safe_local_iterator<_Iterator, _Sequence>&,
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const _Safe_local_iterator<_Iterator, _Sequence>&,
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typename _Distance_traits<_Iterator>::__type&);
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#endif
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template<typename _InputIterator>
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_GLIBCXX14_CONSTEXPR
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inline bool
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__valid_range(_InputIterator __first, _InputIterator __last)
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{
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#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
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if (__builtin_is_constant_evaluated())
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// Detected by the compiler directly.
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return true;
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#endif
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typedef typename std::__is_integer<_InputIterator>::__type _Integral;
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return __valid_range_aux(__first, __last, _Integral());
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}
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template<typename _Iterator, typename _Sequence, typename _Category>
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bool
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__valid_range(const _Safe_iterator<_Iterator, _Sequence, _Category>&,
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const _Safe_iterator<_Iterator, _Sequence, _Category>&);
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#if __cplusplus >= 201103L
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template<typename _Iterator, typename _Sequence>
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bool
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__valid_range(const _Safe_local_iterator<_Iterator, _Sequence>&,
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const _Safe_local_iterator<_Iterator, _Sequence>&);
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#endif
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// Fallback method, always ok.
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template<typename _InputIterator, typename _Size>
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_GLIBCXX_CONSTEXPR
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inline bool
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__can_advance(_InputIterator, _Size)
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{ return true; }
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template<typename _Iterator, typename _Sequence, typename _Category,
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typename _Size>
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bool
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__can_advance(const _Safe_iterator<_Iterator, _Sequence, _Category>&,
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_Size);
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/** Helper function to extract base iterator of random access safe iterator
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* in order to reduce performance impact of debug mode. Limited to random
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* access iterator because it is the only category for which it is possible
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* to check for correct iterators order in the __valid_range function
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* thanks to the < operator.
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*/
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template<typename _Iterator>
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_GLIBCXX_CONSTEXPR
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inline _Iterator
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__base(_Iterator __it)
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{ return __it; }
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#if __cplusplus < 201103L
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template<typename _Iterator>
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struct _Unsafe_type
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{ typedef _Iterator _Type; };
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#endif
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/* Remove debug mode safe iterator layer, if any. */
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template<typename _Iterator>
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inline _Iterator
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__unsafe(_Iterator __it)
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{ return __it; }
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}
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#endif
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