PR72792 detect allocator pointer types without invalid rebinding
PR libstdc++/72792 * include/bits/alloc_traits.h (__allocator_traits_base::__diff_type) (__allocator_traits_base::__size_type): Remove. (allocator_traits::_Ptr): New class template to detect const and void pointer types without instantiating pointer_traits::rebind unnecessarily. (allocator_traits::_Diff): Likewise for detecting difference_type. (allocator_traits::_Size): New class template to detect size_type without instantiating make_unsigned unnecessarily. * include/bits/ptr_traits.h (pointer_traits::element_type): Use __detected_or_t instead of __detected_or_t_. * include/std/type_traits (__detected_or_t_): Remove. * testsuite/20_util/allocator_traits/members/pointers.cc: New test. From-SVN: r244706
This commit is contained in:
Jonathan Wakely
Jonathan Wakely
parent
2ebd93e1d7
commit
4dfdda108f
5 changed files with 104 additions and 25 deletions
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@ -1,5 +1,19 @@
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2017-01-20 Jonathan Wakely <jwakely@redhat.com>
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PR libstdc++/72792
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* include/bits/alloc_traits.h (__allocator_traits_base::__diff_type)
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(__allocator_traits_base::__size_type): Remove.
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(allocator_traits::_Ptr): New class template to detect const and void
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pointer types without instantiating pointer_traits::rebind
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unnecessarily.
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(allocator_traits::_Diff): Likewise for detecting difference_type.
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(allocator_traits::_Size): New class template to detect size_type
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without instantiating make_unsigned unnecessarily.
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* include/bits/ptr_traits.h (pointer_traits::element_type): Use
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__detected_or_t instead of __detected_or_t_.
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* include/std/type_traits (__detected_or_t_): Remove.
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* testsuite/20_util/allocator_traits/members/pointers.cc: New test.
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PR libstdc++/72792
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PR libstdc++/72793
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* include/bits/alloc_traits.h (__allocator_traits_base::__rebind):
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@ -61,10 +61,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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using __v_pointer = typename _Tp::void_pointer;
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template<typename _Tp>
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using __cv_pointer = typename _Tp::const_void_pointer;
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template<typename _Tp>
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using __diff_type = typename _Tp::difference_type;
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template<typename _Tp>
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using __size_type = typename _Tp::size_type;
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template<typename _Tp>
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using __pocca = typename _Tp::propagate_on_container_copy_assignment;
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template<typename _Tp>
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@ -98,15 +94,45 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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*/
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using pointer = __detected_or_t<value_type*, __pointer, _Alloc>;
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private:
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// Select _Func<_Alloc> or pointer_traits<pointer>::rebind<_Tp>
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template<template<typename> class _Func, typename _Tp, typename = void>
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struct _Ptr
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{
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using type = typename pointer_traits<pointer>::template rebind<_Tp>;
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};
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template<template<typename> class _Func, typename _Tp>
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struct _Ptr<_Func, _Tp, __void_t<_Func<_Alloc>>>
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{
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using type = _Func<_Alloc>;
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};
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// Select _A2::difference_type or pointer_traits<_Ptr>::difference_type
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template<typename _A2, typename _PtrT, typename = void>
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struct _Diff
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{ using type = typename pointer_traits<_PtrT>::difference_type; };
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template<typename _A2, typename _PtrT>
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struct _Diff<_A2, _PtrT, __void_t<typename _A2::difference_type>>
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{ using type = typename _A2::difference_type; };
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// Select _A2::size_type or make_unsigned<_DiffT>::type
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template<typename _A2, typename _DiffT, typename = void>
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struct _Size : make_unsigned<_DiffT> { };
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template<typename _A2, typename _DiffT>
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struct _Size<_A2, _DiffT, __void_t<typename _A2::size_type>>
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{ using type = typename _A2::size_type; };
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public:
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/**
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* @brief The allocator's const pointer type.
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*
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* @c Alloc::const_pointer if that type exists, otherwise
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* <tt> pointer_traits<pointer>::rebind<const value_type> </tt>
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*/
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using const_pointer
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= __detected_or_t<__ptr_rebind<pointer, const value_type>,
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__c_pointer, _Alloc>;
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using const_pointer = typename _Ptr<__c_pointer, const value_type>::type;
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/**
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* @brief The allocator's void pointer type.
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@ -114,8 +140,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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* @c Alloc::void_pointer if that type exists, otherwise
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* <tt> pointer_traits<pointer>::rebind<void> </tt>
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*/
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using void_pointer
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= __detected_or_t<__ptr_rebind<pointer, void>, __v_pointer, _Alloc>;
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using void_pointer = typename _Ptr<__v_pointer, void>::type;
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/**
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* @brief The allocator's const void pointer type.
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@ -123,9 +148,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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* @c Alloc::const_void_pointer if that type exists, otherwise
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* <tt> pointer_traits<pointer>::rebind<const void> </tt>
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*/
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using const_void_pointer
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= __detected_or_t<__ptr_rebind<pointer, const void>, __cv_pointer,
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_Alloc>;
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using const_void_pointer = typename _Ptr<__cv_pointer, const void>::type;
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/**
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* @brief The allocator's difference type
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@ -133,9 +156,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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* @c Alloc::difference_type if that type exists, otherwise
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* <tt> pointer_traits<pointer>::difference_type </tt>
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*/
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using difference_type
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= __detected_or_t<typename pointer_traits<pointer>::difference_type,
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__diff_type, _Alloc>;
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using difference_type = typename _Diff<_Alloc, pointer>::type;
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/**
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* @brief The allocator's size type
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@ -143,9 +164,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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* @c Alloc::size_type if that type exists, otherwise
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* <tt> make_unsigned<difference_type>::type </tt>
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*/
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using size_type
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= __detected_or_t<typename make_unsigned<difference_type>::type,
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__size_type, _Alloc>;
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using size_type = typename _Size<_Alloc, difference_type>::type;
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/**
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* @brief How the allocator is propagated on copy assignment
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@ -97,7 +97,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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/// The type pointed to.
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using element_type
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= __detected_or_t_<__get_first_arg_t, __element_type, _Ptr>;
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= __detected_or_t<__get_first_arg_t<_Ptr>, __element_type, _Ptr>;
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/// The type used to represent the difference between two pointers.
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using difference_type
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@ -2565,12 +2565,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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using __detected_or_t
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= typename __detected_or<_Default, _Op, _Args...>::type;
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// _Op<_Args...> if that is a valid type, otherwise _Default<_Args...>.
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template<template<typename...> class _Default,
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template<typename...> class _Op, typename... _Args>
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using __detected_or_t_ =
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__detected_or_t<_Default<_Args...>, _Op, _Args...>;
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/// @} group metaprogramming
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/**
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@ -0,0 +1,52 @@
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// Copyright (C) 2017 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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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING3. If not see
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// <http://www.gnu.org/licenses/>.
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// { dg-do compile { target c++11 } }
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#include <memory>
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// Non-type template param means pointer_traits::rebind can't be instantiated.
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template<typename T, int = 0>
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struct Pointer
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{
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using element_type = T;
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Pointer(T* p = nullptr) : ptr(p) { }
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T* ptr;
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};
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template<typename T>
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struct Alloc
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{
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using value_type = T;
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using pointer = Pointer<T>;
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using const_pointer = Pointer<const T>;
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using void_pointer = Pointer<void>;
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using const_void_pointer = Pointer<const void>;
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pointer allocate(std::size_t n)
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{ return std::allocator<T>().allocate(n); }
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void allocate(pointer p, std::size_t n)
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{ return std::allocator<T>().deallocate(p, n); }
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};
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// The nested pointer types in Alloc should be found without attempting to
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// instantiate pointer_traits::rebind (which would fail):
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std::allocator_traits<Alloc<int>>::pointer p;
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std::allocator_traits<Alloc<int>>::const_pointer cp;
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std::allocator_traits<Alloc<int>>::void_pointer vp;
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std::allocator_traits<Alloc<int>>::const_void_pointer cvp;
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