fc6f1128ae
When I added the std::allocator_traits<std::allocator<void>> specialization it broke code like this: std::allocate_shared<const int>(std::allocator<void>()); The problem is that allocator_traits<allocator<void>>::construct(a, p) now uses std::_Construct(p), which only does a static_cast<void*>(p) and so fails if the pointer has cv-quals. This changes std::_Construct (and the related std::_Construct_novalue) to use a C-style cast to (void*) which matches the effects of the "voidify" helper in the C++20 standard. libstdc++-v3/ChangeLog: * include/bits/stl_construct.h (_Construct, _Construct_novalue): Also cast away cv-qualifiers when converting pointer to void. * testsuite/20_util/allocator/void.cc: Test construct function with cv-qualified types.
110 lines
3.7 KiB
C++
110 lines
3.7 KiB
C++
// Copyright (C) 2016-2022 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 run { target c++11 } }
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#include <memory>
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#include <testsuite_hooks.h>
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template class std::allocator<void>;
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void
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test01()
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{
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int i;
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using alloc_type = std::allocator<void>;
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alloc_type a;
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std::allocator_traits<alloc_type>::construct(a, &i, 42);
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VERIFY( i == 42 );
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std::allocator_traits<alloc_type>::destroy(a, &i);
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}
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static_assert( std::allocator<void>::propagate_on_container_move_assignment(),
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"POCMA trait should always be present" );
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static_assert( std::allocator<void>::is_always_equal(),
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"is_always_equal trait should always be present" );
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static_assert(
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std::is_same<std::allocator<void>::size_type, std::size_t>(),
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"size_type is size_t" );
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static_assert(
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std::is_same<std::allocator<void>::difference_type, std::ptrdiff_t>(),
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"size_type is size_t" );
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// These properties are formally unspecified, but have always been true for
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// the libstdc++ definition of allocator<void>.
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static_assert(
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std::is_trivially_default_constructible<std::allocator<void>>::value,
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"explicit specialization has trivial default constructor");
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static_assert(
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std::is_trivially_copy_constructible<std::allocator<void>>::value,
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"explicit specialization has trivial copy constructor");
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static_assert(
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std::is_trivially_move_constructible<std::allocator<void>>::value,
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"explicit specialization has trivial move constructor");
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static_assert(
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std::is_trivially_destructible<std::allocator<void>>::value,
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"explicit specialization has trivial destructor");
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#if __cplusplus >= 202002L
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// C++20 removes the allocator<void> explicit specialization, so it can now be
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// constructed using the converting constructor from other specializations.
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static_assert( std::is_nothrow_constructible_v<std::allocator<void>,
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std::allocator<int>> );
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template<typename T>
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concept has_pointer = requires { typename T::pointer; };
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template<typename T>
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concept has_const_pointer = requires { typename T::const_pointer; };
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template<typename T>
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concept has_size_type = requires { typename T::size_type; };
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template<typename T>
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concept has_difference_type = requires { typename T::difference_type; };
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// These were removed for C++20
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static_assert( ! has_pointer<std::allocator<void>> );
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static_assert( ! has_const_pointer<std::allocator<void>> );
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#else
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static_assert(
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std::is_same<std::allocator<void>::pointer, void*>(),
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"pointer is void*" );
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static_assert( std::is_same<std::allocator<void>::const_pointer, const void*>(),
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"const_pointer is const void*" );
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#endif // C++20
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void
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test02()
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{
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std::allocator<void> av;
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int* p = std::allocator<int>().allocate(1);
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const int* c = p;
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std::allocator_traits<std::allocator<void>>::construct(av, c, 0);
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volatile int* v = p;
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std::allocator_traits<std::allocator<void>>::construct(av, v, 0);
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const volatile int* cv = p;
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std::allocator_traits<std::allocator<void>>::construct(av, cv, 0);
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std::allocator<int>().deallocate(p, 1);
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}
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int
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main()
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{
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test01();
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test02();
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}
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