mirror of
https://github.com/gcc-mirror/gcc.git
synced 2026-05-06 14:59:39 +02:00
f60dbb5796
Using requires { sizeof(T); } in __new_allocator::allocate gives a
better diagnostic when the static_assert fails.
We can also reduce the total number of diagnostics due to invalid
sizeof(T) and alignof(T) by using the same requires-expression to make
the body of the function a discarded statement when the static_assert
already failed. This fixes a regression in diagnostic quality due to
making __new_allocator::allocate constexpr in r16-7271-g7197d0cce70525,
which caused a cascade of seven errors instead of just one for
std::allocator<incomplete-type>().allocate(1).
libstdc++-v3/ChangeLog:
* include/bits/allocator.h (allocator::allocate): Use specific
feature test macro for constexpr allocate and deallocate. Make
consteval path a discarded statement if sizeof(T) is ill-formed.
* include/bits/new_allocator.h (__new_allocator::allocate): Use
requires-expression for static_cast. Make function body a
discarded stament if sizeof(T) is ill-formed. Use if-constexpr
for alignment checks.
Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
256 lines
7.7 KiB
C++
256 lines
7.7 KiB
C++
// Allocator that wraps operator new -*- C++ -*-
|
|
|
|
// Copyright (C) 2001-2026 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.
|
|
|
|
// Under Section 7 of GPL version 3, you are granted additional
|
|
// permissions described in the GCC Runtime Library Exception, version
|
|
// 3.1, as published by the Free Software Foundation.
|
|
|
|
// You should have received a copy of the GNU General Public License and
|
|
// a copy of the GCC Runtime Library Exception along with this program;
|
|
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
// <http://www.gnu.org/licenses/>.
|
|
|
|
/** @file bits/new_allocator.h
|
|
* This is an internal header file, included by other library headers.
|
|
* Do not attempt to use it directly. @headername{memory}
|
|
*/
|
|
|
|
#ifndef _STD_NEW_ALLOCATOR_H
|
|
#define _STD_NEW_ALLOCATOR_H 1
|
|
|
|
#include <bits/c++config.h>
|
|
#include <new>
|
|
#include <bits/new_throw.h>
|
|
#include <bits/move.h>
|
|
#if __cplusplus >= 201103L
|
|
#include <type_traits>
|
|
#endif
|
|
|
|
namespace std _GLIBCXX_VISIBILITY(default)
|
|
{
|
|
_GLIBCXX_BEGIN_NAMESPACE_VERSION
|
|
|
|
/**
|
|
* @brief An allocator that uses global `new`, as per C++03 [20.4.1].
|
|
* @ingroup allocators
|
|
*
|
|
* This is precisely the allocator defined in the C++ Standard.
|
|
* - all allocation calls `operator new`
|
|
* - all deallocation calls `operator delete`
|
|
*
|
|
* This is the default base-class implementation of `std::allocator`,
|
|
* and is also the base-class of the `__gnu_cxx::new_allocator` extension.
|
|
* You should use either `std::allocator` or `__gnu_cxx::new_allocator`
|
|
* instead of using this directly.
|
|
*
|
|
* @tparam _Tp Type of allocated object.
|
|
*
|
|
* @headerfile memory
|
|
*/
|
|
template<typename _Tp>
|
|
class __new_allocator
|
|
{
|
|
public:
|
|
typedef _Tp value_type;
|
|
typedef std::size_t size_type;
|
|
typedef std::ptrdiff_t difference_type;
|
|
#if __cplusplus <= 201703L
|
|
typedef _Tp* pointer;
|
|
typedef const _Tp* const_pointer;
|
|
typedef _Tp& reference;
|
|
typedef const _Tp& const_reference;
|
|
|
|
template<typename _Tp1>
|
|
struct rebind
|
|
{ typedef __new_allocator<_Tp1> other; };
|
|
#endif
|
|
|
|
#if __cplusplus >= 201103L
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// 2103. propagate_on_container_move_assignment
|
|
typedef std::true_type propagate_on_container_move_assignment;
|
|
#endif
|
|
|
|
__attribute__((__always_inline__))
|
|
_GLIBCXX20_CONSTEXPR
|
|
__new_allocator() _GLIBCXX_USE_NOEXCEPT { }
|
|
|
|
__attribute__((__always_inline__))
|
|
_GLIBCXX20_CONSTEXPR
|
|
__new_allocator(const __new_allocator&) _GLIBCXX_USE_NOEXCEPT { }
|
|
|
|
template<typename _Tp1>
|
|
__attribute__((__always_inline__))
|
|
_GLIBCXX20_CONSTEXPR
|
|
__new_allocator(const __new_allocator<_Tp1>&) _GLIBCXX_USE_NOEXCEPT { }
|
|
|
|
#if __cplusplus >= 201103L
|
|
__new_allocator& operator=(const __new_allocator&) = default;
|
|
#endif
|
|
|
|
#if __cplusplus <= 201703L
|
|
~__new_allocator() _GLIBCXX_USE_NOEXCEPT { }
|
|
|
|
pointer
|
|
address(reference __x) const _GLIBCXX_NOEXCEPT
|
|
{ return std::__addressof(__x); }
|
|
|
|
const_pointer
|
|
address(const_reference __x) const _GLIBCXX_NOEXCEPT
|
|
{ return std::__addressof(__x); }
|
|
#endif
|
|
|
|
#if __has_builtin(__builtin_operator_new) >= 201802L
|
|
# define _GLIBCXX_OPERATOR_NEW __builtin_operator_new
|
|
# define _GLIBCXX_OPERATOR_DELETE __builtin_operator_delete
|
|
#else
|
|
# define _GLIBCXX_OPERATOR_NEW ::operator new
|
|
# define _GLIBCXX_OPERATOR_DELETE ::operator delete
|
|
#endif
|
|
|
|
#pragma GCC diagnostic push
|
|
#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
|
|
|
|
// NB: __n is permitted to be 0. The C++ standard says nothing
|
|
// about what the return value is when __n == 0.
|
|
_GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR _Tp*
|
|
allocate(size_type __n, const void* = static_cast<const void*>(0))
|
|
{
|
|
#if __cplusplus >= 201103L
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// 3308. std::allocator<void>().allocate(n)
|
|
#if ! __cpp_concepts
|
|
static_assert(sizeof(_Tp) != 0, "cannot allocate incomplete types");
|
|
#else
|
|
static_assert(requires { sizeof(_Tp); },
|
|
"cannot allocate incomplete types");
|
|
|
|
if constexpr (!requires { sizeof(_Tp); })
|
|
return nullptr; // static_assert already failed
|
|
else
|
|
#endif
|
|
#endif
|
|
if (__builtin_expect(__n > this->_M_max_size(), false))
|
|
{
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// 3190. allocator::allocate sometimes returns too little storage
|
|
if (__n > (std::size_t(-1) / sizeof(_Tp)))
|
|
std::__throw_bad_array_new_length();
|
|
std::__throw_bad_alloc();
|
|
}
|
|
#if __cpp_aligned_new && __cplusplus >= 201103L
|
|
else if constexpr (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
|
|
{
|
|
std::align_val_t __al = std::align_val_t(alignof(_Tp));
|
|
return static_cast<_Tp*>(_GLIBCXX_OPERATOR_NEW(__n * sizeof(_Tp),
|
|
__al));
|
|
}
|
|
#endif
|
|
else
|
|
return static_cast<_Tp*>(_GLIBCXX_OPERATOR_NEW(__n * sizeof(_Tp)));
|
|
}
|
|
|
|
// __p is not permitted to be a null pointer.
|
|
_GLIBCXX20_CONSTEXPR void
|
|
deallocate(_Tp* __p, size_type __n __attribute__ ((__unused__)))
|
|
{
|
|
#if __cpp_sized_deallocation
|
|
# define _GLIBCXX_SIZED_DEALLOC(p, n) (p), (n) * sizeof(_Tp)
|
|
#else
|
|
# define _GLIBCXX_SIZED_DEALLOC(p, n) (p)
|
|
#endif
|
|
|
|
#if __cpp_aligned_new && __cplusplus >= 201103L
|
|
if constexpr (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
|
|
{
|
|
_GLIBCXX_OPERATOR_DELETE(_GLIBCXX_SIZED_DEALLOC(__p, __n),
|
|
std::align_val_t(alignof(_Tp)));
|
|
return;
|
|
}
|
|
#endif
|
|
_GLIBCXX_OPERATOR_DELETE(_GLIBCXX_SIZED_DEALLOC(__p, __n));
|
|
}
|
|
|
|
#pragma GCC diagnostic pop
|
|
#undef _GLIBCXX_SIZED_DEALLOC
|
|
#undef _GLIBCXX_OPERATOR_DELETE
|
|
#undef _GLIBCXX_OPERATOR_NEW
|
|
|
|
#if __cplusplus <= 201703L
|
|
__attribute__((__always_inline__))
|
|
size_type
|
|
max_size() const _GLIBCXX_USE_NOEXCEPT
|
|
{ return _M_max_size(); }
|
|
|
|
#if __cplusplus >= 201103L
|
|
template<typename _Up, typename... _Args>
|
|
__attribute__((__always_inline__))
|
|
void
|
|
construct(_Up* __p, _Args&&... __args)
|
|
noexcept(__is_nothrow_new_constructible<_Up, _Args...>)
|
|
{ ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
|
|
|
|
template<typename _Up>
|
|
__attribute__((__always_inline__))
|
|
void
|
|
destroy(_Up* __p)
|
|
noexcept(std::is_nothrow_destructible<_Up>::value)
|
|
{ __p->~_Up(); }
|
|
#else
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// 402. wrong new expression in [some_] allocator::construct
|
|
__attribute__((__always_inline__))
|
|
void
|
|
construct(pointer __p, const _Tp& __val)
|
|
{ ::new((void *)__p) _Tp(__val); }
|
|
|
|
__attribute__((__always_inline__))
|
|
void
|
|
destroy(pointer __p) { __p->~_Tp(); }
|
|
#endif
|
|
#endif // ! C++20
|
|
|
|
template<typename _Up>
|
|
friend __attribute__((__always_inline__)) _GLIBCXX20_CONSTEXPR bool
|
|
operator==(const __new_allocator&, const __new_allocator<_Up>&)
|
|
_GLIBCXX_NOTHROW
|
|
{ return true; }
|
|
|
|
#if __cpp_impl_three_way_comparison < 201907L
|
|
template<typename _Up>
|
|
friend __attribute__((__always_inline__)) _GLIBCXX20_CONSTEXPR bool
|
|
operator!=(const __new_allocator&, const __new_allocator<_Up>&)
|
|
_GLIBCXX_NOTHROW
|
|
{ return false; }
|
|
#endif
|
|
|
|
private:
|
|
__attribute__((__always_inline__))
|
|
_GLIBCXX_CONSTEXPR size_type
|
|
_M_max_size() const _GLIBCXX_USE_NOEXCEPT
|
|
{
|
|
#if __PTRDIFF_MAX__ < __SIZE_MAX__
|
|
return std::size_t(__PTRDIFF_MAX__) / sizeof(_Tp);
|
|
#else
|
|
return std::size_t(-1) / sizeof(_Tp);
|
|
#endif
|
|
}
|
|
};
|
|
|
|
_GLIBCXX_END_NAMESPACE_VERSION
|
|
} // namespace
|
|
|
|
#endif
|