This patch is the first part of library support for constexpr
std::vector and std::string. This only includes the changes to
std::allocator, std::allocator_traits, std::construct_at,
std::destroy_at, std::destroy and std::destroy_n.
std::allocator::allocate and std::allocator::deallocate need to be
added so that they can be intercepted by the compiler during constant
evaluation. Outside of constant evaluation those new member functions
just forward to the existing implementation in the base class.
PR c++/91369 Implement P0784R7 changes to allocation and construction
* include/bits/alloc_traits.h: Include <bits/stl_construct.h>.
(allocator_traits::_S_allocate, allocator_traits::_S_construct)
(allocator_traits::_S_destroy, allocator_traits::_S_max_size)
(allocator_traits::_S_select, allocator_traits::allocate)
(allocator_traits::deallocate, allocator_traits::construct)
(allocator_traits::destroy, allocator_traits::max_size)
(allocator_traits::select_on_container_copy_construction)
(allocator_traits<allocator<T>>): Add constexpr specifier for C++20.
(allocator_traits<allocator<T>>::construct): Use construct_at.
(allocator_traits<allocator<T>>::destroy): Use destroy_at.
(__alloc_on_copy, __alloc_on_move, __alloc_on_swap): Add constexpr
specifier.
(_Destroy(ForwardIterator, ForwardIterator, Alloc&))
(_Destroy(ForwardIterator, ForwardIterator, allocator<T>&)): Move here
from <bits/stl_construct.h>.
* include/bits/allocator.h (allocator::~allocator): Remove for C++20.
(allocator::allocate, allocate::deallocate): Define for C++20 and up.
(operator==, operator!=): Add constexpr specifier for C++20.
* include/bits/stl_construct.h: Don't include <ext/alloc_traits.h>.
(destroy_at): For C++20 add constexpr specifier and support for
destroying arrays.
(construct_at): Define new function for C++20.
(_Construct): Return result of placement new-expression. For C++11 and
up add constexpr. For C++20 dispatch to std::construct_at during
constant evaluation.
(_Destroy(pointer)): Add constexpr specifier. For C++20 dispatch to
std::destroy_at during constant evaluation.
(_Destroy_aux::__destroy, _Destroy_n_aux::__destroy_n): Add constexpr
specifier for C++20.
(_Destroy(ForwardIterator, ForwardIterator))
(_Destroy(ForwardIterator, Size)): Likewise. Do not elide trivial
destructors during constant evaluation.
(destroy, destroy_n): Add constexpr specifier for C++20.
(_Destroy(ForwardIterator, ForwardIterator, Alloc&))
(_Destroy(ForwardIterator, ForwardIterator, allocator<T>&)): Move to
<bits/alloc_traits.h>, to remove dependency on allocators.
* include/bits/stl_uninitialized.h: Include <ext/alloc_traits.h>.
Include <bits/stl_pair.h> instead of <utility>.
* include/ext/alloc_traits.h: Always include <bits/alloc_traits.h>.
(__alloc_traits::construct, __alloc_traits::destroy)
(__alloc_traits::_S_select_on_copy, __alloc_traits::_S_on_swap): Add
constexpr specifier.
* include/ext/malloc_allocator.h (operator==, operator!=): Add
constexpr specifier for C++20.
* include/ext/new_allocator.h (operator==, operator!=): Likewise.
* testsuite/20_util/headers/memory/synopsis.cc: Add constexpr.
* testsuite/20_util/scoped_allocator/69293_neg.cc: Ignore additional
errors due to constexpr function called after failed static_assert.
* testsuite/20_util/specialized_algorithms/construct_at/1.cc: New test.
* testsuite/23_containers/vector/cons/destructible_debug_neg.cc:
Ignore additional errors due to constexpr function called after failed
static_assert.
* testsuite/23_containers/vector/cons/destructible_neg.cc: Likewise.
From-SVN: r277342
file: libstdc++-v3/README
New users may wish to point their web browsers to the file
index.html in the 'doc/html' subdirectory. It contains brief
building instructions and notes on how to configure the library in
interesting ways.
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