https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91369
--- Comment #18 from Jonathan Wakely <redi at gcc dot gnu.org> --- Author: redi Date: Wed Oct 23 17:42:11 2019 New Revision: 277342 URL: https://gcc.gnu.org/viewcvs?rev=277342&root=gcc&view=rev Log: PR c++/91369 Implement P0784R7 changes to allocation and construction 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. Added: trunk/libstdc++-v3/testsuite/20_util/specialized_algorithms/construct_at/ trunk/libstdc++-v3/testsuite/20_util/specialized_algorithms/construct_at/1.cc Modified: trunk/libstdc++-v3/ChangeLog trunk/libstdc++-v3/include/bits/alloc_traits.h trunk/libstdc++-v3/include/bits/allocator.h trunk/libstdc++-v3/include/bits/stl_construct.h trunk/libstdc++-v3/include/bits/stl_uninitialized.h trunk/libstdc++-v3/include/ext/alloc_traits.h trunk/libstdc++-v3/include/ext/malloc_allocator.h trunk/libstdc++-v3/include/ext/new_allocator.h trunk/libstdc++-v3/testsuite/20_util/headers/memory/synopsis.cc trunk/libstdc++-v3/testsuite/20_util/scoped_allocator/69293_neg.cc trunk/libstdc++-v3/testsuite/23_containers/vector/cons/destructible_debug_neg.cc trunk/libstdc++-v3/testsuite/23_containers/vector/cons/destructible_neg.cc
