Rationale:

[ 2020-05-03 Reflector discussion ]

Resolved by P1210R0 accepted during the San Diego 2018 meeting.

[ 2018-07-20 Priority set to 3 after reflector discussion ]

Addresses: fund.ts.v3

The LFTSv3 prospective-working-paper N4758 contains two aliases that are already in C++17:

• void_t in [meta.type.synop]

• uses_allocator_v in [header.memory.synop]

I'd like to propose deleting both, but separate discussion is warranted:

void_t belongs with the larger "detection idiom", which has not been merged into C++17. We may prefer to keep our own local version of the alias.

uses_allocator_v aliases a version of uses_allocator that is modified by this TS. However, as specified the alias may actually end up referring to std::uses_allocator (because <memory> is included), not to std::experimental::uses_allocator, as may have been intended.