Issue 3200: midpoint should not constrain T is complete

Title: midpoint should not constrain T is complete
Status: c++20
Section: [numeric.ops.midpoint]
Submitter: Paolo Torres

Created on 2019-04-10.00:00:00 last changed 45 months ago

Messages

msg11112 (view)

Date: 2020-02-14.11:00:18

Proposed resolution:

This wording is relative to N4810.

Modify [numeric.ops.midpoint] as indicated:
```
template<class T>
  constexpr T* midpoint(T* a, T* b);
```
-4- Constraints: T is an ~~complete~~ object type.
-?- Mandates: T is a complete type.
[…]

msg10432 (view)

Date: 2020-02-14.11:00:18

[ 2020-02 Status to Immediate on Thursday night in Prague. ]

msg10391 (view)

Date: 2019-06-12.00:00:00

[ 2019-06-12 Priority set to 2 after reflector discussion ]

msg10390 (view)

Date: 2019-04-10.00:00:00

The constraint of the midpoint overload in [numeric.ops.midpoint]:

template<class T>
constexpr T* midpoint(T* a, T* b);
-4- Constraints: T is a complete object type.

is incorrect. Paragraph 4 states T is constrained to be a complete object type, however it does not seem to be possible to implement T is complete. This means behavior is conditioned dependent on whether a type is complete, and this seems inconsistent with the library precedent.

History
Date	User	Action	Args
2021-02-25 10:48:01	admin	set	status: wp -> c++20
2020-02-24 16:02:59	admin	set	status: immediate -> wp
2020-02-14 11:00:18	admin	set	messages: + msg11112
2020-02-14 11:00:18	admin	set	status: new -> immediate
2019-06-10 05:16:56	admin	set	messages: + msg10432
2019-04-13 16:42:43	admin	set	messages: + msg10391
2019-04-10 00:00:00	admin	create