Issue 2740: constexpr optional<T>::operator->

Title: constexpr optional<T>::operator->
Status: c++17
Section: [optional.observe]
Submitter: Agustín K-ballo Bergé

Created on 2016-07-02.00:00:00 last changed 81 months ago

Messages

msg8280 (view)

Date: 2016-08-01.18:34:48

Proposed resolution:

This wording is relative to N4594.

Modify [optional.object.observe] as indicated:
```
constexpr T const* operator->() const;
constexpr T* operator->();
```
-1- Requires: *this contains a value.
-2- Returns: val.
-3- Throws: Nothing.
-4- Remarks: ~~Unless T is a user-defined type with overloaded unary operator&, t~~These functions shall be constexpr functions.

msg8238 (view)

Date: 2016-08-01.18:34:48

[ 2016-07 Chicago ]

Monday: P0 - tentatively ready

msg8237 (view)

Date: 2016-07-02.00:00:00

optional<T>::operator->s are constrained to be constexpr functions only when T is not a type with an overloaded unary operator&. This constrain comes from the need to use addressof (or a similar mechanism), and the inability to do so in a constant expression in C++14. Given that addressof is now constexpr, this constrain is no longer needed.

History
Date	User	Action	Args
2017-07-30 20:15:43	admin	set	status: wp -> c++17
2016-11-14 03:59:28	admin	set	status: pending -> wp
2016-11-14 03:55:22	admin	set	status: ready -> pending
2016-08-01 18:34:48	admin	set	messages: + msg8280
2016-08-01 18:34:48	admin	set	status: new -> ready
2016-07-03 18:13:32	admin	set	messages: + msg8238
2016-07-02 00:00:00	admin	create