Issue 3198 - WG21 LWG Issues
Title
Bad constraint on std::span::span()
Status
c++20
Section
[span.cons]
Submitter
Lars Gullik Bjønnes

Created on 2019-04-03.00:00:00 last changed 38 months ago

Messages

msg10387 (view)
Date: 2019-04-06.16:20:33

Proposed resolution:

This wording is relative to N4810.

  1. Modify [span.cons] as indicated:

    constexpr span() noexcept;

    -1- Constraints: Extent <== dynamic_extent || Extent == 0 is true.

msg10386 (view)
Date: 2019-06-10.05:20:17

It seems that this was left out of P1089. The constraint on span() ([span.cons]) in the current draft is:

Constraints: Extent <= 0 is true.

This does not seem to make much sense.

The proposal is to change the constraint to be:

Constraints: Extent == dynamic_extent || Extent == 0 is true.

[2019-06-09; Priority to 0 and Status to Tentatively Ready after five positive votes on the reflector.]
History
Date User Action Args
2021-02-25 10:48:01adminsetstatus: wp -> c++20
2019-07-22 15:46:37adminsetstatus: voting -> wp
2019-06-17 05:25:36adminsetstatus: ready -> voting
2019-06-10 05:20:17adminsetstatus: new -> ready
2019-04-06 16:20:33adminsetmessages: + msg10387
2019-04-03 00:00:00admincreate