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### 2808. Requirements for `fpos` and `stateT`

Section: 29.5.3.2 [fpos.operations] Status: Resolved Submitter: Great Britain Opened: 2016-11-09 Last modified: 2020-05-12

Priority: 4

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Discussion:

Addresses GB 60

The requirements on the `stateT` type used to instantiate class template `fpos` are not clear, and the following Table 108 — "Position type requirements" is a bit of a mess. This is old wording, and should be cleaned up with better terminology from the Clause 17 Requirements. For example, `stateT` might be require `CopyConstructible`?, `CopyAssignable`?, and `Destructible`. Several entries in the final column of the table appear to be post-conditions, but without the `post` markup to clarify they are not assertions or preconditions. They frequently refer to identifiers that do not apply to all entries in their corresponding `Expression` column, leaving some expressions without a clearly defined semantic. If `stateT` is a trivial type, is `fpos` also a trivial type, or is a default constructor not required/supported?

Proposed change:

Clarify the requirements and the table.

[Issues Telecon 16-Dec-2016]

Priority 4; no consensus for any concrete change

[2019-03-17; Daniel comments]

With the acceptance of P0759R1 at the Rapperswil 2018 meeting this issue should be closed as Resolved (Please note that this paper resolves a historic NB comment that was originally written against C++17 but was at that time responded: "invite a paper if anybody wants to change it - no concensus for change").

[2020-05-12; Reflector discussions]

Resolved by P0759R1.

Rationale:

Resolved by P0759R1.

Proposed resolution: