Issue 2679: Inconsistent Use of Effects and Equivalent To

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Section: 16.3.2.4 [structure.specifications] Status: C++17 Submitter: Dawn Perchik Opened: 2016-04-14 Last modified: 2017-07-30

Priority: 3

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Discussion:

Some Effects: were intended to include the "Equivalent to" phrasing where no or different words were used. See examples in std::filesystem and throughout the library.
The wording in [structure.specifications]/4 is incorrect and Effects: throughout the library which use (or were intended to use) the "Equivalent to" phrasing need to be checked to make sure they fit the intended wording.

[2016-04, Issues Telecon]

The PR is fine; but bullet #1 in the report really should have a list of places to change.

Jonathan checked throughout the library for bullet #2 and found two problems in [string.access], which have been added to the PR.

[2016-08-03 Chicago]

Fri PM: Move to Tentatively Ready

Proposed resolution:

Change [structure.specifications]/4 as indicated:

"[…] if F has no Returns: element, a non-void return from F is specified by the ~~Returns: elements~~return statements in the code sequence."
Add two return keywords to [string.access]:
```
const charT& front() const;
charT& front();
```
-7- Requires: !empty().

-8- Effects: Equivalent to return operator[](0).
```
const charT& back() const;
charT& back();
```
-9- Requires: !empty().

-10- Effects: Equivalent to return operator[](size() - 1).