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### 2990. `optional::value_type` is not always a value type

Section: 20.6.3 [optional.optional] Status: Open Submitter: Casey Carter Opened: 2017-06-27 Last modified: 2018-01-28

Priority: 3

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Discussion:

`optional<T>::value_type` is `T`, which can be a cv-qualified object type. This is inconsistent with the uses of the name `value_type` elsewhere in the standard. We should either require `optional<T>::value_type` to be `remove_cv_t<T>` — a true value type — or rename the type alias to `element_type`.

[2017-07 Toronto Tuesday PM issue prioritization]

Priority 3; may also affect `array`

[2018-1-26 issues processing telecon]

Status to 'Open'

Proposed resolution:

This wording is relative to N4659.

1. Edit 20.6.3 [optional.optional], class template `optional` synopsis, as indicated:

   >     template <class T>
   >       class optional {
   >       public:
   >         using value_type = remove_cv_t<T>;
   >         […]
   >       };