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### 3666. `join_view`'s difference type is too small

Section: 24.7.12 [range.join] Status: New Submitter: Tomasz Kamiński Opened: 2022-01-30 Last modified: 2022-01-31

Priority: 2

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Discussion:

Despite the fact that `join_view` may produce more elements than each joined view(s) contains, we require implementations to use the `common_type` of their difference types (per 24.7.12.3 [range.join.iterator] p3), which may lead to UB. As we already have provided implementation freedom to define extended integer-like types we should make provision for them to be used here as well. The same issue applies to the `join_with_view` as proposed by P2441.

[2022-03-04; Reflector poll]

Set priority to 2 after reflector poll. Might be a design issue.

Proposed resolution: