Section: 25.3.4.13 [iterator.concept.random.access] Status: C++20 Submitter: Eric Niebler Opened: 2019-09-10 Last modified: 2021-02-25 10:48:01 UTC
Priority: 0
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Discussion:
25.3.4.13 [iterator.concept.random.access]/p2.7 says:
(b += -n) is equal to a
Unary minus can do integer promotion. That is not the intent here.
[2019-10-12 Issue Prioritization]
Status to Tentatively Ready and priority to 0 after five positive votes on the reflector.
Proposed resolution:
This wording is relative to N4830.
Modify 25.3.4.13 [iterator.concept.random.access] as indicated:
-2- Let a and b be valid iterators of type I such that b is reachable from a after n applications of ++a, let D be iter_difference_t<I>, and let n denote a value of type D. I models random_access_iterator only if:
(2.1) — (a += n) is equal to b.
[…]
(2.7) — (b += D(-n)) is equal to a.
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