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ExactSizeIterator should be an unsafe trait #958

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theemathas opened this Issue Mar 10, 2015 · 2 comments

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@theemathas @huonw @nikomatsakis
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theemathas commented Mar 10, 2015

I think that ExactSizeIterator should be an unsafe trait, so that its invariant can be relied upon by unsafe code.
See also #956 and http://internals.rust-lang.org/t/the-trusted-iterator-length-problem/1302
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huonw commented Mar 10, 2015

FWIW, ExactSizeIterator doesn't help that much with size_hint (covered by the linked internals thread), since we want the guarantees to apply when a type is used as a plain Iterator generic.

@nikomatsakis nikomatsakis referenced this issue Apr 9, 2015

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Unsafe, optimization-oriented traits for precise sizes, orderings, and so forth #1051

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nikomatsakis commented Apr 9, 2015

Closing in favor of the more general #1051.

@nikomatsakis nikomatsakis closed this Apr 9, 2015

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