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Add checks to guard against overflow in iterator methods. #76

merged 1 commit into from Nov 17, 2019

Add checks to guard against overflow in iterator methods. #76

merged 1 commit into from Nov 17, 2019


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@hermanventer hermanventer commented Nov 8, 2019

When a generated iterator runs of the end it keeps on incrementing the index variable, which is undesirable. Furthermore the size_hint method does not guard against the index being greater than the variant count, which causes an overflow.

These issues cause our static analyses tool to generate warnings when analyzing code generated by strum, which is annoying.

Thanks for considering this.

@Peternator7 Peternator7 merged commit e981f24 into Peternator7:master Nov 17, 2019
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@Peternator7 Peternator7 commented Nov 17, 2019

Looks great! Thanks for the PR :)

@hermanventer hermanventer deleted the guard_against_overflow branch Nov 17, 2019

fn size_hint(&self) -> (usize, Option<usize>) {
let t = #variant_count - self.idx;
let t = if self.idx >= #variant_count { 0 } else { #variant_count - self.idx };
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@Ten0 Ten0 Nov 23, 2021

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Looks like this is unnecessary given that the above guarantees this will never underflow.

Additionally, this property is FusedIterator (which is not a requirement for Iterator, and it's the responsibility of the caller to stop calling it). If we choose to have it, then we should also signify that we have it by implementing FusedIterator.

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3 participants