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Rollup merge of #81741 - sdroege:zip-trusted-random-access-specialization-panic-safety, r=KodrAus 

Increment `self.index` before calling `Iterator::self.a.__iterator_ge…

…`t_unchecked` in `Zip` `TrustedRandomAccess` specialization

Otherwise if `Iterator::self.a.__iterator_get_unchecked` panics the
index would not have been incremented yet and another call to
`Iterator::next` would read from the same index again, which is not
allowed according to the API contract of `TrustedRandomAccess` for
`!Clone`.

Fixes https://github.com/rust-lang/rust/issues/81740
This commit is contained in:
Dylan DPC 2021-02-12 22:53:32 +01:00 committed by GitHub
parent 58d72aedee 86a4b27475
commit 0cfba2fd09
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1 changed files with 6 additions and 5 deletions
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11
library/core/src/iter/adapters/zip.rs
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@ -198,12 +198,13 @@ where
Some((self.a.__iterator_get_unchecked(i), self.b.__iterator_get_unchecked(i)))
}
} else if A::may_have_side_effect() && self.index < self.a.size() {
// match the base implementation's potential side effects
// SAFETY: we just checked that `self.index` < `self.a.len()`
unsafe {
self.a.__iterator_get_unchecked(self.index);
}
let i = self.index;
self.index += 1;
// match the base implementation's potential side effects
// SAFETY: we just checked that `i` < `self.a.len()`
unsafe {
self.a.__iterator_get_unchecked(i);
}
None
} else {
None