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InterleaveShortest: don't overflow size_hint lower bound #1102

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InterleaveShortest: don't overflow size_hint lower bound #1102

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2 changes: 1 addition & 1 deletion src/adaptors/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -179,7 +179,7 @@ where
let (combined_lower, combined_upper) =
size_hint::mul_scalar(size_hint::min(curr_hint, next_hint), 2);
let lower = if curr_lower > next_lower {
combined_lower + 1
combined_lower.saturating_add(1)
} else {
combined_lower
};
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8 changes: 8 additions & 0 deletions tests/test_std.rs
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Expand Up @@ -83,6 +83,14 @@ fn interleave_shortest() {
let i1 = ::std::iter::repeat(1);
let it = v0.into_iter().interleave_shortest(i1);
assert_eq!(it.size_hint(), (6, Some(6)));

// Issue #1068: combined lower bound used to overflow when both halves
// reported saturating lower bounds, panicking in debug builds.
let i0 = ::std::iter::repeat(0).take(usize::MAX);
let i1 = ::std::iter::repeat(1);
let it = i0.interleave_shortest(i1);
let (lower, _) = it.size_hint();
assert_eq!(lower, usize::MAX);
}

#[test]
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