cdeca5cbd3
Some history: The Zip TrustedRandomAccess specialization has tried to emulate the side-effects of the naive implementation for a long time, including backwards iteration. 82292¹ tried to fix unsoundness (82291¹) in that side-effect-preservation code, but this introduced some panic-safety unsoundness (86443¹), but the fix 86452¹ didn't fix it for nested Zip iterators (137255¹). Rather than piling yet another fix ontop of this heap of fixes this PR reduces the number of cases in which side-effects will be preserved; the necessary API guarantee change was approved in 83791¹ but we haven't made use of that so far. ¹ see merge commit for linkfied issues.
54 lines
1.5 KiB
Rust
54 lines
1.5 KiB
Rust
use core::iter::*;
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#[test]
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fn test_cloned() {
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let xs = [2, 4, 6, 8];
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let mut it = xs.iter().cloned();
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assert_eq!(it.len(), 4);
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assert_eq!(it.next(), Some(2));
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assert_eq!(it.len(), 3);
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assert_eq!(it.next(), Some(4));
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assert_eq!(it.len(), 2);
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assert_eq!(it.next_back(), Some(8));
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assert_eq!(it.len(), 1);
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assert_eq!(it.next_back(), Some(6));
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assert_eq!(it.len(), 0);
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assert_eq!(it.next_back(), None);
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}
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#[test]
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fn test_cloned_side_effects() {
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let mut count = 0;
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{
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let iter = [1, 2, 3]
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.iter()
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.map(|x| {
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count += 1;
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x
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})
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.cloned()
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.zip(&[1]);
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for _ in iter {}
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}
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// Zip documentation provides some leeway about side-effects
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assert!([1, 2].iter().any(|v| *v == count));
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}
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#[test]
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fn test_cloned_try_folds() {
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let a = [1, 2, 3, 4, 5, 6, 7, 8, 9];
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let f = &|acc, x| i32::checked_add(2 * acc, x);
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let f_ref = &|acc, &x| i32::checked_add(2 * acc, x);
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assert_eq!(a.iter().cloned().try_fold(7, f), a.iter().try_fold(7, f_ref));
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assert_eq!(a.iter().cloned().try_rfold(7, f), a.iter().try_rfold(7, f_ref));
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let a = [10, 20, 30, 40, 100, 60, 70, 80, 90];
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let mut iter = a.iter().cloned();
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assert_eq!(iter.try_fold(0_i8, |acc, x| acc.checked_add(x)), None);
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assert_eq!(iter.next(), Some(60));
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let mut iter = a.iter().cloned();
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assert_eq!(iter.try_rfold(0_i8, |acc, x| acc.checked_add(x)), None);
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assert_eq!(iter.next_back(), Some(70));
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}
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