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Diffstat (limited to 'library/core/tests/iter/traits/iterator.rs')
| -rw-r--r-- | library/core/tests/iter/traits/iterator.rs | 593 |
1 files changed, 593 insertions, 0 deletions
diff --git a/library/core/tests/iter/traits/iterator.rs b/library/core/tests/iter/traits/iterator.rs new file mode 100644 index 000000000..37345c1d3 --- /dev/null +++ b/library/core/tests/iter/traits/iterator.rs @@ -0,0 +1,593 @@ +/// A wrapper struct that implements `Eq` and `Ord` based on the wrapped +/// integer modulo 3. Used to test that `Iterator::max` and `Iterator::min` +/// return the correct element if some of them are equal. +#[derive(Debug)] +struct Mod3(i32); + +impl PartialEq for Mod3 { + fn eq(&self, other: &Self) -> bool { + self.0 % 3 == other.0 % 3 + } +} + +impl Eq for Mod3 {} + +impl PartialOrd for Mod3 { + fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> { + Some(self.cmp(other)) + } +} + +impl Ord for Mod3 { + fn cmp(&self, other: &Self) -> core::cmp::Ordering { + (self.0 % 3).cmp(&(other.0 % 3)) + } +} + +#[test] +fn test_lt() { + let empty: [isize; 0] = []; + let xs = [1, 2, 3]; + let ys = [1, 2, 0]; + + assert!(!xs.iter().lt(ys.iter())); + assert!(!xs.iter().le(ys.iter())); + assert!(xs.iter().gt(ys.iter())); + assert!(xs.iter().ge(ys.iter())); + + assert!(ys.iter().lt(xs.iter())); + assert!(ys.iter().le(xs.iter())); + assert!(!ys.iter().gt(xs.iter())); + assert!(!ys.iter().ge(xs.iter())); + + assert!(empty.iter().lt(xs.iter())); + assert!(empty.iter().le(xs.iter())); + assert!(!empty.iter().gt(xs.iter())); + assert!(!empty.iter().ge(xs.iter())); + + // Sequence with NaN + let u = [1.0f64, 2.0]; + let v = [0.0f64 / 0.0, 3.0]; + + assert!(!u.iter().lt(v.iter())); + assert!(!u.iter().le(v.iter())); + assert!(!u.iter().gt(v.iter())); + assert!(!u.iter().ge(v.iter())); + + let a = [0.0f64 / 0.0]; + let b = [1.0f64]; + let c = [2.0f64]; + + assert!(a.iter().lt(b.iter()) == (a[0] < b[0])); + assert!(a.iter().le(b.iter()) == (a[0] <= b[0])); + assert!(a.iter().gt(b.iter()) == (a[0] > b[0])); + assert!(a.iter().ge(b.iter()) == (a[0] >= b[0])); + + assert!(c.iter().lt(b.iter()) == (c[0] < b[0])); + assert!(c.iter().le(b.iter()) == (c[0] <= b[0])); + assert!(c.iter().gt(b.iter()) == (c[0] > b[0])); + assert!(c.iter().ge(b.iter()) == (c[0] >= b[0])); +} + +#[test] +fn test_cmp_by() { + use core::cmp::Ordering; + + let f = |x: i32, y: i32| (x * x).cmp(&y); + let xs = || [1, 2, 3, 4].iter().copied(); + let ys = || [1, 4, 16].iter().copied(); + + assert_eq!(xs().cmp_by(ys(), f), Ordering::Less); + assert_eq!(ys().cmp_by(xs(), f), Ordering::Greater); + assert_eq!(xs().cmp_by(xs().map(|x| x * x), f), Ordering::Equal); + assert_eq!(xs().rev().cmp_by(ys().rev(), f), Ordering::Greater); + assert_eq!(xs().cmp_by(ys().rev(), f), Ordering::Less); + assert_eq!(xs().cmp_by(ys().take(2), f), Ordering::Greater); +} + +#[test] +fn test_partial_cmp_by() { + use core::cmp::Ordering; + + let f = |x: i32, y: i32| (x * x).partial_cmp(&y); + let xs = || [1, 2, 3, 4].iter().copied(); + let ys = || [1, 4, 16].iter().copied(); + + assert_eq!(xs().partial_cmp_by(ys(), f), Some(Ordering::Less)); + assert_eq!(ys().partial_cmp_by(xs(), f), Some(Ordering::Greater)); + assert_eq!(xs().partial_cmp_by(xs().map(|x| x * x), f), Some(Ordering::Equal)); + assert_eq!(xs().rev().partial_cmp_by(ys().rev(), f), Some(Ordering::Greater)); + assert_eq!(xs().partial_cmp_by(xs().rev(), f), Some(Ordering::Less)); + assert_eq!(xs().partial_cmp_by(ys().take(2), f), Some(Ordering::Greater)); + + let f = |x: f64, y: f64| (x * x).partial_cmp(&y); + let xs = || [1.0, 2.0, 3.0, 4.0].iter().copied(); + let ys = || [1.0, 4.0, f64::NAN, 16.0].iter().copied(); + + assert_eq!(xs().partial_cmp_by(ys(), f), None); + assert_eq!(ys().partial_cmp_by(xs(), f), Some(Ordering::Greater)); +} + +#[test] +fn test_eq_by() { + let f = |x: i32, y: i32| x * x == y; + let xs = || [1, 2, 3, 4].iter().copied(); + let ys = || [1, 4, 9, 16].iter().copied(); + + assert!(xs().eq_by(ys(), f)); + assert!(!ys().eq_by(xs(), f)); + assert!(!xs().eq_by(xs(), f)); + assert!(!ys().eq_by(ys(), f)); + + assert!(!xs().take(3).eq_by(ys(), f)); + assert!(!xs().eq_by(ys().take(3), f)); + assert!(xs().take(3).eq_by(ys().take(3), f)); +} + +#[test] +fn test_iterator_nth() { + let v: &[_] = &[0, 1, 2, 3, 4]; + for i in 0..v.len() { + assert_eq!(v.iter().nth(i).unwrap(), &v[i]); + } + assert_eq!(v.iter().nth(v.len()), None); +} + +#[test] +fn test_iterator_nth_back() { + let v: &[_] = &[0, 1, 2, 3, 4]; + for i in 0..v.len() { + assert_eq!(v.iter().nth_back(i).unwrap(), &v[v.len() - 1 - i]); + } + assert_eq!(v.iter().nth_back(v.len()), None); +} + +#[test] +fn test_iterator_advance_by() { + let v: &[_] = &[0, 1, 2, 3, 4]; + + for i in 0..v.len() { + let mut iter = v.iter(); + assert_eq!(iter.advance_by(i), Ok(())); + assert_eq!(iter.next().unwrap(), &v[i]); + assert_eq!(iter.advance_by(100), Err(v.len() - 1 - i)); + } + + assert_eq!(v.iter().advance_by(v.len()), Ok(())); + assert_eq!(v.iter().advance_by(100), Err(v.len())); +} + +#[test] +fn test_iterator_advance_back_by() { + let v: &[_] = &[0, 1, 2, 3, 4]; + + for i in 0..v.len() { + let mut iter = v.iter(); + assert_eq!(iter.advance_back_by(i), Ok(())); + assert_eq!(iter.next_back().unwrap(), &v[v.len() - 1 - i]); + assert_eq!(iter.advance_back_by(100), Err(v.len() - 1 - i)); + } + + assert_eq!(v.iter().advance_back_by(v.len()), Ok(())); + assert_eq!(v.iter().advance_back_by(100), Err(v.len())); +} + +#[test] +fn test_iterator_rev_advance_back_by() { + let v: &[_] = &[0, 1, 2, 3, 4]; + + for i in 0..v.len() { + let mut iter = v.iter().rev(); + assert_eq!(iter.advance_back_by(i), Ok(())); + assert_eq!(iter.next_back().unwrap(), &v[i]); + assert_eq!(iter.advance_back_by(100), Err(v.len() - 1 - i)); + } + + assert_eq!(v.iter().rev().advance_back_by(v.len()), Ok(())); + assert_eq!(v.iter().rev().advance_back_by(100), Err(v.len())); +} + +#[test] +fn test_iterator_last() { + let v: &[_] = &[0, 1, 2, 3, 4]; + assert_eq!(v.iter().last().unwrap(), &4); + assert_eq!(v[..1].iter().last().unwrap(), &0); +} + +#[test] +fn test_iterator_max() { + let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; + assert_eq!(v[..4].iter().cloned().max(), Some(3)); + assert_eq!(v.iter().cloned().max(), Some(10)); + assert_eq!(v[..0].iter().cloned().max(), None); + assert_eq!(v.iter().cloned().map(Mod3).max().map(|x| x.0), Some(8)); +} + +#[test] +fn test_iterator_min() { + let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; + assert_eq!(v[..4].iter().cloned().min(), Some(0)); + assert_eq!(v.iter().cloned().min(), Some(0)); + assert_eq!(v[..0].iter().cloned().min(), None); + assert_eq!(v.iter().cloned().map(Mod3).min().map(|x| x.0), Some(0)); +} + +#[test] +fn test_iterator_size_hint() { + let c = (0..).step_by(1); + let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]; + let v2 = &[10, 11, 12]; + let vi = v.iter(); + + assert_eq!((0..).size_hint(), (usize::MAX, None)); + assert_eq!(c.size_hint(), (usize::MAX, None)); + assert_eq!(vi.clone().size_hint(), (10, Some(10))); + + assert_eq!(c.clone().take(5).size_hint(), (5, Some(5))); + assert_eq!(c.clone().skip(5).size_hint().1, None); + assert_eq!(c.clone().take_while(|_| false).size_hint(), (0, None)); + assert_eq!(c.clone().map_while(|_| None::<()>).size_hint(), (0, None)); + assert_eq!(c.clone().skip_while(|_| false).size_hint(), (0, None)); + assert_eq!(c.clone().enumerate().size_hint(), (usize::MAX, None)); + assert_eq!(c.clone().chain(vi.clone().cloned()).size_hint(), (usize::MAX, None)); + assert_eq!(c.clone().zip(vi.clone()).size_hint(), (10, Some(10))); + assert_eq!(c.clone().scan(0, |_, _| Some(0)).size_hint(), (0, None)); + assert_eq!(c.clone().filter(|_| false).size_hint(), (0, None)); + assert_eq!(c.clone().map(|_| 0).size_hint(), (usize::MAX, None)); + assert_eq!(c.filter_map(|_| Some(0)).size_hint(), (0, None)); + + assert_eq!(vi.clone().take(5).size_hint(), (5, Some(5))); + assert_eq!(vi.clone().take(12).size_hint(), (10, Some(10))); + assert_eq!(vi.clone().skip(3).size_hint(), (7, Some(7))); + assert_eq!(vi.clone().skip(12).size_hint(), (0, Some(0))); + assert_eq!(vi.clone().take_while(|_| false).size_hint(), (0, Some(10))); + assert_eq!(vi.clone().map_while(|_| None::<()>).size_hint(), (0, Some(10))); + assert_eq!(vi.clone().skip_while(|_| false).size_hint(), (0, Some(10))); + assert_eq!(vi.clone().enumerate().size_hint(), (10, Some(10))); + assert_eq!(vi.clone().chain(v2).size_hint(), (13, Some(13))); + assert_eq!(vi.clone().zip(v2).size_hint(), (3, Some(3))); + assert_eq!(vi.clone().scan(0, |_, _| Some(0)).size_hint(), (0, Some(10))); + assert_eq!(vi.clone().filter(|_| false).size_hint(), (0, Some(10))); + assert_eq!(vi.clone().map(|&i| i + 1).size_hint(), (10, Some(10))); + assert_eq!(vi.filter_map(|_| Some(0)).size_hint(), (0, Some(10))); +} + +#[test] +fn test_all() { + let v: Box<[isize]> = Box::new([1, 2, 3, 4, 5]); + assert!(v.iter().all(|&x| x < 10)); + assert!(!v.iter().all(|&x| x % 2 == 0)); + assert!(!v.iter().all(|&x| x > 100)); + assert!(v[..0].iter().all(|_| panic!())); +} + +#[test] +fn test_any() { + let v: Box<[isize]> = Box::new([1, 2, 3, 4, 5]); + assert!(v.iter().any(|&x| x < 10)); + assert!(v.iter().any(|&x| x % 2 == 0)); + assert!(!v.iter().any(|&x| x > 100)); + assert!(!v[..0].iter().any(|_| panic!())); +} + +#[test] +fn test_find() { + let v: &[isize] = &[1, 3, 9, 27, 103, 14, 11]; + assert_eq!(*v.iter().find(|&&x| x & 1 == 0).unwrap(), 14); + assert_eq!(*v.iter().find(|&&x| x % 3 == 0).unwrap(), 3); + assert!(v.iter().find(|&&x| x % 12 == 0).is_none()); +} + +#[test] +fn test_try_find() { + let xs: &[isize] = &[]; + assert_eq!(xs.iter().try_find(testfn), Ok(None)); + let xs: &[isize] = &[1, 2, 3, 4]; + assert_eq!(xs.iter().try_find(testfn), Ok(Some(&2))); + let xs: &[isize] = &[1, 3, 4]; + assert_eq!(xs.iter().try_find(testfn), Err(())); + + let xs: &[isize] = &[1, 2, 3, 4, 5, 6, 7]; + let mut iter = xs.iter(); + assert_eq!(iter.try_find(testfn), Ok(Some(&2))); + assert_eq!(iter.try_find(testfn), Err(())); + assert_eq!(iter.next(), Some(&5)); + + fn testfn(x: &&isize) -> Result<bool, ()> { + if **x == 2 { + return Ok(true); + } + if **x == 4 { + return Err(()); + } + Ok(false) + } +} + +#[test] +fn test_try_find_api_usability() -> Result<(), Box<dyn std::error::Error>> { + let a = ["1", "2"]; + + let is_my_num = |s: &str, search: i32| -> Result<bool, std::num::ParseIntError> { + Ok(s.parse::<i32>()? == search) + }; + + let val = a.iter().try_find(|&&s| is_my_num(s, 2))?; + assert_eq!(val, Some(&"2")); + + Ok(()) +} + +#[test] +fn test_position() { + let v = &[1, 3, 9, 27, 103, 14, 11]; + assert_eq!(v.iter().position(|x| *x & 1 == 0).unwrap(), 5); + assert_eq!(v.iter().position(|x| *x % 3 == 0).unwrap(), 1); + assert!(v.iter().position(|x| *x % 12 == 0).is_none()); +} + +#[test] +fn test_count() { + let xs = &[1, 2, 2, 1, 5, 9, 0, 2]; + assert_eq!(xs.iter().filter(|x| **x == 2).count(), 3); + assert_eq!(xs.iter().filter(|x| **x == 5).count(), 1); + assert_eq!(xs.iter().filter(|x| **x == 95).count(), 0); +} + +#[test] +fn test_max_by_key() { + let xs: &[isize] = &[-3, 0, 1, 5, -10]; + assert_eq!(*xs.iter().max_by_key(|x| x.abs()).unwrap(), -10); +} + +#[test] +fn test_max_by() { + let xs: &[isize] = &[-3, 0, 1, 5, -10]; + assert_eq!(*xs.iter().max_by(|x, y| x.abs().cmp(&y.abs())).unwrap(), -10); +} + +#[test] +fn test_min_by_key() { + let xs: &[isize] = &[-3, 0, 1, 5, -10]; + assert_eq!(*xs.iter().min_by_key(|x| x.abs()).unwrap(), 0); +} + +#[test] +fn test_min_by() { + let xs: &[isize] = &[-3, 0, 1, 5, -10]; + assert_eq!(*xs.iter().min_by(|x, y| x.abs().cmp(&y.abs())).unwrap(), 0); +} + +#[test] +fn test_by_ref() { + let mut xs = 0..10; + // sum the first five values + let partial_sum = xs.by_ref().take(5).fold(0, |a, b| a + b); + assert_eq!(partial_sum, 10); + assert_eq!(xs.next(), Some(5)); +} + +#[test] +fn test_is_sorted() { + assert!([1, 2, 2, 9].iter().is_sorted()); + assert!(![1, 3, 2].iter().is_sorted()); + assert!([0].iter().is_sorted()); + assert!(std::iter::empty::<i32>().is_sorted()); + assert!(![0.0, 1.0, f32::NAN].iter().is_sorted()); + assert!([-2, -1, 0, 3].iter().is_sorted()); + assert!(![-2i32, -1, 0, 3].iter().is_sorted_by_key(|n| n.abs())); + assert!(!["c", "bb", "aaa"].iter().is_sorted()); + assert!(["c", "bb", "aaa"].iter().is_sorted_by_key(|s| s.len())); +} + +#[test] +fn test_partition() { + fn check(xs: &mut [i32], ref p: impl Fn(&i32) -> bool, expected: usize) { + let i = xs.iter_mut().partition_in_place(p); + assert_eq!(expected, i); + assert!(xs[..i].iter().all(p)); + assert!(!xs[i..].iter().any(p)); + assert!(xs.iter().is_partitioned(p)); + if i == 0 || i == xs.len() { + assert!(xs.iter().rev().is_partitioned(p)); + } else { + assert!(!xs.iter().rev().is_partitioned(p)); + } + } + + check(&mut [], |_| true, 0); + check(&mut [], |_| false, 0); + + check(&mut [0], |_| true, 1); + check(&mut [0], |_| false, 0); + + check(&mut [-1, 1], |&x| x > 0, 1); + check(&mut [-1, 1], |&x| x < 0, 1); + + let ref mut xs = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]; + check(xs, |_| true, 10); + check(xs, |_| false, 0); + check(xs, |&x| x % 2 == 0, 5); // evens + check(xs, |&x| x % 2 == 1, 5); // odds + check(xs, |&x| x % 3 == 0, 4); // multiple of 3 + check(xs, |&x| x % 4 == 0, 3); // multiple of 4 + check(xs, |&x| x % 5 == 0, 2); // multiple of 5 + check(xs, |&x| x < 3, 3); // small + check(xs, |&x| x > 6, 3); // large +} + +#[test] +fn test_iterator_rev_advance_by() { + let v: &[_] = &[0, 1, 2, 3, 4]; + + for i in 0..v.len() { + let mut iter = v.iter().rev(); + assert_eq!(iter.advance_by(i), Ok(())); + assert_eq!(iter.next().unwrap(), &v[v.len() - 1 - i]); + assert_eq!(iter.advance_by(100), Err(v.len() - 1 - i)); + } + + assert_eq!(v.iter().rev().advance_by(v.len()), Ok(())); + assert_eq!(v.iter().rev().advance_by(100), Err(v.len())); +} + +#[test] +fn test_find_map() { + let xs: &[isize] = &[]; + assert_eq!(xs.iter().find_map(half_if_even), None); + let xs: &[isize] = &[3, 5]; + assert_eq!(xs.iter().find_map(half_if_even), None); + let xs: &[isize] = &[4, 5]; + assert_eq!(xs.iter().find_map(half_if_even), Some(2)); + let xs: &[isize] = &[3, 6]; + assert_eq!(xs.iter().find_map(half_if_even), Some(3)); + + let xs: &[isize] = &[1, 2, 3, 4, 5, 6, 7]; + let mut iter = xs.iter(); + assert_eq!(iter.find_map(half_if_even), Some(1)); + assert_eq!(iter.find_map(half_if_even), Some(2)); + assert_eq!(iter.find_map(half_if_even), Some(3)); + assert_eq!(iter.next(), Some(&7)); + + fn half_if_even(x: &isize) -> Option<isize> { + if x % 2 == 0 { Some(x / 2) } else { None } + } +} + +#[test] +fn test_try_reduce() { + let v = [1usize, 2, 3, 4, 5]; + let sum = v.into_iter().try_reduce(|x, y| x.checked_add(y)); + assert_eq!(sum, Some(Some(15))); + + let v = [1, 2, 3, 4, 5, usize::MAX]; + let sum = v.into_iter().try_reduce(|x, y| x.checked_add(y)); + assert_eq!(sum, None); + + let v: [usize; 0] = []; + let sum = v.into_iter().try_reduce(|x, y| x.checked_add(y)); + assert_eq!(sum, Some(None)); + + let v = ["1", "2", "3", "4", "5"]; + let max = v.into_iter().try_reduce(|x, y| { + if x.parse::<usize>().ok()? > y.parse::<usize>().ok()? { Some(x) } else { Some(y) } + }); + assert_eq!(max, Some(Some("5"))); + + let v = ["1", "2", "3", "4", "5"]; + let max: Result<Option<_>, <usize as std::str::FromStr>::Err> = + v.into_iter().try_reduce(|x, y| { + if x.parse::<usize>()? > y.parse::<usize>()? { Ok(x) } else { Ok(y) } + }); + assert_eq!(max, Ok(Some("5"))); +} + +#[test] +fn test_iterator_len() { + let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; + assert_eq!(v[..4].iter().count(), 4); + assert_eq!(v[..10].iter().count(), 10); + assert_eq!(v[..0].iter().count(), 0); +} + +#[test] +fn test_collect() { + let a = vec![1, 2, 3, 4, 5]; + let b: Vec<isize> = a.iter().cloned().collect(); + assert!(a == b); +} + +#[test] +fn test_try_collect() { + use core::ops::ControlFlow::{Break, Continue}; + + let u = vec![Some(1), Some(2), Some(3)]; + let v = u.into_iter().try_collect::<Vec<i32>>(); + assert_eq!(v, Some(vec![1, 2, 3])); + + let u = vec![Some(1), Some(2), None, Some(3)]; + let mut it = u.into_iter(); + let v = it.try_collect::<Vec<i32>>(); + assert_eq!(v, None); + let v = it.try_collect::<Vec<i32>>(); + assert_eq!(v, Some(vec![3])); + + let u: Vec<Result<i32, ()>> = vec![Ok(1), Ok(2), Ok(3)]; + let v = u.into_iter().try_collect::<Vec<i32>>(); + assert_eq!(v, Ok(vec![1, 2, 3])); + + let u = vec![Ok(1), Ok(2), Err(()), Ok(3)]; + let v = u.into_iter().try_collect::<Vec<i32>>(); + assert_eq!(v, Err(())); + + let numbers = vec![1, 2, 3, 4, 5]; + let all_positive = numbers + .iter() + .cloned() + .map(|n| if n > 0 { Some(n) } else { None }) + .try_collect::<Vec<i32>>(); + assert_eq!(all_positive, Some(numbers)); + + let numbers = vec![-2, -1, 0, 1, 2]; + let all_positive = + numbers.into_iter().map(|n| if n > 0 { Some(n) } else { None }).try_collect::<Vec<i32>>(); + assert_eq!(all_positive, None); + + let u = [Continue(1), Continue(2), Break(3), Continue(4), Continue(5)]; + let mut it = u.into_iter(); + + let v = it.try_collect::<Vec<_>>(); + assert_eq!(v, Break(3)); + + let v = it.try_collect::<Vec<_>>(); + assert_eq!(v, Continue(vec![4, 5])); +} + +#[test] +fn test_collect_into() { + let a = vec![1, 2, 3, 4, 5]; + let mut b = Vec::new(); + a.iter().cloned().collect_into(&mut b); + assert!(a == b); +} + +#[test] +fn iter_try_collect_uses_try_fold_not_next() { + // This makes sure it picks up optimizations, and doesn't use the `&mut I` impl. + struct PanicOnNext<I>(I); + impl<I: Iterator> Iterator for PanicOnNext<I> { + type Item = I::Item; + fn next(&mut self) -> Option<Self::Item> { + panic!("Iterator::next should not be called!") + } + fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R + where + Self: Sized, + F: FnMut(B, Self::Item) -> R, + R: std::ops::Try<Output = B>, + { + self.0.try_fold(init, f) + } + } + + let it = (0..10).map(Some); + let _ = PanicOnNext(it).try_collect::<Vec<_>>(); + // validation is just that it didn't panic. +} + +#[test] +fn test_next_chunk() { + let mut it = 0..12; + assert_eq!(it.next_chunk().unwrap(), [0, 1, 2, 3]); + assert_eq!(it.next_chunk().unwrap(), []); + assert_eq!(it.next_chunk().unwrap(), [4, 5, 6, 7, 8, 9]); + assert_eq!(it.next_chunk::<4>().unwrap_err().as_slice(), &[10, 11]); +} + +// just tests by whether or not this compiles +fn _empty_impl_all_auto_traits<T>() { + use std::panic::{RefUnwindSafe, UnwindSafe}; + fn all_auto_traits<T: Send + Sync + Unpin + UnwindSafe + RefUnwindSafe>() {} + + all_auto_traits::<std::iter::Empty<T>>(); +} |