src/test/ui/zero-sized/zero-sized-vec-deque-push.rs


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// run-pass
use std::collections::VecDeque;
use std::iter::Iterator;

fn main() {
    const N: usize = 8;

    // Zero sized type
    struct Zst;

    // Test that for all possible sequences of push_front / push_back,
    // we end up with a deque of the correct size

    for len in 0..N {
        let mut tester = VecDeque::with_capacity(len);
        assert_eq!(tester.len(), 0);
        assert!(tester.capacity() >= len);
        for case in 0..(1 << len) {
            assert_eq!(tester.len(), 0);
            for bit in 0..len {
                if case & (1 << bit) != 0 {
                    tester.push_front(Zst);
                } else {
                    tester.push_back(Zst);
                }
            }
            assert_eq!(tester.len(), len);
            assert_eq!(tester.iter().count(), len);
            tester.clear();
        }
    }
}