rust/tests/ui/range_inclusive.rs

// run-pass
// Test inclusive range syntax.
#![allow(unused_braces)]
#![allow(unused_comparisons)]

use std::ops::RangeToInclusive;

fn foo() -> isize { 42 }

// Test that range syntax works in return statements
pub fn return_range_to() -> RangeToInclusive<i32> { return ..=1; }

#[derive(Debug)]
struct P(#[allow(unused_tuple_struct_fields)] u8);

pub fn main() {
    let mut count = 0;
    for i in 0_usize..=10 {
        assert!(i >= 0 && i <= 10);
        count += i;
    }
    assert_eq!(count, 55);

    let mut count = 0;
    let range = 0_usize..=10;
    for i in range {
        assert!(i >= 0 && i <= 10);
        count += i;
    }
    assert_eq!(count, 55);

    let mut count = 0;
    for i in (0_usize..=10).step_by(2) {
        assert!(i >= 0 && i <= 10 && i % 2 == 0);
        count += i;
    }
    assert_eq!(count, 30);

    let _ = 0_usize..=4+4-3;
    let _ = 0..=foo();

    let _ = { &42..=&100 }; // references to literals are OK
    let _ = ..=42_usize;

    // Test we can use two different types with a common supertype.
    let x = &42;
    {
        let y = 42;
        let _ = x..=&y;
    }

    // test collection indexing
    let vec = (0..=10).collect::<Vec<_>>();
    let slice: &[_] = &*vec;
    let string = String::from("hello world");
    let stir = "hello world";

    assert_eq!(&vec[3..=6], &[3, 4, 5, 6]);
    assert_eq!(&vec[ ..=6], &[0, 1, 2, 3, 4, 5, 6]);

    assert_eq!(&slice[3..=6], &[3, 4, 5, 6]);
    assert_eq!(&slice[ ..=6], &[0, 1, 2, 3, 4, 5, 6]);

    assert_eq!(&string[3..=6], "lo w");
    assert_eq!(&string[ ..=6], "hello w");

    assert_eq!(&stir[3..=6], "lo w");
    assert_eq!(&stir[ ..=6], "hello w");

    // test the size hints and emptying
    let mut long = 0..=255u8;
    let mut short = 42..=42u8;
    assert_eq!(long.size_hint(), (256, Some(256)));
    assert_eq!(short.size_hint(), (1, Some(1)));
    long.next();
    short.next();
    assert_eq!(long.size_hint(), (255, Some(255)));
    assert_eq!(short.size_hint(), (0, Some(0)));
    assert!(short.is_empty());

    assert_eq!(long.len(), 255);
    assert_eq!(short.len(), 0);

    // test iterating backwards
    assert_eq!(long.next_back(), Some(255));
    assert_eq!(long.next_back(), Some(254));
    assert_eq!(long.next_back(), Some(253));
    assert_eq!(long.next(), Some(1));
    assert_eq!(long.next(), Some(2));
    assert_eq!(long.next_back(), Some(252));
    for i in 3..=251 {
        assert_eq!(long.next(), Some(i));
    }
    assert!(long.is_empty());

    // check underflow
    let mut narrow = 1..=0;
    assert_eq!(narrow.next_back(), None);
    assert!(narrow.is_empty());
    let mut zero = 0u8..=0;
    assert_eq!(zero.next_back(), Some(0));
    assert_eq!(zero.next_back(), None);
    assert!(zero.is_empty());
    let mut high = 255u8..=255;
    assert_eq!(high.next_back(), Some(255));
    assert_eq!(high.next_back(), None);
    assert!(high.is_empty());

    // what happens if you have a nonsense range?
    let mut nonsense = 10..=5;
    assert_eq!(nonsense.next(), None);
    assert!(nonsense.is_empty());

    // output
    assert_eq!(format!("{:?}", 0..=10), "0..=10");
    assert_eq!(format!("{:?}", ..=10), "..=10");
    assert_eq!(format!("{:?}", 9..=6), "9..=6");

    // ensure that constructing a RangeInclusive does not need PartialOrd bound
    assert_eq!(format!("{:?}", P(1)..=P(2)), "P(1)..=P(2)");
}