rust/tests/ui/never_loop.rs

// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#![allow(
    clippy::single_match,
    unused_assignments,
    unused_variables,
    clippy::while_immutable_condition
)]

fn test1() {
    let mut x = 0;
    loop {
        // clippy::never_loop
        x += 1;
        if x == 1 {
            return;
        }
        break;
    }
}

fn test2() {
    let mut x = 0;
    loop {
        x += 1;
        if x == 1 {
            break;
        }
    }
}

fn test3() {
    let mut x = 0;
    loop {
        // never loops
        x += 1;
        break;
    }
}

fn test4() {
    let mut x = 1;
    loop {
        x += 1;
        match x {
            5 => return,
            _ => (),
        }
    }
}

fn test5() {
    let i = 0;
    loop {
        // never loops
        while i == 0 {
            // never loops
            break;
        }
        return;
    }
}

fn test6() {
    let mut x = 0;
    'outer: loop {
        x += 1;
        loop {
            // never loops
            if x == 5 {
                break;
            }
            continue 'outer;
        }
        return;
    }
}

fn test7() {
    let mut x = 0;
    loop {
        x += 1;
        match x {
            1 => continue,
            _ => (),
        }
        return;
    }
}

fn test8() {
    let mut x = 0;
    loop {
        x += 1;
        match x {
            5 => return,
            _ => continue,
        }
    }
}

fn test9() {
    let x = Some(1);
    while let Some(y) = x {
        // never loops
        return;
    }
}

fn test10() {
    for x in 0..10 {
        // never loops
        match x {
            1 => break,
            _ => return,
        }
    }
}

fn test11<F: FnMut() -> i32>(mut f: F) {
    loop {
        return match f() {
            1 => continue,
            _ => (),
        };
    }
}

pub fn test12(a: bool, b: bool) {
    'label: loop {
        loop {
            if a {
                continue 'label;
            }
            if b {
                break;
            }
        }
        break;
    }
}

pub fn test13() {
    let mut a = true;
    loop {
        // infinite loop
        while a {
            if true {
                a = false;
                continue;
            }
            return;
        }
    }
}

pub fn test14() {
    let mut a = true;
    'outer: while a {
        // never loops
        while a {
            if a {
                a = false;
                continue;
            }
        }
        break 'outer;
    }
}

// Issue #1991: the outter loop should not warn.
pub fn test15() {
    'label: loop {
        while false {
            break 'label;
        }
    }
}

fn main() {
    test1();
    test2();
    test3();
    test4();
    test5();
    test6();
    test7();
    test8();
    test9();
    test10();
    test11(|| 0);
    test12(true, false);
    test13();
    test14();
}