rust-clippy/tests/ui/infinite_loop.rs

fn fn_val(i: i32) -> i32 {
    unimplemented!()
}
fn fn_constref(i: &i32) -> i32 {
    unimplemented!()
}
fn fn_mutref(i: &mut i32) {
    unimplemented!()
}
fn fooi() -> i32 {
    unimplemented!()
}
fn foob() -> bool {
    unimplemented!()
}

fn immutable_condition() {
    // Should warn when all vars mentioned are immutable
    let y = 0;
    while y < 10 {
        println!("KO - y is immutable");
    }

    let x = 0;
    while y < 10 && x < 3 {
        let mut k = 1;
        k += 2;
        println!("KO - x and y immutable");
    }

    let cond = false;
    while !cond {
        println!("KO - cond immutable");
    }

    let mut i = 0;
    while y < 10 && i < 3 {
        i += 1;
        println!("OK - i is mutable");
    }

    let mut mut_cond = false;
    while !mut_cond || cond {
        mut_cond = true;
        println!("OK - mut_cond is mutable");
    }

    while fooi() < x {
        println!("OK - Fn call results may vary");
    }

    while foob() {
        println!("OK - Fn call results may vary");
    }

    let mut a = 0;
    let mut c = move || {
        while a < 5 {
            a += 1;
            println!("OK - a is mutable");
        }
    };
    c();

    let mut tup = (0, 0);
    while tup.0 < 5 {
        tup.0 += 1;
        println!("OK - tup.0 gets mutated")
    }
}

fn unused_var() {
    // Should warn when a (mutable) var is not used in while body
    let (mut i, mut j) = (0, 0);

    while i < 3 {
        j = 3;
        println!("KO - i not mentioned");
    }

    while i < 3 && j > 0 {
        println!("KO - i and j not mentioned");
    }

    while i < 3 {
        let mut i = 5;
        fn_mutref(&mut i);
        println!("KO - shadowed");
    }

    while i < 3 && j > 0 {
        i = 5;
        println!("OK - i in cond and mentioned");
    }
}

fn used_immutable() {
    let mut i = 0;

    while i < 3 {
        fn_constref(&i);
        println!("KO - const reference");
    }

    while i < 3 {
        fn_val(i);
        println!("KO - passed by value");
    }

    while i < 3 {
        println!("OK - passed by mutable reference");
        fn_mutref(&mut i)
    }

    while i < 3 {
        fn_mutref(&mut i);
        println!("OK - passed by mutable reference");
    }
}

const N: i32 = 5;
const B: bool = false;

fn consts() {
    while false {
        println!("Constants are not linted");
    }

    while B {
        println!("Constants are not linted");
    }

    while N > 0 {
        println!("Constants are not linted");
    }
}

use std::cell::Cell;

fn maybe_i_mutate(i: &Cell<bool>) {
    unimplemented!()
}

fn internally_mutable() {
    let b = Cell::new(true);

    while b.get() {
        // b cannot be silently coerced to `bool`
        maybe_i_mutate(&b);
        println!("OK - Method call within condition");
    }
}

struct Counter {
    count: usize,
}

impl Counter {
    fn inc(&mut self) {
        self.count += 1;
    }

    fn inc_n(&mut self, n: usize) {
        while self.count < n {
            self.inc();
        }
        println!("OK - self borrowed mutably");
    }

    fn print_n(&self, n: usize) {
        while self.count < n {
            println!("KO - {} is not mutated", self.count);
        }
    }
}

fn while_loop_with_break_and_return() {
    let y = 0;
    while y < 10 {
        if y == 0 {
            break;
        }
        println!("KO - loop contains break");
    }

    while y < 10 {
        if y == 0 {
            return;
        }
        println!("KO - loop contains return");
    }
}

fn immutable_condition_false_positive(mut n: u64) -> u32 {
    let mut count = 0;
    while {
        n >>= 1;
        n != 0
    } {
        count += 1;
    }
    count
}

fn main() {
    immutable_condition();
    unused_var();
    used_immutable();
    internally_mutable();
    immutable_condition_false_positive(5);

    let mut c = Counter { count: 0 };
    c.inc_n(5);
    c.print_n(2);

    while_loop_with_break_and_return();
}