rust-clippy/tests/ui/self_assignment.rs

#![warn(clippy::self_assignment)]
#![allow(clippy::useless_vec, clippy::needless_pass_by_ref_mut)]

pub struct S<'a> {
    a: i32,
    b: [i32; 10],
    c: Vec<Vec<i32>>,
    e: &'a mut i32,
    f: &'a mut i32,
}

pub fn positives(mut a: usize, b: &mut u32, mut s: S) {
    a = a;
    //~^ ERROR: self-assignment of `a` to `a`
    //~| NOTE: `-D clippy::self-assignment` implied by `-D warnings`
    *b = *b;
    //~^ ERROR: self-assignment of `*b` to `*b`
    s = s;
    //~^ ERROR: self-assignment of `s` to `s`
    s.a = s.a;
    //~^ ERROR: self-assignment of `s.a` to `s.a`
    s.b[9] = s.b[5 + 4];
    //~^ ERROR: self-assignment of `s.b[5 + 4]` to `s.b[9]`
    s.c[0][1] = s.c[0][1];
    //~^ ERROR: self-assignment of `s.c[0][1]` to `s.c[0][1]`
    s.b[a] = s.b[a];
    //~^ ERROR: self-assignment of `s.b[a]` to `s.b[a]`
    *s.e = *s.e;
    //~^ ERROR: self-assignment of `*s.e` to `*s.e`
    s.b[a + 10] = s.b[10 + a];
    //~^ ERROR: self-assignment of `s.b[10 + a]` to `s.b[a + 10]`

    let mut t = (0, 1);
    t.1 = t.1;
    //~^ ERROR: self-assignment of `t.1` to `t.1`
    t.0 = (t.0);
    //~^ ERROR: self-assignment of `(t.0)` to `t.0`
}

pub fn negatives_not_equal(mut a: usize, b: &mut usize, mut s: S) {
    dbg!(&a);
    a = *b;
    dbg!(&a);
    s.b[1] += s.b[1];
    s.b[1] = s.b[2];
    s.c[1][0] = s.c[0][1];
    s.b[a] = s.b[*b];
    s.b[a + 10] = s.b[a + 11];
    *s.e = *s.f;

    let mut t = (0, 1);
    t.0 = t.1;
}

#[allow(clippy::mixed_read_write_in_expression)]
pub fn negatives_side_effects() {
    let mut v = vec![1, 2, 3, 4, 5];
    let mut i = 0;
    v[{
        i += 1;
        i
    }] = v[{
        i += 1;
        i
    }];

    fn next(n: &mut usize) -> usize {
        let v = *n;
        *n += 1;
        v
    }

    let mut w = vec![1, 2, 3, 4, 5];
    let mut i = 0;
    let i = &mut i;
    w[next(i)] = w[next(i)];
    w[next(i)] = w[next(i)];
}

fn main() {}