LYR-SEM0203

an assignment of a value to itself

warning · spec 08-expressions · lint self-assignment, group correctness, warn unless said

An = whose value is its own target — x = x, a.b = a.b — or x = x++, which keeps the old value.

Explanation

Assigning a place to itself changes nothing. It is usually a typo for another name, and x = x++ reads as an increment while it is none: the value assigned is the old one.

Assign what was meant, or take the statement out; write x++ alone to increment.

Wrong

fn main(): void {
    var x = 1;
    x = x;
    let _ = x;
}

Right

fn main(): void {
    var x = 1;
    x = x + 1;
    let _ = x;
}