Why is this an issue?

There is no reason to re-assign a variable to itself. Either this statement is redundant and should be removed, or the re-assignment is a mistake and some other value or variable was intended for the assignment instead.

Noncompliant code example

let mut x = 5;
x = x; // Self-assignment - does nothing

Compliant solution

let mut x = 5;
// Removed the self-assignment

Resources

Documentation

• Clippy Lints - https://rust-lang.github.io/rust-clippy/master/index.html#self_assignment