Suggest .as_ref() and .as_mut() instead of Some(ref ...) and Some(ref mut ...) patterns

What it does

Suggests using .as_ref() and .as_mut() on Option to avoid using ref and ref mut in patterns.

Lint Name

useless_ref

Category

style, pedantic

Advantage

ref and ref mut patterns are rarely used comapred to as_ref(), so code using it is hard to read, especially for new contributors who never encountered these constructions.

Drawbacks

.as_ref() is slightly longer than ref

Example

let Some(ref x) = y;
let Some(ref mut x) = y;

Could be written as:

let Some(x) = y.as_ref();
let Some(x) = y.as_mut();

Start by locating the Clippy implementation for the useless_ref lint and examining comparable pattern-rewriting lints. Use the issue’s Some(ref ...) and Some(ref mut ...) examples to define the cases that should receive suggestions, then add or update coverage so the lint recommends .as_ref() and .as_mut() without changing unrelated patterns.