Suggest String::clone and forbid String::to_string

[MarkusTieger]

What it does

We should add a lint that causes a warning if the to_string method is used on a String / &String, (not on a &str ofc).

Advantage

The Clone trait is the more commonly used method. Afaik there is no disadvantage of using it instead of ToString.

Drawbacks

None afaik

Example

// 1)
let variable1 = String::new();
let variable2 = variable1.to_string();

// 2)
let variable1 = Some(&variable1);
let variable2 = variable1.map(String::to_string);

Could be written as:

// 1)
let variable1 = String::new();
let variable2 = variable1.clone();

// 2)
let variable1 = Some(String::new());
let variable2 = variable1.cloned();

[Centri3]

This already exists in the form of string_to_string.

[MarkusTieger]

This already exists in the form of string_to_string.

Hmm, I see. I would be interested in knowing why this lint isn't enabled by default.
(btw "2)", doesn't get picked up by string_to_string in my example)

[smoelius]

Maybe string_to_string should be merged into implicit_clone?

More people would benefit from it if it were pedantic.

[MarkusTieger]

Maybe string_to_string should be merged into implicit_clone?

More people would benefit from it if it were pedantic.

Makes sense