Suggest Iterator::min_by_key (and similar methods)

What it does

Similarly to unnecessary_sort_by, detect instances of Iterator::min_by() (and Iterator::max_by()) that could be better written with min_by_key() or min().

Lint Name

unnecessary_iter_by

Category

complexity

Advantage

It is clearer to use Iterator::min_by_key (or Iterator::min if possible) than to use Iterator::min_by and a more complicated closure.

Drawbacks

Same as https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_sort_by?

Example

struct Point { x: i32, y: i32 }
let array = [Point { x: 1, y: 0 }, Point { x: 0, y: 1 }];
array.iter().min_by(|a, b| a.x.cmp(&b.x));

Could be written as:

array.iter().min_by_key(|p| &p.x);

Start by comparing the proposed unnecessary_iter_by lint with unnecessary_sort_by, then inspect how Iterator::min_by(), max_by(), min_by_key(), and min() are represented in the existing linting logic. Done means detecting the eligible closure forms and providing suggestions for min_by_key() or min(), with coverage for both min_by() and max_by().