lint if/else to match enum variant if we could use match

What it does

lint if-else chains on enums that could be more compact and idiomatic matches.
We might want to bail out of the if/else also includes conditions that are unrelated to the enum variant (if x = 2 && E == E::A)

#[derive(Eq, PartialEq)]
enum E {
    A,
    B,
    C
}


fn fun(e: &E) -> i32 {
    if e == &E::A {
        1
    } else if e == &E::B {
        2
    } else {
        3
    }
}

// suggest instead:
fn fun2(e: &E) -> i32 {
    match e {
        E::A => 1,
        E::B => 2,
        _ => 3,
    }
}

There might be other subtle differences regarding lifetimes/peformance or whatever that I'm not aware of right now

Lint Name

?

Category

style

Advantage

I think the match statements are more compact and idiomatic and easier to understand

Drawbacks

No response

Example

fn fun(e: &E) -> i32 {
    if e == &E::A {
        1
    } else if e == &E::B {
        2
    } else {
        3
    }
}

Could be written as:

fn fun2(e: &E) -> i32 {
    match e {
        E::A => 1,
        E::B => 2,
        _ => 3,
    }
}

The issue names no source files, tests, or entry points. Start from the Rust examples and proposed style category, then establish the lint's exact matching scope, including unrelated conditions, and define how accepted and rejected cases will be tested; done means the behavior and limitations are agreed.