Fix suggestion for collapsible_if and collapsible_else_if when the inner if is enclosed in parentheses

[folkertdev]

changelog: [collapsible_else_if]: fix suggestion when inner if as wrapped in parentheses
changelog: [collapsible_if]: fix suggestion when inner if as wrapped in parentheses

fixes #15303

I'm sure this is a bit dirty, but don't currently see a better way.

[rustbot]

r? @llogiq

rustbot has assigned @llogiq.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[llogiq]

I just have a small suggestion to improve the code, otherwise this looks mergeworthy.

[llogiq]

We could simplify this loop: first we create a function that returns Option<Span>, trimming the outermost parens, then this can be a while let loop, updating the span.

[folkertdev]

The tricky thing there is that we need to update 3 variables, so it gets kind of verbose. Anyway, I've now solved it using recursion, lmk what you think.

[profetia]

Does blocks also leads to the same FN? If so, it would be great to also include fix for that too

[folkertdev]

These lints don't fire when the inner if is wrapped in a block, e.g. these fail because the lint is not found

fn in_brackets() {
    if true {
        {if true {
            println!("In parens, linted");
        }}
    }
    //~^^^^^ collapsible_if
}

fn in_brackets() {
    let x = "hello";
    let y = "world";

    if x == "hello" {
        print!("Hello ");
    } else {
        {if y == "world" { println!("world") } else { println!("!") }}
    }
    //~^^^ collapsible_else_if
}

[llogiq]

@folkertdev perhaps we could add that to the tests, so that future implementers know what to expect.

[folkertdev]

Sure, done.

[folkertdev]

Anything else?

[llogiq]

No, sorry for the delay.