auto-insert semicolon in let-else statements

[roife]

It would be very convenient if the ; were automatically added when typing { in let-else statements; I often forget it. :)

let Some(x) = x else {|}

// ==>

let Some(x) = x else {|};

[roife]

I implemented this, and it works well in vscode!

But I found that in some editors (e.g. emacs), it conflicts with the editor's own bracket auto-pairing:

fn main() {
    let x = Some(0);
    let Some(x) = x else {| // insert { here
}

// ==>

fn main() {
    let x = Some(0);
    let Some(x) = x else {|
}; // the semicolon was inserted here :(

The } for fn is parsed to be paired with the preceding {.

[roife]

Or we can add an assist, for let y| = x;, it can be split into let Enum::Variant(y|) = x else { };

[Veykril]

Hmm that does sound tricky relying on bracket completion by the editor here. I don't think having a typing handler for that sounds good (I added a couple of things to the on typing handler recently and they all seemed to worsen the UX experience...).

An assist sounds reasonable, it would be in a similar vein to the other case splitting ideas I think? (just for let else, not if let / match)