Merge #1279

1279: Implement type checking for the `IfLet` expression. r=philberty a=antego

Addresses #1177.

This change implements the type check for the `IfLet` expression. This is the adapted type checking code from the `MatchExpr`.

Tested on this code
```
enum E {
    X(u8),
}

fn main() -> i32 {
    let mut res = 0;
    let v = E::X(4);
    if let E::X(n) = v {
        res = n;
    }

    0
}
```
Compilation finishes without errors.

Next is the implementation of the code generation but I'll need help to find where it's located.

Co-authored-by: antego <antego@users.noreply.github.com>

0 files changed, 0 insertions, 0 deletions