Wrong inferred type in while and if with block conditions

[lnicola]

fn main() {
    while { true } {}
       // ^ Expected (), got bool
}

[lnicola]

This regressed in #11375, which removed a bunch of code and a cov-mark around https://github.com/rust-analyzer/rust-analyzer/pull/11375/files#diff-29c34fde1addff90d60e0f941fff6fc91a02b5be6f0f8ed4a448d9a6fe6f1985L285.

[lnicola]

CC @ChayimFriedman2

[Veykril]

Ah, that is because condition is now an Expr node, so when it is a BlockExpr we actually have two BlockExpr children for these which causes the HasLoopBody::loop_body call to return the condition instead of the body tripping up lowering and typecheck.

Similar thing I assume will happen for if expressions as well now.

It's the same problem I have fixed for for loops some time ago here #10668

[Veykril]

Problematic parts for if expressions are here
https://github.com/rust-analyzer/rust-analyzer/blob/a153b18d6d38e06db9465d616dc3b316a0c1b717/crates/syntax/src/ast/expr_ext.rs#L50-L69
https://github.com/rust-analyzer/rust-analyzer/blob/a153b18d6d38e06db9465d616dc3b316a0c1b717/crates/syntax/src/ast/generated/nodes.rs#L887

[ChayimFriedman2]

It's interesting as it's very hard to prevent this kind of issues ahead of time. Fixed syntax trees can do that, but in our current model things can break unexpectedly.

CC #6584.