ICE: typeck: `no index for a field` about rust HOT 8 CLOSED

#126320 cc @oli-obk :D

from rust.

wtf. why does that wrong comma cause the struct to be different from a struct with no fields

from rust.

minimized

struct X {,}

fn main() {
    || {
        if let X { x: 1,} = (X {}) {}
    };
}

from rust.

wtf. why does that wrong comma cause the struct to be different from a struct with no fields

An extra , is a recovered struct variant, and it is skipped here:

so we didn't emit the error like an empty struct:

error[E0026]: struct `X` does not have a field named `x`
 --> src/main.rs:5:20
  |
5 |         if let X { x: 1,} = (X {}) {}
  |                    ^ struct `X` does not have this field

So the compiler continues until the ICE point.

I think a trivial fix will be ok here?

from rust.

Hmm... I'd look into reporting that error even for recovered structs and figuring out how to avoid it just for the cases that this skip was intended to avoid

from rust.

seems there is nothing else we are trying to avoid:

2ea2bb4

I'd prefer not to report the no-field error, since the first error in parsing will point out the root cause, and there is a case like #126344, which may introduce noise when there are too many type errors, it's also applied to this issue.

from rust.

Oh... we can probably just replace the is_recovered method with a new tainted_by_errors method and return an Result<(), ErrorGuaranteed>. This way we act as if we reported an error, and thus not continue to the ICE

from rust.

Since we cannot encode an ErrorGuaranteed in the flags list, either take a TyCtxt argument on the tainted_by_errors method, or check if replacing the field field with Result<IndexVec<FieldIdx, FieldDef>, ErrorGuaranteed> works out nicely

from rust.