false report of "missing match arm" when matching on nested pattern with unknown type

[8051Enthusiast]

rust-analyzer version: 0.3.1402
rustc version: 1.69.0-nightly (2d14db321 2023-02-15), rustc 1.67.1 (d5a82bbd2 2023-02-07)
relevant settings: uses vs code with fairly standard settings

somewhat minimized example

pub trait ExpressionPart: Sized {
    type K: ExpressionKind;
    type TransExpr<ToK: ExpressionKind>: ExpressionPart<K = ToK>;
}

pub struct ExpressionHead<K: ExpressionKind>(K::MonadicOp);

impl<K: ExpressionKind> ExpressionPart for ExpressionHead<K> {
    type K = K;
    type TransExpr<ToK: ExpressionKind> = ExpressionHead<ToK>;
}

pub trait ExpressionKind {
    type MonadicOp;
}

pub trait Expression<K: ExpressionKind>: Sized {
    type Part: ExpressionPart<K = K>;
    fn fold(self, _: impl FnMut(<Self::Part as ExpressionPart>::TransExpr<K>)) {
        todo!()
    }
}

pub struct IdxExpression<K: ExpressionKind> {
    pub heads: Vec<ExpressionHead<K>>,
}

impl<K: ExpressionKind> Expression<K> for IdxExpression<K> {
    type Part = ExpressionHead<K>;
}

pub enum UnOp {
    Neg,
}

pub fn as_string<K>(expr: IdxExpression<K>)
where
    K: ExpressionKind<MonadicOp = UnOp>,
{
    expr.fold(|head| match head {
        ExpressionHead(UnOp::Neg) => {} // <- missing match arm: `ExpressionHead(_)` not covered
    });
}

rust-analyzer reports missing match arm: ExpressionHead(_) not covered on the match in line 41 even though it is covered.

writing

    expr.fold(|head| match head.0 {
        UnOp::Neg => {}
    });

instead makes the error disappear.

[lowr]

A bit reduced:

trait Rec {
    type K;
    type Rebind<Tok>: Rec<K = Tok>;
}

trait Expr<K> {
    type Part: Rec<K = K>;
    fn foo(_: <Self::Part as Rec>::Rebind<i32>) {}
}

struct Head<K>(K);
impl<K> Rec for Head<K> {
    type K = K;
    type Rebind<Tok> = Head<Tok>;
}

fn test<E>()
where
    E: Expr<usize, Part = Head<usize>>,
{
    let head;
      //^^^^ {unknown}, but should be Head<i32>
    E::foo(head);
}

I've looked at chalk's debug log, and I'm like 80% sure this is chalk's bug.