[BUG] Inferred parameter bug when nesting parameters

[nmsmith]

Bug description

The below code snippet generates the following error message:
error: 'Bar' parameter #2 has 'Foo[?]' type, but value has type 'Foo[x]'

I believe this signature is well-typed, so I assume this is a compiler bug.

@Mogball, I expect this bug is for you.

Steps to reproduce

@value
struct Foo[x: Int]:
    pass


@value
struct Bar[x: Int, //, y: Int, foo: Foo[x]]:
    pass


fn test(arg: Bar[5, _]) -> Bar[5, arg.foo]:
    return Bar[5, arg.foo]()

System information

Mojo nightly 2024.5.2605 (9c328b12)