Capture set variable does not work for class parameter

[odersky]

Compiler version

3.8 nightly

Minimized example

class C

trait A[T]

trait B[CC^] extends A[C^{CC}] // error: CC not found

trait D[CC^]:
  val x: Object^{CC} = ???

Output

-- [E006] Not Found Error: cap-inheritance.scala:6:26 --------------------------
6 |trait B[CC^] extends A[C^{CC}] // error: CC not found
  |                          ^^
  |                          Not found: capability CC - did you mean CT?
  |
  | longer explanation available when compiling with `-explain`
1 error found

Expectation

Should compile. Note that trait D does compile. So it seems the term surrogate for CC in B is created, but is created too late to be visible in the parent clause.

[noti0na1]

I find the cause: we use completerCtx.superCallContext to type parent types, and it does not include term params.