Bad parameter reference CC[A]#C at typer

[griggt]

This is a reproducer for the community build failure of scala-tessella/ring-seq reported in #15647

Compiler version

3.2.0-RC2
Works in 3.1.2
Fails in 3.1.3
Fails in 3.2.0-RC*
Fails in 3.2.1-RC1-bin-20220711-6efd92d-NIGHTLY

Minimized code

trait SeqOps[+A, +CC[_], +C]:   // scala.collection.SeqOps
  def reverse: C

extension[A, CC[B] <: SeqOps[B, CC, CC[B]]](ring: CC[A])
  def startAt(i: Int): CC[A] = ???
  def reflectAt(i: Int): CC[A] =
    startAt(i).reverse

Output

-- Error: ring.scala:7:11 ------------------------------------------------------
7 |    startAt(i).reverse
  |           ^
  |           bad parameter reference CC[A]#C at typer
  |           the parameter is type C in trait SeqOps but the prefix CC[A]
  |           does not define any corresponding arguments.
  |           idx = 2, args = [A]

Workaround

-    startAt(i).reverse
+    val c = startAt(i)
+    c.reverse

[griggt]

First bad commit is f7e38af from #14762