Merge pull request #7899 from dotty-staging/fix-#7890

Fix #7890: Add test case

Author: nicolasstucki

tests/neg/i7890.scala

@@ -0,0 +1,16 @@
+trait Instrument {
+  type R
+  def result: R
+}
+
+trait InstrumentFactory[I <: Instrument] {
+  def createInstrument: I
+}
+
+case class Instrumented[I <: Instrument](
+  instrumentation: I#R)  // error
+
+def instrumented[D, I <: Instrument](instrumentFactory: InstrumentFactory[I]): Instrumented[I] = {
+  val instrument = instrumentFactory.createInstrument
+  Instrumented(instrument.result)
+}