Stack overflow in SymDenotations with cyclic class inheritance

[panacekcz]

This code attempting to inherit a class from itself through a parameterized alias causes a stack overflow:

object O{
  type T[R] = X
  class X extends T[Int]
}

Output:

java.lang.StackOverflowError while compiling CyclicInheritance.scala
Exception in thread "main" java.lang.StackOverflowError
	at java.lang.ref.ReferenceQueue$Lock.<init>(ReferenceQueue.java:54)
	at java.lang.ref.ReferenceQueue.<init>(ReferenceQueue.java:55)
	at java.util.WeakHashMap.<init>(WeakHashMap.java:180)
	at java.util.WeakHashMap.<init>(WeakHashMap.java:241)
	at dotty.tools.dotc.core.SymDenotations$InheritedCacheImpl.addDependent(SymDenotations.scala:2098)
	at dotty.tools.dotc.core.SymDenotations$MemberNamesImpl.apply(SymDenotations.scala:2149)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.memberNames(SymDenotations.scala:1776)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.$anonfun$computeMemberNames$1(SymDenotations.scala:1783)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.$anonfun$computeMemberNames$1$adapted(SymDenotations.scala:1782)
	at scala.collection.immutable.List.foreach(List.scala:388)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.computeMemberNames(SymDenotations.scala:1782)
	at dotty.tools.dotc.core.SymDenotations$MemberNamesImpl.apply(SymDenotations.scala:2144)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.memberNames(SymDenotations.scala:1776)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.$anonfun$computeMemberNames$1(SymDenotations.scala:1783)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.$anonfun$computeMemberNames$1$adapted(SymDenotations.scala:1782)
	at scala.collection.immutable.List.foreach(List.scala:388)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.computeMemberNames(SymDenotations.scala:1782)
	at dotty.tools.dotc.core.SymDenotations$MemberNamesImpl.apply(SymDenotations.scala:2144)
...

[smarter]

@odersky Did you intend to close this ? I see there's a commit to fix this, but it's not part of any PR and hasn't been merged.

[odersky]

Ah I was wondering about that.