Xtend IDE crashes with StackOverflowError

Hi,

I've extracted a minimal example of Xtend code that makes the Xtend IDE (version 2.18) crash with the following message:

org.eclipse.xtext.ui.editor.outline.impl.OutlinePage - Error initializing outline

java.lang.StackOverflowError

Here is the code making the IDE crash:

class Ouch<T> {
	def void crazyStuff() {
		new CrashMe<T> {
			override foo(T t) {
			}
		}
	}
}

abstract class CrashMe<T> extends Ouch<T> {
	def void foo(T t)
}

It looks like a case of infinite recursion, here is an extract of the stack trace:

java.lang.StackOverflowError
	at org.eclipse.xtext.xbase.typesystem.references.ParameterizedTypeReference.accept(ParameterizedTypeReference.java:857)
	at org.eclipse.xtext.xbase.typesystem.util.TypeParameterSubstitutor.getBoundTypeArgument(TypeParameterSubstitutor.java:154)
	at org.eclipse.xtext.xbase.typesystem.util.TypeParameterSubstitutor.doVisitParameterizedTypeReference(TypeParameterSubstitutor.java:112)
	at org.eclipse.xtext.xbase.typesystem.util.TypeParameterSubstitutor.doVisitParameterizedTypeReference(TypeParameterSubstitutor.java:36)
	at org.eclipse.xtext.xbase.typesystem.references.ParameterizedTypeReference.accept(ParameterizedTypeReference.java:857)
	at org.eclipse.xtext.xbase.typesystem.util.TypeParameterSubstitutor.getBoundTypeArgument(TypeParameterSubstitutor.java:154)
	at org.eclipse.xtext.xbase.typesystem.util.TypeParameterSubstitutor.doVisitParameterizedTypeReference(TypeParameterSubstitutor.java:112)
	at org.eclipse.xtext.xbase.typesystem.util.TypeParameterSubstitutor.doVisitParameterizedTypeReference(TypeParameterSubstitutor.java:36)
	at org.eclipse.xtext.xbase.typesystem.references.ParameterizedTypeReference.accept(ParameterizedTypeReference.java:857)
	at org.eclipse.xtext.xbase.typesystem.util.TypeParameterSubstitutor.getBoundTypeArgument(TypeParameterSubstitutor.java:154)
	at org.eclipse.xtext.xbase.typesystem.util.TypeParameterSubstitutor.doVisitParameterizedTypeReference(TypeParameterSubstitutor.java:112)
	at org.eclipse.xtext.xbase.typesystem.util.TypeParameterSubstitutor.doVisitParameterizedTypeReference(TypeParameterSubstitutor.java:36)
	at org.eclipse.xtext.xbase.typesystem.references.ParameterizedTypeReference.accept(ParameterizedTypeReference.java:857)
	at org.eclipse.xtext.xbase.typesystem.util.TypeParameterSubstitutor.getBoundTypeArgument(TypeParameterSubstitutor.java:154)
	at org.eclipse.xtext.xbase.typesystem.util.TypeParameterSubstitutor.doVisitParameterizedTypeReference(TypeParameterSubstitutor.java:112)
	at org.eclipse.xtext.xbase.typesystem.util.TypeParameterSubstitutor.doVisitParameterizedTypeReference(TypeParameterSubstitutor.java:36)
	at org.eclipse.xtext.xbase.typesystem.references.ParameterizedTypeReference.accept(ParameterizedTypeReference.java:857)

Start by reproducing the minimal Xtend example and inspect the outline initialization failure in the stack trace. Read ParameterizedTypeReference.java and TypeParameterSubstitutor.java, especially the recursive calls shown; done means the example no longer raises StackOverflowError and the IDE outline initializes successfully.