[GROOVY-5742] CompileStatic goes into infinite loop when handling self-referential generics

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.4
• Fix Version/s: 2.1.7, 2.2.0-beta-2
• Component/s: Static compilation, Static Type Checker
• Assignee: Jochen Theodorou
• Reporter: Paul King
• Created: 03/Oct/12 21:51
• Updated: 07/Apr/15 19:07
• Resolved: 16/Jul/13 08:34

Description

When using @CompileStatic or @TypeChecked the StaticTypeCheckingVisitor recursively calls itself on the following example:

abstract class Base<A extends Base<A>> {}
class Done extends Base<Done> { }
class Next<H, T extends Base<T>> extends Base<Next<H, T>> {
  H head; T tail
  static Next<H, T> next(H h, T t) { new Next<H, T>(head:h, tail:t) }
  String toString() { "Next($head, ${tail.toString()})" }
}
import static Next.*

@groovy.transform.CompileStatic
def foo() {
  Next<Integer, Next<String, Done>> x = next(3, next("foo", new Done()))
}

println foo() // => Next(3, Next(foo, Done@9b3ec2))

My real example is when using Functional Java's heterogeneous list classes but the above is a cut-down equivalent. The stack trace is:

java.lang.StackOverflowError
...
org.codehaus.groovy.transform.stc.StaticTypeCheckingVisitor.fullyResolve(StaticTypeCheckingVisitor.java:2836)
	at org.codehaus.groovy.transform.stc.StaticTypeCheckingVisitor.fullyResolveType(StaticTypeCheckingVisitor.java:2873)
	at org.codehaus.groovy.transform.stc.StaticTypeCheckingVisitor.fullyResolve(StaticTypeCheckingVisitor.java:2840)
	at org.codehaus.groovy.transform.stc.StaticTypeCheckingVisitor.fullyResolveType(StaticTypeCheckingVisitor.java:2873)
	at org.codehaus.groovy.transform.stc.StaticTypeCheckingVisitor.fullyResolve(StaticTypeCheckingVisitor.java:2840)
	at org.codehaus.groovy.transform.stc.StaticTypeCheckingVisitor.fullyResolveType(StaticTypeCheckingVisitor.java:2873)