groovyc hangs when compiling nested enum

This problem was discovered in a Jenkins pipeline, but then nailed down and found it failed with groovyc compiler too.

Creating a script with two nested enums, like:

class TestClass {
    enum OuterEnum {
        VALUE,
        enum InnerEnum {
            A
        }
    }
}

And compiling with groovyc script.groovy makes the compiler freeze with 100% CPU usage.

In Jenkins, this results in the Job and executor being freezed and zombie (need to kill the job and executor thread), but I am reporting this to Jenkins as an independent issue.

As the problem seems to happen in a stripped down groovy script, I am reporting it here too.