[GROOVY-9501] MissingPropertyException for access to private static field from inner class when subclassing

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.5.10
• Fix Version/s: 4.0.0-alpha-1, 3.0.4, 2.5.12
• Assignee: Eric Milles
• Reporter: Eric Milles
• Created: 10/Apr/20 19:53
• Updated: 22/May/20 04:02
• Resolved: 07/May/20 22:55

Description

Consider the following:

class Main extends Outer {
  static main(args) {
    newInstance().newThread()
  }
}

abstract class Outer {
  private static volatile boolean flag

  protected void newThread() {
    Thread thread = new Inner()
    thread.start()
    thread.join()
  }

  private final class Inner extends Thread {
    void run() {
     try {
      if (!flag) {
        sleep(1000)
      }
     } catch (Throwable t) {
      t.printStackTrace()
     }
    }
  }
}

In this example, Main extends Outer and is the type that is instantiated and used. Inner makes reference to private static field flag of Outer. When Inner is non-static as in this example, it gets the following error when reading "flag":

groovy.lang.MissingPropertyException: No such property: flag for class: Main
Possible solutions: class
	at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:65)
	at org.codehaus.groovy.runtime.callsite.GetEffectivePogoPropertySite.getProperty(GetEffectivePogoPropertySite.java:87)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callGroovyObjectGetProperty(AbstractCallSite.java:309)
	at Outer$Inner.run(Script1.groovy:20)

Note: changing Inner from final to static fixes this specific case. However, non-static inners that need to be that way are going to have this problem.

This is possibly related to: GROOVY-8999, et al.