[GROOVY-5625] Static initialization done in wrong order

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Cannot Reproduce
• Affects Version/s: 1.5.5, 1.7.10, 1.8.4, 2.0.0
• Component/s: bytecode, class generator
• Labels: breaking initialization static
• Environment: Linux 2.6.32-41-generic Ubuntu SMP i686
• Assignee: Jochen Theodorou
• Reporter: Benjamin Schmidt
• Created: 24/Jul/12 10:48
• Updated: 25/Aug/13 16:59
• Resolved: 21/Aug/13 07:30

Description

When a class variable, which is initialized in a static block, is assigned to another static variable, the latter will stay null throughout execution.

The decompiled class file looks like this (verbosity omitted):

StaticInitializerBugGroovy.class

// ...
public class StaticInitializerBug implements GroovyObject {

  private static String VAR1;
  private static String VAR2;

  // ...

  static {
    __$swapInit();
    // ...
    String str1 = (String)VAR1;
    VAR2 = (String)str1;
    String str2 = "Hi.";
    VAR1 = str2;
    // ...
  }

  // ...
}

I guess, the problem is clearly visible, as the swapping via temporary variables is done in the wrong order.

The same scenario written and compiled in Java 6 and then decompiled again produces the following:

StaticInitializerBugJava.class

public class StaticInitializerBug {
  static String VAR1;
  static String VAR2;

  // ...

  static {
    VAR1 = "Hi.";
    VAR2 = VAR1;
  }

  // ...
}