JDK-7003595 : IncompatibleClassChangeError with unreferenced local class with subclass
  • Type: Bug
  • Component: tools
  • Sub-Component: javac
  • Affected Version: 6u22
  • Priority: P3
  • Status: Closed
  • Resolution: Fixed
  • OS: linux
  • CPU: x86
  • Submitted: 2010-11-30
  • Updated: 2013-09-12
  • Resolved: 2012-02-02
The Version table provides details related to the release that this issue/RFE will be addressed.

Unresolved : Release in which this issue/RFE will be addressed.
Resolved: Release in which this issue/RFE has been resolved.
Fixed : Release in which this issue/RFE has been fixed. The release containing this fix may be available for download as an Early Access Release or a General Availabitlity Release.

To download the current JDK release, click here.
JDK 6 JDK 7 JDK 8
6u32 b01Fixed 7u4Resolved 8Resolved
Related Reports
Relates :  
Description
FULL PRODUCT VERSION :
1.6.0_22-b04 and 1.7.0-ea-b119

A DESCRIPTION OF THE PROBLEM :
Compiling and running a class with a local class that is only used via a subclass causes an IncompatibleClassChangeError. See the attached example.

It could be either a jvm or a compiler bug.
I suspect it is a compiler bug because it works with the Eclipse compiler, and adding a dummy reference to the class fixes it. My guess is that the compiler forgets to add an entry in the InnerClasses attribute because it doesn't notice that the class is being referenced.

The problem does not occur when running with a Java 5 jvm (compiled with 5,6 or 7-ea compiler), but that might be because that version doesn't check the InnerClasses attribute (or is less strict).


ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "main" java.lang.IncompatibleClassChangeError: LocalClassTest and LocalClassTest$1A disagree on InnerClasses attribute
        at java.lang.Class.getDeclaringClass(Native Method)
        at LocalClassTest.main(LocalClassTest.java:5)


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class LocalClassTest {
	public static void main(String... args) {
		class A {}
		class B extends A {}
		B.class.getSuperclass().getDeclaringClass();
		// using A directly anywhere works around the problem:
		// new A();
	}
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Add a reference to the local class, e.g. the dummy "new A()" in the example.