There are two parts to this bug. Both of them are the compiler dying
in unhelpful ways when someone tries to define java.lang.Object for
themselves. Believe it or not, people try to do this (in order to
give new functionality to all objects...)

Part 1:

package java.lang;

public class Object implements Cloneable
{
    public void wait()
    {
        System.out.println("Wait!");
    }
}

causes:

sun.tools.java.CompilerError: collectInheritedMethods()
        at sun.tools.java.ClassDefinition.collectInheritedMethods(ClassDefinition.java:1167)
        at sun.tools.java.BinaryClass.basicCheck(BinaryClass.java:60)
        at sun.tools.java.ClassDeclaration.getClassDefinition(ClassDeclaration.java:122)
        at sun.tools.java.ClassDefinition.collectOneClass(ClassDefinition.java:968)
        at sun.tools.java.ClassDefinition.collectInheritedMethods(ClassDefinition.java:1214)
        at sun.tools.java.ClassDefinition.getInheritableMethods(ClassDefinition.java:1236)
        at sun.tools.java.ClassDefinition.collectOneClass(ClassDefinition.java:969)
        at sun.tools.java.ClassDefinition.collectInheritedMethods(ClassDefinition.java:1205)
        at sun.tools.java.BinaryClass.basicCheck(BinaryClass.java:60)
        at sun.tools.java.ClassDeclaration.getClassDefinition(ClassDeclaration.java:122)
        at sun.tools.javac.SourceClass.checkSupers(SourceClass.java:629)
        at sun.tools.javac.SourceClass.basicCheck(SourceClass.java:860)
        at sun.tools.java.ClassDeclaration.getClassDefinition(ClassDeclaration.java:122)
        at sun.tools.javac.Main.compile(Main.java:345)
        at sun.tools.javac.Main.main(Main.java:571)
error: An error has occurred in the compiler; please file a bug report (http://java.sun.com/cgi-bin/bugreport.cgi).
1 error

Part 2:

package java.lang;
 
public class Object // no implements this time
{
    public void wait()
    {
        System.out.println("Wait!");
    }
}

The first time this is compiled, life is good. The second time the
binary .class gets picked up and causes the VM to say:

Can't build argument array