Up until now the compiler has been generating incorrect byte code for calling a subinterface method on an interface. Specifically, the generated code references Object.method() instead of interface.method(). When we tried to fix that recently (4392595) we immediately ran into VM failures.

You won't be able to use the compiler to produce these correct class files, as all the existing compilers have hacks to work around this VM problem. I have produced the class file for you to test against.

The class file is attached to this bug report, but shown below:


frog$ cat -n T.java
     1 public class T
     2 {
     3 public static interface I1 {
     4 public Object clone();
     5 }
     6
     7 public static interface I2 extends I1 {
     8 }
     9
    10 public static class C implements I2 {
    11 public Object clone() {
    12 try {
    13 return super.clone();
    14 } catch (CloneNotSupportedException e) {
    15 return null;
    16 }
    17 }
    18 }
    19
    20 public static void main(String[] args) {
    21 I2 i = new C();
    22 i.clone();
    23 }
    24 }
frog$ jdis T.class
super public class T
{


public Method "<init>":"()V"
stack 1 locals 1
{
aload_0;
invokespecial Method java/lang/Object."<init>":"()V";
return;
}

public static Method main:"([Ljava/lang/String;)V"
stack 2 locals 2
{
new class T$C;
dup;
invokespecial Method T$C."<init>":"()V";
astore_1;
aload_1;
invokeinterface InterfaceMethod T$I2.clone:"()Ljava/lang/Object;", 1;
pop;
return;
}

public static InnerClass C=class T$C of class T;
public static abstract interface InnerClass I2=class T$I2 of class T;
public static abstract interface InnerClass I1=class T$I1 of class T;

} // end Class T
frog$ newjava T
+ /net/frog/gafter/gjc-neal/build/solaris-sparc/bin/java T
Exception in thread "main" java.lang.AbstractMethodError
at T.main(T.java:22)
frog$ newjava -version
+ /net/frog/gafter/gjc-neal/build/solaris-sparc/bin/java -version
java version "1.4.0internal"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0internal--001215-12:08)
Java HotSpot(TM) Client VM (build 1.4beta-B45, mixed mode)
frog$