Code not compiling with java7 but compiling with java6

955312

Hello all,

I have following class:
public class StrangeClass<T extends StrangeClass<S, T>, S extends StrangeClass<T, S>> {

public static void main(String[] args) throws InstantiationException, IllegalAccessException {
System.out.println("test");
}
}

It's compiling with eclipse (Java 7) and with java 6u33 (oracle) but not compiling with java 7u5 (oracle)

StrangeClass.java:1: error: type argument S is not within bounds of type-variable T
public class StrangeClass<T extends StrangeClass<S, T>, S extends StrangeClass<T, S>> {
^
where S,T are type-variables:
S extends StrangeClass<T,S> declared in class StrangeClass
T extends StrangeClass<S,T> declared in class StrangeClass
1 error

Do you think it's a bug or expected behavior?

gimbal2

Because they're two separate things? Java 7 is NOT simply an "upgrade" from Java 6, its a new platform. Therefore things can and will be different.

Might in this case simply be that a bug in the compiler was plugged though.

EJP

I'm inclined to agree with the Java 7 compiler here. Did you really mean to put S and T back to front in the specification of T?

955312

As name of the class says it's strange one...
It's just stupid example - more interesting is change of compiler behavior...
If it should not compile why is it compiling under java 6?

gimbal2

Because they're two separate things? Java 7 is NOT simply an "upgrade" from Java 6, its a new platform. Therefore things can and will be different.

Might in this case simply be that a bug in the compiler was plugged though.

955312

Thank you for answer.