Please describe the problem:
It is not possible to implement a generic interface with a concrete type.

Steps to reproduce:
public interface MyInterface<G> {
    public abstract void method_a (G param);
    public abstract G method_b ();
}

public class MyIterator : GLib.Object, MyInterface<int> {

    public void method_a (int param) {
        // do something
    }

    public int method_b () {
        return 0;
    }
}


Actual results:
testcase.vala:8.5-8.24: error: overriding method `MyIterator.method_a' is incompatible with base method `MyInterface.method_a': incompatible type of parameter 1.
    public void method_a (int param) {
    ^^^^^^^^^^^^^^^^^^^^
testcase.vala:12.5-12.23: error: overriding method `MyIterator.method_b' is incompatible with base method `MyInterface.method_b': incompatible return type.
    public int method_b () {
    ^^^^^^^^^^^^^^^^^^^
Compilation failed: 2 error(s), 0 warning(s)


Expected results:
The generic parts of the parent interface should be fixated to the specified type, in this case 'int'.

Does this happen every time?


Other information: