WildcardOverride.java

package nullness.generics;

//see also framework/tests/all-systems/WildcardSuper2

import java.util.List;
import org.checkerframework.checker.nullness.qual.NonNull;

interface ToOverride<T> {
    // For nullness this should default to type @NonNull List<? [ extends @Nullable Object
    //                                                             super @NonNull  T ]>
    public abstract int transform(List<? super T> function);
}

class WildcardOverride implements ToOverride<Object> {
    // invalid because the overriden method takes @Nullable args and this one doesn't
    @Override
    //:: error: (override.param.invalid)
    public int transform(List<Object> function) {
        return 0;
    }
}

interface ToOverride2<T> {
    // For nullness this should be typed as @NonNull List<? [ extends @NonNull Object
    //                                                         super T [ extends @Nullable super @NonNull ]>
    //:: error: (bound.type.incompatible)
    public abstract int transform(List<@NonNull ? super T> function);
}

class WildcardOverride2 implements ToOverride2<Object> {
    // valid because the overriden method takes ONLY @NonNull args and this one takes @NonNull args as well
    @Override
    public int transform(List<Object> function) {
        return 0;
    }
}