Issue289.java

// Test for Issue 289:
// https://github.com/typetools/checker-framework/issues/289

import java.util.ArrayList;
import java.util.List;
import org.checkerframework.checker.nullness.qual.*;

class Issue289 {
    void simple() {
        List<Object> lo = new ArrayList<>();
        List<String> ls = new ArrayList<>();

        List<@Nullable Object> lno = new ArrayList<>();
        List<@Nullable String> lns = new ArrayList<>();

        List<List<String>> lls = new ArrayList<>();
        lls.add(new ArrayList<>());

        // TODO: add a similar test that uses method type variables.
    }

    // TODO: work on more complex examples:

    class Upper<U1> {}

    class Middle<M1, M2> extends Upper<M2> {}

    class Lower1<L1> extends Middle<L1, @Nullable String> {}

    class Lower2<L1> extends Middle<L1, @NonNull String> {}

    void complex() {
        Upper<@Nullable String> uns = new Lower1<>();
        //:: error: (assignment.type.incompatible)
        Upper<String> us = new Lower1<>();

        //:: error: (assignment.type.incompatible)
        uns = new Lower2<>();
        us = new Lower2<>();
    }
}