codeql/csharp/ql/test/library-tests/dataflow/fields/H.cs

public class H
{
    class A
    {
        public object FieldA;
    }

    class B
    {
        public object FieldB;
    }

    A Clone(A a)
    {
        var ret = new A();
        ret.FieldA = a.FieldA;
        return ret;
    }

    void M1(object o)
    {
        var a = new A();
        a.FieldA = Source<object>(1);
        var clone = Clone(a);
        Sink(clone.FieldA); //  $ hasValueFlow=1

        a = new A();
        a.FieldA = o;
        clone = Clone(a);
        Sink(clone.FieldA); // no flow
    }

    B Transform(A a)
    {
        var b = new B();
        b.FieldB = a.FieldA;
        return b;
    }

    void M2(object o)
    {
        var a = new A();
        a.FieldA = Source<object>(2);
        var b = Transform(a);
        Sink(b.FieldB); // $ hasValueFlow=2

        a = new A();
        a.FieldA = o;
        b = Transform(a);
        Sink(b.FieldB); // no flow
    }

    void TransformArg(A a, B b1, B b2)
    {
        b1.FieldB = a.FieldA;
    }

    void M3(object o)
    {
        var a = new A();
        var b1 = new B();
        var b2 = new B();
        a.FieldA = Source<object>(3);
        TransformArg(a, b1, b2);
        Sink(b1.FieldB); // $ hasValueFlow=3
        Sink(b2.FieldB); // no flow

        a = new A();
        b1 = new B();
        b2 = new B();
        a.FieldA = o;
        TransformArg(a, b1, b2);
        Sink(b1.FieldB); // no flow
        Sink(b2.FieldB); // no flow
    }

    void SetArgs(A a, object o, B b1, B b2)
    {
        a.FieldA = o;
        TransformArg(a, b1, b2);
    }

    void M4(object o)
    {
        var a = new A();
        var b1 = new B();
        var b2 = new B();
        SetArgs(a, Source<object>(4), b1, b2);
        Sink(a.FieldA); // $ hasValueFlow=4
        Sink(b1.FieldB); // $ hasValueFlow=4
        Sink(b2.FieldB); // no flow

        a = new A();
        b1 = new B();
        b2 = new B();
        SetArgs(a, o, b1, b2);
        Sink(a.FieldA); // no flow
        Sink(b1.FieldB); // no flow
        Sink(b2.FieldB); // no flow
    }

    B TransformWrap(A a)
    {
        var temp = new B();
        temp.FieldB = a;
        return Transform((A)temp.FieldB);
    }

    void M5(object o)
    {
        var a = new A();
        a.FieldA = Source<object>(5);
        var b = TransformWrap(a);
        Sink(b.FieldB); // $ hasValueFlow=5

        a = new A();
        a.FieldA = o;
        b = TransformWrap(a);
        Sink(b.FieldB); // no flow
    }

    object Get(A a)
    {
        return Transform(a).FieldB;
    }

    void M6(object o)
    {
        var a = new A();
        a.FieldA = Source<object>(6);
        Sink(Get(a)); // $ hasValueFlow=6

        a = new A();
        a.FieldA = o;
        Sink(Get(a)); // no flow
    }

    object Through(object o)
    {
        var a = new A();
        a.FieldA = o as A;
        return Transform(a).FieldB;
    }

    void M7()
    {
        var a = Through(Source<A>(7.1));
        Sink(a); // $ hasValueFlow=7.1
        var b = Through(Source<B>(7.2));
        Sink(b); // no flow
    }

    void SetNested(A a, object o)
    {
        var b = Source<B>(8.1);
        b.FieldB = o;
        a.FieldA = b;
    }

    void M8()
    {
        var a = new A();
        var o = Source<object>(8.2);
        SetNested(a, o);
        var b = (B)a.FieldA;
        Sink(b); // $ hasValueFlow=8.1
        Sink(b.FieldB); // $ hasValueFlow=8.2
    }

    public static void Sink(object o) { }

    static T Source<T>(object source) => throw null;
}