public class Operators
{

    static void Sink(object o) { }
    static T Source<T>(object source) => throw null;

    public interface I<T> where T : I<T>
    {
        static virtual T operator *(T x, T y) => x;
        static abstract T operator /(T x, T y);
        static abstract T operator checked /(T x, T y);
    }

    public class C : I<C>
    {
        public static C operator +(C x, C y) => x;

        public static C operator checked -(C x, C y) => y;
        public static C operator -(C x, C y) => x;

        public static C operator /(C x, C y) => y;
        public static C operator checked /(C x, C y) => y;
    }

    public void M1()
    {
        var x = Source<C>(1);
        var y = Source<C>(2);
        var z = x + y;
        Sink(z); // $ hasValueFlow=1
    }

    public void M2()
    {
        var x = Source<C>(3);
        var y = Source<C>(4);
        var z = unchecked(x - y);
        Sink(z); // $ hasValueFlow=3
    }

    public void M3()
    {
        var x = Source<C>(5);
        var y = Source<C>(6);
        var z = checked(x - y);
        Sink(z); // $ hasValueFlow=6
    }

    public void M4Aux<T>(T x, T y) where T : I<T>
    {
        var z = x * y;
        Sink(z); // $ hasValueFlow=7
    }

    public void M4()
    {
        var x = Source<C>(7);
        var y = Source<C>(8);
        M4Aux(x, y);
    }

    public void M5Aux<T>(T x, T y) where T : I<T>
    {
        var z = x / y;
        Sink(z); // $ hasValueFlow=10
    }

    public void M5()
    {
        var x = Source<C>(9);
        var y = Source<C>(10);
        M5Aux(x, y);
    }

    public void M6Aux<T>(T x, T y) where T : I<T>
    {
        var z = checked(x / y);
        Sink(z); // $ hasValueFlow=12
    }

    public void M6()
    {
        var x = Source<C>(11);
        var y = Source<C>(12);
        M6Aux(x, y);
    }
}

public class CompoundAssignmentOperators
{
    static void Sink(object o) { }
    static T Source<T>(object source) => throw null;

    public class C
    {
        public object Field { get; private set; }

        public C()
        {
            Field = new object();
        }

        public C(object o)
        {
            Field = o;
        }

        public void operator +=(C x)
        {
            Field = x.Field;
        }
    }

    public void M1()
    {
        var tainted = Source<object>(1);
        var x = new C();
        var y = new C(tainted);
        x += y;
        Sink(x.Field); // $ hasValueFlow=1
    }
}
