Cannot implicitly convert derived type to its base generic type

Question

I have the following classes and interfaces:

public interface IThing
{
    string Name { get; }
}

public class Thing : IThing
{
    public string Name { get         


        

Answer 1

The compiler is stumbling over the conversion from MyThingConsumer to ThingConsumer even though T:IThing and MyThingConsumer:Thingconsumer and Thing:IThing. Which is quite a few hoops for it to jump through!

The code works if you use return new MyThingConsumer() as ThingConsumer; instead of a direct cast. You know the result will never be null, and the compiler is happy because it is guaranteed a return value of the right type at runtime.

Edit: Here is the full code I used for testing (in Snippy):

public interface IThing
{
    string Name { get; }
}

public class Thing : IThing
{
    public string Name { get; set; }
}

public abstract class ThingConsumer where T : IThing
{
    public string Name { get; set; }
}

public class MyThingConsumer : ThingConsumer
{
}

public static class ThingConsumerFactory where T : IThing
{
    public static ThingConsumer GetThingConsumer()
    {
        if (typeof(T) == typeof(Thing))
        {
            return new MyThingConsumer() as ThingConsumer;
        }
        else
        {
            return null;
        }
    }
}

...

var thing = ThingConsumerFactory.GetThingConsumer();
Console.WriteLine(thing);