C# generic method resolution fails with an ambiguous call error

Question

Suppose I have defined two unrelated types and two extension methods with the same signature but different type filters:

public class Foo {}
public class Bar {}
         


        

Answer 1

The constraint of a generic type parameter is not part of the method's signature. These two methods are essentially the same from a resolution point of view; when the compiler tries to resolve the call it sees two valid methods and it has no way to choose the better one, therefore the call is flagged as ambiguous.

You can read more about this issue here.