C# Generics: Constraining T where T : Object doesn't compile; Error: Constraint cannot be special class 'object'

Question

When I constrain T with : Object like this:

public interface IDoWork where T : Object
{
    T DoWork();
}

I get the error:

Answer 1

If you want to constrain a generic type to be a reference type, use : class.

public interface IDoWork where T : class
{
    T DoWork();
}

This will forbid the generic type from being a value type, such as int or a struct.