Code inspection: Type parameter could be declared as covariant or contravariant

This inspection reports an interface or delegate type parameter that can be marked out or in. This makes the generic API more flexible for callers without changing its meaning.

Example

                interface IProducer<T>
                {
                    T Create();
                }
            

                interface IProducer<out T>
                {
                    T Create();
                }
            

Quick-fix

Add the suggested variance modifier, such as out or in, to the type parameter.

29 March 2026