Using type matchers with .Callback and .Returns should be forbidden

[stakx]

This is a follow-up to #1137.

interface IX
{
    void Method<T>(T arg);
}

var mock = new Mock<IX>();
mock.Setup(m => m.Method(It.IsAny<It.IsAnyType>()))
    .Callback<It.IsAnyType>(arg => ...);

While all static type checking will check out fine, there's still an error here: at runtime, the callback's arg will never have type It.IsAnyType—it should really be typed object. Otherwise the callback will throw an ArgumentException ("Object of type '...' cannot be converted to type 'Moq.It+IsAnyType'.").

I believe that any use of type matchers with setup callbacks should be forbidden to catch that kind of mistake early.