I am curious as to why an implicit cast fails in...
int? someValue = SomeCondition ? ResultOfSomeCalc() : null;
and why I have to perform an explicit cast instead
int? someValue = SomeCondition ? ResultofSomeCalc() : (int?)null;
It seems to me that the compiler has all the information it need to make an implicit casting decision, no?
I also am annoyed that it can't infer the type based on the assignment, especially when it's a value type. There are reasons though when you get into object heirarchies.
If "ResultOfSomeCalc()" returned a "int?", then this would work. C# needs to figure out the type regardless of what is to the left of the assignment. So you are telling it that you'll return a null or an int - and the logic in the compiler doesn't exist to have it substitute a Nullable as a common denominator.
Notice that these variants DO work, and it may help you understand:
object someValue = true ? new Nullable<int>(ResultOfSomeCalc()) : null;
object someValue = true ? (int?)ResultOfSomeCalc() : null;
Hope this helps.