Refer to: http://www.digitalmars.com/d/2.0/struct.html
and scroll down to the last section, "Nested Structs". A struct defined inside a function has a hidden pointer to that function's stack frame and therefore can use function's local variables.
Nested classes do a similar trick, but for those there's a bit of motivation - you could create a nested class and use it as a sort of closure by returning a base class or interface of it.
With nested structs, however, you can't do much. You can pass them to a template, but I can't see some solid use cases there. My understanding is that nested structs have been implemented for completeness and consistency with nested classes.
Any good example of nested struct uses? Andrei
