Is this a DMD bug, or correct behavior?

[Adam D. Ruppe]

On Wednesday, 13 March 2019 at 00:27:02 UTC, Foo Bar wrote:
> I came across this strange behavior, however I am unsure as to 
> whether this is correct behavior, or just an expected behavior 
> of shadowing.

Yes, it is correct behavior, though it does trip a lot of people 
up.

Each variable set in a class declaration is independent. Lookups 
go for the first one they see up a chain from the static type.

Inside the override foo, it looks up and sees B.boolean. But 
outside, you cased to A, so it can only see A.boolean.

Object-oriented pattern here is typically to keep your member 
vars private and read/write through accessor methods instead, 
which can be virtual and thus be overridden in child classes as 
needed.