[Issue 20867] class subtyping doen't work in separate files

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20867

--- Comment #1 from mw <mingwu at gmail.com> ---
Created attachment 1792
  --> https://issues.dlang.org/attachment.cgi?id=1792&action=edit
class subtyping doen't work in separate files

Two files:

queue.d
t.d

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