[Issue 20920] Typedef!int + Typedef!int => int? is this a typedef overlook?

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20920

--- Comment #4 from mw <mingwu at gmail.com> ---
Created attachment 1896
  --> https://issues.dlang.org/attachment.cgi?id=1896&action=edit
reduced to 2 lines: s2.i

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