October 30, 2019
https://issues.dlang.org/show_bug.cgi?id=20336

--- Comment #1 from Andrej Mitrovic <andrej.mitrovich@gmail.com> ---
It looks like the `ref` is gone in the mangling of `two`.

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November 01, 2019
https://issues.dlang.org/show_bug.cgi?id=20336

Mathias LANG <pro.mathias.lang@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |pro.mathias.lang@gmail.com
         Resolution|---                         |FIXED

--- Comment #2 from Mathias LANG <pro.mathias.lang@gmail.com> ---
Fixed by https://github.com/dlang/dmd/pull/10477 (commit named: "dmd/cppmangle.d: Fix regression in ref substitution").

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