[Issue 17740] ghost "internal" symbols show up sometimes

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17740

--- Comment #2 from Jonathan M Davis <issues.dlang at jmdavisProg.com> ---
Well, it looks like it relates to directly assigning a non-null value to the
_timezone member at compile time. The new TimeZone class declaration is not
required. All you have to do to trigger it is to change line # 8996 at the
bottom of std.datetime.systime from

    Rebindable!(immutable TimeZone) _timezone;
to

    Rebindable!(immutable TimeZone) _timezone = UTC();

Unfortunately, declaring a struct like

    struct S
    {
        Rebindable!(immutable TimeZone) _timezone = UTC();
    }

does not exhibit the problem. So, I don't know how to create a small test case
that doesn't require the std.datetime code. But assigning UTC() like this
before used to work. A backend bug on Windows prevened me from getting a
similar PR merged where it added a new TimeZone class, and assigning UTC() in
that case had exactly the same problem as I recall (certainly, assigning the
new time zone class did, because that's what blocked the PR). But it worked
perfectly fine on other OSes, and I'm fairly certain that I tried those changes
again at some point, and the backend bug was gone - I just wanted to rework the
changes, so they weren't committed. Regardless, it worked perfectly fine on
non-Windows OSes previously. So, something about this broke in the last several
releases. I'd have to do some research to figure out when it broke though.

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