[Issue 22579] Unittests defined in a template are instantiated indiscriminately in betterC mode AND cause inscrutable errors

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=22579

--- Comment #2 from Andrei Alexandrescu <andrei at erdani.com> ---
Thanks, Paul.

Raising this to blocker status because versioning won't scale without it being
fixed, see
https://github.com/dlang/phobos/pull/8309/commits/207e77af7d6aa5c384cb9a91db9e843dc2069769.

This also raises the question of instantiating and running unittests - who is
responsible with each?

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