[Issue 13877] Problem with map+join

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13877

--- Comment #4 from Peter Alexander <peter.alexander.au at gmail.com> ---
https://github.com/D-Programming-Language/phobos/pull/2837

For now, I'm limiting the optimization to arrays only. Any other range is
conservatively assumed to have arbitrarily expensive iteration, so the normal
appender path is used for those.

--