[Issue 18870] Link failure only with -allinst for code in isExpression

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18870

--- Comment #2 from Simon Arneaud <sarn at theartofmachinery.com> ---
Because the isExpression code isn't being used at runtime, I've been working
around the problem with hacks like this.  (Not pretty, but at least it stops
the bug from being a blocker.)

pragma(mangle,
"_D3std6format__T11hasToStringTSQBd8datetime4date9TimeOfDayTaZ9__lambda2MFZ1S3putMFNaNbNiNfaZv")
void bug18870kludge1(char c)
{
        import logger = std.experimental.logger;
        logger.fatal("https://issues.dlang.org/show_bug.cgi?id=18870");
}

--