Tricky DMD bug, but I have no idea how to report

[JN]

On Monday, 17 December 2018 at 22:22:05 UTC, H. S. Teoh wrote:
> A less likely possibility might be an optimizer bug -- do you 
> get different results if you add / remove '-O' (and/or 
> '-inline') from your dmd command-line?  If some combination of 
> -O and -inline (or their removal thereof) "fixes" the problem, 
> it could be an optimizer bug. But those are rare, and usually 
> only show up when you use an obscure D feature combined with 
> another obscure corner case, in a way that people haven't 
> thought of.  My bet is still on a pointer bug somewhere in your 
> code.
>

I played around with dmd commandline. It works with -O. Works 
with -O -inline. As soon as I add -boundscheck=off it breaks.

As I understand it, out of bounds access is UB. Which would fit 
my problems because they look like UB. But if I run without 
boundscheck=off, shouldn't I get a RangeError somewhere?