I used to be able to use a bffer for toUTF operation, what happened ?

[deadalnix]

This used to be an option:

dchar val = ...;
char[4] buf;
toUTF8(buf, val);

Now I'm getting an error. Looking at the doc, it seems that there 
are only option returning a string, which I assume is allocated 
on the GC. Has the function moved somewhere else ? If not, what's 
going on ?