Functions imported via ImportC are not "visible" unless there's a collision with a C and D enum.

[solidstate1991 via Digitalmars-d-learn]

I wanted to move my LZW library to ImportC, thus people don't 
have to deal with libraries (I have PTSD with C build systems and 
not getting the same exact version of every dependency and build 
tool), and I can only access C-side functions if I intentionally 
make a collision with a C-side enum, otherwise it'll ask for a 
library that contains said functions.