You can also mkdir vlib in whichever directory you're trying to run vc and it will generate that temporary directory automatically.

Unfortunately, that doesn't seem to be enough to actually generate output (or I just can't find the output file).

EDIT: The generated C code gets put in /var/tmp/vlang0.0.12/v.c and compiling it gives me a new compiler which outputs slightly different C, so it seems to work. The description in the README doesn't mention that manual compilation step, so something seems to have gone wrong.

EDIT2: It works if you have clang installed, which I didn't. The compilation step should probably default to cc instead.