requesting help debugging error in libclang bindings

Hello,

I'm working to write CFFI binding for libclang [1], I've used swig to
generate CFFI declarations of all libclang bindings, and I'm hoping to
wrap those in a nice CLOS-based interface (my code is up here [2]).

However I've run into an error which I'm having trouble getting past.
Although the following simple C code [3] compiles and runs w/o problem.
A direct translation into lisp [4] using the swig-generated cffi
bindings throws this error [5].  For some reason the
`clang_getTranslationUnitCursor' function always throws an error.  FWIW
I'll include the original C function headers [6] and the swig-generate
CFFI declarations [7] below.

I'm using SBCL version 1.0.57 and CFFI version 0.10.6 installed with
quicklisp.

Any idea what could be causing this error?  Could the problem lie in
SBCL, in CFFI, or possibly in some difference in state between the C
world and the lisp world?

Thanks,

Footnotes: 
[1]  http://clang.llvm.org/doxygen/group__CINDEX.html

[2]  https://github.com/eschulte/cl-libclang

[3]  hello-cursor.c
     // -*- C -*-