Very cool project, wanted to look what my structs looked like but possibly my project pulls in too many things? I'll dump some output here:
$ struct_layout.py build/main.o 2>&1 | pbcopy
... see dump file
main.o comes from one of my projects: https://github.com/warfare/prototype,
dump: https://gist.github.com/aktau/8219878
OS: OSX 10.9.1
Compiler: clang 3.3, debugging flags on