As far as my tests and research show, you can't call function pointers on a C struct with CGo (best source: https://code.google.com/p/go/issues/detail?id=3364).

There is a comment at the link above dated Mar 25, 2014; it references an alternative pattern in https://code.google.com/p/go/source/browse/misc/cgo/test/fpvar.go .

If you have any resources to point me toward to solve this another way, please send. If not, our options seem to be:

1. Use the pattern I've submitted in wrappers.c
2. Implement the pattern from the link above in wrappers.c
3. Don't implement backend freeing in Go