[Pharo-users] UFFI and opaque(ish) types

How are opaque(ish) types normally handled in UFFI (or FFI)? E.g. if I want to use libstuff which defines the following structure: struct stuffstruct { typeA a; typeB b; } stufftype; I might know they're integers, but not the size, signed vs. unsigned, etc. The definitions of typeA and typeB are buried in multiple layers of header files, dependent on #if tests, can be different sizes on different platforms (e.g. Linux vs. MacOS), etc.? Is this documented somewhere? Thanks, Alistair