Handle more conversions between Rust types and C types.

[sean1708]

Handle more conversions between Rust types and C types.

[Sean1708]

zsiciarz/rust-ffi-stringtools might come in handy.

[Sean1708]

Also this.

[Sean1708]

Do we force the programmers to use pointers or do we do some magic behind the scenes with references?

We can't do anything behind the scenes now that we use a drop-in so error on references.

How do we handle strings?

Error, note that you should be using *u8 or *mut u8.

[Sean1708]

52a98fc means that the only thing left is to warn/error on incompatible type.

The best thing to do would be to warn/error on types which aren't pointers, fn pointers, or paths and warn/error on non-libc paths which have multiple components.