Feature Request: Support Rc, Arc and other smart pointer types

[ZhennanWu]

Currently this crate only generate thin Box pointers, it would be great if it also supports other std smart pointer types. Additional attributes can be introduced to flag the generation of those pointers on demand.

Does this feature fit with this crate's future goal list?

Finally, thank you for your marvellous work on this crate!

[kotauskas]

I've had some thoughts about this feature as well, but the problem with it is that it requires implementing Rc/Arc with either a support crate (macro in thin_trait_object-macros, support code in thin_trait_object), or by macro-pasting the exact same Rc/Arc code for all TTOs (which is a direct path to adverse code bloat). Either way, substantial duplication of std functionality occurs.

My idea of resolving this issue was to release a separate crate that implements Rc and Arc in an ABI-stable and transparent fashion, then use that as infrastructure for reference-counting shared-ownership TTOs in thin_trait_object. As I'm working on polishing and cleaning up another crate of mine, interprocess, I'm not actively working on that endeavor. Once that's done though, I'll be sure revisit this topic.