selfstack

selfstack is a procedural macro that produces a stack-like self-referential data structure with a safe interface. This is safe because layers in the stack can only reference layers below them, and lower layers outlive higher layers. This restriction prevents cycles, dangling references, and other unsoundness that would generally be possible with self-reference.

The tests are also run with miri to check generated unsafe code for compliance with stacked borrows.

selfstack vs rental

rental is a similar approach to a similar problem, but it has a few differences.

• Rental requires all fields except the last to implement StableDeref. Typically this means you must Box all but the last element. However, this allows the rental to be moved. selfstack does not require fields to implement any trait, but the store struct cannot be moved once it is initialized (although the substruct used to access the fields can be moved).
• Rental must be fully constructed in 1 call to new or try_new. selfstack incrementally builds each field in successive calls. The selfstack can be safely used at any level of initialization. You can emulate this feature in rental by boxing a rental and making it the first field of another rental.
• Rental has more convenience features like IntoSuffix, which derefs the rental as the last field and into_head, which drops all fields but the first and returns it.
• Rental has more configuration options (e.g. mutability, subrentals, covariance, deref). selfstack always works the same way and does not special require configuration.

License

Licensed under either of

• Apache License, Version 2.0
• MIT License

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.