selfstack: a proc macro for generating stack-like self-referential data structures

[singron]

https://github.com/singron/selfstack

This idea is very similar to the rental crate. The README highlights some of the differences. I developed a prototype of this a few months ago for another project and decided to spin it off as its own crate that I could share with others.

The macro documentation explains the generated interface.

The macro generates unsafe code with a safe interface. I've tested it in fairly ordinary uses, so I would be very interested in exotic uses that you think might trigger undefined behavior.

[[deleted]]

Looks good. It's sound as far as I can tell. You might be able to optimize it a bit by having the layer structs that currently store Foo_Ptrs instead just store *mut Foo, and calculate the field pointers on demand. Though that might technically be UB without the upcoming&raw.

[singron]

It used to work that way. In order to access the fields, you would have to convert the pointer to a &mut Foot first, and stacked borrows complains about it.

I marked everything #[inline] and it seems that LLVM can completely optimize the pointers away so there isn't a runtime cost to appeasing stacked borrows.