marker VS buck2

Check out this, which aims to implement said stable interface!

Hey, I might be able to give some input how I deal with it in [rust-linting](https://github.com/rust-linting/rust-linting). For some context, the project needs to load several dynamic libraries and provide each of them with an abstract syntax tree. Serializing and deserializing the types for every step would most likely be too expensive. That's why I opted for a Rust <-> Rust FFI. There are two parts of this: 1. The loaded libraries needed to accept data from a driver. For this, I generate functions in the library crates which are marked as `extern "C"` and only use FFI safe types. Passing information to the loaded crates then always calls the generated functions, which intern call access a thread local struct instance in the dynamic crate. It's important that the instance implement a specific trait. For the library creation, it seems like magic. 2. Callbacks. The loaded libraries need to pass information back to the driver. For this, I use a struct with function pointers. These are also marked as `extern "C"` and need to only use FFI safe types. The definition of FFI safe, is a bit difficult. Slices, `str`, `Option<>` and most of the rusts STD types don't have a stable layout to the point, that it can change between compilations with the same compiler. Therefore, it's required that each passed type is `#[repr(C)]`. Options are wrapped in an enum, which has `#[repr(C)]`, slices and strings are dismantled into a data pointer and a length. On the receiving and they're reconstructed again. A small warning. I'm not an expert on FFI interfaces. My implementation would probably have some problems with lifetimes, if I'd use a slightly different memory model. So far, this has worked well (Besides the required boilerplate). The project is currently sadly lacking documentation, as it's still under heavy development. If you want, feel free to lock around the code base. The stable types and most of the interface is inside the `linter_api` crate.

https://buck2.build/ https://github.com/facebook/buck2

Rust support is also rather good ;) https://github.com/facebookincubator/reindeer

Buck 2 by Facebook

NOTE: I won’t mention SBT and Leiningen here because, with all due respect, they are niche build tools. I also won’t discuss Kobalt for the same reason (besides, it’s no longer actively maintained). Additionally, I won’t touch upon Bazel and Buck in this context, mainly because I’m not very familiar with them. If you have insights or comments about these tools, please feel free to share them in the comments 👇

There's a new build system which works on similar ideas to buck: https://buck2.build/

I don't think all these pieces are open source yet, but https://github.com/facebook/buck2/blob/main/prelude/rust/rust-analyzer/resolve_deps.bxl is a snippet that is used to drive Rust Analyzer

We have a small example project that demonstrates what that would look like with buck2: https://github.com/facebook/buck2/tree/main/examples/bootstrap

There are a few references to NixOS on the code/issues.[0] I wonder what Meta's use case is for NixOS.

[0] https://github.com/facebook/buck2/search?q=nixos&type=issues