[WIP] cargo2buck2

A very much WIP tool that let's you use buck2 to build your rust projects without needing to write your own rules.

As a general rule, users should not need to care about the generated BUCK files, and their build cacheability should automagically improve!

The main goals for this project are

• Automatically generate BUILD files from existing Cargo.toml/Cargo.lock files.
• Treat Cargo.toml as the source of truth
• Resolve deps/features in the same way that cargo does (we use the cargo crate for this)
• Add new optional enhancements to the build process
• Provide many pre-build "fixups" to allow different crates to compile correctly (zstd-sys, libsqlite3_sys, aws_lc_sys, etc...)
• In general if a crate does not compile, we will try to add a "fixup" for it.

Planed enhancments

• Ability to mark a proc-macros as "sandboxed", so we won't need to re-run it if the inputs did not change.
• Ability to explicitly name inputs to a build-script (files/environment variables) so we don't need to re-run it if the inputs did not change

Progress

Example projects

• Simple no dependency bin
• Simple single dependency bin
• Simple no dependency build-script
• Proc macro dependency bin
• Simple workspace

Features

• Package renaming (https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html#renaming-dependencies-in-cargotoml)
• Cargo env vars (https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-crates)

Acknowledgements

• dtolnay: for all your work on rust, the ecosystem, buck2 and reindeer. Thank you!❤️