Buck2

WARNING: This project is not yet polished. We are continuing to develop it in the open, but don't expect it to be suitable for most people until Mar/Apr/May 2023 (at which point we'll properly announce it). If you try and use it, you will probably have a bad time. If you are willing to work closely with us, please give it a go and let us know what is blocking you.

This repo contains the code for the Buck2 build system - the successor to the original Buck build system. To understand why it might be interesting, see this explainer. For the moment, we only test it on Linux.

Getting started

To clone, build, and install buck2:

git clone https://github.com/facebook/buck2.git
cd buck2/
cargo install --path=cli

To build and install the latest buck2 executable:

rustup install nightly
cargo +nightly install --git https://github.com/facebook/buck2.git cli

Build uses prebuilt protoc binary from protoc-bin-vendored crate. If these binaries to do not work on your machine (for example, when building for NixOS), path to protoc binary and protobuf include path can be specified via BUCK2_BUILD_PROTOC and BUCK2_BUILD_PROTOC_INCLUDE environment variables.

To build a project with buck2, go to the getting started guide.

Terminology conventions

Frequently used terms and their definitions can be found in the glossary page.

Coding conventions

Beyond the obvious (well-tested, easy to read) we prefer guidelines that are automatically enforced, e.g. through rust fmt, Clippy or the custom linter we have written. Some rules:

• Use the utilities from Gazebo where they are useful, in particular, dupe.
• Prefer to_owned to convert &str to String.
• Qualify anyhow::Result rather than use anyhow::Result.
• Most errors should be returned as anyhow::Result. Inspecting errors outside tests and the top-level error handler is strongly discouraged.
• Most errors should be constructed with thiserror deriving enum values, not raw anyhow!.
• We use the derivative library to derive the PartialEq and Hash traits when some fields should be ignored.
• Prefer use crate::foo::bar over use super::bar or use crate::foo::*, apart from test modules which often have use super::* at the top.
• Modules should either have submodules or types/functions/constants, but not both.
• Prefer anyhow::Error for checking internal invariants that are maintained between multiple files, while panic!/unreachable! are reasonable if the invariant is file-local.

Error messages

• Names (of variables, targets, files, etc) should be quoted with backticks, e.g. Variable `x` not defined.
• Lists should use square brackets, e.g. Available targets: [`aa`, `bb`].
• Error messages should start with an upper case letter. Error messages should not end with a period.

License

Buck2 is both MIT and Apache License, Version 2.0 licensed, as found in the LICENSE-MIT and LICENSE-APACHE files.