Bazel C/C++ toolchain definitions for CloudABI cross compilation

This repository contains toolchain definitions for the Bazel build system to cross compile C/C++ code for CloudABI. Instead of relying on a toolchain that is provided by the host operating system, these rules automatically download development tools (e.g. Clang) and cross compile core C/C++ libraries (e.g., cloudlibc) during build. This has the following advantages:

It allows you to develop CloudABI applications without making any system-level changes. There is no need to install anything on your system, apart from an officially released version of Bazel.
The toolchain may be versioned as part of the project, making it easier to obtain reproducible build output.
It makes it easier to test upcoming versions of individual components (e.g., Clang, libc++, cloudlibc).

Using these rules

Add the following code to your WORKSPACE file to declare the toolchain.

load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")

git_repository(
    name = "org_cloudabi_bazel_toolchains_cloudabi",
    # NOT VALID!  Replace this with a Git commit SHA.
    commit = "...",
    remote = "https://github.com/NuxiNL/bazel-toolchains-cloudabi.git",
)

load("@org_cloudabi_bazel_toolchains_cloudabi//:toolchains.bzl", "toolchains_cloudabi_dependencies")

toolchains_cloudabi_dependencies()

And add the following lines to .bazelrc to use the toolchain as part of builds. This file may be stored in the same directory as WORKSPACE.

build --cpu=x86_64-unknown-cloudabi
build --crosstool_top=@org_cloudabi_bazel_toolchains_cloudabi//:toolchain

Commands like bazel build and bazel test will now cross compile targets for CloudABI on x86-64.