[![builds.sr.ht status](https://builds.sr.ht/~motiejus/bazel-zig-cc.svg)](https://builds.sr.ht/~motiejus/bazel-zig-cc) # Bazel zig cc toolchain This is a C/C++ toolchain that can (cross-)compile C/C++ programs. It contains clang-13, musl, glibc (versions 2-2.34, selectable), all in a ~40MB package. Read [here](https://andrewkelley.me/post/zig-cc-powerful-drop-in-replacement-gcc-clang.html) about zig-cc; the rest of the README will present how to use this toolchain from Bazel. # Usage Add this to your `WORKSPACE`: ``` BAZEL_ZIG_CC_VERSION = "v0.4.0-rc2" http_archive( name = "bazel-zig-cc", sha256 = "3fd0a8ed10adaa49cdb709a9ecb05990c9762849f6098412e205e3a2260fecc4", strip_prefix = "bazel-zig-cc-{}".format(BAZEL_ZIG_CC_VERSION), urls = ["https://git.sr.ht/~motiejus/bazel-zig-cc/archive/{}.tar.gz".format(BAZEL_ZIG_CC_VERSION)], ) load("@bazel-zig-cc//toolchain:defs.bzl", zig_register_toolchains = "register_toolchains") zig_register_toolchains(register = [ "x86_64-linux-gnu.2.28", "x86_64-macos-gnu", ]) ``` The snippet above will download the zig toolchain and register it for the following platforms: - `x86_64-linux-gnu.2.28` for `["@platforms//os:linux", "@platforms//cpu:x86_64"]`. - `x86_64-macos-gnu` for `["@platforms//os:macos", "@platforms//cpu:x86_64"]`. Note that both Go and Bazel naming schemes are accepted. For convenience with Go, the following Go-style toolchain aliases are created: |Bazel (zig) name |Go name| --- | --- |`x86_64`|`amd64`| |`aarch64`|`arm64`| |`macos`|`darwin`| For example, the toolchain `linux_amd64_gnu` is aliased to `x86_64-linux-gnu.2.28`. To find out which toolchains can be registered or used, run: ``` $ bazel query @zig_sdk//... | sed -En '/.*_toolchain$/ s/.*:(.*)_toolchain$/\1/p' ``` # Known Issues in bazel-zig-cc These are the things you may stumble into when using bazel-zig-cc. I am unlikely to implement them, but patches implementing those will be accepted. See [Questions & Contributions](#questions-amp-contributions) on how to contribute. ## OSX: sysroot MacOS SDK (`--sysroot`) may be necessary for non-trivial programs (and is required for all cgo darwin/arm64 ones). Read [Jakub's comment][sysroot] about it. Support for OSX sysroot is currently not implemented. ## OSX: different OS targets (Catalina -- Monterey) Since [zig 0.9.0](https://ziglang.org/download/0.9.0/release-notes.html#macOS) zig may target macos.10 (Catalina), macos.11 (Big Sur) or macos.12 (Monterey). It currently targets the lowest version. ## Zig cache Currently zig cache is in `$HOME` so `bazel clean --expunge` does not clear the zig cache. Zig's cache should be stored somewhere in the project's path. ## Alternative download URLs Currently zig is downloaded from [dl.jakstys.lt](https://dl.jakstys.lt/zig/), which is nuts. One should provide a way to specify alternative URLs for the zig toolchain. ## Bazel toolchain target locations The path to Bazel toolchains is `@zig_sdk//:_toolchain`. It should be moved to `@zig_sdk//toolchain:` or similar; so the user-facing targets are in their own namespace. # Known Issues in upstream This section lists issues that I've stumbled into when using `zig cc`, and is outside of control bazel-zig-cc's control. ## using glibc 2.27 or older **Severity: Low** Task: [ziglang/zig #9485 glibc 2.27 or older: fcntl64 not found, but zig's glibc headers refer it](https://github.com/ziglang/zig/issues/9485) Background: when glibc 2.27 or older is selected, it may miss `fcntl64`. A workaround is applied for `x86_64`, but not for aarch64. The same workaround may apply to aarch64, but the author didn't find a need to test it (yet). # Closed upstream issues - [ziglang/zig misplaced relocated glibc stubs (pthread_sigmask) #7667](https://github.com/ziglang/zig/issues/7667) (CLOSED, thanks mjonaitis and andrewrk) - [ziglang/zig macho: fail if requested -framework is not found #10312](https://github.com/ziglang/zig/pull/10312) (CLOSED, thanks kubkon) - [ziglang/zig [darwin aarch64 cgo] regression #10299](https://github.com/ziglang/zig/issues/10299) (CLOSED, thanks kubkon) - [ziglang/zig [darwin x86_64 cgo] regression #10297](https://github.com/ziglang/zig/issues/10297) (CLOSED, thanks kubkon) - [ziglang/zig #9431 FileNotFound when compiling macos](https://github.com/ziglang/zig/issues/9431) (CLOSED, thanks andrewrk) - [rules/go #2894 Per-arch_target linker flags](https://github.com/bazelbuild/rules_go/issues/2894) (CLOSED, thanks mjonaitis) - [ziglang/zig #7915 ar-compatible command for zig cc](https://github.com/ziglang/zig/issues/7915) (CLOSED, thanks andrewrk) - [ziglang/zig #7917 [meta] better c/c++ toolchain compatibility](https://github.com/ziglang/zig/issues/7917) (CLOSED, thanks andrewrk) - [ziglang/zig #9050 golang linker segfault](https://github.com/ziglang/zig/issues/9050) (CLOSED, thanks kubkon) - [golang/go #46644 cmd/link: with CC=zig: SIGSERV when cross-compiling to darwin/amd64](https://github.com/golang/go/issues/46644) (CLOSED, thanks kubkon) - [ziglang/zig #9139 zig c++ hanging when compiling in parallel](https://github.com/ziglang/zig/issues/9139) (CLOSED, thanks andrewrk) # Testing ## linux cgo + glibc 2.28 ``` $ bazel build --platforms @io_bazel_rules_go//go/toolchain:linux_amd64_cgo //test:hello $ file bazel-out/k8-fastbuild-ST-d17813c235ce/bin/test/hello_/hello bazel-out/k8-fastbuild-ST-d17813c235ce/bin/test/hello_/hello: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.0.0, Go BuildID=redacted, with debug_info, not stripped ``` ## linux cgo + musl ``` $ bazel build \ --platforms @io_bazel_rules_go//go/toolchain:linux_amd64_cgo \ --extra_toolchains @zig_sdk//:linux_amd64_musl_toolchain //test:hello ... $ file ../bazel-out/k8-fastbuild-ST-d17813c235ce/bin/test/hello_/hello ../bazel-out/k8-fastbuild-ST-d17813c235ce/bin/test/hello_/hello: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, Go BuildID=redacted, with debug_info, not stripped $ ../bazel-out/k8-fastbuild-ST-d17813c235ce/bin/test/hello_/hello hello, world ``` ## macos cgo ``` $ bazel build --platforms @io_bazel_rules_go//go/toolchain:darwin_amd64_cgo //test:hello ... $ file bazel-bin/test/hello_/hello bazel-bin/test/hello_/hello: Mach-O 64-bit x86_64 executable, flags: ``` ## Transient docker environment ``` $ docker run -e CC=/usr/bin/false -ti --rm -v $(pwd):/x -w /x debian:bullseye-slim # apt update && apt install direnv git -y # . .envrc ``` And run the `bazel build` commands above. Take a look at `.build.yml` and see how CI does it. # Future & Roadmap This section lists things that I think will happen at some point: either by myself, or my colleagues, or outside contributors. # Questions & Contributions Project's mailing list is [~motiejus/bazel-zig-cc][mailing-list]. The mailing list is used for: - announcements (I am aiming to send an email with every release). - user discussions. - raising issues. - contributions. I will generally respond to emails about issues. I may even be able to fix them. However, no promises: you are much more likely (and welcome!) to get it fixed by submitting a patch. To contribute, send your patches to the mailing list, as described in [git-send-email.io][git-send-email] or via [Sourcehut web UI][video]. Copyright is retained by the contributors. # Thanks Many thanks to Adam Bouhenguel and his [bazel-zig-cc][ajbouh], the parent of this repository. Also, the Zig team for making this all possible and handling the issues promptly. [mailing-list]: https://lists.sr.ht/~motiejus/bazel-zig-cc [ajbouh]: https://github.com/ajbouh/bazel-zig-cc/ [git-send-email]: https://git-send-email.io/ [video]: https://spacepub.space/w/no6jnhHeUrt2E5ST168tRL [sysroot]: https://github.com/ziglang/zig/issues/10299#issuecomment-989153750