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bin | ||
ci | ||
contrib | ||
rules | ||
test/go | ||
toolchain | ||
.bazelrc | ||
.bazelversion | ||
.build.yml | ||
.envrc | ||
.gitignore | ||
BUILD | ||
LICENSE | ||
README.md | ||
WORKSPACE | ||
go.mod | ||
go.sum | ||
release | ||
relnotes.awk | ||
repositories.bzl |
README.md
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 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 = "v0.5.0"
http_archive(
name = "bazel-zig-cc",
sha256 = "7d7e2bcfe15fce3a6d46ab1ed6f06e36a4729ff5e75916023a09b425ef6f32dd",
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()
# Or, if you are using this in production, you probably want more control:
zig_register_toolchains(
version = "<...>",
url_formats = [
"https://example.internal/zig/zig-{host_platform}-{version}.tar.xz",
],
host_platform_sha256 = { ... },
)
And this to .bazelrc
:
build --incompatible_enable_cc_toolchain_resolution
build --extra_toolchains @zig_sdk//:linux_amd64_gnu.2.19_toolchain
build --extra_toolchains @zig_sdk//:linux_arm64_gnu.2.28_toolchain
build --extra_toolchains @zig_sdk//:darwin_amd64_toolchain
build --extra_toolchains @zig_sdk//:darwin_arm64_toolchain
The snippets above will download the zig toolchain and register it for the following platforms:
x86_64-linux-gnu.2.19
for["@platforms//os:linux", "@platforms//cpu:x86_64"]
.x86_64-linux-gnu.2.28
for["@platforms//os:linux", "@platforms//cpu:aarch64"]
.x86_64-macos-gnu
for["@platforms//os:macos", "@platforms//cpu:x86_64"]
.aarch64-macos-gnu
for["@platforms//os:macos", "@platforms//cpu:aarch64"]
.
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.2.28
is aliased to
x86_64-linux-gnu.2.28
. To find out which toolchains can be registered or
used, run:
$ bazel query @zig_sdk//... | grep _toolchain$
Specifying non-default toolchains
You may explicitly request Bazel to use a specific toolchain, even though a
different one is registered using --extra_toolchains <toolchain>
in
.bazelrc
. For example, if you wish to compile a specific binary (or run
tests) on linux/amd64/musl, you may specify:
--extra_toolchains @zig_sdk//:linux_amd64_musl_toolchain
UBSAN and "SIGILL: Illegal Instruction"
zig cc
differs from "mainstream" compilers by enabling UBSAN by
default. Which means your program may compile successfully and crash
with:
SIGILL: illegal instruction
This is by design: it encourages program authors to fix the undefined behavior. There are many ways to find the undefined behavior.
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 any time soon, but patches implementing those will be accepted. See Questions & Contributions on how to contribute.
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.
Toolchain and platform target locations
The path to Bazel toolchains is @zig_sdk//:<toolchain>_toolchain
. It should
be moved to @zig_sdk//toolchain:<toolchain>
or similar; so the user-facing
targets are in their own namespace.
Likewise, platforms are @zig_sdk//:<platform>_platform
, and should be moved
to @zig_sdk//:platform:<platform>
.
OSX: sysroot
For non-trivial programs (and for all darwin/arm64 cgo programs) MacOS SDK may be necessary. Read Jakub's comment about it. Support for OSX sysroot is currently not implemented.
OSX: different OS targets (Catalina -- Monterey)
Zig 0.9.0 may target macos.10 (Catalina), macos.11 (Big Sur) or macos.12 (Monterey). It currently targets the lowest version, without ability to change it.
Known Issues In Upstream
This section lists issues that I've stumbled into when using zig cc
, and is
outside of 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
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 #10386 zig cc regression in 0.9.0(CLOSED, thanks Xavier)
- ziglang/zig #10312 macho: fail if requested -framework is not found (CLOSED, thanks kubkon)
- ziglang/zig #10299 [darwin aarch64 cgo] regression (CLOSED, thanks kubkon)
- ziglang/zig #10297 [darwin x86_64 cgo] regression (CLOSED, thanks kubkon)
- ziglang/zig #9431 FileNotFound when compiling macos (CLOSED, thanks andrewrk)
- ziglang/zig #9139 zig c++ hanging when compiling in parallel (CLOSED, thanks andrewrk)
- ziglang/zig #9050 golang linker segfault (CLOSED, thanks kubkon)
- ziglang/zig #7917 [meta] better c/c++ toolchain compatibility (CLOSED, thanks andrewrk)
- ziglang/zig #7915 ar-compatible command for zig cc (CLOSED, thanks andrewrk)
- ziglang/zig #7667 misplaced relocated glibc stubs (pthread_sigmask) (CLOSED, thanks mjonaitis and andrewrk)
- rules/go #2894 Per-arch_target linker flags (CLOSED, thanks mjonaitis)
- golang/go #46644 cmd/link: with CC=zig: SIGSERV when cross-compiling to darwin/amd64 (CLOSED, thanks kubkon)
Testing
build & run linux cgo + glibc
$ bazel build --platforms @zig_sdk//:linux_amd64_platform //test/go:go
$ file bazel-out/k8-opt-ST-d17813c235ce/bin/test/go/go_/go
bazel-out/k8-opt-ST-d17813c235ce/bin/test/go/go_/go: 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
$ bazel-out/k8-opt-ST-d17813c235ce/bin/test/go/go_/go
hello, world
test linux cgo + musl on arm64 (under qemu-aarch64)
$ bazel test \
--config=qemu-aarch64 \
--platforms @zig_sdk//:linux_arm64_platform \
--extra_toolchains @zig_sdk//:linux_arm64_musl_toolchain //test/...
...
INFO: Build completed successfully, 10 total actions
//test/go:go_test PASSED in 0.2s
macos cgo
$ bazel build --platforms @zig_sdk//:darwin_amd64_platform //test/go:go
...
$ file bazel-out/k8-opt-ST-d17813c235ce/bin/test/go/go_/go
bazel-out/k8-opt-ST-d17813c235ce/bin/test/go/go_/go: Mach-O 64-bit x86_64 executable, flags:<NOUNDEFS|DYLDLINK|TWOLEVEL|PIE|HAS_TLV_DESCRIPTORS>
Transient docker environment
$ docker run -e CC=/usr/bin/false -ti --rm -v $(pwd):/x -w /x debian:bullseye-slim
# apt update && apt install -y direnv git
# . .envrc
And run the bazel build
commands above. Take a look at .build.yml
and see
how CI does it.
Questions & Contributions
Project's mailing list is ~motiejus/bazel-zig-cc. 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 or via Sourcehut web UI.
Copyright is retained by the contributors.
Thanks
Many thanks to Adam Bouhenguel and his bazel-zig-cc, the parent of this repository. Also, the Zig team for making this all possible and handling the issues promptly.