241 lines
9.0 KiB
Markdown
241 lines
9.0 KiB
Markdown
[](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 = "v0.4.4"
|
|
|
|
http_archive(
|
|
name = "bazel-zig-cc",
|
|
sha256 = "ad6384b4d16ebb3e5047df6548a195e598346da84e5f320250beb9198705ac81",
|
|
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",
|
|
])
|
|
```
|
|
|
|
And this to `.bazelrc`:
|
|
|
|
```
|
|
build --incompatible_enable_cc_toolchain_resolution
|
|
```
|
|
|
|
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.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//... | sed -En '/.*_toolchain$/ s/.*:(.*)_toolchain$/\1/p'
|
|
```
|
|
|
|
## UBSAN and "SIGILL: Illegal Instruction"
|
|
|
|
`zig cc` differs from "mainstream" compilers by [enabling UBSAN by
|
|
default][ubsan1]. 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][ubsan2] to find the undefined behavior.
|
|
|
|
## Specifying non-default toolchains (and not registering at all)
|
|
|
|
You may explicitly request Bazel to use a specific toolchain, even though one
|
|
is registered using `--extra_toolchains <toolchain>` flag. For example, if you
|
|
wish to compile a specific binary (or run tests) using musl on linux/amd64, you
|
|
may specify:
|
|
|
|
```
|
|
--extra_toolchains @zig_sdk//:linux_amd64_musl_toolchain
|
|
```
|
|
|
|
As an extension to this, you may not register the toolchains at all:
|
|
|
|
```
|
|
zig_register_toolchains()
|
|
```
|
|
|
|
In that case, you will need to specify the `--extra_toolchains <toolchain>`
|
|
command-line argument. Otherwise Bazel will use the default one -- the host
|
|
toolchain.
|
|
|
|
# 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
|
|
|
|
For non-trivial programs (and for all darwin/arm64 cgo programs) MacOS SDK may
|
|
be necessary. Read [Jakub's comment][sysroot] about it. Support for OSX sysroot
|
|
is currently not implemented.
|
|
|
|
## OSX: different OS targets (Catalina -- Monterey)
|
|
|
|
[Zig 0.9.0](https://ziglang.org/download/0.9.0/release-notes.html#macOS) may
|
|
target macos.10 (Catalina), macos.11 (Big Sur) or macos.12 (Monterey). It
|
|
currently targets the lowest version, without ability to change it.
|
|
|
|
## 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/zig](https://dl.jakstys.lt/zig/), which is nuts. One should
|
|
provide a way to specify alternative URLs for the zig toolchain.
|
|
|
|
## 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>`.
|
|
|
|
# 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](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 #10386 zig cc regression in 0.9.0](https://github.com/ziglang/zig/issues/10386)(CLOSED, thanks Xavier)
|
|
- [ziglang/zig #10312 macho: fail if requested -framework is not found](https://github.com/ziglang/zig/pull/10312) (CLOSED, thanks kubkon)
|
|
- [ziglang/zig #10299 [darwin aarch64 cgo] regression](https://github.com/ziglang/zig/issues/10299) (CLOSED, thanks kubkon)
|
|
- [ziglang/zig #10297 [darwin x86_64 cgo] regression](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)
|
|
- [ziglang/zig #9139 zig c++ hanging when compiling in parallel](https://github.com/ziglang/zig/issues/9139) (CLOSED, thanks andrewrk)
|
|
- [ziglang/zig #9050 golang linker segfault](https://github.com/ziglang/zig/issues/9050) (CLOSED, thanks kubkon)
|
|
- [ziglang/zig #7917 [meta] better c/c++ toolchain compatibility](https://github.com/ziglang/zig/issues/7917) (CLOSED, thanks andrewrk)
|
|
- [ziglang/zig #7915 ar-compatible command for zig cc](https://github.com/ziglang/zig/issues/7915) (CLOSED, thanks andrewrk)
|
|
- [ziglang/zig #7667 misplaced relocated glibc stubs (pthread_sigmask)](https://github.com/ziglang/zig/issues/7667) (CLOSED, thanks mjonaitis and andrewrk)
|
|
- [rules/go #2894 Per-arch_target linker flags](https://github.com/bazelbuild/rules_go/issues/2894) (CLOSED, thanks mjonaitis)
|
|
- [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)
|
|
|
|
# Testing
|
|
|
|
## linux cgo + glibc 2.28
|
|
|
|
```
|
|
$ 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
|
|
```
|
|
|
|
## linux cgo + musl
|
|
|
|
```
|
|
$ bazel build \
|
|
--platforms @zig_sdk//:linux_amd64_platform \
|
|
--extra_toolchains @zig_sdk//:linux_amd64_musl_toolchain //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), statically linked, Go BuildID=redacted, stripped
|
|
$ bazel-out/k8-opt-ST-d17813c235ce/bin/test/go/go_/go
|
|
hello, world
|
|
```
|
|
|
|
## 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 direnv git -y
|
|
# . .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][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
|
|
[ubsan1]: https://github.com/ziglang/zig/issues/4830#issuecomment-605491606
|
|
[ubsan2]: https://github.com/ziglang/zig/issues/5163
|