145 lines
5.1 KiB
Markdown
145 lines
5.1 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-12, musl, glibc (versions 2-2.33, 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 = "0.2"
|
|
|
|
http_archive(
|
|
name = "bazel-zig-cc",
|
|
sha256 = "0af0493e2d4822a94803e8a83703d25e0f9d8fe6ec4daf3b0ed3ca4cd6076650",
|
|
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(["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'
|
|
```
|
|
|
|
Read [#Known Issues](#known-issues) before using.
|
|
|
|
# Known Issues
|
|
|
|
## Parallel `zig c++` invocations may fail
|
|
|
|
Task: [ziglang/zig #9431 FileNotFound when compiling macos](https://github.com/ziglang/zig/issues/9431)
|
|
|
|
Background: there is a race when calling `zig c++`, which Bazel does a lot.
|
|
This may fail compilation. Yours truly only reproduced it on macos with a cold
|
|
cache. Based on that, a workaround in the toolchain exists, named
|
|
`speed_first_safety_later`. The possible values are `auto` (default), `yes`,
|
|
`no`.
|
|
|
|
## glibc 2.27 or older
|
|
|
|
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).
|
|
|
|
## cgo for darwin (macos)
|
|
|
|
Task: [rules/go #2894 Per-arch_target linker flags](https://github.com/bazelbuild/rules_go/issues/2894)
|
|
|
|
Background: until there is a better "global" way (i.e. the task is solved), all
|
|
`go_binary` targets destined for Darwin (macos) need an extra `gc_linkopts`
|
|
flag:
|
|
|
|
```
|
|
go_binary(
|
|
<...>
|
|
gc_linkopts = select({
|
|
"@platforms//os:macos": ["-s", "-w", "-buildmode=pie"],
|
|
"//conditions:default": [],
|
|
}),
|
|
)
|
|
```
|
|
|
|
# Closed issues
|
|
|
|
- [ziglang/zig #9139 zig c++ hanging when compiling in parallel](https://github.com/ziglang/zig/issues/9139) (CLOSED)
|
|
- [golang/go #46644 cmd/link: with CC=zig: SIGSERV when cross-compiling to darwin/amd64](https://github.com/golang/go/issues/46644) (CLOSED)
|
|
- [ziglang/zig #9050 golang linker segfault](https://github.com/ziglang/zig/issues/9050) (CLOSED)
|
|
- [ziglang/zig #7917 [meta] better c/c++ toolchain compatibility](https://github.com/ziglang/zig/issues/7917) (CLOSED)
|
|
- [ziglang/zig #7915 ar-compatible command for zig cc](https://github.com/ziglang/zig/issues/7915) (CLOSED)
|
|
|
|
# Testing
|
|
|
|
## linux cgo + glibc 2.19
|
|
|
|
```
|
|
$ 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//:x86_64-linux-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:gognu
|
|
...
|
|
$ file bazel-bin/test/gognu_/gognu
|
|
bazel-bin/test/gognu_/gognu: Mach-O 64-bit x86_64 executable, flags:<NOUNDEFS|DYLDLINK|TWOLEVEL|PIE>
|
|
```
|
|
|
|
## Transient docker environment
|
|
|
|
```
|
|
$ docker run -e CC=/usr/bin/false -ti --rm -v $(pwd):/x -w /x debian:buster-slim
|
|
# apt update && apt install wget git -y
|
|
# . .envrc
|
|
```
|
|
|
|
And run the `bazel build` commands above. Take a look at `.build.yml` and see
|
|
how CI does it.
|