Bazel zig cc toolchain for Go

This is a prototype zig-cc toolchain that can compile cgo programs with these c libraries:

glibc 2.19
musl

glibc 2.19 is the default. That means, glibc 2.19 toolchain is registered with these basic constraints:

[
    "@platforms//os:linux",
    "@platforms//cpu:x86_64",
]

Testing

linux cgo + glibc 2.19

Using the default toolchain:

$ bazel build --toolchain_resolution_debug=true //test:gognu
...
$ ../bazel-bin/test/gognu_/gognu
hello, world
$ file ../bazel-bin/test/gognu_/gognu
../bazel-bin/test/gognu_/gognu: 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

Explicitly the toolchain explicitly -gnu:

$ bazel run --platforms @com_github_ziglang_zig//:platform_x86_64-linux-gnu //test:gognu

linux cgo + musl

$ bazel build --platforms @com_github_ziglang_zig//:platform_x86_64-linux-musl //test:gomusl
...
$ file ../bazel-out/k8-fastbuild-ST-d17813c235ce/bin/test/gomusl_/gomusl
../bazel-out/k8-fastbuild-ST-d17813c235ce/bin/test/gomusl_/gomusl: 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/gomusl_/gomusl
hello, world

macos cgo + gnu

Does not work?

$ bazel build --platforms @com_github_ziglang_zig//:platform_x86_64-macos-musl //test:gognu
...

Transient docker environment

$ docker run -ti --rm -v $(pwd):/x -w /x debian:buster-slim
# apt update && apt install curl ca-certificates -y && curl -L https://github.com/bazelbuild/bazelisk/releases/download/v1.7.5/bazelisk-linux-amd64 > /usr/local/bin/bazel && chmod +x /usr/local/bin/bazel
# export CC=/usr/bin/false

And run the bazel build commands above. Take a look at .build.yml and see how CI does it.

Appendix: compiling manually

zcc

#!/bin/bash
exec zig cc -target x86_64-macos-gnu "$@"

Build: `` GOOS=darwin GOARCH=amd64 CC=zcc go build -ldflags "-linkmode external -extldflags -static" hello.go

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