Bazel zig cc toolchain for Go

This is a prototype zig-cc toolchain that can cross-compile cgo programs to these os/archs:

• x86_64-linux-gnu.2.19
• x86_64-linux-musl
• aarch-linux-gnu.2.19
• aarch-linux-musl
• x86_64-macos-gnu
• aarch64-macos-gnu

GNU toolchain is the default, musl toolchain can be selected by adding it to --extra_toolchains @zig_sdk//:ARCH-linux-musl_toolchain.

Don't use this yet, see Known Issues).

Testing

linux cgo + glibc 2.19

Glibc toolchain is suffixed with -gnu:

$ bazel run --platforms @zig_sdk//:x86_64-linux-gnu //test:gognu
$ 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

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 @zig_sdk//:x86_64-macos-gnu //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 -ti --rm -v $(pwd):/x -w /x debian:buster-slim
# apt update && apt install curl -y && curl -L https://github.com/bazelbuild/bazelisk/releases/download/v1.9.0/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.

Known Issues

• rules/go #2894 Per-arch_target linker flags

Closed issues:

• ziglang/zig #9139 zig c++ hanging when compiling in parallel (CLOSED)
• golang/go #46644: cmd/link: with CC=zig: SIGSERV when cross-compiling to darwin/amd64 (CLOSED)
• ziglang/zig #9050 golang linker segfault (CLOSED)
• ziglang/zig #7917 [meta] better c/c++ toolchain compatibility (CLOSED)
• ziglang/zig #7915 ar-compatible command for zig cc (CLOSED)