How to cross compile a rust project using zig? wtf.

I was able to compile and cross compile the gnu and musl variants to all of our target triples :)

1. Install the cargo-zigbuild and dependencies (requires python3)

   pip3 install ziglang
   cargo install cargo-zigbuild

2. Cross compiling for all musl variants

   musl

   rustup target add x86_64-unknown-linux-musl
   cargo zigbuild --target x86_64-unknown-linux-musl
   
   rustup target add aarch64-unknown-linux-musl
   cargo zigbuild --target aarch64-unknown-linux-musl
   
   rustup target add armv7-unknown-linux-musleabihf
   cargo zigbuild --target armv7-unknown-linux-musleabihf
   
   rustup target add arm-unknown-linux-musleabihf
   cargo zigbuild --target arm-unknown-linux-musleabihf

   gnu

   rustup target add x86_64-unknown-linux-gnu
   cargo zigbuild --target x86_64-unknown-linux-gnu
   
   rustup target add aarch64-unknown-linux-gnu
   cargo zigbuild --target aarch64-unknown-linux-gnu
   
   rustup target add armv7-unknown-linux-gnueabihf
   cargo zigbuild --target armv7-unknown-linux-gnueabihf
   
   rustup target add arm-unknown-linux-gnueabihf
   cargo zigbuild --target arm-unknown-linux-gnueabihf

Working hosts

The following hosts were able to succesfully build/compile the above targets.

• MacOS M1 (aarch64) natively
• MacOS M1 (aarch64) in arm64 debian container
• Linux (x86_64) GitHub Runner (ubuntu-20.04)

What didn't work

It seems that arm 32 bit targets don't work so well due to some compile issues with the ring dependency. The following targets failed to compile:

• armv5te-unknown-linux-musleabi
• armv5te-unknown-linux-gnueabi
• arm-unknown-linux-musleabi
• arm-unknown-linux-gnueabi

Troubleshooting tips

Compile errors when building on MacOS M1 native

I ran into an initial problem building natively on MacOS M1. It turned out that there was a conflict between homebrew installed rust package and the rust version installed via rustup. Solution was to uninstall the homebrew rust package.

Fix was provided by this post.

References

• https://github.com/rust-cross/cargo-zigbuild
• https://andrewkelley.me/post/zig-cc-powerful-drop-in-replacement-gcc-clang.html