Cross-compilation to macos aarch64-apple-darwin target using Maturin Docker

[mikwieczorek]

I am attempting to cross-compile Python Rust bindings for macOS aarch64-apple-darwin using maturin. I've tried using the maturin Docker image, but it fails with an error related to the Python interpreter. I've also looked into using osxcross for cross-compilation, but I'm not sure how to integrate it with maturin.

Based on the GitHub issue #375 and the comments from @messense mentioning the --zig option and python-build-standalone (not sure how to use it), I'm seeking a more streamlined solution.

I followed the tips from the aforementioned Issue and docs from PyO3 here. I tried using latest maturin docker image, but I couldn't make it work and compile my project to aarch64-apple-darwin.

When I run:

  export PYO3_PYTHON=/python/bin/python3.8
  export PYO3_CROSS=1
  export PYO3_CROSS_LIB_DIR=/python/lib
  export PYO3_CROSS_PYTHON_VERSION=3.8
  export PYO3_CROSS_PYTHON_IMPLEMENTATION=CPython
  maturin build --interpreter $(which python3.8)--release --target aarch64-apple-darwin;

( I tired with and without additional flags in Cargo.toml: rustflags = [ "-C", "link-arg=-undefined", "-C", "link-arg=dynamic_lookup",]

I got

  error: linking with `cc` failed: exit status: 1 cc: error: arm64: No such file or directory
  cc: error: dynamic_lookup: No such file or directory
  cc: error: unrecognized command line option '-arch'; did you mean '-march='?

When I added --zig flag (and installed ziglang) then the error from build changed to: note: error: unsupported linker arg: -exported_symbols_list

I also tried add maturin on top of osxcross and playing with CC and CXX variables but to no effect.

Finally I tried using abi3-py38 feature to avoid providing path to macOS complied python lib, but this also didn't work.

Questions

1. Is there a straightforward way to cross-compile to macOS aarch64-apple-darwin using the maturin Docker image?
2. Do I need to use osxcross with maturin for cross-compilation?
3. Could you provide a minimal working example for either of the above methods?

I would greatly appreciate any guidance or examples to help resolve this issue. Thank you!

[messense]

1. Is there a straightforward way to cross-compile to macOS aarch64-apple-darwin using the maturin Docker image?

No, the docker image is for native compilation only.

2. Do I need to use osxcross with maturin for cross-compilation?

No, but you can use it, there is nothing in maturin that prevents you from using a custom toolchain. You can use zig, but you should probably use zig 0.10.1 instead of 0.11.x because zig 0.11.x errors on unsuppported linker flags (instead of warning like in 0.10.1).

3. Could you provide a minimal working example for either of the above methods?

Sorry I don't have the free time to do that.

It's hard to guess what's the real problem without a repro, so please provide a minimal repro. If you can't provide a repro in public for reasons, I'm up for paid private support if you want.

[mikwieczorek]

Thank you @messense you tip on using zig 0.10.1.post1 solved the problem.
Additionally I had to prepare some info following format in lib/_sysconfigdata*.py file to allow proper extensions etc. for built wheels. Setting PYO3_CROSS_LIB_DIR to this prepared '_sysconfigdata*.py` resulted in successful build.