/zig-macho-bug

A minimal reproduction of a suspected Zig CC Mach-O linker bug.

Primary LanguageDockerfileMIT LicenseMIT

Zig: Suspected Mach-O Linker Bug Example

Retesting with zig-linux-x86_64-0.11.0-dev.2375+771d07268 shows that this bug has been resolved.

I believe that there may be a Mach-O linker bug in Zig CC that affects the compilation of dynamic libraries targeting aarch64-macos.

This repo aims to provide a minimal example that reproduces the issue.

Basic Reproduction

Simply run make -f make-zig-cross.mk to reproduce the issue. This will attempt to cross-compile a dynamic library for aarch64-macos using the source file foo.c. It is in this source file that the problematic code is contained.

More Detailed Example Using Docker

A Docker image can be built that will setup an environment in which both native and cross compilation using both clang and zig cc can be executed in order to reproduce the issue. I built and ran this image on an x86_64 machine.

To build the image, run the following:

export DOCKER_BUILDKIT=1
docker build -t zig-macho-bug:latest .

To run the container interactively:

docker run -it zig-macho-bug:latest

Then cd into /home/test in order to test the various builds.

Test builds:

  • make -f make-zig-cross.mk: attempt to cross-compile the dynamic lib for aarch64-macos (this should exhibit the issue).
  • make -f make-clang-cross.mk: cross-compile the dynamic lib for aarch64-macos (this should build successfully).
  • make -f make-zig-native.mk: compile the dynamic lib for the host os (i.e. Ubuntu 22.04 - this should build successfully).
  • make -f make-clang-native.mk: compile the dynamic lib for the host os (i.e. Ubuntu 22.04 - this should build successfully).
  • Append exec to any of the make calls above to compile the dynamic lib and link it into an executable (build/app, e.g. make -f make-zig-native.mk exec).

Versions used

Zig:

  • zig-linux-x86_64-0.11.0-dev.2375+771d07268

Host:

  • x86_64 Ubuntu 22.04

Clang:

  • Ubuntu clang version 14.0.0-1ubuntu1
  • Target: x86_64-pc-linux-gnu
  • Thread model: posix

MacOS SDK: