On: Using Zig as cross-platform C toolchain

[fpoling]

Apple does not allow to use their SDK on non-Apple hardware. So if you need to use MacOS headers and libraries, the hardware where the compiler runs must be from Apple. Apple has no problem if you run Linux on that and cross-compile from it to Mac.

At work we could not for that reason use the same compilation server setup to cross-compile for Linux, MacOS, Windows and ended up with a separated MacPro box for the compilation farm.

EDIT: cross-compilation from Windows works after one gets Windows SDK and Visual Studio libraries (the later is not free, but free alternatives often are sufficient). The biggest headache is that Windows headers assume a case-insensitive file system and includes, for example, windows.h when the file is Windows.h. One can either use case-insensitive mount option for ext4 or symlink relevant files to the proper case.

[slimsag → fpoling]

Note however Zig actually provides libSystem.tbd stubs out of the box, so you can cross-compile from any OS to macOS too as long as you only depend on libSystem (the macOS libc.)

If you need the rest of the Apple SDK, then you'd need a sysroot (and face the challenges you described.)

[smeenai → fpoling]

VS community edition is free (but not an option for commercial work).

Another Clang-specific way to handle the case insensitivity is by making use of a virtual file system (VFS) overlay. https://github.com/llvm/llvm-project/blob/4976d1fe58f89169ef... demonstrates how that works. (There's no linker equivalent that I'm aware of, so you do have to use the symlinks or something like ciopfs for that; https://github.com/llvm/llvm-project/blob/4976d1fe58f89169ef... is an example of symlink generation.)