That would solve the compilation problem, but there is more to create a working binary. For MacOS the official (and I believe only legal) way is to use a Mac with XCode installed for linking.

Now, you can download all the necessary files from a Mac and build a cross-compilation toolchain on your Linux system. I believe you could not legally distribute a project doing this and that is why these projects don't exist or are usually short-lived (with the notable exception of zig).

We will see how that goes for OP.

So, solutions like osxcross resort to shipping scripts that help you to acquire the necessary files and make that process easier.

The OP builds on osxcross, but is "batteries included".

zig has an even more difficult problem to solve because it tries to compile and link for many platforms. Shipping all the different requirements in their original form would make a zig distribution huge. So it does some clever magic I do not fully understand to create the necessary files from just the necessary subset of data. This reduces the size because there is overlap between platforms. It also means that they are not shipping the Mac files in their complete and original form and have gotten away with this legally so far.

At least that is what I believe is happening. I hope someone with more knowledge about zig could explain it better.

You don’t need the OSX SDK to make runnable Rust binaries from other OS: https://betterprogramming.pub/cross-compiling-rust-from-mac-...

The link is about making Linux binaries on MacOS, which works because almost everything to build for Linux is already on OSX. The other way around it's not true. A Linux system does come neither with the OSX SDK nor the Apple patched llvm linker. I believe at least part of the required files cannot be legally distributed with a Linux system, but I might be wrong on that.

It appears you’re right, thank you! I’m very surprised there isn’t a llvm linker available, minus all the foundation kits that rust doesn’t need.

The llvm linker is a cross-linker in principle. I think it is more about the specialities that Apple needs, like code signing.

Ah. For what it's worth, those have been reverse engineered and copied elsewhere. I maintain a project that does cross-compiled macOS builds and our own signing on Linux.

Rustup arch only adds support for static libraries (unliked objects), and craps out as soon as you try to build a binary.

Rust did not do the legwork that zig did to bundle libc and a working linker, and Cargo is exceptionally naive in its default configuration, so it won't even find a usable cross-linker on the system, nor even try the chronically-unfinished rustc-lld integration there is.

I could be mistaken, but I believe that installs a completely parallel toolchain which is relatively large compared with zigs approach of having all the platforms generatable from a single toolchain.