MACOSX_DEPLOYMENT_TARGET ignored?

[daemontus]

Hi!

I'm building a library that depends on the z3-sys crate which internally uses the Z3 theorem prover. The problem is that z3-sys can link Z3 statically (which I want: my python tool is rather standalone and I don't want to force people to hunt for extra dependencies). However, this means that I'm building whole Z3 alongside my crate. This is not an issue on linux or windows, but on macos, Z3 uses some APIs that are only available on newer macOS versions (e.g. 11.0, whereas default "minimum" for rust is 10.8 I believe).

Normally, you set this limit using MACOSX_DEPLOYMENT_TARGET environment variable, which should propagate to cmake that is actually building Z3. However, no matter how I try to set this variable, the build process for Z3 does not seem to notice or care and I get API compatibility errors (see for example here).

Interestingly, on my local macOS laptop with macOS 13, the problem does not seem to be occurring. That is, I don't even have to set MACOSX_DEPLOYMENT_TARGET and everything works. However, so far I haven't found a single difference between my local setup and the github actions runner that could explain this.

Does anyone have any idea how to resolve this? Have you encountered something similar? (I guess I could try to fork z3-sys and force the variable in the build script, but I'd like to avoid that if possible)

[messense]

In maturin we only use MACOSX_DEPLOYMENT_TARGET in two places

1. maturin/src/target.rs

   Line 294 in 82aa66a

   let ((x86_64_major, x86_64_minor), (arm64_major, arm64_minor)) = macosx_deployment_target(env::var("MACOSX_DEPLOYMENT_TARGET").ok().as_deref(), universal2)?;

   to calculate wheel tags, doesn't affect cargo build.

2. maturin/src/compile.rs

   Lines 402 to 407 in 82aa66a

   	// Set default macOS deployment target version
   	if target.is_macos() && env::var_os("MACOSX_DEPLOYMENT_TARGET").is_none() {
   	use crate::target::rustc_macosx_target_version;
   	let (major, minor) = rustc_macosx_target_version(target.target_triple());
   	build_command.env("MACOSX_DEPLOYMENT_TARGET", format!("{}.{}", major, minor));

   set default MACOSX_DEPLOYMENT_TARGET when the env var isn't set by user which in your case won't be used since you already set it.

so in conclusion maturin doesn't ignore MACOSX_DEPLOYMENT_TARGET, cargo rustc will inherit the env var you set normally.

echo "MACOSX_DEPLOYMENT_TARGET=10.16" >> $GITHUB_ENV

Maybe try 11.0? I don't think there is a macOS 10.16 release.

[daemontus]

Thank you for the suggestions! I tried 11.0 later (e.g. here), but it didn't do anything.

But I think I figured it out! Based on this, I tried setting CMAKE_OSX_DEPLOYMENT_TARGET to 11.0 and that actually seems to resolve the problem. So, either I don't understand how cmakes propagates this information (because based on the documentation above, I would assume MACOSX_DEPLOYMENT_TARGET is read from the environment by cmake), or the github runner has some version of cmake where this behaves differently?

Regardless... it seems to be working. Thank you for your help!

[daemontus]

Just to close this with an actual answer...

For whatever reason, MACOSX_DEPLOYMENT_TARGET did not do anything, but setting CMAKE_OSX_DEPLOYMENT_TARGET seems to resolve this.

Edit: I stand corrected. It turns out that both variables need to be set for the build to work.

[messense]

Turns out there was a hardcoded MACOSX_DEPLOYMENT_TARGET = 10.9 in maturin-action: PyO3/maturin-action#112, it might have caused issue for universal2/aarch64 build, fixed now.

[daemontus]