macOS binaries should probably have deliberate OS min version

[marktsuchida]

This is a non-urgent technicality.

On macOS, every binary has a minimum supported OS version in its metadata ("load commands"). This can be inspected using vtool -show path/to/binary (vtool is part of Xcode or the Command Line Tools). Note that the output format is different for x86_64 (LC_VERSION_MIN_MACOSX/version) vs arm64 (LC_BUILD_VERSION/minos).

Jaunch 1.0.3 release binaries have the following values, which are probably perfectly fine:

Architecture	Binary	Min OS version
x64	launcher	10.12
arm64	launcher	11.0
x64	jaunch	11.0
arm64	launcher	11.0

For the launcher (C), these are currently set by the -target compiler option.
The C compiler also can set this value via -mmacos-version-min=<value> or the environment variable MACOSX_DEPLOYMENT_TARGET (provided that the version number is removed from the -target option argument, as in -target arm64-apple-macos). The default is quite high: I get minos 15.0 using SDK 15.5 (Sequoia).

For Kotlin, presumably 11.0 is the compiler's default. According to my testing, MACOSX_DEPLOYMENT_TARGET is not honored. Claude thinks it can be set in the Gradle file (complicated) or in konan.properties (osVersionMin.macos_x64=11.0, osVersionMin.macos_arm64=11.0), but I could not get either to work immediately.

It is possible to determine the minimum supported deployment target when building with the current (or given) macOS SDK: plutil -extract SupportedTargets.macosx.MinimumDeploymentTarget raw "$(xcrun --show-sdk-path --sdk macosx)/SDKSettings.plist". But Kotlin may not use the same SDK version or otherwise might have a different minimum deployment target.

Potential actions:

• It might be worth setting the launcher's min version to 11.0 also for x64, given that the configurator requires 11.0 anyway.
• It will be good to ensure that the min version is not set too high in future releases.

[ctrueden]

It might be worth setting the launcher's min version to 11.0 also for x64, given that the configurator requires 11.0 anyway.

The launcher can be used independently of the configurator shipped with Jaunch. That is: one could slot in one's own configurator that behaves in whatever fashion—it could be as simple as a series of printf statements issuing hardcoded directives to the native launcher, compiled to target 10.12 (or even earlier). So I think it makes sense to let the launcher target the earliest feasible macOS version.

It will be good to ensure that the min version is not set too high in future releases.

Agreed. I like the current behavior, but documenting it more precisely would be nice—right now the OS version minimums are stated in the docs, but it does not distinguish between the launcher and the configurator binaries. Furthermore, the 11.0 minimum for the configurator could change out from under us in the future; we should be careful whenever updating the Kotlin version to double check this before proceeding.

I will leave this open until at least the documentation is more carefully stated.