Apple watchOS targets.

Tier: 3

  • aarch64-apple-watchos: Apple WatchOS on ARM64.
  • aarch64-apple-watchos-sim: Apple WatchOS Simulator on ARM64.
  • x86_64-apple-watchos-sim: Apple WatchOS Simulator on 64-bit x86.
  • arm64_32-apple-watchos: Apple WatchOS on Arm 64_32.
  • armv7k-apple-watchos: Apple WatchOS on Armv7k.

Target maintainers


These targets are cross-compiled, and require the corresponding watchOS SDK (WatchOS.sdk or WatchSimulator.sdk), as provided by Xcode. To build the ARM64 targets, Xcode 12 or higher is required.

The path to the SDK can be passed to rustc using the common SDKROOT environment variable.

OS version

The minimum supported version is watchOS 5.0.

This can be raised per-binary by changing the deployment target. rustc respects the common environment variables used by Xcode to do so, in this case WATCHOS_DEPLOYMENT_TARGET.

Building the target

The targets can be built by enabling them for a rustc build in config.toml, by adding, for example:

build-stage = 1
target = ["aarch64-apple-watchos", "aarch64-apple-watchos-sim"]

Using the unstable -Zbuild-std with a nightly Cargo may also work.

Building Rust programs

Rust programs can be built for these targets by specifying --target, if rustc has been built with support for them. For example:

$ rustc --target aarch64-apple-watchos-sim your-code.rs


There is no support for running the Rust or standard library testsuite at the moment. Testing has mostly been done manually with builds of static libraries embedded into applications called from Xcode or a simulator.

It hopefully will be possible to improve this in the future.