🦾 Adopt swift-subprocess

[goergisn]

Background

Currently, our Shell module uses Foundation's Process API to execute command line commands. The Swift team has released swift-subprocess, a new cross-platform package for spawning processes with a more modern, Swift-native API.

Benefits of swift-subprocess

• Async/await native - Built for Swift concurrency from the ground up
• More Swifty API - Cleaner syntax compared to the imperative Process API
• Cross-platform - Designed to work across macOS, Linux, and Windows (Right now we use Process essentially only to execute xcodebuild commands which are only available on macOS)
• Maintained by Swift team - Part of the official swiftlang organization

Current blockers

1. Requires Swift 6.1 - The package uses swift-tools-version: 6.1, while we currently target Swift 5.9
2. Uses experimental features - Relies on StrictConcurrency, NonescapableTypes, LifetimeDependence, and Span
3. iOS not supported - Platform requirement is set to .iOS("99.0") (effectively disabled), though this doesn't affect us since Shell only runs on macOS

References

• https://github.com/swiftlang/swift-subprocess