Question: why are @available directives commented out?

[BasThomas]

Like e.g. here:

swift-system/Sources/System/FileDescriptor.swift

Line 17 in 8ffa04c

// @available(macOS 10.16, iOS 14.0, watchOS 7.0, tvOS 14.0, *)

Are these supposed to be commented out, and if so, why?

[Snowy1803]

I’d guess System was supposed to be included in those versions of the OSes, but then they decided to make it an open source Swift Package, compatible with Linux

[milseman]

This is due to language/tooling issues. We'd like the ability to add availability based on conditional compilation for ABI-stable builds of Swift System while not adding availability for package builds (i.e. a source dependency). For now, we include, but comment out, the availability declarations matching what has already been shipped in binary releases.

[stephentyrone]

@Snowy1803 Note that System is included in those versions of the OSes (https://developer.apple.com/documentation/system).

[BasThomas]

Would it help to add an explanation to it somewhere, either in comment(s) or in the documentation?

[milseman]

@BasThomas definitely. I'm trying to put together some more extensive documentation and this should be part of that.

[milseman]

I put this in the new FAQ issue: #18

[BasThomas]

Great!