NSLock does not conform to Sendable on Linux

[maartene]

As per the documentation NSLock should conform to Sendable. And indeed, when compiling my code with strict concurrency checking on macOS, no warnings are issued.

However, when compiling on Linux, I get the warning:

warning: static property 'lock' is not concurrency-safe because it is not either conforming to 'Sendable' or isolated to a global actor; this is an error in Swift 6
    static private let lock = NSLock()

From discussion on the Swift forum, I conclude that this is unintended and NSLock on Linux too should conform to Sendable.

Perhaps this can be fixed?