[stormbrew]

The bridging is actually in the swift libraries. Much of it in C++, not in swift, but still. https://github.com/apple/swift/blob/master/stdlib/public/cor... is where the magic starts (and mostly refers to where the actual work is done).

AFAIK Foundation does not have any special handling for swift at all. Swift is just taking advantage of the fact that the people working on it can act with authority on the memory layout of Objective-C Foundation objects.

Also the OSS Foundation is... not quite the same thing as what apple ships on their platforms.

[JonathonW]

That's where Objective C bridging happens. That's irrelevant on Linux or Android, since there's no Obj-C runtime.

OSS Foundation (which is composed of pure Swift code, plus the plain C CoreFoundation which is also open) implements bridging between Swift types and Foundation types itself-- see (for example) the Array extension for bridging to NSArray at [1]. That code's what will (again, eventually) ship on Linux and presumably on Android, because it provides compatibility support for Swift libraries originally targeted to Apple platforms and fills out certain core functionality that's not part of Swift's stdlib (networking being a big one). This work is still ongoing and, if one were to try to actually use it right now, you'd run into lots of bits that aren't implemented yet.

[1] https://github.com/apple/swift-corelibs-foundation/blob/mast...

[stormbrew]

That is true. I recognize that to some extent I was talking past you, but I really just wanted to clarify where the responsibility lies when there is an objc runtime.