Is there a way to annotate an Objective-C API with `sending`?

Using Swift
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I was just doing some research on Obj-C/Concurrency interoperability. I cannot find anything in clang's documentation, but I was wondering if an annotation exists to add sending?

3 Likes
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(Apologies, my brain for some reason read Matt's post as "Sendable", not "sending". It's too early in the afternoon, apparently.)

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4

No worries at all! I should have included a link to the clang docs right from the beginning.

https://clang.llvm.org/docs/AttributeReference.html#customizing-swift-import

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I thought I figured this out by using __attribute__((swift_attr("sending"))), but nope that does not work.

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This should work. Are you sure that you are using the syntax correctly? Here is an example from the test that validates that this works:

1 Like
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I think this was a combination of:

a) it actually being slightly hard to conclusively prove that sending was in effect on the Swift side because region-based isolation makes the compiler hard to trick
b) probably me making a mistake with the syntax
c) Not all concurrency annotations added to Objective-C are visible in the Swift translation · Issue #74629 · swiftlang/swift · GitHub