Avoid C atomic operations in Swift 5.9+

lorentey commented 1 year ago

Importing _AtomicsShims with C++ interoperability enabled uncovers some issues with double-wide atomics as currently implemented in C.

It's time to stop tweaking these C definitions -- instead, disable C atomics, and switch to using native Swift atomic operations from Swift 5.9 onward.

(For now, we'll still need _AtomicsShims for its swift_retain_n/swift_release_n wrappers. I'm planning to get rid of the need for those, too, but that'll need some compiler tweaks that aren't targeted for 5.9.)

Resolves #88.

Checklist

[X] I've read the Contribution Guidelines
[X] My contributions are licensed under the Swift license.
[X] I've followed the coding style of the rest of the project.
[ ] I've added tests covering all new code paths my change adds to the project (if appropriate).
[X] I've verified that my change does not break any existing tests.
[ ] I've updated the documentation if necessary.

lorentey commented 1 year ago

@swift-ci test

lorentey commented 1 year ago

@swift-ci test

finagolfin commented 1 year ago

This pull breaks building the latest trunk of this package with Swift 5.8, as can be seen on my daily Android CI, and presumably 5.7 too.

Maybe this can be reconfigured in such a way that #if compiler(>5.8) or similar checks are used in the Package manifest instead, to choose whether native builtins are used or not?

apple / swift-atomics

Avoid C atomic operations in Swift 5.9+ #90

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