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This attribute can be attached to a noncopyable struct to specify that its storage is raw, meaning the type definition is (with some limitations) able to do as it pleases with the storage. This provides a basis for implementing types for things like atomics, locks, and data structures that use inline storage to store conditionally-initialized values. The example in `test/Prototypes/UnfairLock.swift` demonstrates the use of a raw layout type to wrap Darwin's `os_unfair_lock` APIs, allowing a lock value to be stored inside of classes or other types without needing a separate allocation, and using the borrow model to enforce safe access to lock-guarded storage.
35 lines
1.0 KiB
Swift
35 lines
1.0 KiB
Swift
// RUN: %target-swift-frontend -enable-experimental-feature StrictConcurrency -enable-experimental-feature RawLayout -typecheck -verify %s
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func checkSendable(_: @Sendable () -> ()) {}
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@_rawLayout(size: 4, alignment: 4)
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struct NotAutomaticallySendableAndNotUsedAsSendable: ~Copyable {}
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@_rawLayout(size: 4, alignment: 4)
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struct NotAutomaticallySendable: ~Copyable {} // expected-note{{}}
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func testNotAutomaticallySendable() {
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let s = NotAutomaticallySendable()
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checkSendable { _ = s } // expected-warning{{capture of 's' with non-sendable type 'NotAutomaticallySendable'}}
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}
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@_rawLayout(size: 4, alignment: 4)
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struct UnuncheckedSendable: ~Copyable, Sendable {} // expected-warning{{@_rawLayout does not conform to the 'Sendable' protocol}}
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func testUnuncheckedSendable() {
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let s = UnuncheckedSendable()
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checkSendable { _ = s }
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}
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@_rawLayout(size: 4, alignment: 4)
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struct UncheckedSendable: ~Copyable, @unchecked Sendable {}
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func testUncheckedSendable() {
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let s = UncheckedSendable()
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checkSendable { _ = s }
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}
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