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a554ad632b
Replace the existing warning about any access to a local variable from concurrently-executing code with a more tailored error: concurrently-executing code may read a mutable varable, but cannot modify it. This is safe so long as we either always do by-value captures in concurrent closures or we ensure that no mutation of that variable can occur after the point of capture. We'll follow up with one of those. For now... be careful out there. Since we're promoting this to an error, narrow it down to concurrent closures and local functions, dropping the assumption that escaping closures "may execute concurrently."
38 lines
1.2 KiB
Swift
38 lines
1.2 KiB
Swift
// RUN: %target-typecheck-verify-swift -enable-experimental-concurrency
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// REQUIRES: concurrency
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actor class MyActor {
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let immutable: Int = 17
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var text: [String] = []
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func synchronous() -> String { text.first ?? "nothing" } // expected-note 2 {{calls to instance method 'synchronous()' from outside of its actor context are implicitly asynchronous}}
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func asynchronous() async -> String { synchronous() }
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func testAsyncLetIsolation() async {
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async let x = self.synchronous()
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// expected-error @-1{{actor-isolated instance method 'synchronous()' cannot be referenced from 'async let' initializer}}
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async let y = await self.asynchronous()
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async let z = synchronous()
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// expected-error @-1{{actor-isolated instance method 'synchronous()' cannot be referenced from 'async let' initializer}}
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var localText = text
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async let w = localText.removeLast()
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// expected-error@-1{{mutation of captured var 'localText' in concurrently-executing code}}
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_ = await x
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_ = await y
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_ = await z
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_ = await w
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}
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}
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func outside() async {
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let a = MyActor()
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async let x = a.synchronous() // okay, await is implicit
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async let y = await a.synchronous()
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_ = await x
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_ = await y
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}
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