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[Concurrency] Fix @Sendable closures not inferring `nonisolated(non… #84117

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Merged
merged 1 commit into from
Sep 10, 2025
Merged

[Concurrency] Fix @Sendable closures not inferring `nonisolated(non… #84117

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20 changes: 10 additions & 10 deletions lib/Sema/TypeCheckConcurrency.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4988,16 +4988,6 @@ ActorIsolation ActorIsolationChecker::determineClosureIsolation(
return ActorIsolation::forActorInstanceCapture(param);
}

// If we have a closure that acts as an isolation inference boundary, then
// we return that it is non-isolated.
//
// NOTE: Since we already checked for global actor isolated things, we
// know that all Sendable closures must be nonisolated. That is why it is
// safe to rely on this path to handle Sendable closures.
if (isIsolationInferenceBoundaryClosure(closure,
/*canInheritActorContext=*/true))
return ActorIsolation::forNonisolated(/*unsafe=*/false);

// A non-Sendable closure gets its isolation from its context.
auto parentIsolation = getActorIsolationOfContext(
closure->getParent(), getClosureActorIsolation);
Expand Down Expand Up @@ -5029,6 +5019,16 @@ ActorIsolation ActorIsolationChecker::determineClosureIsolation(
}
}

// If we have a closure that acts as an isolation inference boundary, then
// we return that it is non-isolated.
//
// NOTE: Since we already checked for global actor isolated things, we
// know that all Sendable closures must be nonisolated. That is why it is
// safe to rely on this path to handle Sendable closures.
if (isIsolationInferenceBoundaryClosure(closure,
/*canInheritActorContext=*/true))
return ActorIsolation::forNonisolated(/*unsafe=*/false);

return normalIsolation;
}();

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2 changes: 1 addition & 1 deletion test/Concurrency/actor_inout_isolation.swift
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Expand Up @@ -220,7 +220,7 @@ if #available(SwiftStdlib 5.1, *) {
let _ = Task.detached { await { (_ foo: inout Int) async in foo += 1 }(&number) }
// expected-error @-1 {{actor-isolated var 'number' cannot be passed 'inout' to 'async' function call}}
// expected-minimal-error @-2 {{global actor 'MyGlobalActor'-isolated var 'number' can not be used 'inout' from a nonisolated context}}
// expected-complete-error @-3 {{main actor-isolated var 'number' can not be used 'inout' from a nonisolated context}}
// expected-complete-warning @-3 {{main actor-isolated var 'number' can not be used 'inout' from a nonisolated context}}
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@jamieQ jamieQ Sep 5, 2025 •
edited
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out of curiosity, why were the adjustments to these existing tests necessary (here & below)?

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I mentioned that in the description:

The change pushes isIsolationInferenceBoundaryClosure check down with added benefit of getting preconcurrency context from the parent.

The check was preventing from preferring "preconcurrency" from parent context.

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thanks for elaborating!

}

// attempt to pass global state owned by the global actor to another async function
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8 changes: 8 additions & 0 deletions test/Concurrency/attr_execution/conversions_silgen.swift
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Expand Up @@ -613,3 +613,11 @@ func testConvertToThrowing(isolation: isolated (any Actor)? = #isolation) async
observe()
}
}

func testSendableClosureNonisolatedNonSendingInference() {
// CHECK-LABEL: sil private [ossa] @$s21attr_execution_silgen49testSendableClosureNonisolatedNonSendingInferenceyyFySiYaYbYCcfU_ : $@convention(thin) @Sendable @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, Int) -> ()
// CHECK: bb0([[EXECUTOR:%.*]] : @guaranteed $Optional<any Actor>, %1 : $Int):
// CHECK: hop_to_executor [[EXECUTOR]]
// CHECK: // end sil function '$s21attr_execution_silgen49testSendableClosureNonisolatedNonSendingInferenceyyFySiYaYbYCcfU_'
let _: nonisolated(nonsending) @Sendable (Int) async -> Void = { _ in }
}
2 changes: 1 addition & 1 deletion test/Concurrency/sendable_checking_captures_swift5.swift
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Expand Up @@ -92,5 +92,5 @@ do {

let c: Class
test(c)
// expected-complete-warning@-1:8 {{implicit capture of 'c' requires that 'Class' conforms to 'Sendable'; this is an error in the Swift 6 language mode}}
// expected-complete-warning@-1:8 {{implicit capture of 'c' requires that 'Class' conforms to 'Sendable'}}
}