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[Concurrency] Infer @preconcurrency @MainActor in default main acto… #81627

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Merged
merged 1 commit into from
May 20, 2025
Merged

[Concurrency] Infer @preconcurrency @MainActor in default main acto… #81627

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9 changes: 7 additions & 2 deletions lib/Sema/TypeCheckConcurrency.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5818,8 +5818,13 @@ computeDefaultInferredActorIsolation(ValueDecl *value) {
if (isa<TypeDecl>(value) || isa<ExtensionDecl>(value) ||
isa<AbstractStorageDecl>(value) || isa<FuncDecl>(value) ||
isa<ConstructorDecl>(value)) {
return {
{{ActorIsolation::forGlobalActor(globalActor), {}}, nullptr, {}}};
// Preconcurrency here is used to stage the diagnostics
// when users select `@MainActor` default isolation with
// non-strict concurrency modes (pre Swift 6).
auto isolation =
ActorIsolation::forGlobalActor(globalActor)
.withPreconcurrency(!ctx.LangOpts.isSwiftVersionAtLeast(6));
return {{{isolation, {}}, nullptr, {}}};
}
}

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22 changes: 16 additions & 6 deletions test/Concurrency/assume_mainactor_typechecker_errors.swift
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
// RUN: %target-swift-frontend -swift-version 6 -emit-sil -default-isolation MainActor %s -verify
// RUN: %target-swift-frontend -swift-version 5 -emit-sil -default-isolation MainActor %s -verify -verify-additional-prefix swift5-
// RUN: %target-swift-frontend -swift-version 6 -emit-sil -default-isolation MainActor %s -verify -verify-additional-prefix swift6-

// READ THIS! This test is meant to check the specific isolation when
// `-default-isolation` is set to `MainActor` in combination with validating
Expand All @@ -7,13 +8,16 @@

// Fake Sendable Data
class SendableData : @unchecked Sendable {}
// expected-swift5-note@-1 {{calls to initializer 'init()' from outside of its actor context are implicitly asynchronous}}

nonisolated func getDataFromSocket() -> SendableData { SendableData() }
// expected-swift5-warning@-1 {{call to main actor-isolated initializer 'init()' in a synchronous nonisolated context; this is an error in the Swift 6 language mode}}

class Klass { // expected-note 3 {{}}
class Klass { // expected-swift5-note 3 {{}} expected-swift6-note 3 {{}}
let s = SendableData()
// expected-swift5-note@-1 2 {{}}

init() { s = SendableData() }
init() { s = SendableData() } // expected-swift5-error {{immutable value 'self.s' may only be initialized once}}
init(_ s: SendableData) {}

func doSomething() {}
Expand Down Expand Up @@ -50,9 +54,15 @@ func unspecifiedFunctionTest2() async {

nonisolated func nonisolatedFunctionTest() async {
let k = await StructContainingKlass()
await unspecifiedAsync(k.k) // expected-error {{non-sendable type 'Klass' of property 'k' cannot exit main actor-isolated context}}
await nonisolatedAsync(k.k) // expected-error {{non-sendable type 'Klass' of property 'k' cannot exit main actor-isolated context}}
await mainActorAsync(k.k) // expected-error {{non-sendable type 'Klass' of property 'k' cannot exit main actor-isolated context}}
await unspecifiedAsync(k.k)
// expected-swift5-warning@-1 {{non-sendable type 'Klass' of property 'k' cannot exit main actor-isolated context}}
// expected-swift6-error@-2 {{non-sendable type 'Klass' of property 'k' cannot exit main actor-isolated context}}
await nonisolatedAsync(k.k)
// expected-swift5-warning@-1 {{non-sendable type 'Klass' of property 'k' cannot exit main actor-isolated context}}
// expected-swift6-error@-2 {{non-sendable type 'Klass' of property 'k' cannot exit main actor-isolated context}}
await mainActorAsync(k.k)
// expected-swift5-warning@-1 {{non-sendable type 'Klass' of property 'k' cannot exit main actor-isolated context}}
// expected-swift6-error@-2 {{non-sendable type 'Klass' of property 'k' cannot exit main actor-isolated context}}
}

func testTask() async {
Expand Down