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[SE-0470] Enable isolated conformances by default
The IsolatedConformances feature moves to a normal, supported feature. Remove all of the experimental-feature flags on test cases and such. The InferIsolatedConformances feature moves to an upcoming feature for Swift 7. This should become an adoptable feature, adding "nonisolated" where needed. (cherry picked from commit 3380331)
1 parent 69758f6 commit 5e29333

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-70
lines changed

‎CHANGELOG.md‎

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@@ -32,6 +32,34 @@
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strategy, given that the code would eventually become ambiguous anyways when
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the deployment target is raised.
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* [SE-0470][]:
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A protocol conformance can be isolated to a specific global actor, meaning that the conformance can only be used by code running on that actor. Isolated conformances are expressed by specifying the global actor on the conformance itself:
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```swift
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protocol P {
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func f()
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}
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@MainActor
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class MyType: @MainActor P {
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/*@MainActor*/ func f() {
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// must be called on the main actor
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}
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}
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```
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Swift will produce diagnostics if the conformance is directly accessed in code that isn't guaranteed to execute in the same global actor. For example:
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```swift
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func acceptP<T: P>(_ value: T) { }
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/*nonisolated*/ func useIsolatedConformance(myType: MyType) {
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acceptP(myType) // error: main actor-isolated conformance of 'MyType' to 'P' cannot be used in nonisolated context
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}
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```
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To address such issues, only use an isolated conformance from code that executes on the same global actor.
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* [SE-0419][]:
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Introduced the new `Runtime` module, which contains a public API that can
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generate backtraces, presently supported on macOS and Linux. Capturing a
@@ -10759,6 +10787,7 @@ using the `.dynamicType` member to retrieve the type of an expression should mig
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[SE-0442]: https://github.com/swiftlang/swift-evolution/blob/main/proposals/0442-allow-taskgroup-childtaskresult-type-to-be-inferred.md
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[SE-0444]: https://github.com/swiftlang/swift-evolution/blob/main/proposals/0444-member-import-visibility.md
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[SE-0458]: https://github.com/swiftlang/swift-evolution/blob/main/proposals/0458-strict-memory-safety.md
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[SE-0470]: https://github.com/swiftlang/swift-evolution/blob/main/proposals/0470-isolated-conformances.md
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[#64927]: <https://github.com/apple/swift/issues/64927>
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[#42697]: <https://github.com/apple/swift/issues/42697>
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[#42728]: <https://github.com/apple/swift/issues/42728>

‎include/swift/AST/DiagnosticsSema.def‎

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@@ -8486,10 +8486,6 @@ ERROR(attr_abi_failable_mismatch,none,
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//===----------------------------------------------------------------------===//
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// MARK: Isolated conformances
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//===----------------------------------------------------------------------===//
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GROUPED_ERROR(isolated_conformance_experimental_feature,IsolatedConformances,
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none,
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"isolated conformances require experimental feature "
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" 'IsolatedConformances'", ())
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NOTE(note_isolate_conformance_to_global_actor,none,
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"isolate this conformance to the %select{global actor %0|main actor}1 "
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"with '@%2'", (Type, bool, StringRef))

‎include/swift/Basic/Features.def‎

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@@ -254,6 +254,7 @@ SUPPRESSIBLE_LANGUAGE_FEATURE(MemorySafetyAttributes, 458, "@unsafe attribute")
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LANGUAGE_FEATURE(ValueGenerics, 452, "Value generics feature (integer generics)")
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LANGUAGE_FEATURE(RawIdentifiers, 451, "Raw identifiers")
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LANGUAGE_FEATURE(SendableCompletionHandlers, 463, "Objective-C completion handler parameters are imported as @Sendable")
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LANGUAGE_FEATURE(IsolatedConformances, 407, "Global-actor isolated conformances")
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// Swift 6
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UPCOMING_FEATURE(ConciseMagicFile, 274, 6)
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ADOPTABLE_UPCOMING_FEATURE(ExistentialAny, 335, 7)
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UPCOMING_FEATURE(InternalImportsByDefault, 409, 7)
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UPCOMING_FEATURE(MemberImportVisibility, 444, 7)
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UPCOMING_FEATURE(InferIsolatedConformances, 470, 7)
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// Optional language features / modes
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/// Allow custom availability domains to be defined and referenced.
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EXPERIMENTAL_FEATURE(CustomAvailability, true)
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<<<<<<< HEAD
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/// Allow public enumerations to be extensible by default
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/// regardless of whether the module they are declared in
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/// is resilient or not.
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/// Infer conformance isolation on global-actor-conforming types.
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EXPERIMENTAL_FEATURE(InferIsolatedConformances, true)
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=======
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>>>>>>> 3380331e7eb ([SE-0470] Enable isolated conformances by default)
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/// Allow SwiftSettings
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EXPERIMENTAL_FEATURE(SwiftSettings, false)
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‎lib/AST/ConformanceLookup.cpp‎

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@@ -386,33 +386,30 @@ static ProtocolConformanceRef getBuiltinMetaTypeTypeConformance(
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// All metatypes are Copyable, Escapable, and BitwiseCopyable.
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if (auto kp = protocol->getKnownProtocolKind()) {
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switch (*kp) {
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case KnownProtocolKind::Sendable:
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case KnownProtocolKind::Sendable: {
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// Metatypes are generally Sendable, but with isolated conformances we
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// cannot assume that metatypes based on type parameters are Sendable.
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// Therefore, check for conformance to SendableMetatype.
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if (ctx.LangOpts.hasFeature(Feature::IsolatedConformances)) {
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auto sendableMetatypeProto =
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ctx.getProtocol(KnownProtocolKind::SendableMetatype);
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if (sendableMetatypeProto) {
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Type instanceType = metatypeType->getInstanceType();
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// If the instance type is a type parameter, it is not necessarily
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// Sendable. There will need to be a Sendable requirement.
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if (instanceType->isTypeParameter())
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break;
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// If the instance type conforms to SendableMetatype, then its
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// metatype is Sendable.
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auto instanceConformance = lookupConformance(
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instanceType, sendableMetatypeProto);
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if (instanceConformance.isInvalid() ||
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instanceConformance.hasMissingConformance())
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break;
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}
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// Every other metatype is Sendable.
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auto sendableMetatypeProto =
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ctx.getProtocol(KnownProtocolKind::SendableMetatype);
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if (sendableMetatypeProto) {
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Type instanceType = metatypeType->getInstanceType();
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// If the instance type is a type parameter, it is not necessarily
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// Sendable. There will need to be a Sendable requirement.
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if (instanceType->isTypeParameter())
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break;
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// If the instance type conforms to SendableMetatype, then its
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// metatype is Sendable.
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auto instanceConformance = lookupConformance(
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instanceType, sendableMetatypeProto);
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if (instanceConformance.isInvalid() ||
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instanceConformance.hasMissingConformance())
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break;
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}
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LLVM_FALLTHROUGH;
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}
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case KnownProtocolKind::Copyable:
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case KnownProtocolKind::Escapable:

‎lib/Parse/ParseType.cpp‎

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@@ -163,9 +163,7 @@ ParserResult<TypeRepr> Parser::parseTypeSimple(
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Diag<> MessageID, ParseTypeReason reason) {
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ParserResult<TypeRepr> ty;
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if (isParameterSpecifier() &&
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!(!Context.LangOpts.hasFeature(Feature::IsolatedConformances) &&
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Tok.isContextualKeyword("isolated"))) {
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if (isParameterSpecifier()) {
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// Type specifier should already be parsed before here. This only happens
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// for construct like 'P1 & inout P2'.
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diagnose(Tok.getLoc(), diag::attr_only_on_parameters, Tok.getRawText());

‎lib/Sema/TypeCheckConcurrency.cpp‎

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// FIXME: When passing to a sending parameter, should this be handled
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// by region isolation? Or should it always be handled by region
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// isolation?
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if (ctx.LangOpts.hasFeature(Feature::IsolatedConformances) &&
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(mayExecuteConcurrentlyWith(
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if (mayExecuteConcurrentlyWith(
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localFunc.getAsDeclContext(), getDeclContext()) ||
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(explicitClosure && explicitClosure->isPassedToSendingParameter()))) {
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(explicitClosure && explicitClosure->isPassedToSendingParameter())) {
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GenericSignature genericSig;
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if (auto afd = localFunc.getAbstractFunctionDecl())
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genericSig = afd->getGenericSignature();
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auto dc = rootNormal->getDeclContext();
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ASTContext &ctx = dc->getASTContext();
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if (!ctx.LangOpts.hasFeature(Feature::IsolatedConformances))
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return ActorIsolation::forNonisolated(false);
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// If the protocol itself is isolated, don't infer isolation for the
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// conformance.

‎lib/Sema/TypeCheckProtocol.cpp‎

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ComplainLoc, diag::unchecked_conformance_not_special, ProtoType);
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}
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// Complain if the global-actor-isolated conformances are not enabled.
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if (conformance->isIsolated() &&
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!Context.LangOpts.hasFeature(Feature::IsolatedConformances)) {
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Context.Diags.diagnose(
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ComplainLoc, diag::isolated_conformance_experimental_feature);
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}
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bool allowImpliedConditionalConformance = false;
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if (Proto->isSpecificProtocol(KnownProtocolKind::Sendable)) {
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// In -swift-version 5 mode, a conditional conformance to a protocol can imply
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}
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// Suggest isolating the conformance, if possible.
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if (ctx.LangOpts.hasFeature(Feature::IsolatedConformances) &&
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potentialIsolation && potentialIsolation->isGlobalActor() &&
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if (potentialIsolation && potentialIsolation->isGlobalActor() &&
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!conformance->isIsolated()) {
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bool isMainActor = false;
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Type globalActorIsolation = potentialIsolation->getGlobalActor();

‎test/Concurrency/Runtime/isolated_conformance.swift‎

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// RUN: %target-run-simple-swift(-enable-experimental-feature IsolatedConformances -target %target-swift-5.1-abi-triple) | %FileCheck %s
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// RUN: %target-run-simple-swift(-target %target-swift-5.1-abi-triple) | %FileCheck %s
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// REQUIRES: executable_test
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// REQUIRES: concurrency
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// REQUIRES: concurrency_runtime
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// REQUIRES: swift_feature_IsolatedConformances
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// UNSUPPORTED: back_deployment_runtime
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// FIXME: WebAssembly doesn't currently have a good way to install the

‎test/Concurrency/isolated_conformance.swift‎

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// RUN: %target-swift-frontend -typecheck -verify -target %target-swift-5.1-abi-triple -swift-version 5 -strict-concurrency=complete -enable-experimental-feature IsolatedConformances %s
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// RUN: %target-swift-frontend -typecheck -verify -target %target-swift-5.1-abi-triple -swift-version 5 -strict-concurrency=complete %s
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// REQUIRES: swift_feature_IsolatedConformances
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// REQUIRES: concurrency
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protocol P {

‎test/Concurrency/isolated_conformance_default_actor.swift‎

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// RUN: %target-swift-frontend -typecheck -verify -target %target-swift-5.1-abi-triple -swift-version 6 -enable-experimental-feature IsolatedConformances -default-isolation MainActor %s
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// RUN: %target-swift-frontend -typecheck -verify -target %target-swift-5.1-abi-triple -swift-version 6 -default-isolation MainActor %s
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// REQUIRES: swift_feature_IsolatedConformances
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// REQUIRES: concurrency
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nonisolated

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