[Concurrency] Two isolation inference changes for default isolation mode.

lib/Sema/TypeCheckConcurrency.cpp

@@ -5636,7 +5636,26 @@ InferredActorIsolation ActorIsolationRequest::evaluate(
   // within our module, make our default isolation main actor.
   if (ctx.LangOpts.hasFeature(Feature::UnspecifiedMeansMainActorIsolated) &&
       value->getModuleContext() == ctx.MainModule) {
-    defaultIsolation = ActorIsolation::forMainActor(ctx);
+
+    // Default global actor isolation does not apply to any declarations
+    // within actors and distributed actors.
+    bool inActorContext = false;
+    auto *dc = value->getInnermostDeclContext();
+    while (dc && !inActorContext) {
+      if (auto *nominal = dc->getSelfNominalTypeDecl()) {
+        inActorContext = nominal->isAnyActor();
+      }
+      dc = dc->getParent();
+    }
+
+    if (!inActorContext) {
+      // FIXME: deinit should be implicitly MainActor too.
+      if (isa<TypeDecl>(value) || isa<ExtensionDecl>(value) ||
+          isa<AbstractStorageDecl>(value) || isa<FuncDecl>(value) ||
+          isa<ConstructorDecl>(value)) {
+        defaultIsolation = ActorIsolation::forMainActor(ctx);
+      }
+    }
   }
 
   // If we have an async function... by default we inherit isolation.
@@ -5782,32 +5801,6 @@ InferredActorIsolation ActorIsolationRequest::evaluate(
     }
   }
 
-  // If this is an actor, use the actor isolation of the actor.
-  if (ctx.LangOpts.hasFeature(Feature::UnspecifiedMeansMainActorIsolated)) {
-    // non-async inits and deinits need to be always nonisolated since we can
-    // run the deinit anywhere.
-    //
-    // TODO: We should add a check for if they are marked with global actor
-    // isolation.
-    if (auto *func = dyn_cast<AbstractFunctionDecl>(value)) {
-      if (isa<DestructorDecl>(func) && !func->isAsyncContext())
-        return {ActorIsolation::forNonisolated(false /*unsafe*/),
-                IsolationSource(func, IsolationSource::LexicalContext)};
-
-      if (isa<ConstructorDecl>(func) && !func->isAsyncContext())
-        return {ActorIsolation::forNonisolated(false /*unsafe*/),
-                IsolationSource(func, IsolationSource::LexicalContext)};
-    }
-
-    if (auto nominal = dyn_cast<NominalTypeDecl>(value)) {
-      if (nominal->isActor() && !nominal->isGlobalActor()) {
-        auto isolation = ActorIsolation::forActorInstanceSelf(value);
-        return {inferredIsolation(isolation),
-                IsolationSource(nominal, IsolationSource::LexicalContext)};
-      }
-    }
-  }
-
   // If this is an accessor, use the actor isolation of its storage
   // declaration.
   if (auto accessor = dyn_cast<AccessorDecl>(value)) {

test/Concurrency/Runtime/unspecified_is_main_actor.swift

@@ -76,15 +76,17 @@ tests.test("checkIfOnMainQueue crashes off the main queue 2") { @CustomActor ()
 class Klass {}
 
 struct MainActorIsolated {
-  init() {}
+  init() {
+    checkIfOnMainQueue()
+  }
 
   func test() async {
     checkIfOnMainQueue()
   }
 };
 
 tests.test("callNominalType") { @CustomActor () -> () in
-  let x = MainActorIsolated()
+  let x = await MainActorIsolated()
   // We would crash without hopping here.
   await x.test()
 }

test/Concurrency/assume_mainactor.swift

@@ -10,7 +10,7 @@
 class Klass {
   // Implicit deinit
   // CHECK: // Klass.deinit
-  // CHECK-NEXT: // Isolation: nonisolated
+  // CHECK-NEXT: // Isolation: unspecified
   // CHECK-NEXT: sil hidden [ossa] @$s16assume_mainactor5KlassCfd : $@convention(method) (@guaranteed Klass) -> @owned Builtin.NativeObject {
 
   // Implicit deallocating deinit
@@ -163,7 +163,7 @@ nonisolated func nonisolatedFunctionTest() async {
 
 actor MyActor {
   // CHECK: // variable initialization expression of MyActor.k
-  // CHECK-NEXT: // Isolation: actor_instance
+  // CHECK-NEXT: // Isolation: unspecified
   // CHECK-NEXT: sil hidden [transparent] [ossa] @$s16assume_mainactor7MyActorC1kAA5KlassCvpfi : $@convention(thin) () -> @owned Klass {
 
   // CHECK: // MyActor.k.getter
@@ -175,9 +175,21 @@ actor MyActor {
   // CHECK-NEXT: sil hidden [transparent] [ossa] @$s16assume_mainactor7MyActorC1kAA5KlassCvs : $@convention(method) (@owned Klass, @sil_isolated @guaranteed MyActor) -> () {
   var k = Klass()
 
+  // CHECK: // static MyActor.f()
+  // CHECK-NEXT: // Isolation: unspecified
+  // CHECK-NEXT: sil hidden [ossa] @$s16assume_mainactor7MyActorC1fyyFZ : $@convention(method) (@thick MyActor.Type) -> ()
+  static func f() {}
+
+  struct Nested {
+    // CHECK: // MyActor.Nested.f()
+    // CHECK-NEXT: // Isolation: unspecified
+    // CHECK-NEXT: sil hidden [ossa] @$s16assume_mainactor7MyActorC6NestedV1fyyF : $@convention(method) (MyActor.Nested) -> ()
+    func f() {}
+  }
+
   // Implicit deinit
   // CHECK: // MyActor.deinit
-  // CHECK-NEXT: // Isolation: nonisolated
+  // CHECK-NEXT: // Isolation: unspecified
   // CHECK-NEXT: sil hidden [ossa] @$s16assume_mainactor7MyActorCfd : $@convention(method) (@guaranteed MyActor) -> @owned Builtin.NativeObject {
 
   // Non-async init should be nonisolated

test/Concurrency/assume_mainactor_typechecker_errors.swift

@@ -51,7 +51,7 @@ func unspecifiedFunctionTest2() async {
 }
 
 nonisolated func nonisolatedFunctionTest() async {
-  let k = StructContainingKlass()
+  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}}
@@ -66,7 +66,7 @@ func testTask() async {
 
 func testTaskDetached() async {
   Task.detached {
-    let k = Klass(getDataFromSocket())
+    let k = await Klass(getDataFromSocket())
     // Have to pop back onto the main thread to do something.
     await k.doSomething()
   }