Merge pull request swiftlang#70858 from angela-laar/actor-isolated-properties-for-classes

[Sema] Classes with actor-isolated mutable properties should conform to Sendable

Author: angela-laar

lib/Sema/TypeCheckConcurrency.cpp

@@ -5334,22 +5334,28 @@ static bool checkSendableInstanceStorage(
 
     /// Handle a stored property.
     bool operator()(VarDecl *property, Type propertyType) override {
-      // Classes with mutable properties are not Sendable.
-      if (property->supportsMutation() && isa<ClassDecl>(nominal)) {
-        if (isImplicitSendableCheck(check)) {
-          invalid = true;
+      // Classes with mutable properties are Sendable if property is
+      // actor-isolated
+      if (isa<ClassDecl>(nominal)) {
+        ActorIsolation isolation = getActorIsolation(property);
+
+        if (property->supportsMutation() &&
+            (isolation.isNonisolated() || isolation.isUnspecified())) {
+          auto behavior =
+              SendableCheckContext(dc, check).defaultDiagnosticBehavior();
+          if (behavior != DiagnosticBehavior::Ignore) {
+            property
+                ->diagnose(diag::concurrent_value_class_mutable_property,
+                           property->getName(), nominal)
+                .limitBehavior(behavior);
+          }
+          invalid = invalid || (behavior == DiagnosticBehavior::Unspecified);
           return true;
         }
 
-        auto behavior = SendableCheckContext(
-            dc, check).defaultDiagnosticBehavior();
-        if (behavior != DiagnosticBehavior::Ignore) {
-          property->diagnose(diag::concurrent_value_class_mutable_property,
-                             property->getName(), nominal)
-              .limitBehavior(behavior);
+        if (!(isolation.isNonisolated() || isolation.isUnspecified())) {
+          return false; // skip sendable check on actor-isolated properties
         }
-        invalid = invalid || (behavior == DiagnosticBehavior::Unspecified);
-        return true;
       }
 
       // Check that the property type is Sendable.

test/Concurrency/concurrent_value_checking.swift

@@ -342,6 +342,26 @@ final class C7<T>: Sendable { }
 
 class C9: Sendable { } // expected-warning{{non-final class 'C9' cannot conform to 'Sendable'; use '@unchecked Sendable'}}
 
+@globalActor
+struct SomeActor {
+  static let shared = A1()
+}
+
+class NotSendable {}
+
+// actor-isolated mutable properties are valid
+final class C10: Sendable {
+  @MainActor var x = 0
+  @MainActor var ns1 : NotSendable?
+  @MainActor let ns : NotSendable? = nil
+}
+
+final class C14: Sendable {
+  @SomeActor var y = 1
+  @SomeActor var nc = NotConcurrent()
+  @SomeActor let nc1 = NotConcurrent()
+}
+
 extension NotConcurrent {
   func f() { }