[Sema] Skip Sendable checking for actor-isolated stored properties

Author: angela-laar

lib/Sema/TypeCheckConcurrency.cpp

@@ -5219,18 +5219,13 @@ static bool checkSendableInstanceStorage(
 
     /// Handle a stored property.
     bool operator()(VarDecl *property, Type propertyType) override {
-      // Classes with mutable properties are not Sendable unless property is
+      // Classes with mutable properties are Sendable if property is
       // actor-isolated
-      if (property->supportsMutation() && isa<ClassDecl>(nominal)) {
+      if (isa<ClassDecl>(nominal)) {
         ActorIsolation isolation = getActorIsolation(property);
 
-        if (isolation.getKind() == ActorIsolation::Kind::Nonisolated ||
-            isolation.getKind() == ActorIsolation::Kind::Unspecified) {
-          if (isImplicitSendableCheck(check)) {
-            invalid = true;
-            return true;
-          }
-
+        if (property->supportsMutation() &&
+            (isolation.isNonisolated() || isolation.isUnspecified())) {
           auto behavior =
               SendableCheckContext(dc, check).defaultDiagnosticBehavior();
           if (behavior != DiagnosticBehavior::Ignore) {
@@ -5242,6 +5237,10 @@ static bool checkSendableInstanceStorage(
           invalid = invalid || (behavior == DiagnosticBehavior::Unspecified);
           return true;
         }
+
+        if (!(isolation.isNonisolated() || isolation.isUnspecified())) {
+          return false; // skip sendable check on actor-isolated properties
+        }
       }
 
       // Check that the property type is Sendable.

test/Concurrency/concurrent_value_checking.swift

@@ -343,17 +343,22 @@ class C9: Sendable { } // expected-warning{{non-final class 'C9' cannot conform
 
 @globalActor
 struct SomeActor {
-  static var shared = A1()
+  static let shared = A1()
 }
+
+class NotSendable {}
+
 // actor-isolated mutable properties are valid
 final class C10: Sendable {
   @MainActor var x = 0
-  @SomeActor var y = 1
+  @MainActor var ns1 : NotSendable?
+  @MainActor let ns : NotSendable? = nil
 }
 
-// 'nonisolated (unsafe)' mutable properties are valid
-final class C13: Sendable {
-  nonisolated (unsafe) var z = 2
+final class C14: Sendable {
+  @SomeActor var y = 1
+  @SomeActor var nc = NotConcurrent()
+  @SomeActor let nc1 = NotConcurrent()
 }
 
 extension NotConcurrent {