[ConstraintSystem] InferSendableFromCaptures: Use of actor isolated members makes key path non-Sendable

Author: xedin

lib/Sema/ConstraintSystem.cpp

@@ -7551,6 +7551,20 @@ ConstraintSystem::inferKeyPathLiteralCapability(KeyPathExpr *keyPath) {
       if (!storage)
         return fail();
 
+      switch (getActorIsolation(storage)) {
+      case ActorIsolation::Unspecified:
+      case ActorIsolation::Nonisolated:
+      case ActorIsolation::NonisolatedUnsafe:
+        break;
+
+      // A reference to an actor isolated state make key path non-Sendable.
+      case ActorIsolation::ActorInstance:
+      case ActorIsolation::GlobalActor:
+      case ActorIsolation::GlobalActorUnsafe:
+        isSendable = false;
+        break;
+      }
+
       if (isReadOnlyKeyPathComponent(storage, component.getLoc())) {
         mutability = KeyPathMutability::ReadOnly;
         continue;

test/Concurrency/sendable_keypaths.swift

@@ -138,3 +138,19 @@ do {
 
   _ = Test(obj: "Hello").utf8.count // Ok
 }
+
+// Global actor isolated properties.
+do {
+  @MainActor struct Isolated {
+    var data: Int = 42
+    subscript(v: Int) -> Bool { false }
+  }
+
+  let dataKP = \Isolated.data
+  let subscriptKP = \Isolated.[42]
+
+  let _: KeyPath<Isolated, Int> & Sendable = dataKP
+  // expected-warning@-1 {{type 'WritableKeyPath<Isolated, Int>' does not conform to the 'Sendable' protocol}}
+  let _: KeyPath<Isolated, Bool> & Sendable = subscriptKP
+  // expected-warning@-1 {{type 'KeyPath<Isolated, Bool>' does not conform to the 'Sendable' protocol}}
+}