[Sema] Diagnose 'nonisolated' attribute on wrapped properties (#60475)

* [Sema] Diagnose 'nonisolated' attribute on wrapped properties

* [AST] Update diagnostic wording for nonisolated_wrapped_property

Author: theblixguy

include/swift/AST/DiagnosticsSema.def

@@ -4788,6 +4788,9 @@ ERROR(nonisolated_local_var,none,
 ERROR(nonisolated_actor_sync_init,none,
       "'nonisolated' on an actor's synchronous initializer is invalid",
       ())
+ERROR(nonisolated_wrapped_property,none,
+      "'nonisolated' is not supported on properties with property wrappers",
+      ())
 
 ERROR(actor_instance_property_wrapper,none,
       "%0 property in property wrapper type %1 cannot be isolated to "

lib/Sema/TypeCheckAttr.cpp

@@ -6026,6 +6026,14 @@ void AttributeChecker::visitNonisolatedAttr(NonisolatedAttr *attr) {
       }
     }
 
+    // Using 'nonisolated' with wrapped properties is unsupported, because
+    // backing storage is a stored 'var' that is part of the internal state
+    // of the actor which could only be accessed in actor's isolation context.
+    if (var->hasAttachedPropertyWrapper()) {
+      diagnoseAndRemoveAttr(attr, diag::nonisolated_wrapped_property);
+      return;
+    }
+
     // nonisolated can not be applied to local properties.
     if (dc->isLocalContext()) {
       diagnoseAndRemoveAttr(attr, diag::nonisolated_local_var);

test/Concurrency/global_actor_inference.swift

@@ -457,6 +457,23 @@ func testInferredFromWrapper(x: InferredFromPropertyWrapper) { // expected-note{
   _ = x.test() // expected-error{{call to global actor 'SomeGlobalActor'-isolated instance method 'test()' in a synchronous nonisolated context}}
 }
 
+@propertyWrapper 
+struct SimplePropertyWrapper {
+  var wrappedValue: Int { .zero }
+  var projectedValue: Int { .max }
+}
+
+@MainActor
+class WrappedContainsNonisolatedAttr {
+  @SimplePropertyWrapper nonisolated var value 
+  // expected-error@-1 {{'nonisolated' is not supported on properties with property wrappers}}
+  // expected-note@-2 2{{property declared here}}
+
+  nonisolated func test() {
+    _ = value // expected-error {{main actor-isolated property 'value' can not be referenced from a non-isolated context}}
+    _ = $value // expected-error {{main actor-isolated property '$value' can not be referenced from a non-isolated context}}
+  }
+}
 
 
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