Merge pull request #76518 from slavapestov/fix-issue-76513

Concurrency: Reject nonisolated lazy properties

Author: slavapestov

include/swift/AST/DiagnosticsSema.def

@@ -5810,6 +5810,9 @@ ERROR(nonisolated_actor_sync_init,none,
 ERROR(nonisolated_wrapped_property,none,
       "'nonisolated' is not supported on properties with property wrappers",
       ())
+ERROR(nonisolated_lazy,none,
+      "'nonisolated' is not supported on lazy properties",
+      ())
 
 ERROR(non_sendable_from_deinit,none,
         "cannot access %1 %2 with a non-sendable type %0 from nonisolated deinit",

lib/Sema/TypeCheckAttr.cpp

@@ -7224,15 +7224,22 @@ 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.
+    // Using 'nonisolated' with lazy properties and 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)
         .warnUntilSwiftVersionIf(attr->isImplicit(), 6);
       return;
     }
 
+    if (var->getAttrs().hasAttribute<LazyAttr>()) {
+      diagnoseAndRemoveAttr(attr, diag::nonisolated_lazy)
+        .warnUntilSwiftVersionIf(attr->isImplicit(), 6);
+      return;
+    }
+
     // nonisolated can not be applied to local properties unless qualified as
     // 'unsafe'.
     if (dc->isLocalContext() && !attr->isUnsafe()) {

test/Concurrency/actor_isolation.swift

@@ -834,21 +834,29 @@ actor LazyActor {
     lazy var l25: Int = { [unowned self] in self.l }()
 
     nonisolated lazy var l31: Int = { v }()
-    // expected-warning@-1 {{actor-isolated default value in a nonisolated context; this is an error in the Swift 6 language mode}}
+    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
+    // expected-warning@-2 {{actor-isolated default value in a nonisolated context; this is an error in the Swift 6 language mode}}
     nonisolated lazy var l32: Int = v
-    // expected-warning@-1 {{actor-isolated default value in a nonisolated context; this is an error in the Swift 6 language mode}}
+    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
     nonisolated lazy var l33: Int = { self.v }()
-    // expected-warning@-1 {{actor-isolated default value in a nonisolated context; this is an error in the Swift 6 language mode}}
+    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
+    // expected-warning@-2 {{actor-isolated default value in a nonisolated context; this is an error in the Swift 6 language mode}}
     nonisolated lazy var l34: Int = self.v
-    // expected-warning@-1 {{actor-isolated default value in a nonisolated context; this is an error in the Swift 6 language mode}}
+    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
     nonisolated lazy var l35: Int = { [unowned self] in self.v }()
-    // expected-warning@-1 {{actor-isolated default value in a nonisolated context; this is an error in the Swift 6 language mode}}
+    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
+    // expected-warning@-2 {{actor-isolated default value in a nonisolated context; this is an error in the Swift 6 language mode}}
 
     nonisolated lazy var l41: Int = { l }()
+    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
     nonisolated lazy var l42: Int = l
+    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
     nonisolated lazy var l43: Int = { self.l }()
+    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
     nonisolated lazy var l44: Int = self.l
+    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
     nonisolated lazy var l45: Int = { [unowned self] in self.l }()
+    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
 }
 
 // Infer global actors from context only for instance members.

test/Concurrency/mutable_storage_nonisolated.swift

@@ -2,26 +2,67 @@
 // RUN: %target-swift-frontend  -disable-availability-checking -strict-concurrency=complete -parse-as-library %s -emit-sil -o /dev/null -verify -strict-concurrency=complete
 
 // REQUIRES: concurrency
-// REQUIRES: asserts
+
+@propertyWrapper struct P {
+  var wrappedValue = 0
+}
 
 class NonSendable {}
 
 struct ImplicitlySendable {
-  var x: Int
-  nonisolated var y: Int // okay
+  var a: Int
+
+  // always okay
+  nonisolated let b = 0
+  nonisolated var c: Int { 0 }
+
+  // okay
+  nonisolated var d = 0
+
+  // never okay
+  nonisolated lazy var e = 0  // expected-error {{'nonisolated' is not supported on lazy properties}}
+  @P nonisolated var f = 0  // expected-error {{'nonisolated' is not supported on properties with property wrappers}}
 }
 
 struct ImplicitlyNonSendable {
-  let x: NonSendable
-  // expected-note@+1 {{convert 'y' to a 'let' constant or consider declaring it 'nonisolated(unsafe)' if manually managing concurrency safety}}
-  nonisolated var y: Int // expected-error {{'nonisolated' cannot be applied to mutable stored properties}}
+  let a: NonSendable
+
+  // always okay
+  nonisolated let b = 0
+  nonisolated var c: Int { 0 }
+
+  // not okay
+  nonisolated var d = 0  // expected-error {{'nonisolated' cannot be applied to mutable stored properties}}
+  // expected-note@-1 {{convert 'd' to a 'let' constant or consider declaring it 'nonisolated(unsafe)' if manually managing concurrency safety}}
+
+  // never okay
+  nonisolated lazy var e = 0  // expected-error {{'nonisolated' is not supported on lazy properties}}
+  @P nonisolated var f = 0  // expected-error {{'nonisolated' is not supported on properties with property wrappers}}
 }
 
 public struct PublicSendable: Sendable {
-  nonisolated var x: Int // okay
+  // always okay
+  nonisolated let b = 0
+  nonisolated var c: Int { 0 }
+
+  // okay
+  nonisolated var d = 0
+
+  // never okay
+  nonisolated lazy var e = 0  // expected-error {{'nonisolated' is not supported on lazy properties}}
+  @P nonisolated var f = 0  // expected-error {{'nonisolated' is not supported on properties with property wrappers}}
 }
 
 public struct PublicNonSendable {
-  // expected-note@+1 {{convert 'x' to a 'let' constant or consider declaring it 'nonisolated(unsafe)' if manually managing concurrency safety}}
-  nonisolated var x: Int // expected-error {{'nonisolated' cannot be applied to mutable stored properties}}
+  // always okay
+  nonisolated let b = 0
+  nonisolated var c: Int { 0 }
+
+  // not okay
+  nonisolated var d = 0  // expected-error {{'nonisolated' cannot be applied to mutable stored properties}}
+  // expected-note@-1 {{convert 'd' to a 'let' constant or consider declaring it 'nonisolated(unsafe)' if manually managing concurrency safety}}
+
+  // never okay
+  nonisolated lazy var e = 0  // expected-error {{'nonisolated' is not supported on lazy properties}}
+  @P nonisolated var f = 0  // expected-error {{'nonisolated' is not supported on properties with property wrappers}}
 }