Merge pull request #69607 from hborla/5.10-isolated-static-let

[5.10][Concurrency] Isolated `static let`s are not safe to access across actors.

Author: hborla

lib/Sema/TypeCheckConcurrency.cpp

@@ -514,6 +514,11 @@ static bool varIsSafeAcrossActors(const ModuleDecl *fromModule,
     if (var->getAttrs().hasAttribute<NonisolatedAttr>())
       return true;
 
+    // Static 'let's are initialized upon first access, so they cannot be
+    // synchronously accessed across actors.
+    if (var->isGlobalStorage() && var->isLazilyInitializedGlobal())
+      return false;
+
     // If it's distributed, generally variable access is not okay...
     if (auto nominalParent = var->getDeclContext()->getSelfNominalTypeDecl()) {
       if (nominalParent->isDistributedActor())

test/Concurrency/Runtime/actor_assert_precondition_executor.swift

@@ -61,6 +61,17 @@ actor Someone {
   }
 }
 
+@MainActor let global = TestStaticVar()
+
+@MainActor
+struct TestStaticVar {
+  @MainActor static let shared = TestStaticVar()
+
+  init() {
+    checkPreconditionMainActor()
+  }
+}
+
 @main struct Main {
   static func main() async {
     let tests = TestSuite("AssertPreconditionActorExecutor")
@@ -78,6 +89,11 @@ actor Someone {
         await MainFriend().callCheckMainActor()
       }
 
+      tests.test("MainActor.assertIsolated() from static let initializer") {
+        _ = await TestStaticVar.shared
+        _ = await global
+      }
+
       #if !os(WASI)
       tests.test("precondition on actor (main): wrongly assume the main executor, from actor on other executor") {
         expectCrashLater(withMessage: "Incorrect actor executor assumption; Expected 'MainActor' executor.")

test/Concurrency/actor_existentials.swift

@@ -49,7 +49,7 @@ func from_isolated_concrete(_ x: isolated A) async {
 actor Act {
     var i = 0 // expected-note {{mutation of this property is only permitted within the actor}}
 }
-let act = Act()
+nonisolated let act = Act()
 
 func bad() async {
     // expected-warning@+2 {{no 'async' operations occur within 'await' expression}}

test/Concurrency/concurrent_value_checking.swift

@@ -116,7 +116,9 @@ func globalAsync(_: NotConcurrent?) async {
 }
 
 func globalTest() async {
-  let a = globalValue // expected-warning{{non-sendable type 'NotConcurrent?' in asynchronous access to global actor 'SomeGlobalActor'-isolated let 'globalValue' cannot cross actor boundary}}
+  // expected-error@+2 {{expression is 'async' but is not marked with 'await'}}
+  // expected-note@+1 {{property access is 'async'}}
+  let a = globalValue // expected-warning{{non-sendable type 'NotConcurrent?' in implicitly asynchronous access to global actor 'SomeGlobalActor'-isolated let 'globalValue' cannot cross actor boundary}}
   await globalAsync(a) // expected-complete-warning{{passing argument of non-sendable type 'NotConcurrent?' into global actor 'SomeGlobalActor'-isolated context may introduce data races}}
   await globalSync(a)  // expected-complete-warning{{passing argument of non-sendable type 'NotConcurrent?' into global actor 'SomeGlobalActor'-isolated context may introduce data races}}
 }
@@ -137,7 +139,9 @@ class ClassWithGlobalActorInits { // expected-note 2{{class 'ClassWithGlobalActo
 
 @MainActor
 func globalTestMain(nc: NotConcurrent) async {
-  let a = globalValue // expected-warning{{non-sendable type 'NotConcurrent?' in asynchronous access to global actor 'SomeGlobalActor'-isolated let 'globalValue' cannot cross actor boundary}}
+  // expected-error@+2 {{expression is 'async' but is not marked with 'await'}}
+  // expected-note@+1 {{property access is 'async'}}
+  let a = globalValue // expected-warning{{non-sendable type 'NotConcurrent?' in implicitly asynchronous access to global actor 'SomeGlobalActor'-isolated let 'globalValue' cannot cross actor boundary}}
   await globalAsync(a) // expected-complete-warning{{passing argument of non-sendable type 'NotConcurrent?' into global actor 'SomeGlobalActor'-isolated context may introduce data races}}
   await globalSync(a)  // expected-complete-warning{{passing argument of non-sendable type 'NotConcurrent?' into global actor 'SomeGlobalActor'-isolated context may introduce data races}}
   _ = await ClassWithGlobalActorInits(nc) // expected-complete-warning{{passing argument of non-sendable type 'NotConcurrent' into global actor 'SomeGlobalActor'-isolated context may introduce data races}}