[Concurrency] CaseIterable synthesized allCases must be nonisolated

Author: ktoso

lib/Sema/DerivedConformanceCaseIterable.cpp

@@ -79,6 +79,8 @@ static Type deriveCaseIterable_AllCases(DerivedConformance &derived) {
 }
 
 ValueDecl *DerivedConformance::deriveCaseIterable(ValueDecl *requirement) {
+  auto &C = requirement->getASTContext();
+
   // Conformance can't be synthesized in an extension.
   if (checkAndDiagnoseDisallowedContext(requirement))
     return nullptr;
@@ -102,6 +104,9 @@ ValueDecl *DerivedConformance::deriveCaseIterable(ValueDecl *requirement) {
       SynthesizedIntroducer::Var, Context.Id_allCases, returnTy, returnTy,
       /*isStatic=*/true, /*isFinal=*/true);
 
+  propDecl->getAttrs().add(
+              new (C) NonisolatedAttr(/*unsafe=*/false, /*implicit=*/true));
+
   // Define the getter.
   auto *getterDecl = addGetterToReadOnlyDerivedProperty(propDecl, returnTy);
 

test/Concurrency/CaseIterableIsolation.swift

@@ -0,0 +1,22 @@
+// RUN: %target-swift-frontend  -disable-availability-checking %s -emit-sil -o /dev/null -verify -strict-concurrency=complete
+// RUN: %target-swift-frontend  -disable-availability-checking %s -emit-sil -o /dev/null -verify -strict-concurrency=complete -enable-upcoming-feature RegionBasedIsolation
+
+// REQUIRES: executable_test
+// REQUIRES: concurrency
+
+import StdlibUnittest
+
+var CaseIterableTests = TestSuite("CaseIterableTests")
+
+CaseIterableTests.test("MainActor Isolated Enums") {
+  @MainActor
+  enum EnumMainActor: CaseIterable {
+    case a, b
+  }
+
+  expectEqual(EnumMainActor.allCases.count, 2)
+  expectEqual(EnumMainActor.allCases, [.a, .b])
+}
+
+runAllTests()
+

test/SILGen/synthesized_conformance_enum.swift

@@ -56,6 +56,7 @@ extension Enum: Codable where T: Codable {}
 
 extension NoValues: CaseIterable {}
 // CHECK-LABEL: // static NoValues.allCases.getter
+// CHECK-NEXT: // Isolation: nonisolated
 // CHECK-NEXT: sil hidden [ossa] @$s28synthesized_conformance_enum8NoValuesO8allCasesSayACGvgZ : $@convention(method) (@thin NoValues.Type) -> @owned Array<NoValues> {
 
 extension NoValues: Codable {}

test/stdlib/CaseIterableTests.swift

@@ -1,5 +1,6 @@
 // RUN: %target-run-simple-swift %t
 // REQUIRES: executable_test
+// REQUIRES: concurrency
 
 import StdlibUnittest
 
@@ -16,4 +17,14 @@ CaseIterableTests.test("Simple Enums") {
   expectEqual(SimpleEnum.allCases, [.bar, .baz, .quux])
 }
 
+CaseIterableTests.test("MainActor Isolated Enums") {
+  @MainActor
+  enum EnumMainActor: CaseIterable {
+    case a, b
+  }
+
+  expectEqual(EnumMainActor.allCases.count, 2)
+  expectEqual(EnumMainActor.allCases, [.a, .b])
+}
+
 runAllTests()