[Features] Gate global-actor-isolated types usability changes behind an experimental feature flag.

Author: simanerush

include/swift/Basic/Features.def

@@ -337,6 +337,9 @@ EXPERIMENTAL_FEATURE(BorrowingSwitch, true)
 // Enable isolated(any) attribute on function types.
 CONDITIONALLY_SUPPRESSIBLE_EXPERIMENTAL_FEATURE(IsolatedAny, true)
 
+// Enable usability improvements for global-actor-isolated types.
+EXPERIMENTAL_FEATURE(GlobalActorIsolatedTypesUsability, false)
+
 #undef EXPERIMENTAL_FEATURE_EXCLUDED_FROM_MODULE_INTERFACE
 #undef EXPERIMENTAL_FEATURE
 #undef UPCOMING_FEATURE

lib/AST/FeatureSet.cpp

@@ -654,6 +654,10 @@ static bool usesFeatureIsolatedAny(Decl *decl) {
   });
 }
 
+static bool usesFeatureGlobalActorIsolatedTypesUsability(Decl *decl) {
+  return false;
+}
+
 // ----------------------------------------------------------------------------
 // MARK: - FeatureSet
 // ----------------------------------------------------------------------------

lib/Sema/TypeCheckConcurrency.cpp

@@ -508,14 +508,17 @@ static bool varIsSafeAcrossActors(const ModuleDecl *fromModule,
       (fromModule == var->getDeclContext()->getParentModule());
 
   if (!var->isLet()) {
-    // A mutable storage of a value type accessed from within the module is
-    // okay.
-    if (dyn_cast_or_null<StructDecl>(var->getDeclContext()->getAsDecl()) &&
-        !var->isStatic() &&
-        var->hasStorage() &&
-        var->getTypeInContext()->isSendableType() &&
-        accessWithinModule) {
-      return true;
+    ASTContext &ctx = var->getASTContext();
+    if (ctx.LangOpts.hasFeature(Feature::GlobalActorIsolatedTypesUsability)) {
+      // A mutable storage of a value type accessed from within the module is
+      // okay.
+      if (dyn_cast_or_null<StructDecl>(var->getDeclContext()->getAsDecl()) &&
+          !var->isStatic() && 
+          var->hasStorage() &&
+          var->getTypeInContext()->isSendableType() &&
+          accessWithinModule) {
+        return true;
+      }
     }
     // Otherwise, must be immutable.
     return false;

test/Concurrency/actor_isolation.swift

@@ -2,8 +2,8 @@
 
 // RUN: %target-swift-frontend -emit-module -emit-module-path %t/OtherActors.swiftmodule -module-name OtherActors %S/Inputs/OtherActors.swift -disable-availability-checking
 
-// RUN: %target-swift-frontend -I %t  -disable-availability-checking -strict-concurrency=complete -parse-as-library -emit-sil -o /dev/null -verify %s
-// RUN: %target-swift-frontend -I %t  -disable-availability-checking -strict-concurrency=complete -parse-as-library -emit-sil -o /dev/null -verify -enable-upcoming-feature RegionBasedIsolation %s
+// RUN: %target-swift-frontend -I %t  -disable-availability-checking -strict-concurrency=complete -parse-as-library -emit-sil -o /dev/null -verify -enable-experimental-feature GlobalActorIsolatedTypesUsability %s
+// RUN: %target-swift-frontend -I %t  -disable-availability-checking -strict-concurrency=complete -parse-as-library -emit-sil -o /dev/null -verify -enable-upcoming-feature RegionBasedIsolation -enable-experimental-feature GlobalActorIsolatedTypesUsability %s
 
 // REQUIRES: concurrency
 // REQUIRES: asserts

test/Concurrency/actor_isolation_swift6.swift

@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -disable-availability-checking -swift-version 6 -emit-sil -o /dev/null -verify %s
+// RUN: %target-swift-frontend -disable-availability-checking -swift-version 6 -emit-sil -o /dev/null -verify -enable-experimental-feature GlobalActorIsolatedTypesUsability %s
 
 // REQUIRES: concurrency
 

test/Concurrency/derived_conformances_nonisolated.swift

@@ -1,5 +1,5 @@
-// RUN: %target-swift-frontend  -disable-availability-checking -strict-concurrency=complete -parse-as-library %s -emit-sil -o /dev/null -verify
-// RUN: %target-swift-frontend  -disable-availability-checking -strict-concurrency=complete -parse-as-library %s -emit-sil -o /dev/null -verify -strict-concurrency=complete -enable-upcoming-feature RegionBasedIsolation
+// RUN: %target-swift-frontend  -disable-availability-checking -strict-concurrency=complete -parse-as-library %s -emit-sil -o /dev/null -verify -enable-experimental-feature GlobalActorIsolatedTypesUsability
+// RUN: %target-swift-frontend  -disable-availability-checking -strict-concurrency=complete -parse-as-library %s -emit-sil -o /dev/null -verify -strict-concurrency=complete -enable-upcoming-feature RegionBasedIsolation -enable-experimental-feature GlobalActorIsolatedTypesUsability
 
 // REQUIRES: concurrency
 // REQUIRES: asserts

test/Concurrency/global_actor_inference.swift

@@ -1,10 +1,10 @@
 // RUN: %empty-directory(%t)
 
-// RUN: %target-swift-frontend -emit-module -emit-module-path %t/other_global_actor_inference.swiftmodule -module-name other_global_actor_inference -strict-concurrency=complete %S/Inputs/other_global_actor_inference.swift
-// RUN: %target-swift-frontend -I %t -disable-availability-checking %s -emit-sil -o /dev/null -verify -verify-additional-prefix minimal-targeted-
-// RUN: %target-swift-frontend -I %t -disable-availability-checking %s -emit-sil -o /dev/null -verify -strict-concurrency=targeted -verify-additional-prefix minimal-targeted-
-// RUN: %target-swift-frontend -I %t -disable-availability-checking %s -emit-sil -o /dev/null -verify -strict-concurrency=complete -verify-additional-prefix complete-tns-
-// RUN: %target-swift-frontend -I %t -disable-availability-checking %s -emit-sil -o /dev/null -verify -strict-concurrency=complete -enable-upcoming-feature RegionBasedIsolation -verify-additional-prefix complete-tns-
+// RUN: %target-swift-frontend -emit-module -emit-module-path %t/other_global_actor_inference.swiftmodule -module-name other_global_actor_inference -strict-concurrency=complete %S/Inputs/other_global_actor_inference.swift -enable-experimental-feature GlobalActorIsolatedTypesUsability
+// RUN: %target-swift-frontend -I %t -disable-availability-checking %s -emit-sil -o /dev/null -verify -verify-additional-prefix minimal-targeted- -enable-experimental-feature GlobalActorIsolatedTypesUsability
+// RUN: %target-swift-frontend -I %t -disable-availability-checking %s -emit-sil -o /dev/null -verify -strict-concurrency=targeted -verify-additional-prefix minimal-targeted- -enable-experimental-feature GlobalActorIsolatedTypesUsability
+// RUN: %target-swift-frontend -I %t -disable-availability-checking %s -emit-sil -o /dev/null -verify -strict-concurrency=complete -verify-additional-prefix complete-tns- -enable-experimental-feature GlobalActorIsolatedTypesUsability
+// RUN: %target-swift-frontend -I %t -disable-availability-checking %s -emit-sil -o /dev/null -verify -strict-concurrency=complete -enable-upcoming-feature RegionBasedIsolation -verify-additional-prefix complete-tns- -enable-experimental-feature GlobalActorIsolatedTypesUsability
 
 // REQUIRES: concurrency
 // REQUIRES: asserts

test/Concurrency/sendable_keypaths.swift

@@ -1,4 +1,4 @@
-// RUN: %target-typecheck-verify-swift -enable-upcoming-feature InferSendableFromCaptures -strict-concurrency=complete
+// RUN: %target-typecheck-verify-swift -enable-upcoming-feature InferSendableFromCaptures -strict-concurrency=complete -enable-experimental-feature GlobalActorIsolatedTypesUsability
 
 // REQUIRES: concurrency
 // REQUIRES: asserts