[Concurrency] Don't error on isolated property wrapper initializers inside

MainActor-isolated structs.

(cherry picked from commit a6d9c15)

Author: hborla

include/swift/Basic/Features.def

@@ -379,7 +379,7 @@ EXPERIMENTAL_FEATURE(CImplementation, true)
 EXPERIMENTAL_FEATURE(DebugDescriptionMacro, true)
 
 // Enable usability improvements for global-actor-isolated types.
-EXPERIMENTAL_FEATURE(GlobalActorIsolatedTypesUsability, false)
+EXPERIMENTAL_FEATURE(GlobalActorIsolatedTypesUsability, true)
 
 #undef EXPERIMENTAL_FEATURE_EXCLUDED_FROM_MODULE_INTERFACE
 #undef EXPERIMENTAL_FEATURE

lib/Sema/TypeCheckConcurrency.cpp

@@ -5115,17 +5115,6 @@ ActorIsolation ActorIsolationRequest::evaluate(
         llvm_unreachable("cannot infer erased isolation");
 
       case ActorIsolation::GlobalActor: {
-        // Stored properties of a struct don't need global-actor isolation.
-        if (ctx.isSwiftVersionAtLeast(6))
-          if (auto *var = dyn_cast<VarDecl>(value))
-            if (!var->isStatic() && var->isOrdinaryStoredProperty())
-              if (auto *varDC = var->getDeclContext())
-                if (auto *nominal = varDC->getSelfNominalTypeDecl())
-                  if (isa<StructDecl>(nominal) &&
-                      !isWrappedValueOfPropWrapper(var))
-                    return ActorIsolation::forUnspecified().withPreconcurrency(
-                        inferred.preconcurrency());
-
         auto typeExpr =
             TypeExpr::createImplicit(inferred.getGlobalActor(), ctx);
         auto attr =

test/Concurrency/global_actor_inference_swift6.swift

@@ -2,8 +2,8 @@
 
 // RUN: %target-swift-frontend -swift-version 6 -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 -swift-version 6 -I %t -disable-availability-checking %s -emit-sil -o /dev/null -verify
-// RUN: %target-swift-frontend -swift-version 6 -I %t -disable-availability-checking %s -emit-sil -o /dev/null -verify -enable-upcoming-feature RegionBasedIsolation
+// RUN: %target-swift-frontend -swift-version 6 -I %t -disable-availability-checking %s -emit-sil -o /dev/null -verify -enable-experimental-feature GlobalActorIsolatedTypesUsability
+// RUN: %target-swift-frontend -swift-version 6 -I %t -disable-availability-checking %s -emit-sil -o /dev/null -verify -enable-experimental-feature GlobalActorIsolatedTypesUsability
 
 // REQUIRES: concurrency
 
@@ -132,3 +132,25 @@ struct Carbon {
     return atomicWeight // expected-error {{main actor-isolated property 'atomicWeight' can not be referenced from a non-isolated context}}
   }
 }
+
+@MainActor
+protocol InferMainActor {}
+
+@propertyWrapper
+@preconcurrency @MainActor
+struct Wrapper<T> {
+  var wrappedValue: T {
+    fatalError()
+  }
+
+  init() {}
+}
+
+@MainActor
+class C {
+  nonisolated init() {}
+}
+
+struct S: InferMainActor {
+  @Wrapper var value: C // okay, 'S' is isolated to 'MainActor'
+}