Collapse experimental feature StrictSendableMetatypes into IsolatedConformances

Author: DougGregor

include/swift/AST/DiagnosticsSema.def

@@ -8467,9 +8467,6 @@ NOTE(note_isolate_conformance_to_global_actor,none,
 NOTE(note_depends_on_isolated_conformance,none,
      "conformance depends on %0 conformance of %1 to %kind2",
      (ActorIsolation, Type, const ValueDecl *))
-ERROR(nonisolated_conformance_depends_on_isolated_conformance,none,
-      "conformance of %0 to %1 depends on %2 conformance of %3 to %4; mark it as '%5'",
-      (Type, DeclName, ActorIsolation, Type, DeclName, StringRef))
 ERROR(isolated_conformance_with_sendable,none,
       "%4 conformance of %0 to %1 cannot satisfy conformance "
       "requirement for a %select{`Sendable`|`SendableMetatype`}2 type "

include/swift/Basic/Features.def

@@ -488,9 +488,6 @@ ADOPTABLE_EXPERIMENTAL_FEATURE(AsyncCallerExecution, false)
 /// Allow custom availability domains to be defined and referenced.
 SUPPRESSIBLE_EXPERIMENTAL_FEATURE(CustomAvailability, true)
 
-/// Be strict about the Sendable conformance of metatypes.
-EXPERIMENTAL_FEATURE(StrictSendableMetatypes, true)
-
 /// Allow public enumerations to be extensible by default
 /// regardless of whether the module they are declared in
 /// is resilient or not.

lib/AST/ConformanceLookup.cpp

@@ -387,10 +387,10 @@ static ProtocolConformanceRef getBuiltinMetaTypeTypeConformance(
   if (auto kp = protocol->getKnownProtocolKind()) {
     switch (*kp) {
     case KnownProtocolKind::Sendable:
-      // Metatypes are generally Sendable, but under StrictSendableMetatypes we
+      // Metatypes are generally Sendable, but with isolated conformances we
       // cannot assume that metatypes based on type parameters are Sendable.
       // Therefore, check for conformance to SendableMetatype.
-      if (ctx.LangOpts.hasFeature(Feature::StrictSendableMetatypes)) {
+      if (ctx.LangOpts.hasFeature(Feature::IsolatedConformances)) {
         auto sendableMetatypeProto = 
             ctx.getProtocol(KnownProtocolKind::SendableMetatype);
         if (sendableMetatypeProto) {

lib/AST/FeatureSet.cpp

@@ -276,7 +276,6 @@ UNINTERESTING_FEATURE(NonfrozenEnumExhaustivity)
 UNINTERESTING_FEATURE(ClosureIsolation)
 UNINTERESTING_FEATURE(Extern)
 UNINTERESTING_FEATURE(ConsumeSelfInDeinit)
-UNINTERESTING_FEATURE(StrictSendableMetatypes)
 
 static bool usesFeatureBitwiseCopyable2(Decl *decl) {
   if (!decl->getModuleContext()->isStdlibModule()) {

lib/Sema/TypeCheckConcurrency.cpp

@@ -3011,7 +3011,7 @@ namespace {
       // FIXME: When passing to a sending parameter, should this be handled
       // by region isolation? Or should it always be handled by region
       // isolation?
-      if (ctx.LangOpts.hasFeature(Feature::StrictSendableMetatypes) &&
+      if (ctx.LangOpts.hasFeature(Feature::IsolatedConformances) &&
           (mayExecuteConcurrentlyWith(
               localFunc.getAsDeclContext(), getDeclContext()) ||
            (explicitClosure && explicitClosure->isPassedToSendingParameter()))) {

test/Concurrency/sendable_metatype.swift

@@ -1,7 +1,7 @@
-// RUN: %target-typecheck-verify-swift -swift-version 6 -enable-experimental-feature StrictSendableMetatypes -emit-sil -o /dev/null
+// RUN: %target-typecheck-verify-swift -swift-version 6 -enable-experimental-feature IsolatedConformances -emit-sil -o /dev/null
 
 // REQUIRES: concurrency
-// REQUIRES: swift_feature_StrictSendableMetatypes
+// REQUIRES: swift_feature_IsolatedConformances
 
 
 protocol Q {

test/Concurrency/sendable_metatype_typecheck.swift

@@ -1,7 +1,7 @@
-// RUN: %target-typecheck-verify-swift -swift-version 6 -enable-experimental-feature StrictSendableMetatypes
+// RUN: %target-typecheck-verify-swift -swift-version 6 -enable-experimental-feature IsolatedConformances
 
 // REQUIRES: concurrency
-// REQUIRES: swift_feature_StrictSendableMetatypes
+// REQUIRES: swift_feature_IsolatedConformances
 
 // This test checks for typecheck-only diagnostics involving non-sendable
 // metatypes.