AST: Promote RetroactiveAttribute feature to baseline.

Author: tshortli

include/swift/Basic/Features.def

@@ -181,7 +181,7 @@ BASELINE_LANGUAGE_FEATURE(MoveOnlyResilientTypes, 390, "non-@frozen noncopyable
 BASELINE_LANGUAGE_FEATURE(ParameterPacks, 393, "Value and type parameter packs")
 BASELINE_LANGUAGE_FEATURE(LexicalLifetimes, 0, "@_eagerMove/@_noEagerMove/@_lexicalLifetimes annotations")
 BASELINE_LANGUAGE_FEATURE(FreestandingMacros, 397, "freestanding declaration macros")
-SUPPRESSIBLE_LANGUAGE_FEATURE(RetroactiveAttribute, 364, "@retroactive")
+BASELINE_LANGUAGE_FEATURE(RetroactiveAttribute, 364, "@retroactive")
 BASELINE_LANGUAGE_FEATURE(ExtensionMacroAttr, 0, "@attached(extension)")
 BASELINE_LANGUAGE_FEATURE(TypedThrows, 413, "Typed throws")
 BASELINE_LANGUAGE_FEATURE(OptionalIsolatedParameters, 420, "Optional isolated parameters")

lib/AST/ASTPrinter.cpp

@@ -3035,14 +3035,6 @@ static void suppressingFeatureSpecializeAttributeWithAvailability(
   action();
 }
 
-static void suppressingFeatureRetroactiveAttribute(
-  PrintOptions &options,
-  llvm::function_ref<void()> action) {
-  llvm::SaveAndRestore<PrintOptions> originalOptions(options);
-  options.ExcludeAttrList.push_back(TypeAttrKind::Retroactive);
-  action();
-}
-
 static void suppressingFeatureIsolatedAny(PrintOptions &options,
                                           llvm::function_ref<void()> action) {
   llvm::SaveAndRestore<bool> scope(options.SuppressIsolatedAny, true);

lib/AST/FeatureSet.cpp

@@ -63,16 +63,6 @@ static bool usesFeatureSpecializeAttributeWithAvailability(Decl *decl) {
   return false;
 }
 
-static bool usesFeatureRetroactiveAttribute(Decl *decl) {
-  auto ext = dyn_cast<ExtensionDecl>(decl);
-  if (!ext)
-    return false;
-
-  return llvm::any_of(
-      ext->getInherited().getEntries(),
-      [](const InheritedEntry &entry) { return entry.isRetroactive(); });
-}
-
 static bool usesFeatureAssociatedTypeImplements(Decl *decl) {
   return isa<TypeDecl>(decl) && decl->getAttrs().hasAttribute<ImplementsAttr>();
 }

test/ModuleInterface/retroactive-conformances.swift

@@ -2,30 +2,12 @@
 // RUN: %target-swift-typecheck-module-from-interface(%t.swiftinterface) -module-name Test
 // RUN: %FileCheck %s < %t.swiftinterface
 
-// CHECK: #if compiler(>=5.3) && $RetroactiveAttribute
 // CHECK: extension Swift.Int : @retroactive Swift.Identifiable {
 // CHECK:   public var id: Swift.Int {
 // CHECK:     get
 // CHECK:   }
 // CHECK:   public typealias ID = Swift.Int
 // CHECK: }
-// CHECK: #else
-// CHECK: extension Swift.Int : Swift.Identifiable {
-// CHECK:   public var id: Swift.Int {
-// CHECK:     get
-// CHECK:   }
-// CHECK:   public typealias ID = Swift.Int
-// CHECK: }
-// CHECK: #endif
 extension Int: @retroactive Identifiable {
     public var id: Int { self }
 }
-
-// CHECK: #if compiler(>=5.3) && $RetroactiveAttribute
-// CHECK: extension Swift.String : @retroactive Swift.Identifiable {
-// CHECK-NOT: #else
-// CHECK: #endif
-@_disallowFeatureSuppression(RetroactiveAttribute)
-extension String: @retroactive Identifiable {
-    public var id: String { self }
-}