AST: Promote ExtensionMacroAttr feature to baseline.

Author: tshortli

include/swift/AST/PrintOptions.h

@@ -608,11 +608,6 @@ struct PrintOptions {
   QualifyNestedDeclarations ShouldQualifyNestedDeclarations =
       QualifyNestedDeclarations::Never;
 
-  /// Whether or not to print `@attached(extension)` attributes on
-  /// macro declarations. This is used for feature suppression in
-  /// Swift interface printing.
-  bool PrintExtensionMacroAttributes = true;
-
   /// If this is not \c nullptr then function bodies (including accessors
   /// and constructors) will be printed by this function.
   std::function<void(const ValueDecl *, ASTPrinter &)> FunctionBody;

include/swift/Basic/Features.def

@@ -182,7 +182,7 @@ 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")
-SUPPRESSIBLE_LANGUAGE_FEATURE(ExtensionMacroAttr, 0, "@attached(extension)")
+BASELINE_LANGUAGE_FEATURE(ExtensionMacroAttr, 0, "@attached(extension)")
 BASELINE_LANGUAGE_FEATURE(TypedThrows, 413, "Typed throws")
 CONDITIONALLY_SUPPRESSIBLE_LANGUAGE_FEATURE(OptionalIsolatedParameters, 420, "Optional isolated parameters")
 BASELINE_LANGUAGE_FEATURE(Extern, 0, "@_extern")

lib/AST/ASTPrinter.cpp

@@ -3027,14 +3027,6 @@ void PrintAST::printExtension(ExtensionDecl *decl) {
   }
 }
 
-static void suppressingFeatureExtensionMacroAttr(PrintOptions &options,
-                                                 llvm::function_ref<void()> action) {
-  bool originalPrintExtensionMacroAttrs = options.PrintExtensionMacroAttributes;
-  options.PrintExtensionMacroAttributes = false;
-  action();
-  options.PrintExtensionMacroAttributes = originalPrintExtensionMacroAttrs;
-}
-
 static void suppressingFeatureSpecializeAttributeWithAvailability(
                                         PrintOptions &options,
                                         llvm::function_ref<void()> action) {

lib/AST/Attr.cpp

@@ -1646,12 +1646,6 @@ bool DeclAttribute::printImpl(ASTPrinter &Printer, const PrintOptions &Options,
   case DeclAttrKind::MacroRole: {
     auto Attr = cast<MacroRoleAttr>(this);
 
-    // Suppress @attached(extension) if needed.
-    if (!Options.PrintExtensionMacroAttributes &&
-        Attr->getMacroRole() == MacroRole::Extension) {
-      break;
-    }
-
     switch (Attr->getMacroSyntax()) {
     case MacroSyntax::Freestanding:
       Printer.printAttrName("@freestanding");

lib/AST/FeatureSet.cpp

@@ -148,10 +148,6 @@ static bool usesFeatureRetroactiveAttribute(Decl *decl) {
       [](const InheritedEntry &entry) { return entry.isRetroactive(); });
 }
 
-static bool usesFeatureExtensionMacroAttr(Decl *decl) {
-  return usesFeatureExtensionMacros(decl);
-}
-
 static bool usesFeatureOptionalIsolatedParameters(Decl *decl) {
   auto *value = dyn_cast<ValueDecl>(decl);
   if (!value)