AST: Promote AssociatedTypeAvailability feature to the baseline.

Author: tshortli

include/swift/Basic/Features.def

@@ -169,7 +169,7 @@ BASELINE_LANGUAGE_FEATURE(UnsafeInheritExecutor, 0, "@_unsafeInheritExecutor")
 SUPPRESSIBLE_LANGUAGE_FEATURE(PrimaryAssociatedTypes2, 346, "Primary associated types")
 BASELINE_LANGUAGE_FEATURE(UnavailableFromAsync, 0, "@_unavailableFromAsync")
 BASELINE_LANGUAGE_FEATURE(NoAsyncAvailability, 340, "@available(*, noasync)")
-SUPPRESSIBLE_LANGUAGE_FEATURE(AssociatedTypeAvailability, 0, "Availability on associated types")
+BASELINE_LANGUAGE_FEATURE(AssociatedTypeAvailability, 0, "Availability on associated types")
 SUPPRESSIBLE_LANGUAGE_FEATURE(AsyncSequenceFailure, 0, "Failure associated type on AsyncSequence and AsyncIteratorProtocol")
 BASELINE_LANGUAGE_FEATURE(BuiltinIntLiteralAccessors, 368, "Builtin.IntLiteral accessors")
 LANGUAGE_FEATURE(Macros, 0, "Macros")

lib/AST/ASTPrinter.cpp

@@ -3067,15 +3067,6 @@ static void suppressingFeaturePrimaryAssociatedTypes2(PrintOptions &options,
   options.PrintPrimaryAssociatedTypes = originalPrintPrimaryAssociatedTypes;
 }
 
-static void
-suppressingFeatureAssociatedTypeAvailability(
-    PrintOptions &options, llvm::function_ref<void()> action) {
-  unsigned originalExcludeAttrCount = options.ExcludeAttrList.size();
-  options.ExcludeAttrList.push_back(DeclAttrKind::Available);
-  action();
-  options.ExcludeAttrList.resize(originalExcludeAttrCount);
-}
-
 static void
 suppressingFeatureAsyncSequenceFailure(
     PrintOptions &options, llvm::function_ref<void()> action) {

lib/AST/FeatureSet.cpp

@@ -150,11 +150,6 @@ static bool usesFeaturePrimaryAssociatedTypes2(Decl *decl) {
   return false;
 }
 
-static bool usesFeatureAssociatedTypeAvailability(Decl *decl) {
-  return isa<AssociatedTypeDecl>(decl) &&
-         decl->getAttrs().hasAttribute<AvailableAttr>();
-}
-
 static bool isImplicitRethrowsProtocol(const ProtocolDecl *proto) {
   return proto->isSpecificProtocol(KnownProtocolKind::AsyncSequence) ||
          proto->isSpecificProtocol(KnownProtocolKind::AsyncIteratorProtocol);

test/ModuleInterface/associated_type_availability.swift

@@ -6,12 +6,8 @@
 
 // CHECK: public protocol P
 public protocol P {
-  // CHECK: #if compiler(>=5.3) && $AssociatedTypeAvailability
-  // CHECK-NEXT: @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
+  // CHECK: @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
   // CHECK-NEXT: associatedtype AT = Self
-  // CHECK-NEXT: #else
-  // CHECK-NEXT: associatedtype AT = Self
-  // CHECK-NEXT: #endif
   @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
   associatedtype AT = Self
 }