AST: Promote ParameterPacks feature to the baseline.

Author: tshortli

include/swift/Basic/Features.def

@@ -178,7 +178,7 @@ LANGUAGE_FEATURE(AttachedMacros, 389, "Attached macros")
 LANGUAGE_FEATURE(ExtensionMacros, 402, "Extension macros")
 LANGUAGE_FEATURE(MoveOnly, 390, "noncopyable types")
 LANGUAGE_FEATURE(MoveOnlyResilientTypes, 390, "non-@frozen noncopyable types with library evolution")
-LANGUAGE_FEATURE(ParameterPacks, 393, "Value and type parameter packs")
+BASELINE_LANGUAGE_FEATURE(ParameterPacks, 393, "Value and type parameter packs")
 SUPPRESSIBLE_LANGUAGE_FEATURE(LexicalLifetimes, 0, "@_eagerMove/@_noEagerMove/@_lexicalLifetimes annotations")
 LANGUAGE_FEATURE(FreestandingMacros, 397, "freestanding declaration macros")
 SUPPRESSIBLE_LANGUAGE_FEATURE(RetroactiveAttribute, 364, "@retroactive")

lib/AST/FeatureSet.cpp

@@ -223,29 +223,6 @@ static bool hasParameterPacks(Decl *decl) {
   return false;
 }
 
-/// A declaration needs the $ParameterPacks feature if it declares a
-/// generic parameter pack, or if its type references a generic nominal
-/// or type alias which declares a generic parameter pack.
-static bool usesFeatureParameterPacks(Decl *decl) {
-  if (hasParameterPacks(decl))
-    return true;
-
-  if (auto *valueDecl = dyn_cast<ValueDecl>(decl)) {
-    if (valueDecl->getInterfaceType().findIf([&](Type t) {
-          if (auto *alias = dyn_cast<TypeAliasType>(t.getPointer()))
-            return hasParameterPacks(alias->getDecl());
-          if (auto *nominal = t->getAnyNominal())
-            return hasParameterPacks(nominal);
-
-          return false;
-        })) {
-      return true;
-    }
-  }
-
-  return false;
-}
-
 static bool usesFeatureLexicalLifetimes(Decl *decl) {
   return decl->getAttrs().hasAttribute<EagerMoveAttr>() ||
          decl->getAttrs().hasAttribute<NoEagerMoveAttr>() ||

test/ModuleInterface/pack_expansion_type.swift

@@ -4,18 +4,13 @@
 
 /// Requirements
 
-// CHECK: #if compiler(>=5.3) && $ParameterPacks
-// CHECK-NEXT: public func variadicFunction<each T, each U>(t: repeat each T, u: repeat each U) -> (repeat (each T, each U)) where (repeat (each T, each U)) : Any
+// CHECK: public func variadicFunction<each T, each U>(t: repeat each T, u: repeat each U) -> (repeat (each T, each U)) where (repeat (each T, each U)) : Any
 public func variadicFunction<each T, each U>(t: repeat each T, u: repeat each U) -> (repeat (each T, each U)) {}
-// CHECK-NEXT: #endif
 
-// CHECK: #if compiler(>=5.3) && $ParameterPacks
-// CHECK-NEXT: public func variadicFunctionWithRequirement<each T>(t: repeat each T) where repeat each T : Swift.Equatable
+// CHECK: public func variadicFunctionWithRequirement<each T>(t: repeat each T) where repeat each T : Swift.Equatable
 public func variadicFunctionWithRequirement<each T: Equatable>(t: repeat each T) {}
-// CHECK-NEXT: #endif
 
-// CHECK: #if compiler(>=5.3) && $ParameterPacks
-// CHECK-NEXT: public struct VariadicType<each T> {
+// CHECK: public struct VariadicType<each T> {
 public struct VariadicType<each T> {
   // CHECK: public func variadicMethod<each U>(t: repeat each T, u: repeat each U) -> (repeat (each T, each U)) where (repeat (each T, each U)) : Any
   public func variadicMethod<each U>(t: repeat each T, u: repeat each  U) -> (repeat (each T, each U)) {}
@@ -24,7 +19,6 @@ public struct VariadicType<each T> {
   public func returnsSelf() -> Self {}
 }
 // CHECK: }
-// CHECK-NEXT: #endif
 
 // The second requirement should not be prefixed with 'repeat'
 // CHECK: public struct SameTypeReq<T, each U> where T : Swift.Sequence, T.Element == PackExpansionType.VariadicType<repeat each U> {
@@ -39,27 +33,17 @@ public func returnsVariadicType() -> VariadicType< > {}
 // CHECK: public func returnsVariadicType() -> PackExpansionType.VariadicType<Swift.Int, Swift.String, Swift.Float>
 public func returnsVariadicType() -> VariadicType<Int, String, Float> {}
 
-// CHECK: #if compiler(>=5.3) && $ParameterPacks
-// CHECK-NEXT: public func returnsVariadicType<each T>() -> PackExpansionType.VariadicType<repeat each T>
+// CHECK: public func returnsVariadicType<each T>() -> PackExpansionType.VariadicType<repeat each T>
 public func returnsVariadicType<each T>() -> VariadicType<repeat each T> {}
-// CHECK-NEXT: #endif
 
-// CHECK: #if compiler(>=5.3) && $ParameterPacks
-// CHECK-NEXT: public typealias VariadicAlias<each T> = PackExpansionType.VariadicType<repeat Swift.Array<each T>>
-// CHECK-NEXT: #endif
+// CHECK: public typealias VariadicAlias<each T> = PackExpansionType.VariadicType<repeat Swift.Array<each T>>
 public typealias VariadicAlias<each T> = VariadicType<repeat Array<each T>>
 
-// CHECK: #if compiler(>=5.3) && $ParameterPacks
-// CHECK-NEXT: public func returnsVariadicAlias() -> PackExpansionType.VariadicAlias<>
-// CHECK-NEXT: #endif
+// CHECK: public func returnsVariadicAlias() -> PackExpansionType.VariadicAlias<>
 public func returnsVariadicAlias() -> VariadicAlias< > {}
 
-// CHECK: #if compiler(>=5.3) && $ParameterPacks
-// CHECK-NEXT: public func returnsVariadicAlias() -> PackExpansionType.VariadicAlias<Swift.Int, Swift.String, Swift.Float>
-// CHECK-NEXT: #endif
+// CHECK: public func returnsVariadicAlias() -> PackExpansionType.VariadicAlias<Swift.Int, Swift.String, Swift.Float>
 public func returnsVariadicAlias() -> VariadicAlias<Int, String, Float> {}
 
-// CHECK: #if compiler(>=5.3) && $ParameterPacks
-// CHECK-NEXT: public func returnsVariadicAlias<each T>() -> PackExpansionType.VariadicAlias<repeat each T>
-// CHECK-NEXT: #endif
+// CHECK: public func returnsVariadicAlias<each T>() -> PackExpansionType.VariadicAlias<repeat each T>
 public func returnsVariadicAlias<each T>() -> VariadicAlias<repeat each T> {}