Introduce LocalArchetypeType as an abstract superclass to Element + Opened

This will be used in places like SIL's tracking of locally-opened archetypes.

Author: rjmccall

include/swift/AST/TypeNodes.def

@@ -147,8 +147,10 @@ ABSTRACT_TYPE(Substitutable, Type)
   ABSTRACT_TYPE(Archetype, SubstitutableType)
     ALWAYS_CANONICAL_TYPE(PrimaryArchetype, ArchetypeType)
     ALWAYS_CANONICAL_TYPE(OpaqueTypeArchetype, ArchetypeType)
-    ALWAYS_CANONICAL_TYPE(OpenedArchetype, ArchetypeType)
-    ALWAYS_CANONICAL_TYPE(ElementArchetype, ArchetypeType)
+    ABSTRACT_TYPE(LocalArchetype, ArchetypeType)
+      ALWAYS_CANONICAL_TYPE(OpenedArchetype, LocalArchetypeType)
+      ALWAYS_CANONICAL_TYPE(ElementArchetype, LocalArchetypeType)
+      TYPE_RANGE(LocalArchetype, OpenedArchetype, ElementArchetype)
     ALWAYS_CANONICAL_TYPE(PackArchetype, ArchetypeType)
     TYPE_RANGE(Archetype, PrimaryArchetype, PackArchetype)
   TYPE(GenericTypeParam, SubstitutableType)

include/swift/AST/Types.h

@@ -5914,8 +5914,29 @@ class ReplaceOpaqueTypesWithUnderlyingTypes {
   bool isWholeModule() const { return inContextAndIsWholeModule.getInt(); }
 };
 
+/// An archetype that's only valid in a portion of a local context.
+class LocalArchetypeType : public ArchetypeType {
+protected:
+  using ArchetypeType::ArchetypeType;
+
+public:
+  LocalArchetypeType *getRoot() const {
+    return cast<LocalArchetypeType>(ArchetypeType::getRoot());
+  }
+
+  static bool classof(const TypeBase *type) {
+    return type->getKind() == TypeKind::OpenedArchetype ||
+           type->getKind() == TypeKind::ElementArchetype;
+  }
+};
+BEGIN_CAN_TYPE_WRAPPER(LocalArchetypeType, ArchetypeType)
+  CanLocalArchetypeType getRoot() const {
+    return CanLocalArchetypeType(getPointer()->getRoot());
+  }
+END_CAN_TYPE_WRAPPER(LocalArchetypeType, ArchetypeType)
+
 /// An archetype that represents the dynamic type of an opened existential.
-class OpenedArchetypeType final : public ArchetypeType,
+class OpenedArchetypeType final : public LocalArchetypeType,
     private ArchetypeTrailingObjects<OpenedArchetypeType>
 {
   friend TrailingObjects;
@@ -6016,11 +6037,11 @@ class OpenedArchetypeType final : public ArchetypeType,
                       ArrayRef<ProtocolDecl *> conformsTo, Type superclass,
                       LayoutConstraint layout);
 };
-BEGIN_CAN_TYPE_WRAPPER(OpenedArchetypeType, ArchetypeType)
+BEGIN_CAN_TYPE_WRAPPER(OpenedArchetypeType, LocalArchetypeType)
   CanOpenedArchetypeType getRoot() const {
     return CanOpenedArchetypeType(getPointer()->getRoot());
   }
-END_CAN_TYPE_WRAPPER(OpenedArchetypeType, ArchetypeType)
+END_CAN_TYPE_WRAPPER(OpenedArchetypeType, LocalArchetypeType)
 
 /// A wrapper around a shape type to use in ArchetypeTrailingObjects
 /// for PackArchetypeType.
@@ -6065,7 +6086,7 @@ BEGIN_CAN_TYPE_WRAPPER(PackArchetypeType, ArchetypeType)
 END_CAN_TYPE_WRAPPER(PackArchetypeType, ArchetypeType)
 
 /// An archetype that represents the element type of a pack archetype.
-class ElementArchetypeType final : public ArchetypeType,
+class ElementArchetypeType final : public LocalArchetypeType,
     private ArchetypeTrailingObjects<ElementArchetypeType>
 {
   friend TrailingObjects;
@@ -6104,11 +6125,11 @@ class ElementArchetypeType final : public ArchetypeType,
                        ArrayRef<ProtocolDecl *> conformsTo, Type superclass,
                        LayoutConstraint layout);
 };
-BEGIN_CAN_TYPE_WRAPPER(ElementArchetypeType, ArchetypeType)
+BEGIN_CAN_TYPE_WRAPPER(ElementArchetypeType, LocalArchetypeType)
   CanElementArchetypeType getRoot() const {
     return CanElementArchetypeType(getPointer()->getRoot());
   }
-END_CAN_TYPE_WRAPPER(ElementArchetypeType, ArchetypeType)
+END_CAN_TYPE_WRAPPER(ElementArchetypeType, LocalArchetypeType)
 
 template<typename Type>
 const Type *ArchetypeType::getSubclassTrailingObjects() const {

lib/AST/Type.cpp

@@ -3964,11 +3964,12 @@ OpenedArchetypeType::OpenedArchetypeType(
     GenericEnvironment *environment, Type interfaceType,
     ArrayRef<ProtocolDecl *> conformsTo, Type superclass,
     LayoutConstraint layout)
-  : ArchetypeType(TypeKind::OpenedArchetype, interfaceType->getASTContext(),
-                  RecursiveTypeProperties::HasArchetype
-                    | RecursiveTypeProperties::HasOpenedExistential,
-                  interfaceType, conformsTo, superclass, layout,
-                  environment)
+  : LocalArchetypeType(TypeKind::OpenedArchetype,
+                       interfaceType->getASTContext(),
+                       RecursiveTypeProperties::HasArchetype
+                         | RecursiveTypeProperties::HasOpenedExistential,
+                       interfaceType, conformsTo, superclass, layout,
+                       environment)
 {
   assert(!interfaceType->isParameterPack());
 }
@@ -4022,9 +4023,10 @@ ElementArchetypeType::ElementArchetypeType(
     const ASTContext &Ctx, GenericEnvironment *GenericEnv, Type InterfaceType,
     ArrayRef<ProtocolDecl *> ConformsTo, Type Superclass,
     LayoutConstraint Layout)
-    : ArchetypeType(TypeKind::ElementArchetype, Ctx,
-                    RecursiveTypeProperties::HasArchetype, InterfaceType,
-                    ConformsTo, Superclass, Layout, GenericEnv) {
+    : LocalArchetypeType(TypeKind::ElementArchetype, Ctx,
+                         RecursiveTypeProperties::HasArchetype,
+                         InterfaceType,
+                         ConformsTo, Superclass, Layout, GenericEnv) {
 }
 
 CanTypeWrapper<ElementArchetypeType> ElementArchetypeType::getNew(