[AST] Clean up SubstitutableType

include/swift/AST/TypeNodes.def

@@ -116,11 +116,9 @@ ALWAYS_CANONICAL_TYPE(Module, Type)
 TYPE(DynamicSelf, Type)
 ABSTRACT_TYPE(Substitutable, Type)
   ALWAYS_CANONICAL_TYPE(Archetype, SubstitutableType)
-  ABSTRACT_TYPE(AbstractTypeParam, SubstitutableType)
-    TYPE(GenericTypeParam, AbstractTypeParamType)
-    SUGARED_TYPE(AssociatedType, AbstractTypeParamType)
-    TYPE_RANGE(AbstractTypeParam, GenericTypeParam, AssociatedType)
-  TYPE_RANGE(Substitutable, Archetype, AssociatedType)
+  TYPE(GenericTypeParam, SubstitutableType)
+  TYPE_RANGE(Substitutable, Archetype, GenericTypeParam)
+SUGARED_TYPE(AssociatedType, Type)
 SUGARED_TYPE(Substituted, Type)
 TYPE(DependentMember, Type)
 ABSTRACT_TYPE(AnyFunction, Type)

include/swift/AST/Types.h

@@ -3763,13 +3763,6 @@ class SubstitutableType : public TypeBase {
     : TypeBase(K, C, properties) { }
 
 public:
-  /// \brief Retrieve the name of this type.
-  Identifier getName() const;
-
-  /// \brief Retrieve the parent of this type, or null if this is a
-  /// primary type.
-  SubstitutableType *getParent() const;
-
   // Implement isa/cast/dyncast/etc.
   static bool classof(const TypeBase *T) {
     return T->getKind() >= TypeKind::First_SubstitutableType &&
@@ -4033,29 +4026,10 @@ CanArchetypeType getParent() const {
 }
 END_CAN_TYPE_WRAPPER(ArchetypeType, SubstitutableType)
 
-/// Abstract class used to describe the type of a generic type parameter
-/// or associated type.
-///
-/// \sa AbstractTypeParamDecl
-class AbstractTypeParamType : public SubstitutableType {
-protected:
-  AbstractTypeParamType(TypeKind kind, const ASTContext *ctx,
-                        RecursiveTypeProperties properties)
-    : SubstitutableType(kind, ctx, properties) { }
-
-public:
-  // Implement isa/cast/dyncast/etc.
-  static bool classof(const TypeBase *T) {
-    return T->getKind() >= TypeKind::First_AbstractTypeParamType &&
-           T->getKind() <= TypeKind::Last_AbstractTypeParamType;
-  }
-};
-DEFINE_EMPTY_CAN_TYPE_WRAPPER(AbstractTypeParamType, SubstitutableType)
-
 /// Describes the type of a generic parameter.
 ///
 /// \sa GenericTypeParamDecl
-class GenericTypeParamType : public AbstractTypeParamType {
+class GenericTypeParamType : public SubstitutableType {
   using DepthIndexTy = llvm::PointerEmbeddedInt<unsigned, 31>;
 
   /// The generic type parameter or depth/index.
@@ -4108,28 +4082,28 @@ class GenericTypeParamType : public AbstractTypeParamType {
   friend class GenericTypeParamDecl;
 
   explicit GenericTypeParamType(GenericTypeParamDecl *param)
-    : AbstractTypeParamType(TypeKind::GenericTypeParam, nullptr,
-                            RecursiveTypeProperties::HasTypeParameter),
+    : SubstitutableType(TypeKind::GenericTypeParam, nullptr,
+                        RecursiveTypeProperties::HasTypeParameter),
       ParamOrDepthIndex(param) { }
 
   explicit GenericTypeParamType(unsigned depth,
                                 unsigned index,
                                 const ASTContext &ctx)
-    : AbstractTypeParamType(TypeKind::GenericTypeParam, &ctx,
-                            RecursiveTypeProperties::HasTypeParameter),
+    : SubstitutableType(TypeKind::GenericTypeParam, &ctx,
+                        RecursiveTypeProperties::HasTypeParameter),
       ParamOrDepthIndex(depth << 16 | index) { }
 };
-BEGIN_CAN_TYPE_WRAPPER(GenericTypeParamType, AbstractTypeParamType)
+BEGIN_CAN_TYPE_WRAPPER(GenericTypeParamType, SubstitutableType)
   static CanGenericTypeParamType get(unsigned depth, unsigned index,
                                      const ASTContext &C) {
     return CanGenericTypeParamType(GenericTypeParamType::get(depth, index, C));
   }
-END_CAN_TYPE_WRAPPER(GenericTypeParamType, AbstractTypeParamType)
+END_CAN_TYPE_WRAPPER(GenericTypeParamType, SubstitutableType)
 
 /// Describes the type of an associated type.
 ///
 /// \sa AssociatedTypeDecl
-class AssociatedTypeType : public AbstractTypeParamType {
+class AssociatedTypeType : public TypeBase {
   /// The generic type parameter.
   AssociatedTypeDecl *AssocType;
 
@@ -4151,11 +4125,10 @@ class AssociatedTypeType : public AbstractTypeParamType {
   // These aren't classified as dependent for some reason.
 
   AssociatedTypeType(AssociatedTypeDecl *assocType)
-    : AbstractTypeParamType(TypeKind::AssociatedType, nullptr,
-                            RecursiveTypeProperties()),
+    : TypeBase(TypeKind::AssociatedType, nullptr, RecursiveTypeProperties()),
       AssocType(assocType) { }
 };
-DEFINE_EMPTY_CAN_TYPE_WRAPPER(AssociatedTypeType, AbstractTypeParamType)
+DEFINE_EMPTY_CAN_TYPE_WRAPPER(AssociatedTypeType, Type)
 
 /// SubstitutedType - A type that has been substituted for some other type,
 /// which implies that the replacement type meets all of the requirements of
@@ -4669,22 +4642,6 @@ ParameterTypeFlags::fromParameterType(Type paramTy, bool isVariadic) {
   return {isVariadic, autoclosure, escaping};
 }
 
-inline Identifier SubstitutableType::getName() const {
-  if (auto Archetype = dyn_cast<ArchetypeType>(this))
-    return Archetype->getName();
-  if (auto GenericParam = dyn_cast<GenericTypeParamType>(this))
-    return GenericParam->getName();
-
-  llvm_unreachable("Not a substitutable type");
-}
-
-inline SubstitutableType *SubstitutableType::getParent() const {
-  if (auto Archetype = dyn_cast<ArchetypeType>(this))
-    return Archetype->getParent();
-
-  return nullptr;
-}
-
 inline CanType Type::getCanonicalTypeOrNull() const {
   return isNull() ? CanType() : getPointer()->getCanonicalType();
 }

include/swift/SIL/AbstractionPattern.h

@@ -607,7 +607,7 @@ class AbstractionPattern {
       auto type = getType();
       if (isa<ArchetypeType>(type) ||
           isa<DependentMemberType>(type) ||
-          isa<AbstractTypeParamType>(type)) {
+          isa<GenericTypeParamType>(type)) {
         return true;
       }
       return false;
@@ -636,7 +636,7 @@ class AbstractionPattern {
       if (auto archetype = dyn_cast<ArchetypeType>(type))
         return archetype->requiresClass();
       else if (isa<DependentMemberType>(type) ||
-               isa<AbstractTypeParamType>(type)) {
+               isa<GenericTypeParamType>(type)) {
         assert(GenericSig &&
                "Dependent type in pattern without generic signature?");
         return GenericSig->requiresClass(type, module);

lib/AST/Type.cpp

@@ -2897,9 +2897,13 @@ static Type substType(
       return SubstitutedType::get(type, known->second,
                                   type->getASTContext());
 
+    // For archetypes, we can substitute the parent (if present).
+    auto archetype = substOrig->getAs<ArchetypeType>();
+    if (!archetype) return type;
+
     // If we don't have a substitution for this type and it doesn't have a
     // parent, then we're not substituting it.
-    auto parent = substOrig->getParent();
+    auto parent = archetype->getParent();
     if (!parent)
       return type;
 
@@ -2911,13 +2915,10 @@ static Type substType(
       return type;
 
     // Get the associated type reference from a child archetype.
-    AssociatedTypeDecl *assocType = nullptr;
-    if (auto archetype = substOrig->getAs<ArchetypeType>()) {
-      assocType = archetype->getAssocType();
-    }
-
+    AssociatedTypeDecl *assocType = archetype->getAssocType();
+
     return getMemberForBaseType(conformances, parent, substParent,
-                                assocType, substOrig->getName(),
+                                assocType, archetype->getName(),
                                 options);
   });
 }

lib/AST/TypeWalker.cpp

@@ -67,6 +67,7 @@ class Traversal : public TypeVisitor<Traversal, bool>
     return doIt(ty->getSelfType());
   }
   bool visitSubstitutableType(SubstitutableType *ty) { return false; }
+  bool visitAssociatedTypeType(AssociatedTypeType *ty) { return false; }
 
   bool visitSubstitutedType(SubstitutedType *ty) {
     if (Walker.shouldVisitOriginalSubstitutedType())