[NFC] Migrator: Refactor for recursive MemberTypeRepr representation

Author: AnthonyLatsis

include/swift/AST/TypeRepr.h

@@ -362,6 +362,8 @@ class DeclRefTypeRepr : public TypeRepr {
   /// The identifier that describes the last component.
   DeclNameRef getNameRef() const;
 
+  ArrayRef<TypeRepr *> getGenericArgs() const;
+
   static bool classof(const TypeRepr *T) {
     return T->getKind() == TypeReprKind::SimpleIdent ||
            T->getKind() == TypeReprKind::GenericIdent ||

lib/AST/TypeRepr.cpp

@@ -209,6 +209,15 @@ TypeDecl *DeclRefTypeRepr::getBoundDecl() const {
       ->getBoundDecl();
 }
 
+ArrayRef<TypeRepr *> DeclRefTypeRepr::getGenericArgs() const {
+  auto *lastComp = const_cast<DeclRefTypeRepr *>(this)->getLastComponent();
+  if (auto *genericTR = dyn_cast<GenericIdentTypeRepr>(lastComp)) {
+    return genericTR->getGenericArgs();
+  }
+
+  return {};
+}
+
 DeclNameRef DeclRefTypeRepr::getNameRef() const {
   return const_cast<DeclRefTypeRepr *>(this)->getLastComponent()->getNameRef();
 }

lib/Migrator/APIDiffMigratorPass.cpp

@@ -92,8 +92,8 @@ class ChildIndexFinder : public TypeReprVisitor<ChildIndexFinder, FoundResult> {
   }
 
   bool isUserTypeAlias(TypeRepr *T) const {
-    if (auto Ident = dyn_cast<IdentTypeRepr>(T)) {
-      if (auto Bound = Ident->getBoundDecl()) {
+    if (auto *DeclRefTR = dyn_cast<DeclRefTypeRepr>(T)) {
+      if (auto *Bound = DeclRefTR->getBoundDecl()) {
         return isa<TypeAliasDecl>(Bound) &&
           !Bound->getModuleContext()->isSystemModule();
       }
@@ -189,18 +189,10 @@ class ChildIndexFinder : public TypeReprVisitor<ChildIndexFinder, FoundResult> {
                         /*Suffixable=*/false);
   }
 
-  FoundResult visitSimpleIdentTypeRepr(SimpleIdentTypeRepr *T) {
-    return handleParent(T, ArrayRef<TypeRepr*>());
-  }
-
-  FoundResult visitGenericIdentTypeRepr(GenericIdentTypeRepr *T) {
+  FoundResult visitDeclRefTypeRepr(DeclRefTypeRepr *T) {
     return handleParent(T, T->getGenericArgs());
   }
 
-  FoundResult visitMemberTypeRepr(MemberTypeRepr *T) {
-    return visit(T->getLastComponent());
-  }
-
   FoundResult visitOptionalTypeRepr(OptionalTypeRepr *T) {
     return handleParent(T, T->getBase(), /*Optional=*/true);
   }