Rework the traversal of Objective-C categories and extensions to

consider (sub)module visibility.

The bulk of this change replaces myriad hand-rolled loops over the
linked list of Objective-C categories/extensions attached to an
interface declaration with loops using one of the four new category
iterator kinds:

  visible_categories_iterator: Iterates over all visible categories
  and extensions, hiding any that have their "hidden" bit set. This is
  by far the most commonly used iterator.

  known_categories_iterator: Iterates over all categories and
  extensions, ignoring the "hidden" bit. This tends to be used for
  redeclaration-like traversals.

  visible_extensions_iterator: Iterates over all visible extensions,
  hiding any that have their "hidden" bit set.

  known_extensions_iterator: Iterates over all extensions, whether
  they are visible to normal name lookup or not.

The effect of this change is that any uses of the visible_ iterators
will respect module-import visibility. See the new tests for examples.

Note that the old accessors for categories and extensions are gone;
there are *Raw() forms for some of them, for those (few) areas of the
compiler that have to manipulate the linked list of categories
directly. This is generally discouraged.

Part two of <rdar://problem/10634711>.
 



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@172665 91177308-0d34-0410-b5e6-96231b3b80d8

23 files changed, 533 insertions, 222 deletions

diff --git a/include/clang/AST/DeclObjC.h b/include/clang/AST/DeclObjC.h
index d1067432e3..e7fa5e7d2b 100644
--- a/include/clang/AST/DeclObjC.h
+++ b/include/clang/AST/DeclObjC.h
@@ -894,7 +894,166 @@ public:
                                               : superCls; 
   }
 
-  ObjCCategoryDecl* getCategoryList() const {
+  /// \brief Iterator that walks over the list of categories, filtering out
+  /// those that do not meet specific criteria.
+  ///
+  /// This class template is used for the various permutations of category
+  /// and extension iterators.
+  template<bool (*Filter)(ObjCCategoryDecl *)>
+  class filtered_category_iterator {
+    ObjCCategoryDecl *Current;
+
+    void findAcceptableCategory();
+    
+  public:
+    typedef ObjCCategoryDecl *      value_type;
+    typedef value_type              reference;
+    typedef value_type              pointer;
+    typedef std::ptrdiff_t          difference_type;
+    typedef std::input_iterator_tag iterator_category;
+
+    filtered_category_iterator() : Current(0) { }
+    explicit filtered_category_iterator(ObjCCategoryDecl *Current)
+      : Current(Current)
+    {
+      findAcceptableCategory();
+    }
+
+    reference operator*() const { return Current; }
+    pointer operator->() const { return Current; }
+
+    filtered_category_iterator &operator++();
+
+    filtered_category_iterator operator++(int) {
+      filtered_category_iterator Tmp = *this;
+      ++(*this);
+      return Tmp;
+    }
+
+    friend bool operator==(filtered_category_iterator X,
+                           filtered_category_iterator Y) {
+      return X.Current = Y.Current;
+    }
+
+    friend bool operator!=(filtered_category_iterator X,
+                           filtered_category_iterator Y) {
+      return X.Current != Y.Current;
+    }
+  };
+
+private:
+  /// \brief Test whether the given category is visible.
+  ///
+  /// Used in the \c visible_categories_iterator.
+  static bool isVisibleCategory(ObjCCategoryDecl *Cat);
+                        
+public:
+  /// \brief Iterator that walks over the list of categories and extensions
+  /// that are visible, i.e., not hidden in a non-imported submodule.
+  typedef filtered_category_iterator<isVisibleCategory>
+    visible_categories_iterator;
+
+  /// \brief Retrieve an iterator to the beginning of the visible-categories
+  /// list.
+  visible_categories_iterator visible_categories_begin() const {
+    return visible_categories_iterator(getCategoryListRaw());
+  }
+
+  /// \brief Retrieve an iterator to the end of the visible-categories list.
+  visible_categories_iterator visible_categories_end() const {
+    return visible_categories_iterator();
+  }
+
+  /// \brief Determine whether the visible-categories list is empty.
+  bool visible_categories_empty() const {
+    return visible_categories_begin() == visible_categories_end();
+  }
+
+private:
+  /// \brief Test whether the given category... is a category.
+  ///
+  /// Used in the \c known_categories_iterator.
+  static bool isKnownCategory(ObjCCategoryDecl *) { return true; }
+
+public:
+  /// \brief Iterator that walks over all of the known categories and
+  /// extensions, including those that are hidden.
+  typedef filtered_category_iterator<isKnownCategory> known_categories_iterator;
+
+  /// \brief Retrieve an iterator to the beginning of the known-categories
+  /// list.
+  known_categories_iterator known_categories_begin() const {
+    return known_categories_iterator(getCategoryListRaw());
+  }
+
+  /// \brief Retrieve an iterator to the end of the known-categories list.
+  known_categories_iterator known_categories_end() const {
+    return known_categories_iterator();
+  }
+
+  /// \brief Determine whether the known-categories list is empty.
+  bool known_categories_empty() const {
+    return known_categories_begin() == known_categories_end();
+  }
+
+private:
+  /// \brief Test whether the given category is a visible extension.
+  ///
+  /// Used in the \c visible_extensions_iterator.
+  static bool isVisibleExtension(ObjCCategoryDecl *Cat);
+
+public:
+  /// \brief Iterator that walks over all of the visible extensions, skipping
+  /// any that are known but hidden.
+  typedef filtered_category_iterator<isVisibleExtension>
+    visible_extensions_iterator;
+
+  /// \brief Retrieve an iterator to the beginning of the visible-extensions
+  /// list.
+  visible_extensions_iterator visible_extensions_begin() const {
+    return visible_extensions_iterator(getCategoryListRaw());
+  }
+
+  /// \brief Retrieve an iterator to the end of the visible-extensions list.
+  visible_extensions_iterator visible_extensions_end() const {
+    return visible_extensions_iterator();
+  }
+
+  /// \brief Determine whether the visible-extensions list is empty.
+  bool visible_extensions_empty() const {
+    return visible_extensions_begin() == visible_extensions_end();
+  }
+
+private:
+  /// \brief Test whether the given category is an extension.
+  ///
+  /// Used in the \c known_extensions_iterator.
+  static bool isKnownExtension(ObjCCategoryDecl *Cat);
+  
+public:
+  /// \brief Iterator that walks over all of the known extensions.
+  typedef filtered_category_iterator<isKnownExtension>
+    known_extensions_iterator;
+
+  /// \brief Retrieve an iterator to the beginning of the known-extensions
+  /// list.
+  known_extensions_iterator known_extensions_begin() const {
+    return known_extensions_iterator(getCategoryListRaw());
+  }
+  
+  /// \brief Retrieve an iterator to the end of the known-extensions list.
+  known_extensions_iterator known_extensions_end() const {
+    return known_extensions_iterator();
+  }
+
+  /// \brief Determine whether the known-extensions list is empty.
+  bool known_extensions_empty() const {
+    return known_extensions_begin() == known_extensions_end();
+  }
+
+  /// \brief Retrieve the raw pointer to the start of the category/extension
+  /// list.
+  ObjCCategoryDecl* getCategoryListRaw() const {
     // FIXME: Should make sure no callers ever do this.
     if (!hasDefinition())
       return 0;
@@ -905,12 +1064,12 @@ public:
     return data().CategoryList;
   }
 
-  void setCategoryList(ObjCCategoryDecl *category) {
+  /// \brief Set the raw pointer to the start of the category/extension
+  /// list.
+  void setCategoryListRaw(ObjCCategoryDecl *category) {
     data().CategoryList = category;
   }
 
-  ObjCCategoryDecl* getFirstClassExtension() const;
-
   ObjCPropertyDecl
     *FindPropertyVisibleInPrimaryClass(IdentifierInfo *PropertyId) const;
 
@@ -1351,6 +1510,7 @@ class ObjCCategoryDecl : public ObjCContainerDecl {
       CategoryNameLoc(CategoryNameLoc),
       IvarLBraceLoc(IvarLBraceLoc), IvarRBraceLoc(IvarRBraceLoc) {
   }
+
 public:
 
   static ObjCCategoryDecl *Create(ASTContext &C, DeclContext *DC,
@@ -1394,8 +1554,13 @@ public:
 
   ObjCCategoryDecl *getNextClassCategory() const { return NextClassCategory; }
 
+  /// \brief Retrieve the pointer to the next stored category (or extension),
+  /// which may be hidden.
+  ObjCCategoryDecl *getNextClassCategoryRaw() const {
+    return NextClassCategory;
+  }
+
   bool IsClassExtension() const { return getIdentifier() == 0; }
-  const ObjCCategoryDecl *getNextClassExtension() const;
 
   typedef specific_decl_iterator<ObjCIvarDecl> ivar_iterator;
   ivar_iterator ivar_begin() const {
@@ -2030,5 +2195,33 @@ public:
   friend class ASTDeclReader;
 };
 
+template<bool (*Filter)(ObjCCategoryDecl *)>
+void
+ObjCInterfaceDecl::filtered_category_iterator<Filter>::
+findAcceptableCategory() {
+  while (Current && !Filter(Current))
+    Current = Current->getNextClassCategoryRaw();
+}
+
+template<bool (*Filter)(ObjCCategoryDecl *)>
+inline ObjCInterfaceDecl::filtered_category_iterator<Filter> &
+ObjCInterfaceDecl::filtered_category_iterator<Filter>::operator++() {
+  Current = Current->getNextClassCategoryRaw();
+  findAcceptableCategory();
+  return *this;
+}
+
+inline bool ObjCInterfaceDecl::isVisibleCategory(ObjCCategoryDecl *Cat) {
+  return !Cat->isHidden();
+}
+
+inline bool ObjCInterfaceDecl::isVisibleExtension(ObjCCategoryDecl *Cat) {
+  return Cat->IsClassExtension() && !Cat->isHidden();
+}
+
+inline bool ObjCInterfaceDecl::isKnownExtension(ObjCCategoryDecl *Cat) {
+  return Cat->IsClassExtension();
+}
+
 }  // end namespace clang
 #endif
diff --git a/lib/ARCMigrate/TransProperties.cpp b/lib/ARCMigrate/TransProperties.cpp
index 7196a54efc..b6ddc43dd6 100644
--- a/lib/ARCMigrate/TransProperties.cpp
+++ b/lib/ARCMigrate/TransProperties.cpp
@@ -141,10 +141,12 @@ public:
 
     AtPropDeclsTy AtExtProps;
     // Look through extensions.
-    for (ObjCCategoryDecl *Cat = iface->getCategoryList();
-           Cat; Cat = Cat->getNextClassCategory())
-      if (Cat->IsClassExtension())
-        collectProperties(Cat, AtExtProps, &AtProps);
+    for (ObjCInterfaceDecl::visible_extensions_iterator
+           ext = iface->visible_extensions_begin(),
+           extEnd = iface->visible_extensions_end();
+         ext != extEnd; ++ext) {
+      collectProperties(*ext, AtExtProps, &AtProps);
+    }
 
     for (AtPropDeclsTy::iterator
            I = AtExtProps.begin(), E = AtExtProps.end(); I != E; ++I) {
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index 83e6d6bd28..df64237f70 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -365,10 +365,12 @@ static void addRedeclaredMethods(const ObjCMethodDecl *ObjCMethod,
     if (!ID)
       return;
     // Add redeclared method here.
-    for (const ObjCCategoryDecl *ClsExtDecl = ID->getFirstClassExtension();
-         ClsExtDecl; ClsExtDecl = ClsExtDecl->getNextClassExtension()) {
+    for (ObjCInterfaceDecl::known_extensions_iterator
+           Ext = ID->known_extensions_begin(),
+           ExtEnd = ID->known_extensions_end();
+         Ext != ExtEnd; ++Ext) {
       if (ObjCMethodDecl *RedeclaredMethod =
-            ClsExtDecl->getMethod(ObjCMethod->getSelector(),
+            Ext->getMethod(ObjCMethod->getSelector(),
                                   ObjCMethod->isInstanceMethod()))
         Redeclared.push_back(RedeclaredMethod);
     }
@@ -1689,9 +1691,13 @@ void ASTContext::CollectInheritedProtocols(const Decl *CDecl,
     }
     
     // Categories of this Interface.
-    for (const ObjCCategoryDecl *CDeclChain = OI->getCategoryList(); 
-         CDeclChain; CDeclChain = CDeclChain->getNextClassCategory())
-      CollectInheritedProtocols(CDeclChain, Protocols);
+    for (ObjCInterfaceDecl::visible_categories_iterator
+           Cat = OI->visible_categories_begin(),
+           CatEnd = OI->visible_categories_end();
+         Cat != CatEnd; ++Cat) {
+      CollectInheritedProtocols(*Cat, Protocols);
+    }
+
     if (ObjCInterfaceDecl *SD = OI->getSuperClass())
       while (SD) {
         CollectInheritedProtocols(SD, Protocols);
@@ -1721,10 +1727,13 @@ void ASTContext::CollectInheritedProtocols(const Decl *CDecl,
 unsigned ASTContext::CountNonClassIvars(const ObjCInterfaceDecl *OI) const {
   unsigned count = 0;  
   // Count ivars declared in class extension.
-  for (const ObjCCategoryDecl *CDecl = OI->getFirstClassExtension(); CDecl;
-       CDecl = CDecl->getNextClassExtension())
-    count += CDecl->ivar_size();
-
+  for (ObjCInterfaceDecl::known_extensions_iterator
+         Ext = OI->known_extensions_begin(),
+         ExtEnd = OI->known_extensions_end();
+       Ext != ExtEnd; ++Ext) {
+    count += Ext->ivar_size();
+  }
+  
   // Count ivar defined in this class's implementation.  This
   // includes synthesized ivars.
   if (ObjCImplementationDecl *ImplDecl = OI->getImplementation())
diff --git a/lib/AST/ASTImporter.cpp b/lib/AST/ASTImporter.cpp
index 9bfaa13ddd..305815ebeb 100644
--- a/lib/AST/ASTImporter.cpp
+++ b/lib/AST/ASTImporter.cpp
@@ -3514,10 +3514,13 @@ bool ASTNodeImporter::ImportDefinition(ObjCInterfaceDecl *From,
   
   // Import categories. When the categories themselves are imported, they'll
   // hook themselves into this interface.
-  for (ObjCCategoryDecl *FromCat = From->getCategoryList(); FromCat;
-       FromCat = FromCat->getNextClassCategory())
-    Importer.Import(FromCat);
-
+  for (ObjCInterfaceDecl::known_categories_iterator
+         Cat = From->known_categories_begin(),
+         CatEnd = From->known_categories_end();
+       Cat != CatEnd; ++Cat) {
+    Importer.Import(*Cat);
+  }
+  
   // If we have an @implementation, import it as well.
   if (From->getImplementation()) {
     ObjCImplementationDecl *Impl = cast_or_null<ObjCImplementationDecl>(
diff --git a/lib/AST/DeclObjC.cpp b/lib/AST/DeclObjC.cpp
index 816c43200a..0b1a1ec456 100644
--- a/lib/AST/DeclObjC.cpp
+++ b/lib/AST/DeclObjC.cpp
@@ -129,12 +129,15 @@ ObjCContainerDecl::FindPropertyDeclaration(IdentifierInfo *PropertyId) const {
     }
     case Decl::ObjCInterface: {
       const ObjCInterfaceDecl *OID = cast<ObjCInterfaceDecl>(this);
-      // Look through categories.
-      for (ObjCCategoryDecl *Cat = OID->getCategoryList();
-           Cat; Cat = Cat->getNextClassCategory())
+      // Look through categories (but not extensions).
+      for (ObjCInterfaceDecl::visible_categories_iterator
+             Cat = OID->visible_categories_begin(),
+             CatEnd = OID->visible_categories_end();
+           Cat != CatEnd; ++Cat) {
         if (!Cat->IsClassExtension())
           if (ObjCPropertyDecl *P = Cat->FindPropertyDeclaration(PropertyId))
             return P;
+      }
 
       // Look through protocols.
       for (ObjCInterfaceDecl::all_protocol_iterator
@@ -296,24 +299,6 @@ void ObjCInterfaceDecl::startDefinition() {
   }
 }
 
-/// getFirstClassExtension - Find first class extension of the given class.
-ObjCCategoryDecl* ObjCInterfaceDecl::getFirstClassExtension() const {
-  for (ObjCCategoryDecl *CDecl = getCategoryList(); CDecl;
-       CDecl = CDecl->getNextClassCategory())
-    if (CDecl->IsClassExtension())
-      return CDecl;
-  return 0;
-}
-
-/// getNextClassCategory - Find next class extension in list of categories.
-const ObjCCategoryDecl* ObjCCategoryDecl::getNextClassExtension() const {
-  for (const ObjCCategoryDecl *CDecl = getNextClassCategory(); CDecl; 
-        CDecl = CDecl->getNextClassCategory())
-    if (CDecl->IsClassExtension())
-      return CDecl;
-  return 0;
-}
-
 ObjCIvarDecl *ObjCInterfaceDecl::lookupInstanceVariable(IdentifierInfo *ID,
                                               ObjCInterfaceDecl *&clsDeclared) {
   // FIXME: Should make sure no callers ever do this.
@@ -329,9 +314,12 @@ ObjCIvarDecl *ObjCInterfaceDecl::lookupInstanceVariable(IdentifierInfo *ID,
       clsDeclared = ClassDecl;
       return I;
     }
-    for (const ObjCCategoryDecl *CDecl = ClassDecl->getFirstClassExtension();
-         CDecl; CDecl = CDecl->getNextClassExtension()) {
-      if (ObjCIvarDecl *I = CDecl->getIvarDecl(ID)) {
+
+    for (ObjCInterfaceDecl::visible_extensions_iterator
+           Ext = ClassDecl->visible_extensions_begin(),
+           ExtEnd = ClassDecl->visible_extensions_end();
+         Ext != ExtEnd; ++Ext) {
+      if (ObjCIvarDecl *I = Ext->getIvarDecl(ID)) {
         clsDeclared = ClassDecl;
         return I;
       }
@@ -390,21 +378,22 @@ ObjCMethodDecl *ObjCInterfaceDecl::lookupMethod(Selector Sel,
         return MethodDecl;
     
     // Didn't find one yet - now look through categories.
-    ObjCCategoryDecl *CatDecl = ClassDecl->getCategoryList();
-    while (CatDecl) {
-      if ((MethodDecl = CatDecl->getMethod(Sel, isInstance)))
+    for (ObjCInterfaceDecl::visible_categories_iterator
+           Cat = ClassDecl->visible_categories_begin(),
+           CatEnd = ClassDecl->visible_categories_end();
+         Cat != CatEnd; ++Cat) {
+      if ((MethodDecl = Cat->getMethod(Sel, isInstance)))
         return MethodDecl;
 
       if (!shallowCategoryLookup) {
         // Didn't find one yet - look through protocols.
         const ObjCList<ObjCProtocolDecl> &Protocols =
-          CatDecl->getReferencedProtocols();
+          Cat->getReferencedProtocols();
         for (ObjCList<ObjCProtocolDecl>::iterator I = Protocols.begin(),
              E = Protocols.end(); I != E; ++I)
           if ((MethodDecl = (*I)->lookupMethod(Sel, isInstance)))
             return MethodDecl;
       }
-      CatDecl = CatDecl->getNextClassCategory();
     }
   
     ClassDecl = ClassDecl->getSuperClass();
@@ -816,10 +805,13 @@ static void CollectOverriddenMethodsRecurse(const ObjCContainerDecl *Container,
          P != PEnd; ++P)
       CollectOverriddenMethodsRecurse(*P, Method, Methods, MovedToSuper);
 
-    for (const ObjCCategoryDecl *Category = Interface->getCategoryList();
-         Category; Category = Category->getNextClassCategory())
-      CollectOverriddenMethodsRecurse(Category, Method, Methods,
+    for (ObjCInterfaceDecl::visible_categories_iterator
+           Cat = Interface->visible_categories_begin(),
+           CatEnd = Interface->visible_categories_end();
+         Cat != CatEnd; ++Cat) {
+      CollectOverriddenMethodsRecurse(*Cat, Method, Methods,
                                       MovedToSuper);
+    }
 
     if (const ObjCInterfaceDecl *Super = Interface->getSuperClass())
       return CollectOverriddenMethodsRecurse(Super, Method, Methods,
@@ -881,11 +873,14 @@ static void collectOnCategoriesAfterLocation(SourceLocation Loc,
   if (!Class)
     return;
 
-  for (const ObjCCategoryDecl *Category = Class->getCategoryList();
-       Category; Category = Category->getNextClassCategory())
-    if (SM.isBeforeInTranslationUnit(Loc, Category->getLocation()))
-      CollectOverriddenMethodsRecurse(Category, Method, Methods, true);
-
+  for (ObjCInterfaceDecl::visible_categories_iterator
+         Cat = Class->visible_categories_begin(),
+         CatEnd = Class->visible_categories_end();
+       Cat != CatEnd; ++Cat) {
+    if (SM.isBeforeInTranslationUnit(Loc, Cat->getLocation()))
+      CollectOverriddenMethodsRecurse(*Cat, Method, Methods, true);
+  }
+  
   collectOnCategoriesAfterLocation(Loc, Class->getSuperClass(), SM,
                                    Method, Methods);
 }
@@ -1072,12 +1067,13 @@ ObjCIvarDecl *ObjCInterfaceDecl::all_declared_ivar_begin() {
     for (curIvar = data().IvarList; I != E; curIvar = *I, ++I)
       curIvar->setNextIvar(*I);
   }
-  
-  for (const ObjCCategoryDecl *CDecl = getFirstClassExtension(); CDecl;
-       CDecl = CDecl->getNextClassExtension()) {
-    if (!CDecl->ivar_empty()) {
-      ObjCCategoryDecl::ivar_iterator I = CDecl->ivar_begin(),
-                                          E = CDecl->ivar_end();
+
+  for (ObjCInterfaceDecl::known_extensions_iterator
+         Ext = known_extensions_begin(),
+         ExtEnd = known_extensions_end();
+       Ext != ExtEnd; ++Ext) {
+    if (!Ext->ivar_empty()) {
+      ObjCCategoryDecl::ivar_iterator I = Ext->ivar_begin(),E = Ext->ivar_end();
       if (!data().IvarList) {
         data().IvarList = *I; ++I;
         curIvar = data().IvarList;
@@ -1115,29 +1111,41 @@ ObjCInterfaceDecl::FindCategoryDeclaration(IdentifierInfo *CategoryId) const {
   if (data().ExternallyCompleted)
     LoadExternalDefinition();
 
-  for (ObjCCategoryDecl *Category = getCategoryList();
-       Category; Category = Category->getNextClassCategory())
-    if (Category->getIdentifier() == CategoryId)
-      return Category;
+  for (visible_categories_iterator Cat = visible_categories_begin(),
+                                   CatEnd = visible_categories_end();
+       Cat != CatEnd;
+       ++Cat) {
+    if (Cat->getIdentifier() == CategoryId)
+      return *Cat;
+  }
+  
   return 0;
 }
 
 ObjCMethodDecl *
 ObjCInterfaceDecl::getCategoryInstanceMethod(Selector Sel) const {
-  for (ObjCCategoryDecl *Category = getCategoryList();
-       Category; Category = Category->getNextClassCategory())
-    if (ObjCCategoryImplDecl *Impl = Category->getImplementation())
+  for (visible_categories_iterator Cat = visible_categories_begin(),
+                                   CatEnd = visible_categories_end();
+       Cat != CatEnd;
+       ++Cat) {
+    if (ObjCCategoryImplDecl *Impl = Cat->getImplementation())
       if (ObjCMethodDecl *MD = Impl->getInstanceMethod(Sel))
         return MD;
+  }
+
   return 0;
 }
 
 ObjCMethodDecl *ObjCInterfaceDecl::getCategoryClassMethod(Selector Sel) const {
-  for (ObjCCategoryDecl *Category = getCategoryList();
-       Category; Category = Category->getNextClassCategory())
-    if (ObjCCategoryImplDecl *Impl = Category->getImplementation())
+  for (visible_categories_iterator Cat = visible_categories_begin(),
+                                   CatEnd = visible_categories_end();
+       Cat != CatEnd;
+       ++Cat) {
+    if (ObjCCategoryImplDecl *Impl = Cat->getImplementation())
       if (ObjCMethodDecl *MD = Impl->getClassMethod(Sel))
         return MD;
+  }
+  
   return 0;
 }
 
@@ -1169,10 +1177,13 @@ bool ObjCInterfaceDecl::ClassImplementsProtocol(ObjCProtocolDecl *lProto,
 
   // 2nd, look up the category.
   if (lookupCategory)
-    for (ObjCCategoryDecl *CDecl = IDecl->getCategoryList(); CDecl;
-         CDecl = CDecl->getNextClassCategory()) {
-      for (ObjCCategoryDecl::protocol_iterator PI = CDecl->protocol_begin(),
-           E = CDecl->protocol_end(); PI != E; ++PI)
+    for (visible_categories_iterator Cat = visible_categories_begin(),
+                                     CatEnd = visible_categories_end();
+         Cat != CatEnd;
+         ++Cat) {
+      for (ObjCCategoryDecl::protocol_iterator PI = Cat->protocol_begin(),
+                                               E = Cat->protocol_end();
+           PI != E; ++PI)
         if (getASTContext().ProtocolCompatibleWithProtocol(lProto, *PI))
           return true;
     }
@@ -1393,9 +1404,9 @@ ObjCCategoryDecl *ObjCCategoryDecl::Create(ASTContext &C, DeclContext *DC,
                                                        IvarLBraceLoc, IvarRBraceLoc);
   if (IDecl) {
     // Link this category into its class's category list.
-    CatDecl->NextClassCategory = IDecl->getCategoryList();
+    CatDecl->NextClassCategory = IDecl->getCategoryListRaw();
     if (IDecl->hasDefinition()) {
-      IDecl->setCategoryList(CatDecl);
+      IDecl->setCategoryListRaw(CatDecl);
       if (ASTMutationListener *L = C.getASTMutationListener())
         L->AddedObjCCategoryToInterface(CatDecl, IDecl);
     }
diff --git a/lib/AST/DumpXML.cpp b/lib/AST/DumpXML.cpp
index 1e7523f3b9..be22ae450b 100644
--- a/lib/AST/DumpXML.cpp
+++ b/lib/AST/DumpXML.cpp
@@ -748,14 +748,6 @@ struct XMLDumper : public XMLDeclVisitor<XMLDumper>,
     visitDeclContext(D);
   }
 
-  // ObjCInterfaceDecl
-  void visitCategoryList(ObjCCategoryDecl *D) {
-    if (!D) return;
-
-    TemporaryContainer C(*this, "categories");
-    for (; D; D = D->getNextClassCategory())
-      visitDeclRef(D);
-  }
   void visitObjCInterfaceDeclAttrs(ObjCInterfaceDecl *D) {
     setPointer("typeptr", D->getTypeForDecl());
     setFlag("forward_decl", !D->isThisDeclarationADefinition());
@@ -770,7 +762,17 @@ struct XMLDumper : public XMLDeclVisitor<XMLDumper>,
              I = D->protocol_begin(), E = D->protocol_end(); I != E; ++I)
         visitDeclRef(*I);
     }
-    visitCategoryList(D->getCategoryList());
+
+    if (!D->visible_categories_empty()) {
+      TemporaryContainer C(*this, "categories");
+
+      for (ObjCInterfaceDecl::visible_categories_iterator
+               Cat = D->visible_categories_begin(),
+             CatEnd = D->visible_categories_end();
+           Cat != CatEnd; ++Cat) {
+        visitDeclRef(*Cat);
+      }
+    }
   }
   void visitObjCInterfaceDeclAsContext(ObjCInterfaceDecl *D) {
     visitDeclContext(D);
diff --git a/lib/Rewrite/Frontend/RewriteModernObjC.cpp b/lib/Rewrite/Frontend/RewriteModernObjC.cpp
index d69106cfb0..53b5591ad4 100644
--- a/lib/Rewrite/Frontend/RewriteModernObjC.cpp
+++ b/lib/Rewrite/Frontend/RewriteModernObjC.cpp
@@ -7298,11 +7298,8 @@ void RewriteModernObjC::RewriteObjCCategoryImplDecl(ObjCCategoryImplDecl *IDecl,
   WriteModernMetadataDeclarations(Context, Result);
   ObjCInterfaceDecl *ClassDecl = IDecl->getClassInterface();
   // Find category declaration for this implementation.
-  ObjCCategoryDecl *CDecl=0;
-  for (CDecl = ClassDecl->getCategoryList(); CDecl;
-       CDecl = CDecl->getNextClassCategory())
-    if (CDecl->getIdentifier() == IDecl->getIdentifier())
-      break;
+  ObjCCategoryDecl *CDecl
+    = ClassDecl->FindCategoryDeclaration(IDecl->getIdentifier());
   
   std::string FullCategoryName = ClassDecl->getNameAsString();
   FullCategoryName += "_$_";
diff --git a/lib/Rewrite/Frontend/RewriteObjC.cpp b/lib/Rewrite/Frontend/RewriteObjC.cpp
index 23719cb345..18b75758ab 100644
--- a/lib/Rewrite/Frontend/RewriteObjC.cpp
+++ b/lib/Rewrite/Frontend/RewriteObjC.cpp
@@ -5744,11 +5744,8 @@ void RewriteObjCFragileABI::RewriteObjCCategoryImplDecl(ObjCCategoryImplDecl *ID
                                               std::string &Result) {
   ObjCInterfaceDecl *ClassDecl = IDecl->getClassInterface();
   // Find category declaration for this implementation.
-  ObjCCategoryDecl *CDecl;
-  for (CDecl = ClassDecl->getCategoryList(); CDecl;
-       CDecl = CDecl->getNextClassCategory())
-    if (CDecl->getIdentifier() == IDecl->getIdentifier())
-      break;
+  ObjCCategoryDecl *CDecl
+    = ClassDecl->FindCategoryDeclaration(IDecl->getIdentifier());
   
   std::string FullCategoryName = ClassDecl->getNameAsString();
   FullCategoryName += '_';
diff --git a/lib/Sema/SemaCodeComplete.cpp b/lib/Sema/SemaCodeComplete.cpp
index 5d5226dddd..5cbba239be 100644
--- a/lib/Sema/SemaCodeComplete.cpp
+++ b/lib/Sema/SemaCodeComplete.cpp
@@ -3433,9 +3433,11 @@ static void AddObjCProperties(ObjCContainerDecl *Container,
   } else if (ObjCInterfaceDecl *IFace = dyn_cast<ObjCInterfaceDecl>(Container)){
     if (AllowCategories) {
       // Look through categories.
-      for (ObjCCategoryDecl *Category = IFace->getCategoryList();
-           Category; Category = Category->getNextClassCategory())
-        AddObjCProperties(Category, AllowCategories, AllowNullaryMethods, 
+      for (ObjCInterfaceDecl::known_categories_iterator
+             Cat = IFace->known_categories_begin(),
+             CatEnd = IFace->known_categories_end();
+           Cat != CatEnd; ++Cat)
+        AddObjCProperties(*Cat, AllowCategories, AllowNullaryMethods,
                           CurContext, AddedProperties, Results);
     }
     
@@ -4806,9 +4808,13 @@ static void AddObjCMethods(ObjCContainerDecl *Container,
                    CurContext, Selectors, AllowSameLength, Results, false);
   
   // Add methods in categories.
-  for (ObjCCategoryDecl *CatDecl = IFace->getCategoryList(); CatDecl;
-       CatDecl = CatDecl->getNextClassCategory()) {
-    AddObjCMethods(CatDecl, WantInstanceMethods, WantKind, SelIdents, 
+  for (ObjCInterfaceDecl::known_categories_iterator
+         Cat = IFace->known_categories_begin(),
+         CatEnd = IFace->known_categories_end();
+       Cat != CatEnd; ++Cat) {
+    ObjCCategoryDecl *CatDecl = *Cat;
+    
+    AddObjCMethods(CatDecl, WantInstanceMethods, WantKind, SelIdents,
                    NumSelIdents, CurContext, Selectors, AllowSameLength, 
                    Results, InOriginalClass);
     
@@ -5076,11 +5082,14 @@ static ObjCMethodDecl *AddSuperSendCompletion(Sema &S, bool NeedSuperKeyword,
 
     // Check in categories or class extensions.
     if (!SuperMethod) {
-      for (ObjCCategoryDecl *Category = Class->getCategoryList(); Category;
-           Category = Category->getNextClassCategory())
-        if ((SuperMethod = Category->getMethod(CurMethod->getSelector(), 
+      for (ObjCInterfaceDecl::known_categories_iterator
+             Cat = Class->known_categories_begin(),
+             CatEnd = Class->known_categories_end();
+           Cat != CatEnd; ++Cat) {
+        if ((SuperMethod = Cat->getMethod(CurMethod->getSelector(),
                                                CurMethod->isInstanceMethod())))
           break;
+      }
     }
   }
 
@@ -5807,11 +5816,15 @@ void Sema::CodeCompleteObjCInterfaceCategory(Scope *S,
   llvm::SmallPtrSet<IdentifierInfo *, 16> CategoryNames;
   NamedDecl *CurClass
     = LookupSingleName(TUScope, ClassName, ClassNameLoc, LookupOrdinaryName);
-  if (ObjCInterfaceDecl *Class = dyn_cast_or_null<ObjCInterfaceDecl>(CurClass))
-    for (ObjCCategoryDecl *Category = Class->getCategoryList(); Category;
-         Category = Category->getNextClassCategory())
-      CategoryNames.insert(Category->getIdentifier());
-  
+  if (ObjCInterfaceDecl *Class = dyn_cast_or_null<ObjCInterfaceDecl>(CurClass)){
+    for (ObjCInterfaceDecl::visible_categories_iterator
+           Cat = Class->visible_categories_begin(),
+           CatEnd = Class->visible_categories_end();
+         Cat != CatEnd; ++Cat) {
+      CategoryNames.insert(Cat->getIdentifier());
+    }
+  }
+
   // Add all of the categories we know about.
   Results.EnterNewScope();
   TranslationUnitDecl *TU = Context.getTranslationUnitDecl();
@@ -5853,11 +5866,14 @@ void Sema::CodeCompleteObjCImplementationCategory(Scope *S,
   Results.EnterNewScope();
   bool IgnoreImplemented = true;
   while (Class) {
-    for (ObjCCategoryDecl *Category = Class->getCategoryList(); Category;
-         Category = Category->getNextClassCategory())
-      if ((!IgnoreImplemented || !Category->getImplementation()) &&
-          CategoryNames.insert(Category->