Pull new version of protobuf sources.

third_party/protobuf/objectivec/GPBMessage.m

Index: third_party/protobuf/objectivec/GPBMessage.m
diff --git a/third_party/protobuf/objectivec/GPBMessage.m b/third_party/protobuf/objectivec/GPBMessage.m
new file mode 100644
index 0000000000000000000000000000000000000000..c655edd328b04bd7ddd87432592970369ab10fbe
--- /dev/null
+++ b/third_party/protobuf/objectivec/GPBMessage.m
@@ -0,0 +1,3181 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#import "GPBMessage_PackagePrivate.h"
+
+#import <objc/runtime.h>
+#import <objc/message.h>
+
+#import "GPBArray_PackagePrivate.h"
+#import "GPBCodedInputStream_PackagePrivate.h"
+#import "GPBCodedOutputStream.h"
+#import "GPBDescriptor_PackagePrivate.h"
+#import "GPBDictionary_PackagePrivate.h"
+#import "GPBExtensionInternals.h"
+#import "GPBExtensionRegistry.h"
+#import "GPBRootObject_PackagePrivate.h"
+#import "GPBUnknownFieldSet_PackagePrivate.h"
+#import "GPBUtilities_PackagePrivate.h"
+
+NSString *const GPBMessageErrorDomain =
+    GPBNSStringifySymbol(GPBMessageErrorDomain);
+
+#ifdef DEBUG
+NSString *const GPBExceptionMessageKey =
+    GPBNSStringifySymbol(GPBExceptionMessage);
+#endif  // DEBUG
+
+static NSString *const kGPBDataCoderKey = @"GPBData";
+
+#ifndef _GPBCompileAssert
+#define _GPBCompileAssertSymbolInner(line, msg) _GPBCompileAssert ## line ## __ ## msg
+#define _GPBCompileAssertSymbol(line, msg) _GPBCompileAssertSymbolInner(line, msg)
+#define _GPBCompileAssert(test, msg) \
+    typedef char _GPBCompileAssertSymbol(__LINE__, msg) [ ((test) ? 1 : -1) ]
+#endif // _GPBCompileAssert
+
+//
+// PLEASE REMEMBER:
+//
+// This is the base class for *all* messages generated, so any selector defined,
+// *public* or *private* could end up colliding with a proto message field. So
+// avoid using selectors that could match a property, use C functions to hide
+// them, etc.
+//
+
+@interface GPBMessage () {
+ @package
+  GPBUnknownFieldSet *unknownFields_;
+  NSMutableDictionary *extensionMap_;
+  NSMutableDictionary *autocreatedExtensionMap_;
+
+  // If the object was autocreated, we remember the creator so that if we get
+  // mutated, we can inform the creator to make our field visible.
+  GPBMessage *autocreator_;
+  GPBFieldDescriptor *autocreatorField_;
+  GPBExtensionDescriptor *autocreatorExtension_;
+}
+@end
+
+static id CreateArrayForField(GPBFieldDescriptor *field,
+                              GPBMessage *autocreator)
+    __attribute__((ns_returns_retained));
+static id GetOrCreateArrayIvarWithField(GPBMessage *self,
+                                        GPBFieldDescriptor *field,
+                                        GPBFileSyntax syntax);
+static id GetArrayIvarWithField(GPBMessage *self, GPBFieldDescriptor *field);
+static id CreateMapForField(GPBFieldDescriptor *field,
+                            GPBMessage *autocreator)
+    __attribute__((ns_returns_retained));
+static id GetOrCreateMapIvarWithField(GPBMessage *self,
+                                      GPBFieldDescriptor *field,
+                                      GPBFileSyntax syntax);
+static id GetMapIvarWithField(GPBMessage *self, GPBFieldDescriptor *field);
+static NSMutableDictionary *CloneExtensionMap(NSDictionary *extensionMap,
+                                              NSZone *zone)
+    __attribute__((ns_returns_retained));
+
+static NSError *MessageError(NSInteger code, NSDictionary *userInfo) {
+  return [NSError errorWithDomain:GPBMessageErrorDomain
+                             code:code
+                         userInfo:userInfo];
+}
+
+static NSError *MessageErrorWithReason(NSInteger code, NSString *reason) {
+  NSDictionary *userInfo = nil;
+  if ([reason length]) {
+    userInfo = @{ @"Reason" : reason };
+  }
+  return MessageError(code, userInfo);
+}
+
+
+static void CheckExtension(GPBMessage *self,
+                           GPBExtensionDescriptor *extension) {
+  if ([self class] != extension.containingMessageClass) {
+    [NSException
+         raise:NSInvalidArgumentException
+        format:@"Extension %@ used on wrong class (%@ instead of %@)",
+               extension.singletonName,
+               [self class], extension.containingMessageClass];
+  }
+}
+
+static NSMutableDictionary *CloneExtensionMap(NSDictionary *extensionMap,
+                                              NSZone *zone) {
+  if (extensionMap.count == 0) {
+    return nil;
+  }
+  NSMutableDictionary *result = [[NSMutableDictionary allocWithZone:zone]
+      initWithCapacity:extensionMap.count];
+
+  for (GPBExtensionDescriptor *extension in extensionMap) {
+    id value = [extensionMap objectForKey:extension];
+    BOOL isMessageExtension = GPBExtensionIsMessage(extension);
+
+    if (extension.repeated) {
+      if (isMessageExtension) {
+        NSMutableArray *list =
+            [[NSMutableArray alloc] initWithCapacity:[value count]];
+        for (GPBMessage *listValue in value) {
+          GPBMessage *copiedValue = [listValue copyWithZone:zone];
+          [list addObject:copiedValue];
+          [copiedValue release];
+        }
+        [result setObject:list forKey:extension];
+        [list release];
+      } else {
+        NSMutableArray *copiedValue = [value mutableCopyWithZone:zone];
+        [result setObject:copiedValue forKey:extension];
+        [copiedValue release];
+      }
+    } else {
+      if (isMessageExtension) {
+        GPBMessage *copiedValue = [value copyWithZone:zone];
+        [result setObject:copiedValue forKey:extension];
+        [copiedValue release];
+      } else {
+        [result setObject:value forKey:extension];
+      }
+    }
+  }
+
+  return result;
+}
+
+static id CreateArrayForField(GPBFieldDescriptor *field,
+                              GPBMessage *autocreator) {
+  id result;
+  GPBDataType fieldDataType = GPBGetFieldDataType(field);
+  switch (fieldDataType) {
+    case GPBDataTypeBool:
+      result = [[GPBBoolArray alloc] init];
+      break;
+    case GPBDataTypeFixed32:
+    case GPBDataTypeUInt32:
+      result = [[GPBUInt32Array alloc] init];
+      break;
+    case GPBDataTypeInt32:
+    case GPBDataTypeSFixed32:
+    case GPBDataTypeSInt32:
+      result = [[GPBInt32Array alloc] init];
+      break;
+    case GPBDataTypeFixed64:
+    case GPBDataTypeUInt64:
+      result = [[GPBUInt64Array alloc] init];
+      break;
+    case GPBDataTypeInt64:
+    case GPBDataTypeSFixed64:
+    case GPBDataTypeSInt64:
+      result = [[GPBInt64Array alloc] init];
+      break;
+    case GPBDataTypeFloat:
+      result = [[GPBFloatArray alloc] init];
+      break;
+    case GPBDataTypeDouble:
+      result = [[GPBDoubleArray alloc] init];
+      break;
+
+    case GPBDataTypeEnum:
+      result = [[GPBEnumArray alloc]
+                  initWithValidationFunction:field.enumDescriptor.enumVerifier];
+      break;
+
+    case GPBDataTypeBytes:
+    case GPBDataTypeGroup:
+    case GPBDataTypeMessage:
+    case GPBDataTypeString:
+      if (autocreator) {
+        result = [[GPBAutocreatedArray alloc] init];
+      } else {
+        result = [[NSMutableArray alloc] init];
+      }
+      break;
+  }
+
+  if (autocreator) {
+    if (GPBDataTypeIsObject(fieldDataType)) {
+      GPBAutocreatedArray *autoArray = result;
+      autoArray->_autocreator =  autocreator;
+    } else {
+      GPBInt32Array *gpbArray = result;
+      gpbArray->_autocreator = autocreator;
+    }
+  }
+
+  return result;
+}
+
+static id CreateMapForField(GPBFieldDescriptor *field,
+                            GPBMessage *autocreator) {
+  id result;
+  GPBDataType keyDataType = field.mapKeyDataType;
+  GPBDataType valueDataType = GPBGetFieldDataType(field);
+  switch (keyDataType) {
+    case GPBDataTypeBool:
+      switch (valueDataType) {
+        case GPBDataTypeBool:
+          result = [[GPBBoolBoolDictionary alloc] init];
+          break;
+        case GPBDataTypeFixed32:
+        case GPBDataTypeUInt32:
+          result = [[GPBBoolUInt32Dictionary alloc] init];
+          break;
+        case GPBDataTypeInt32:
+        case GPBDataTypeSFixed32:
+        case GPBDataTypeSInt32:
+          result = [[GPBBoolInt32Dictionary alloc] init];
+          break;
+        case GPBDataTypeFixed64:
+        case GPBDataTypeUInt64:
+          result = [[GPBBoolUInt64Dictionary alloc] init];
+          break;
+        case GPBDataTypeInt64:
+        case GPBDataTypeSFixed64:
+        case GPBDataTypeSInt64:
+          result = [[GPBBoolInt64Dictionary alloc] init];
+          break;
+        case GPBDataTypeFloat:
+          result = [[GPBBoolFloatDictionary alloc] init];
+          break;
+        case GPBDataTypeDouble:
+          result = [[GPBBoolDoubleDictionary alloc] init];
+          break;
+        case GPBDataTypeEnum:
+          result = [[GPBBoolEnumDictionary alloc]
+              initWithValidationFunction:field.enumDescriptor.enumVerifier];
+          break;
+        case GPBDataTypeBytes:
+        case GPBDataTypeMessage:
+        case GPBDataTypeString:
+          result = [[GPBBoolObjectDictionary alloc] init];
+          break;
+        case GPBDataTypeGroup:
+          NSCAssert(NO, @"shouldn't happen");
+          return nil;
+      }
+      break;
+    case GPBDataTypeFixed32:
+    case GPBDataTypeUInt32:
+      switch (valueDataType) {
+        case GPBDataTypeBool:
+          result = [[GPBUInt32BoolDictionary alloc] init];
+          break;
+        case GPBDataTypeFixed32:
+        case GPBDataTypeUInt32:
+          result = [[GPBUInt32UInt32Dictionary alloc] init];
+          break;
+        case GPBDataTypeInt32:
+        case GPBDataTypeSFixed32:
+        case GPBDataTypeSInt32:
+          result = [[GPBUInt32Int32Dictionary alloc] init];
+          break;
+        case GPBDataTypeFixed64:
+        case GPBDataTypeUInt64:
+          result = [[GPBUInt32UInt64Dictionary alloc] init];
+          break;
+        case GPBDataTypeInt64:
+        case GPBDataTypeSFixed64:
+        case GPBDataTypeSInt64:
+          result = [[GPBUInt32Int64Dictionary alloc] init];
+          break;
+        case GPBDataTypeFloat:
+          result = [[GPBUInt32FloatDictionary alloc] init];
+          break;
+        case GPBDataTypeDouble:
+          result = [[GPBUInt32DoubleDictionary alloc] init];
+          break;
+        case GPBDataTypeEnum:
+          result = [[GPBUInt32EnumDictionary alloc]
+              initWithValidationFunction:field.enumDescriptor.enumVerifier];
+          break;
+        case GPBDataTypeBytes:
+        case GPBDataTypeMessage:
+        case GPBDataTypeString:
+          result = [[GPBUInt32ObjectDictionary alloc] init];
+          break;
+        case GPBDataTypeGroup:
+          NSCAssert(NO, @"shouldn't happen");
+          return nil;
+      }
+      break;
+    case GPBDataTypeInt32:
+    case GPBDataTypeSFixed32:
+    case GPBDataTypeSInt32:
+      switch (valueDataType) {
+        case GPBDataTypeBool:
+          result = [[GPBInt32BoolDictionary alloc] init];
+          break;
+        case GPBDataTypeFixed32:
+        case GPBDataTypeUInt32:
+          result = [[GPBInt32UInt32Dictionary alloc] init];
+          break;
+        case GPBDataTypeInt32:
+        case GPBDataTypeSFixed32:
+        case GPBDataTypeSInt32:
+          result = [[GPBInt32Int32Dictionary alloc] init];
+          break;
+        case GPBDataTypeFixed64:
+        case GPBDataTypeUInt64:
+          result = [[GPBInt32UInt64Dictionary alloc] init];
+          break;
+        case GPBDataTypeInt64:
+        case GPBDataTypeSFixed64:
+        case GPBDataTypeSInt64:
+          result = [[GPBInt32Int64Dictionary alloc] init];
+          break;
+        case GPBDataTypeFloat:
+          result = [[GPBInt32FloatDictionary alloc] init];
+          break;
+        case GPBDataTypeDouble:
+          result = [[GPBInt32DoubleDictionary alloc] init];
+          break;
+        case GPBDataTypeEnum:
+          result = [[GPBInt32EnumDictionary alloc]
+              initWithValidationFunction:field.enumDescriptor.enumVerifier];
+          break;
+        case GPBDataTypeBytes:
+        case GPBDataTypeMessage:
+        case GPBDataTypeString:
+          result = [[GPBInt32ObjectDictionary alloc] init];
+          break;
+        case GPBDataTypeGroup:
+          NSCAssert(NO, @"shouldn't happen");
+          return nil;
+      }
+      break;
+    case GPBDataTypeFixed64:
+    case GPBDataTypeUInt64:
+      switch (valueDataType) {
+        case GPBDataTypeBool:
+          result = [[GPBUInt64BoolDictionary alloc] init];
+          break;
+        case GPBDataTypeFixed32:
+        case GPBDataTypeUInt32:
+          result = [[GPBUInt64UInt32Dictionary alloc] init];
+          break;
+        case GPBDataTypeInt32:
+        case GPBDataTypeSFixed32:
+        case GPBDataTypeSInt32:
+          result = [[GPBUInt64Int32Dictionary alloc] init];
+          break;
+        case GPBDataTypeFixed64:
+        case GPBDataTypeUInt64:
+          result = [[GPBUInt64UInt64Dictionary alloc] init];
+          break;
+        case GPBDataTypeInt64:
+        case GPBDataTypeSFixed64:
+        case GPBDataTypeSInt64:
+          result = [[GPBUInt64Int64Dictionary alloc] init];
+          break;
+        case GPBDataTypeFloat:
+          result = [[GPBUInt64FloatDictionary alloc] init];
+          break;
+        case GPBDataTypeDouble:
+          result = [[GPBUInt64DoubleDictionary alloc] init];
+          break;
+        case GPBDataTypeEnum:
+          result = [[GPBUInt64EnumDictionary alloc]
+              initWithValidationFunction:field.enumDescriptor.enumVerifier];
+          break;
+        case GPBDataTypeBytes:
+        case GPBDataTypeMessage:
+        case GPBDataTypeString:
+          result = [[GPBUInt64ObjectDictionary alloc] init];
+          break;
+        case GPBDataTypeGroup:
+          NSCAssert(NO, @"shouldn't happen");
+          return nil;
+      }
+      break;
+    case GPBDataTypeInt64:
+    case GPBDataTypeSFixed64:
+    case GPBDataTypeSInt64:
+      switch (valueDataType) {
+        case GPBDataTypeBool:
+          result = [[GPBInt64BoolDictionary alloc] init];
+          break;
+        case GPBDataTypeFixed32:
+        case GPBDataTypeUInt32:
+          result = [[GPBInt64UInt32Dictionary alloc] init];
+          break;
+        case GPBDataTypeInt32:
+        case GPBDataTypeSFixed32:
+        case GPBDataTypeSInt32:
+          result = [[GPBInt64Int32Dictionary alloc] init];
+          break;
+        case GPBDataTypeFixed64:
+        case GPBDataTypeUInt64:
+          result = [[GPBInt64UInt64Dictionary alloc] init];
+          break;
+        case GPBDataTypeInt64:
+        case GPBDataTypeSFixed64:
+        case GPBDataTypeSInt64:
+          result = [[GPBInt64Int64Dictionary alloc] init];
+          break;
+        case GPBDataTypeFloat:
+          result = [[GPBInt64FloatDictionary alloc] init];
+          break;
+        case GPBDataTypeDouble:
+          result = [[GPBInt64DoubleDictionary alloc] init];
+          break;
+        case GPBDataTypeEnum:
+          result = [[GPBInt64EnumDictionary alloc]
+              initWithValidationFunction:field.enumDescriptor.enumVerifier];
+          break;
+        case GPBDataTypeBytes:
+        case GPBDataTypeMessage:
+        case GPBDataTypeString:
+          result = [[GPBInt64ObjectDictionary alloc] init];
+          break;
+        case GPBDataTypeGroup:
+          NSCAssert(NO, @"shouldn't happen");
+          return nil;
+      }
+      break;
+    case GPBDataTypeString:
+      switch (valueDataType) {
+        case GPBDataTypeBool:
+          result = [[GPBStringBoolDictionary alloc] init];
+          break;
+        case GPBDataTypeFixed32:
+        case GPBDataTypeUInt32:
+          result = [[GPBStringUInt32Dictionary alloc] init];
+          break;
+        case GPBDataTypeInt32:
+        case GPBDataTypeSFixed32:
+        case GPBDataTypeSInt32:
+          result = [[GPBStringInt32Dictionary alloc] init];
+          break;
+        case GPBDataTypeFixed64:
+        case GPBDataTypeUInt64:
+          result = [[GPBStringUInt64Dictionary alloc] init];
+          break;
+        case GPBDataTypeInt64:
+        case GPBDataTypeSFixed64:
+        case GPBDataTypeSInt64:
+          result = [[GPBStringInt64Dictionary alloc] init];
+          break;
+        case GPBDataTypeFloat:
+          result = [[GPBStringFloatDictionary alloc] init];
+          break;
+        case GPBDataTypeDouble:
+          result = [[GPBStringDoubleDictionary alloc] init];
+          break;
+        case GPBDataTypeEnum:
+          result = [[GPBStringEnumDictionary alloc]
+              initWithValidationFunction:field.enumDescriptor.enumVerifier];
+          break;
+        case GPBDataTypeBytes:
+        case GPBDataTypeMessage:
+        case GPBDataTypeString:
+          if (autocreator) {
+            result = [[GPBAutocreatedDictionary alloc] init];
+          } else {
+            result = [[NSMutableDictionary alloc] init];
+          }
+          break;
+        case GPBDataTypeGroup:
+          NSCAssert(NO, @"shouldn't happen");
+          return nil;
+      }
+      break;
+
+    case GPBDataTypeFloat:
+    case GPBDataTypeDouble:
+    case GPBDataTypeEnum:
+    case GPBDataTypeBytes:
+    case GPBDataTypeGroup:
+    case GPBDataTypeMessage:
+      NSCAssert(NO, @"shouldn't happen");
+      return nil;
+  }
+
+  if (autocreator) {
+    if ((keyDataType == GPBDataTypeString) &&
+        GPBDataTypeIsObject(valueDataType)) {
+      GPBAutocreatedDictionary *autoDict = result;
+      autoDict->_autocreator =  autocreator;
+    } else {
+      GPBInt32Int32Dictionary *gpbDict = result;
+      gpbDict->_autocreator = autocreator;
+    }
+  }
+
+  return result;
+}
+
+#if !defined(__clang_analyzer__)
+// These functions are blocked from the analyzer because the analyzer sees the
+// GPBSetRetainedObjectIvarWithFieldInternal() call as consuming the array/map,
+// so use of the array/map after the call returns is flagged as a use after
+// free.
+// But GPBSetRetainedObjectIvarWithFieldInternal() is "consuming" the retain
+// count be holding onto the object (it is transfering it), the object is
+// still valid after returning from the call.  The other way to avoid this
+// would be to add a -retain/-autorelease, but that would force every
+// repeated/map field parsed into the autorelease pool which is both a memory
+// and performance hit.
+
+static id GetOrCreateArrayIvarWithField(GPBMessage *self,
+                                        GPBFieldDescriptor *field,
+                                        GPBFileSyntax syntax) {
+  id array = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+  if (!array) {
+    // No lock needed, this is called from places expecting to mutate
+    // so no threading protection is needed.
+    array = CreateArrayForField(field, nil);
+    GPBSetRetainedObjectIvarWithFieldInternal(self, field, array, syntax);
+  }
+  return array;
+}
+
+// This is like GPBGetObjectIvarWithField(), but for arrays, it should
+// only be used to wire the method into the class.
+static id GetArrayIvarWithField(GPBMessage *self, GPBFieldDescriptor *field) {
+  id array = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+  if (!array) {
+    // Check again after getting the lock.
+    OSSpinLockLock(&self->readOnlyMutex_);
+    array = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+    if (!array) {
+      array = CreateArrayForField(field, self);
+      GPBSetAutocreatedRetainedObjectIvarWithField(self, field, array);
+    }
+    OSSpinLockUnlock(&self->readOnlyMutex_);
+  }
+  return array;
+}
+
+static id GetOrCreateMapIvarWithField(GPBMessage *self,
+                                      GPBFieldDescriptor *field,
+                                      GPBFileSyntax syntax) {
+  id dict = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+  if (!dict) {
+    // No lock needed, this is called from places expecting to mutate
+    // so no threading protection is needed.
+    dict = CreateMapForField(field, nil);
+    GPBSetRetainedObjectIvarWithFieldInternal(self, field, dict, syntax);
+  }
+  return dict;
+}
+
+// This is like GPBGetObjectIvarWithField(), but for maps, it should
+// only be used to wire the method into the class.
+static id GetMapIvarWithField(GPBMessage *self, GPBFieldDescriptor *field) {
+  id dict = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+  if (!dict) {
+    // Check again after getting the lock.
+    OSSpinLockLock(&self->readOnlyMutex_);
+    dict = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+    if (!dict) {
+      dict = CreateMapForField(field, self);
+      GPBSetAutocreatedRetainedObjectIvarWithField(self, field, dict);
+    }
+    OSSpinLockUnlock(&self->readOnlyMutex_);
+  }
+  return dict;
+}
+
+#endif  // !defined(__clang_analyzer__)
+
+GPBMessage *GPBCreateMessageWithAutocreator(Class msgClass,
+                                            GPBMessage *autocreator,
+                                            GPBFieldDescriptor *field) {
+  GPBMessage *message = [[msgClass alloc] init];
+  message->autocreator_ = autocreator;
+  message->autocreatorField_ = [field retain];
+  return message;
+}
+
+static GPBMessage *CreateMessageWithAutocreatorForExtension(
+    Class msgClass, GPBMessage *autocreator, GPBExtensionDescriptor *extension)
+    __attribute__((ns_returns_retained));
+
+static GPBMessage *CreateMessageWithAutocreatorForExtension(
+    Class msgClass, GPBMessage *autocreator,
+    GPBExtensionDescriptor *extension) {
+  GPBMessage *message = [[msgClass alloc] init];
+  message->autocreator_ = autocreator;
+  message->autocreatorExtension_ = [extension retain];
+  return message;
+}
+
+BOOL GPBWasMessageAutocreatedBy(GPBMessage *message, GPBMessage *parent) {
+  return (message->autocreator_ == parent);
+}
+
+void GPBBecomeVisibleToAutocreator(GPBMessage *self) {
+  // Message objects that are implicitly created by accessing a message field
+  // are initially not visible via the hasX selector. This method makes them
+  // visible.
+  if (self->autocreator_) {
+    // This will recursively make all parent messages visible until it reaches a
+    // super-creator that's visible.
+    if (self->autocreatorField_) {
+      GPBFileSyntax syntax = [self->autocreator_ descriptor].file.syntax;
+      GPBSetObjectIvarWithFieldInternal(self->autocreator_,
+                                        self->autocreatorField_, self, syntax);
+    } else {
+      [self->autocreator_ setExtension:self->autocreatorExtension_ value:self];
+    }
+  }
+}
+
+void GPBAutocreatedArrayModified(GPBMessage *self, id array) {
+  // When one of our autocreated arrays adds elements, make it visible.
+  GPBDescriptor *descriptor = [[self class] descriptor];
+  for (GPBFieldDescriptor *field in descriptor->fields_) {
+    if (field.fieldType == GPBFieldTypeRepeated) {
+      id curArray = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+      if (curArray == array) {
+        if (GPBFieldDataTypeIsObject(field)) {
+          GPBAutocreatedArray *autoArray = array;
+          autoArray->_autocreator = nil;
+        } else {
+          GPBInt32Array *gpbArray = array;
+          gpbArray->_autocreator = nil;
+        }
+        GPBBecomeVisibleToAutocreator(self);
+        return;
+      }
+    }
+  }
+  NSCAssert(NO, @"Unknown autocreated %@ for %@.", [array class], self);
+}
+
+void GPBAutocreatedDictionaryModified(GPBMessage *self, id dictionary) {
+  // When one of our autocreated dicts adds elements, make it visible.
+  GPBDescriptor *descriptor = [[self class] descriptor];
+  for (GPBFieldDescriptor *field in descriptor->fields_) {
+    if (field.fieldType == GPBFieldTypeMap) {
+      id curDict = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+      if (curDict == dictionary) {
+        if ((field.mapKeyDataType == GPBDataTypeString) &&
+            GPBFieldDataTypeIsObject(field)) {
+          GPBAutocreatedDictionary *autoDict = dictionary;
+          autoDict->_autocreator = nil;
+        } else {
+          GPBInt32Int32Dictionary *gpbDict = dictionary;
+          gpbDict->_autocreator = nil;
+        }
+        GPBBecomeVisibleToAutocreator(self);
+        return;
+      }
+    }
+  }
+  NSCAssert(NO, @"Unknown autocreated %@ for %@.", [dictionary class], self);
+}
+
+void GPBClearMessageAutocreator(GPBMessage *self) {
+  if ((self == nil) || !self->autocreator_) {
+    return;
+  }
+
+#if DEBUG && !defined(NS_BLOCK_ASSERTIONS)
+  // Either the autocreator must have its "has" flag set to YES, or it must be
+  // NO and not equal to ourselves.
+  BOOL autocreatorHas =
+      (self->autocreatorField_
+           ? GPBGetHasIvarField(self->autocreator_, self->autocreatorField_)
+           : [self->autocreator_ hasExtension:self->autocreatorExtension_]);
+  GPBMessage *autocreatorFieldValue =
+      (self->autocreatorField_
+           ? GPBGetObjectIvarWithFieldNoAutocreate(self->autocreator_,
+                                                   self->autocreatorField_)
+           : [self->autocreator_->autocreatedExtensionMap_
+                 objectForKey:self->autocreatorExtension_]);
+  NSCAssert(autocreatorHas || autocreatorFieldValue != self,
+            @"Cannot clear autocreator because it still refers to self, self: %@.",
+            self);
+
+#endif  // DEBUG && !defined(NS_BLOCK_ASSERTIONS)
+
+  self->autocreator_ = nil;
+  [self->autocreatorField_ release];
+  self->autocreatorField_ = nil;
+  [self->autocreatorExtension_ release];
+  self->autocreatorExtension_ = nil;
+}
+
+static GPBUnknownFieldSet *GetOrMakeUnknownFields(GPBMessage *self) {
+  if (!self->unknownFields_) {
+    self->unknownFields_ = [[GPBUnknownFieldSet alloc] init];
+    GPBBecomeVisibleToAutocreator(self);
+  }
+  return self->unknownFields_;
+}
+
+@implementation GPBMessage
+
++ (void)initialize {
+  Class pbMessageClass = [GPBMessage class];
+  if ([self class] == pbMessageClass) {
+    // This is here to start up the "base" class descriptor.
+    [self descriptor];
+    // Message shares extension method resolving with GPBRootObject so insure
+    // it is started up at the same time.
+    (void)[GPBRootObject class];
+  } else if ([self superclass] == pbMessageClass) {
+    // This is here to start up all the "message" subclasses. Just needs to be
+    // done for the messages, not any of the subclasses.
+    // This must be done in initialize to enforce thread safety of start up of
+    // the protocol buffer library.
+    // Note: The generated code for -descriptor calls
+    // +[GPBDescriptor allocDescriptorForClass:...], passing the GPBRootObject
+    // subclass for the file.  That call chain is what ensures that *Root class
+    // is started up to support extension resolution off the message class
+    // (+resolveClassMethod: below) in a thread safe manner.
+    [self descriptor];
+  }
+}
+
++ (instancetype)allocWithZone:(NSZone *)zone {
+  // Override alloc to allocate our classes with the additional storage
+  // required for the instance variables.
+  GPBDescriptor *descriptor = [self descriptor];
+  return NSAllocateObject(self, descriptor->storageSize_, zone);
+}
+
++ (instancetype)alloc {
+  return [self allocWithZone:nil];
+}
+
++ (GPBDescriptor *)descriptor {
+  // This is thread safe because it is called from +initialize.
+  static GPBDescriptor *descriptor = NULL;
+  static GPBFileDescriptor *fileDescriptor = NULL;
+  if (!descriptor) {
+    // Use a dummy file that marks it as proto2 syntax so when used generically
+    // it supports unknowns/etc.
+    fileDescriptor =
+        [[GPBFileDescriptor alloc] initWithPackage:@"internal"
+                                            syntax:GPBFileSyntaxProto2];
+
+    descriptor = [GPBDescriptor allocDescriptorForClass:[GPBMessage class]
+                                              rootClass:Nil
+                                                   file:fileDescriptor
+                                                 fields:NULL
+                                             fieldCount:0
+                                                 oneofs:NULL
+                                             oneofCount:0
+                                                  enums:NULL
+                                              enumCount:0
+                                                 ranges:NULL
+                                             rangeCount:0
+                                            storageSize:0
+                                             wireFormat:NO];
+  }
+  return descriptor;
+}
+
++ (instancetype)message {
+  return [[[self alloc] init] autorelease];
+}
+
+- (instancetype)init {
+  if ((self = [super init])) {
+    messageStorage_ = (GPBMessage_StoragePtr)(
+        ((uint8_t *)self) + class_getInstanceSize([self class]));
+
+    readOnlyMutex_ = OS_SPINLOCK_INIT;
+  }
+
+  return self;
+}
+
+- (instancetype)initWithData:(NSData *)data error:(NSError **)errorPtr {
+  return [self initWithData:data extensionRegistry:nil error:errorPtr];
+}
+
+- (instancetype)initWithData:(NSData *)data
+           extensionRegistry:(GPBExtensionRegistry *)extensionRegistry
+                       error:(NSError **)errorPtr {
+  if ((self = [self init])) {
+    @try {
+      [self mergeFromData:data extensionRegistry:extensionRegistry];
+      if (errorPtr) {
+        *errorPtr = nil;
+      }
+    }
+    @catch (NSException *exception) {
+      [self release];
+      self = nil;
+      if (errorPtr) {
+        *errorPtr = MessageErrorWithReason(GPBMessageErrorCodeMalformedData,
+                                           exception.reason);
+      }
+    }
+#ifdef DEBUG
+    if (self && !self.initialized) {
+      [self release];
+      self = nil;
+      if (errorPtr) {
+        *errorPtr = MessageError(GPBMessageErrorCodeMissingRequiredField, nil);
+      }
+    }
+#endif
+  }
+  return self;
+}
+
+- (instancetype)initWithCodedInputStream:(GPBCodedInputStream *)input
+                       extensionRegistry:
+                           (GPBExtensionRegistry *)extensionRegistry
+                                   error:(NSError **)errorPtr {
+  if ((self = [self init])) {
+    @try {
+      [self mergeFromCodedInputStream:input extensionRegistry:extensionRegistry];
+      if (errorPtr) {
+        *errorPtr = nil;
+      }
+    }
+    @catch (NSException *exception) {
+      [self release];
+      self = nil;
+      if (errorPtr) {
+        *errorPtr = MessageErrorWithReason(GPBMessageErrorCodeMalformedData,
+                                           exception.reason);
+      }
+    }
+#ifdef DEBUG
+    if (self && !self.initialized) {
+      [self release];
+      self = nil;
+      if (errorPtr) {
+        *errorPtr = MessageError(GPBMessageErrorCodeMissingRequiredField, nil);
+      }
+    }
+#endif
+  }
+  return self;
+}
+
+- (void)dealloc {
+  [self internalClear:NO];
+  NSCAssert(!autocreator_, @"Autocreator was not cleared before dealloc.");
+  [super dealloc];
+}
+
+- (void)copyFieldsInto:(GPBMessage *)message
+                  zone:(NSZone *)zone
+            descriptor:(GPBDescriptor *)descriptor {
+  // Copy all the storage...
+  memcpy(message->messageStorage_, messageStorage_, descriptor->storageSize_);
+
+  GPBFileSyntax syntax = descriptor.file.syntax;
+
+  // Loop over the fields doing fixup...
+  for (GPBFieldDescriptor *field in descriptor->fields_) {
+    if (GPBFieldIsMapOrArray(field)) {
+      id value = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+      if (value) {
+        // We need to copy the array/map, but the catch is for message fields,
+        // we also need to ensure all the messages as those need copying also.
+        id newValue;
+        if (GPBFieldDataTypeIsMessage(field)) {
+          if (field.fieldType == GPBFieldTypeRepeated) {
+            NSArray *existingArray = (NSArray *)value;
+            NSMutableArray *newArray =
+                [[NSMutableArray alloc] initWithCapacity:existingArray.count];
+            newValue = newArray;
+            for (GPBMessage *msg in existingArray) {
+              GPBMessage *copiedMsg = [msg copyWithZone:zone];
+              [newArray addObject:copiedMsg];
+              [copiedMsg release];
+            }
+          } else {
+            if (field.mapKeyDataType == GPBDataTypeString) {
+              // Map is an NSDictionary.
+              NSDictionary *existingDict = value;
+              NSMutableDictionary *newDict = [[NSMutableDictionary alloc]
+                  initWithCapacity:existingDict.count];
+              newValue = newDict;
+              [existingDict enumerateKeysAndObjectsUsingBlock:^(NSString *key,
+                                                                GPBMessage *msg,
+                                                                BOOL *stop) {
+#pragma unused(stop)
+                GPBMessage *copiedMsg = [msg copyWithZone:zone];
+                [newDict setObject:copiedMsg forKey:key];
+                [copiedMsg release];
+              }];
+            } else {
+              // Is one of the GPB*ObjectDictionary classes.  Type doesn't
+              // matter, just need one to invoke the selector.
+              GPBInt32ObjectDictionary *existingDict = value;
+              newValue = [existingDict deepCopyWithZone:zone];
+            }
+          }
+        } else {
+          // Not messages (but is a map/array)...
+          if (field.fieldType == GPBFieldTypeRepeated) {
+            if (GPBFieldDataTypeIsObject(field)) {
+              // NSArray
+              newValue = [value mutableCopyWithZone:zone];
+            } else {
+              // GPB*Array
+              newValue = [value copyWithZone:zone];
+            }
+          } else {
+            if (field.mapKeyDataType == GPBDataTypeString) {
+              // NSDictionary
+              newValue = [value mutableCopyWithZone:zone];
+            } else {
+              // Is one of the GPB*Dictionary classes.  Type doesn't matter,
+              // just need one to invoke the selector.
+              GPBInt32Int32Dictionary *existingDict = value;
+              newValue = [existingDict copyWithZone:zone];
+            }
+          }
+        }
+        // We retain here because the memcpy picked up the pointer value and
+        // the next call to SetRetainedObject... will release the current value.
+        [value retain];
+        GPBSetRetainedObjectIvarWithFieldInternal(message, field, newValue,
+                                                  syntax);
+      }
+    } else if (GPBFieldDataTypeIsMessage(field)) {
+      // For object types, if we have a value, copy it.  If we don't,
+      // zero it to remove the pointer to something that was autocreated
+      // (and the ptr just got memcpyed).
+      if (GPBGetHasIvarField(self, field)) {
+        GPBMessage *value = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        GPBMessage *newValue = [value copyWithZone:zone];
+        // We retain here because the memcpy picked up the pointer value and
+        // the next call to SetRetainedObject... will release the current value.
+        [value retain];
+        GPBSetRetainedObjectIvarWithFieldInternal(message, field, newValue,
+                                                  syntax);
+      } else {
+        uint8_t *storage = (uint8_t *)message->messageStorage_;
+        id *typePtr = (id *)&storage[field->description_->offset];
+        *typePtr = NULL;
+      }
+    } else if (GPBFieldDataTypeIsObject(field) &&
+               GPBGetHasIvarField(self, field)) {
+      // A set string/data value (message picked off above), copy it.
+      id value = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+      id newValue = [value copyWithZone:zone];
+      // We retain here because the memcpy picked up the pointer value and
+      // the next call to SetRetainedObject... will release the current value.
+      [value retain];
+      GPBSetRetainedObjectIvarWithFieldInternal(message, field, newValue,
+                                                syntax);
+    } else {
+      // memcpy took care of the rest of the primitive fields if they were set.
+    }
+  }  // for (field in descriptor->fields_)
+}
+
+- (id)copyWithZone:(NSZone *)zone {
+  GPBDescriptor *descriptor = [self descriptor];
+  GPBMessage *result = [[descriptor.messageClass allocWithZone:zone] init];
+
+  [self copyFieldsInto:result zone:zone descriptor:descriptor];
+  // Make immutable copies of the extra bits.
+  result->unknownFields_ = [unknownFields_ copyWithZone:zone];
+  result->extensionMap_ = CloneExtensionMap(extensionMap_, zone);
+  return result;
+}
+
+- (void)clear {
+  [self internalClear:YES];
+}
+
+- (void)internalClear:(BOOL)zeroStorage {
+  GPBDescriptor *descriptor = [self descriptor];
+  for (GPBFieldDescriptor *field in descriptor->fields_) {
+    if (GPBFieldIsMapOrArray(field)) {
+      id arrayOrMap = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+      if (arrayOrMap) {
+        if (field.fieldType == GPBFieldTypeRepeated) {
+          if (GPBFieldDataTypeIsObject(field)) {
+            GPBAutocreatedArray *autoArray = arrayOrMap;
+            if (autoArray->_autocreator == self) {
+              autoArray->_autocreator = nil;
+            }
+          } else {
+            // Type doesn't matter, it is a GPB*Array.
+            GPBInt32Array *gpbArray = arrayOrMap;
+            if (gpbArray->_autocreator == self) {
+              gpbArray->_autocreator = nil;
+            }
+          }
+        } else {
+          if ((field.mapKeyDataType == GPBDataTypeString) &&
+              GPBFieldDataTypeIsObject(field)) {
+            GPBAutocreatedDictionary *autoDict = arrayOrMap;
+            if (autoDict->_autocreator == self) {
+              autoDict->_autocreator = nil;
+            }
+          } else {
+            // Type doesn't matter, it is a GPB*Dictionary.
+            GPBInt32Int32Dictionary *gpbDict = arrayOrMap;
+            if (gpbDict->_autocreator == self) {
+              gpbDict->_autocreator = nil;
+            }
+          }
+        }
+        [arrayOrMap release];
+      }
+    } else if (GPBFieldDataTypeIsMessage(field)) {
+      GPBClearAutocreatedMessageIvarWithField(self, field);
+      GPBMessage *value = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+      [value release];
+    } else if (GPBFieldDataTypeIsObject(field) &&
+               GPBGetHasIvarField(self, field)) {
+      id value = GPBGetObjectIvarWithField(self, field);
+      [value release];
+    }
+  }
+
+  // GPBClearMessageAutocreator() expects that its caller has already been
+  // removed from autocreatedExtensionMap_ so we set to nil first.
+  NSArray *autocreatedValues = [autocreatedExtensionMap_ allValues];
+  [autocreatedExtensionMap_ release];
+  autocreatedExtensionMap_ = nil;
+
+  // Since we're clearing all of our extensions, make sure that we clear the
+  // autocreator on any that we've created so they no longer refer to us.
+  for (GPBMessage *value in autocreatedValues) {
+    NSCAssert(GPBWasMessageAutocreatedBy(value, self),
+              @"Autocreated extension does not refer back to self.");
+    GPBClearMessageAutocreator(value);
+  }
+
+  [extensionMap_ release];
+  extensionMap_ = nil;
+  [unknownFields_ release];
+  unknownFields_ = nil;
+
+  // Note that clearing does not affect autocreator_. If we are being cleared
+  // because of a dealloc, then autocreator_ should be nil anyway. If we are
+  // being cleared because someone explicitly clears us, we don't want to
+  // sever our relationship with our autocreator.
+
+  if (zeroStorage) {
+    memset(messageStorage_, 0, descriptor->storageSize_);
+  }
+}
+
+- (BOOL)isInitialized {
+  GPBDescriptor *descriptor = [self descriptor];
+  for (GPBFieldDescriptor *field in descriptor->fields_) {
+    if (field.isRequired) {
+      if (!GPBGetHasIvarField(self, field)) {
+        return NO;
+      }
+    }
+    if (GPBFieldDataTypeIsMessage(field)) {
+      GPBFieldType fieldType = field.fieldType;
+      if (fieldType == GPBFieldTypeSingle) {
+        if (field.isRequired) {
+          GPBMessage *message = GPBGetMessageMessageField(self, field);
+          if (!message.initialized) {
+            return NO;
+          }
+        } else {
+          NSAssert(field.isOptional,
+                   @"%@: Single message field %@ not required or optional?",
+                   [self class], field.name);
+          if (GPBGetHasIvarField(self, field)) {
+            GPBMessage *message = GPBGetMessageMessageField(self, field);
+            if (!message.initialized) {
+              return NO;
+            }
+          }
+        }
+      } else if (fieldType == GPBFieldTypeRepeated) {
+        NSArray *array = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        for (GPBMessage *message in array) {
+          if (!message.initialized) {
+            return NO;
+          }
+        }
+      } else {  // fieldType == GPBFieldTypeMap
+        if (field.mapKeyDataType == GPBDataTypeString) {
+          NSDictionary *map =
+              GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+          if (map && !GPBDictionaryIsInitializedInternalHelper(map, field)) {
+            return NO;
+          }
+        } else {
+          // Real type is GPB*ObjectDictionary, exact type doesn't matter.
+          GPBInt32ObjectDictionary *map =
+              GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+          if (map && ![map isInitialized]) {
+            return NO;
+          }
+        }
+      }
+    }
+  }
+
+  __block BOOL result = YES;
+  [extensionMap_
+      enumerateKeysAndObjectsUsingBlock:^(GPBExtensionDescriptor *extension,
+                                          id obj,
+                                          BOOL *stop) {
+        if (GPBExtensionIsMessage(extension)) {
+          if (extension.isRepeated) {
+            for (GPBMessage *msg in obj) {
+              if (!msg.initialized) {
+                result = NO;
+                *stop = YES;
+                break;
+              }
+            }
+          } else {
+            GPBMessage *asMsg = obj;
+            if (!asMsg.initialized) {
+              result = NO;
+              *stop = YES;
+            }
+          }
+        }
+      }];
+  return result;
+}
+
+- (GPBDescriptor *)descriptor {
+  return [[self class] descriptor];
+}
+
+- (NSData *)data {
+#ifdef DEBUG
+  if (!self.initialized) {
+    return nil;
+  }
+#endif
+  NSMutableData *data = [NSMutableData dataWithLength:[self serializedSize]];
+  GPBCodedOutputStream *stream =
+      [[GPBCodedOutputStream alloc] initWithData:data];
+  @try {
+    [self writeToCodedOutputStream:stream];
+  }
+  @catch (NSException *exception) {
+    // This really shouldn't happen. The only way writeToCodedOutputStream:
+    // could throw is if something in the library has a bug and the
+    // serializedSize was wrong.
+#ifdef DEBUG
+    NSLog(@"%@: Internal exception while building message data: %@",
+          [self class], exception);
+#endif
+    data = nil;
+  }
+  [stream release];
+  return data;
+}
+
+- (NSData *)delimitedData {
+  size_t serializedSize = [self serializedSize];
+  size_t varintSize = GPBComputeRawVarint32SizeForInteger(serializedSize);
+  NSMutableData *data =
+      [NSMutableData dataWithLength:(serializedSize + varintSize)];
+  GPBCodedOutputStream *stream =
+      [[GPBCodedOutputStream alloc] initWithData:data];
+  @try {
+    [self writeDelimitedToCodedOutputStream:stream];
+  }
+  @catch (NSException *exception) {
+    // This really shouldn't happen.  The only way writeToCodedOutputStream:
+    // could throw is if something in the library has a bug and the
+    // serializedSize was wrong.
+#ifdef DEBUG
+    NSLog(@"%@: Internal exception while building message delimitedData: %@",
+          [self class], exception);
+#endif
+    data = nil;
+  }
+  [stream release];
+  return data;
+}
+
+- (void)writeToOutputStream:(NSOutputStream *)output {
+  GPBCodedOutputStream *stream =
+      [[GPBCodedOutputStream alloc] initWithOutputStream:output];
+  [self writeToCodedOutputStream:stream];
+  [stream release];
+}
+
+- (void)writeToCodedOutputStream:(GPBCodedOutputStream *)output {
+  GPBDescriptor *descriptor = [self descriptor];
+  NSArray *fieldsArray = descriptor->fields_;
+  NSUInteger fieldCount = fieldsArray.count;
+  const GPBExtensionRange *extensionRanges = descriptor.extensionRanges;
+  NSUInteger extensionRangesCount = descriptor.extensionRangesCount;
+  for (NSUInteger i = 0, j = 0; i < fieldCount || j < extensionRangesCount;) {
+    if (i == fieldCount) {
+      [self writeExtensionsToCodedOutputStream:output
+                                         range:extensionRanges[j++]];
+    } else if (j == extensionRangesCount ||
+               GPBFieldNumber(fieldsArray[i]) < extensionRanges[j].start) {
+      [self writeField:fieldsArray[i++] toCodedOutputStream:output];
+    } else {
+      [self writeExtensionsToCodedOutputStream:output
+                                         range:extensionRanges[j++]];
+    }
+  }
+  if (descriptor.isWireFormat) {
+    [unknownFields_ writeAsMessageSetTo:output];
+  } else {
+    [unknownFields_ writeToCodedOutputStream:output];
+  }
+}
+
+- (void)writeDelimitedToOutputStream:(NSOutputStream *)output {
+  GPBCodedOutputStream *codedOutput =
+      [[GPBCodedOutputStream alloc] initWithOutputStream:output];
+  [self writeDelimitedToCodedOutputStream:codedOutput];
+  [codedOutput release];
+}
+
+- (void)writeDelimitedToCodedOutputStream:(GPBCodedOutputStream *)output {
+  [output writeRawVarintSizeTAs32:[self serializedSize]];
+  [self writeToCodedOutputStream:output];
+}
+
+- (void)writeField:(GPBFieldDescriptor *)field
+    toCodedOutputStream:(GPBCodedOutputStream *)output {
+  GPBFieldType fieldType = field.fieldType;
+  if (fieldType == GPBFieldTypeSingle) {
+    BOOL has = GPBGetHasIvarField(self, field);
+    if (!has) {
+      return;
+    }
+  }
+  uint32_t fieldNumber = GPBFieldNumber(field);
+
+//%PDDM-DEFINE FIELD_CASE(TYPE, REAL_TYPE)
+//%FIELD_CASE_FULL(TYPE, REAL_TYPE, REAL_TYPE)
+//%PDDM-DEFINE FIELD_CASE_FULL(TYPE, REAL_TYPE, ARRAY_TYPE)
+//%    case GPBDataType##TYPE:
+//%      if (fieldType == GPBFieldTypeRepeated) {
+//%        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+//%        GPB##ARRAY_TYPE##Array *array =
+//%            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+//%        [output write##TYPE##Array:fieldNumber values:array tag:tag];
+//%      } else if (fieldType == GPBFieldTypeSingle) {
+//%        [output write##TYPE:fieldNumber
+//%              TYPE$S  value:GPBGetMessage##REAL_TYPE##Field(self, field)];
+//%      } else {  // fieldType == GPBFieldTypeMap
+//%        // Exact type here doesn't matter.
+//%        GPBInt32##ARRAY_TYPE##Dictionary *dict =
+//%            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+//%        [dict writeToCodedOutputStream:output asField:field];
+//%      }
+//%      break;
+//%
+//%PDDM-DEFINE FIELD_CASE2(TYPE)
+//%    case GPBDataType##TYPE:
+//%      if (fieldType == GPBFieldTypeRepeated) {
+//%        NSArray *array = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+//%        [output write##TYPE##Array:fieldNumber values:array];
+//%      } else if (fieldType == GPBFieldTypeSingle) {
+//%        // GPBGetObjectIvarWithFieldNoAutocreate() avoids doing the has check
+//%        // again.
+//%        [output write##TYPE:fieldNumber
+//%              TYPE$S  value:GPBGetObjectIvarWithFieldNoAutocreate(self, field)];
+//%      } else {  // fieldType == GPBFieldTypeMap
+//%        // Exact type here doesn't matter.
+//%        id dict = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+//%        GPBDataType mapKeyDataType = field.mapKeyDataType;
+//%        if (mapKeyDataType == GPBDataTypeString) {
+//%          GPBDictionaryWriteToStreamInternalHelper(output, dict, field);
+//%        } else {
+//%          [dict writeToCodedOutputStream:output asField:field];
+//%        }
+//%      }
+//%      break;
+//%
+
+  switch (GPBGetFieldDataType(field)) {
+
+//%PDDM-EXPAND FIELD_CASE(Bool, Bool)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeBool:
+      if (fieldType == GPBFieldTypeRepeated) {
+        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+        GPBBoolArray *array =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeBoolArray:fieldNumber values:array tag:tag];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        [output writeBool:fieldNumber
+                    value:GPBGetMessageBoolField(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        GPBInt32BoolDictionary *dict =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [dict writeToCodedOutputStream:output asField:field];
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE(Fixed32, UInt32)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeFixed32:
+      if (fieldType == GPBFieldTypeRepeated) {
+        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+        GPBUInt32Array *array =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeFixed32Array:fieldNumber values:array tag:tag];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        [output writeFixed32:fieldNumber
+                       value:GPBGetMessageUInt32Field(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        GPBInt32UInt32Dictionary *dict =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [dict writeToCodedOutputStream:output asField:field];
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE(SFixed32, Int32)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeSFixed32:
+      if (fieldType == GPBFieldTypeRepeated) {
+        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+        GPBInt32Array *array =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeSFixed32Array:fieldNumber values:array tag:tag];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        [output writeSFixed32:fieldNumber
+                        value:GPBGetMessageInt32Field(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        GPBInt32Int32Dictionary *dict =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [dict writeToCodedOutputStream:output asField:field];
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE(Float, Float)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeFloat:
+      if (fieldType == GPBFieldTypeRepeated) {
+        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+        GPBFloatArray *array =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeFloatArray:fieldNumber values:array tag:tag];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        [output writeFloat:fieldNumber
+                     value:GPBGetMessageFloatField(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        GPBInt32FloatDictionary *dict =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [dict writeToCodedOutputStream:output asField:field];
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE(Fixed64, UInt64)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeFixed64:
+      if (fieldType == GPBFieldTypeRepeated) {
+        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+        GPBUInt64Array *array =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeFixed64Array:fieldNumber values:array tag:tag];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        [output writeFixed64:fieldNumber
+                       value:GPBGetMessageUInt64Field(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        GPBInt32UInt64Dictionary *dict =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [dict writeToCodedOutputStream:output asField:field];
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE(SFixed64, Int64)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeSFixed64:
+      if (fieldType == GPBFieldTypeRepeated) {
+        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+        GPBInt64Array *array =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeSFixed64Array:fieldNumber values:array tag:tag];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        [output writeSFixed64:fieldNumber
+                        value:GPBGetMessageInt64Field(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        GPBInt32Int64Dictionary *dict =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [dict writeToCodedOutputStream:output asField:field];
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE(Double, Double)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeDouble:
+      if (fieldType == GPBFieldTypeRepeated) {
+        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+        GPBDoubleArray *array =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeDoubleArray:fieldNumber values:array tag:tag];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        [output writeDouble:fieldNumber
+                      value:GPBGetMessageDoubleField(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        GPBInt32DoubleDictionary *dict =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [dict writeToCodedOutputStream:output asField:field];
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE(Int32, Int32)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeInt32:
+      if (fieldType == GPBFieldTypeRepeated) {
+        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+        GPBInt32Array *array =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeInt32Array:fieldNumber values:array tag:tag];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        [output writeInt32:fieldNumber
+                     value:GPBGetMessageInt32Field(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        GPBInt32Int32Dictionary *dict =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [dict writeToCodedOutputStream:output asField:field];
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE(Int64, Int64)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeInt64:
+      if (fieldType == GPBFieldTypeRepeated) {
+        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+        GPBInt64Array *array =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeInt64Array:fieldNumber values:array tag:tag];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        [output writeInt64:fieldNumber
+                     value:GPBGetMessageInt64Field(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        GPBInt32Int64Dictionary *dict =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [dict writeToCodedOutputStream:output asField:field];
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE(SInt32, Int32)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeSInt32:
+      if (fieldType == GPBFieldTypeRepeated) {
+        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+        GPBInt32Array *array =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeSInt32Array:fieldNumber values:array tag:tag];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        [output writeSInt32:fieldNumber
+                      value:GPBGetMessageInt32Field(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        GPBInt32Int32Dictionary *dict =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [dict writeToCodedOutputStream:output asField:field];
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE(SInt64, Int64)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeSInt64:
+      if (fieldType == GPBFieldTypeRepeated) {
+        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+        GPBInt64Array *array =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeSInt64Array:fieldNumber values:array tag:tag];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        [output writeSInt64:fieldNumber
+                      value:GPBGetMessageInt64Field(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        GPBInt32Int64Dictionary *dict =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [dict writeToCodedOutputStream:output asField:field];
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE(UInt32, UInt32)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeUInt32:
+      if (fieldType == GPBFieldTypeRepeated) {
+        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+        GPBUInt32Array *array =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeUInt32Array:fieldNumber values:array tag:tag];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        [output writeUInt32:fieldNumber
+                      value:GPBGetMessageUInt32Field(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        GPBInt32UInt32Dictionary *dict =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [dict writeToCodedOutputStream:output asField:field];
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE(UInt64, UInt64)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeUInt64:
+      if (fieldType == GPBFieldTypeRepeated) {
+        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+        GPBUInt64Array *array =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeUInt64Array:fieldNumber values:array tag:tag];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        [output writeUInt64:fieldNumber
+                      value:GPBGetMessageUInt64Field(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        GPBInt32UInt64Dictionary *dict =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [dict writeToCodedOutputStream:output asField:field];
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE_FULL(Enum, Int32, Enum)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeEnum:
+      if (fieldType == GPBFieldTypeRepeated) {
+        uint32_t tag = field.isPackable ? GPBFieldTag(field) : 0;
+        GPBEnumArray *array =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeEnumArray:fieldNumber values:array tag:tag];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        [output writeEnum:fieldNumber
+                    value:GPBGetMessageInt32Field(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        GPBInt32EnumDictionary *dict =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [dict writeToCodedOutputStream:output asField:field];
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE2(Bytes)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeBytes:
+      if (fieldType == GPBFieldTypeRepeated) {
+        NSArray *array = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeBytesArray:fieldNumber values:array];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        // GPBGetObjectIvarWithFieldNoAutocreate() avoids doing the has check
+        // again.
+        [output writeBytes:fieldNumber
+                     value:GPBGetObjectIvarWithFieldNoAutocreate(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        id dict = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        GPBDataType mapKeyDataType = field.mapKeyDataType;
+        if (mapKeyDataType == GPBDataTypeString) {
+          GPBDictionaryWriteToStreamInternalHelper(output, dict, field);
+        } else {
+          [dict writeToCodedOutputStream:output asField:field];
+        }
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE2(String)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeString:
+      if (fieldType == GPBFieldTypeRepeated) {
+        NSArray *array = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeStringArray:fieldNumber values:array];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        // GPBGetObjectIvarWithFieldNoAutocreate() avoids doing the has check
+        // again.
+        [output writeString:fieldNumber
+                      value:GPBGetObjectIvarWithFieldNoAutocreate(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        id dict = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        GPBDataType mapKeyDataType = field.mapKeyDataType;
+        if (mapKeyDataType == GPBDataTypeString) {
+          GPBDictionaryWriteToStreamInternalHelper(output, dict, field);
+        } else {
+          [dict writeToCodedOutputStream:output asField:field];
+        }
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE2(Message)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeMessage:
+      if (fieldType == GPBFieldTypeRepeated) {
+        NSArray *array = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeMessageArray:fieldNumber values:array];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        // GPBGetObjectIvarWithFieldNoAutocreate() avoids doing the has check
+        // again.
+        [output writeMessage:fieldNumber
+                       value:GPBGetObjectIvarWithFieldNoAutocreate(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        id dict = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        GPBDataType mapKeyDataType = field.mapKeyDataType;
+        if (mapKeyDataType == GPBDataTypeString) {
+          GPBDictionaryWriteToStreamInternalHelper(output, dict, field);
+        } else {
+          [dict writeToCodedOutputStream:output asField:field];
+        }
+      }
+      break;
+
+//%PDDM-EXPAND FIELD_CASE2(Group)
+// This block of code is generated, do not edit it directly.
+
+    case GPBDataTypeGroup:
+      if (fieldType == GPBFieldTypeRepeated) {
+        NSArray *array = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [output writeGroupArray:fieldNumber values:array];
+      } else if (fieldType == GPBFieldTypeSingle) {
+        // GPBGetObjectIvarWithFieldNoAutocreate() avoids doing the has check
+        // again.
+        [output writeGroup:fieldNumber
+                     value:GPBGetObjectIvarWithFieldNoAutocreate(self, field)];
+      } else {  // fieldType == GPBFieldTypeMap
+        // Exact type here doesn't matter.
+        id dict = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        GPBDataType mapKeyDataType = field.mapKeyDataType;
+        if (mapKeyDataType == GPBDataTypeString) {
+          GPBDictionaryWriteToStreamInternalHelper(output, dict, field);
+        } else {
+          [dict writeToCodedOutputStream:output asField:field];
+        }
+      }
+      break;
+
+//%PDDM-EXPAND-END (18 expansions)
+  }
+}
+
+#pragma mark - Extensions
+
+- (id)getExtension:(GPBExtensionDescriptor *)extension {
+  CheckExtension(self, extension);
+  id value = [extensionMap_ objectForKey:extension];
+  if (value != nil) {
+    return value;
+  }
+
+  // No default for repeated.
+  if (extension.isRepeated) {
+    return nil;
+  }
+  // Non messages get their default.
+  if (!GPBExtensionIsMessage(extension)) {
+    return extension.defaultValue;
+  }
+
+  // Check for an autocreated value.
+  OSSpinLockLock(&readOnlyMutex_);
+  value = [autocreatedExtensionMap_ objectForKey:extension];
+  if (!value) {
+    // Auto create the message extensions to match normal fields.
+    value = CreateMessageWithAutocreatorForExtension(extension.msgClass, self,
+                                                     extension);
+
+    if (autocreatedExtensionMap_ == nil) {
+      autocreatedExtensionMap_ = [[NSMutableDictionary alloc] init];
+    }
+
+    // We can't simply call setExtension here because that would clear the new
+    // value's autocreator.
+    [autocreatedExtensionMap_ setObject:value forKey:extension];
+    [value release];
+  }
+
+  OSSpinLockUnlock(&readOnlyMutex_);
+  return value;
+}
+
+- (id)getExistingExtension:(GPBExtensionDescriptor *)extension {
+  // This is an internal method so we don't need to call CheckExtension().
+  return [extensionMap_ objectForKey:extension];
+}
+
+- (BOOL)hasExtension:(GPBExtensionDescriptor *)extension {
+#if DEBUG
+  CheckExtension(self, extension);
+#endif  // DEBUG
+  return nil != [extensionMap_ objectForKey:extension];
+}
+
+- (NSArray *)extensionsCurrentlySet {
+  return [extensionMap_ allKeys];
+}
+
+- (void)writeExtensionsToCodedOutputStream:(GPBCodedOutputStream *)output
+                                     range:(GPBExtensionRange)range {
+  NSArray *sortedExtensions = [[extensionMap_ allKeys]
+      sortedArrayUsingSelector:@selector(compareByFieldNumber:)];
+  uint32_t start = range.start;
+  uint32_t end = range.end;
+  for (GPBExtensionDescriptor *extension in sortedExtensions) {
+    uint32_t fieldNumber = extension.fieldNumber;
+    if (fieldNumber >= start && fieldNumber < end) {
+      id value = [extensionMap_ objectForKey:extension];
+      GPBWriteExtensionValueToOutputStream(extension, value, output);
+    }
+  }
+}
+
+- (NSArray *)sortedExtensionsInUse {
+  return [[extensionMap_ allKeys]
+      sortedArrayUsingSelector:@selector(compareByFieldNumber:)];
+}
+
+- (void)setExtension:(GPBExtensionDescriptor *)extension value:(id)value {
+  if (!value) {
+    [self clearExtension:extension];
+    return;
+  }
+
+  CheckExtension(self, extension);
+
+  if (extension.repeated) {
+    [NSException raise:NSInvalidArgumentException
+                format:@"Must call addExtension() for repeated types."];
+  }
+
+  if (extensionMap_ == nil) {
+    extensionMap_ = [[NSMutableDictionary alloc] init];
+  }
+
+  [extensionMap_ setObject:value forKey:extension];
+
+  GPBExtensionDescriptor *descriptor = extension;
+
+  if (GPBExtensionIsMessage(descriptor) && !descriptor.isRepeated) {
+    GPBMessage *autocreatedValue =
+        [[autocreatedExtensionMap_ objectForKey:extension] retain];
+    // Must remove from the map before calling GPBClearMessageAutocreator() so
+    // that GPBClearMessageAutocreator() knows its safe to clear.
+    [autocreatedExtensionMap_ removeObjectForKey:extension];
+    GPBClearMessageAutocreator(autocreatedValue);
+    [autocreatedValue release];
+  }
+
+  GPBBecomeVisibleToAutocreator(self);
+}
+
+- (void)addExtension:(GPBExtensionDescriptor *)extension value:(id)value {
+  CheckExtension(self, extension);
+
+  if (!extension.repeated) {
+    [NSException raise:NSInvalidArgumentException
+                format:@"Must call setExtension() for singular types."];
+  }
+
+  if (extensionMap_ == nil) {
+    extensionMap_ = [[NSMutableDictionary alloc] init];
+  }
+  NSMutableArray *list = [extensionMap_ objectForKey:extension];
+  if (list == nil) {
+    list = [NSMutableArray array];
+    [extensionMap_ setObject:list forKey:extension];
+  }
+
+  [list addObject:value];
+  GPBBecomeVisibleToAutocreator(self);
+}
+
+- (void)setExtension:(GPBExtensionDescriptor *)extension
+               index:(NSUInteger)idx
+               value:(id)value {
+  CheckExtension(self, extension);
+
+  if (!extension.repeated) {
+    [NSException raise:NSInvalidArgumentException
+                format:@"Must call setExtension() for singular types."];
+  }
+
+  if (extensionMap_ == nil) {
+    extensionMap_ = [[NSMutableDictionary alloc] init];
+  }
+
+  NSMutableArray *list = [extensionMap_ objectForKey:extension];
+
+  [list replaceObjectAtIndex:idx withObject:value];
+  GPBBecomeVisibleToAutocreator(self);
+}
+
+- (void)clearExtension:(GPBExtensionDescriptor *)extension {
+  CheckExtension(self, extension);
+
+  // Only become visible if there was actually a value to clear.
+  if ([extensionMap_ objectForKey:extension]) {
+    [extensionMap_ removeObjectForKey:extension];
+    GPBBecomeVisibleToAutocreator(self);
+  }
+}
+
+#pragma mark - mergeFrom
+
+- (void)mergeFromData:(NSData *)data
+    extensionRegistry:(GPBExtensionRegistry *)extensionRegistry {
+  GPBCodedInputStream *input = [[GPBCodedInputStream alloc] initWithData:data];
+  [self mergeFromCodedInputStream:input extensionRegistry:extensionRegistry];
+  [input checkLastTagWas:0];
+  [input release];
+}
+
+#pragma mark - mergeDelimitedFrom
+
+- (void)mergeDelimitedFromCodedInputStream:(GPBCodedInputStream *)input
+                         extensionRegistry:(GPBExtensionRegistry *)extensionRegistry {
+  GPBCodedInputStreamState *state = &input->state_;
+  if (GPBCodedInputStreamIsAtEnd(state)) {
+    return;
+  }
+  NSData *data = GPBCodedInputStreamReadRetainedBytesNoCopy(state);
+  if (data == nil) {
+    return;
+  }
+  [self mergeFromData:data extensionRegistry:extensionRegistry];
+  [data release];
+}
+
+#pragma mark - Parse From Data Support
+
++ (instancetype)parseFromData:(NSData *)data error:(NSError **)errorPtr {
+  return [self parseFromData:data extensionRegistry:nil error:errorPtr];
+}
+
++ (instancetype)parseFromData:(NSData *)data
+            extensionRegistry:(GPBExtensionRegistry *)extensionRegistry
+                        error:(NSError **)errorPtr {
+  return [[[self alloc] initWithData:data
+                   extensionRegistry:extensionRegistry
+                               error:errorPtr] autorelease];
+}
+
++ (instancetype)parseFromCodedInputStream:(GPBCodedInputStream *)input
+                        extensionRegistry:(GPBExtensionRegistry *)extensionRegistry
+                                    error:(NSError **)errorPtr {
+  return
+      [[[self alloc] initWithCodedInputStream:input
+                            extensionRegistry:extensionRegistry
+                                        error:errorPtr] autorelease];
+}
+
+#pragma mark - Parse Delimited From Data Support
+
++ (instancetype)parseDelimitedFromCodedInputStream:(GPBCodedInputStream *)input
+                                 extensionRegistry:
+                                     (GPBExtensionRegistry *)extensionRegistry
+                                             error:(NSError **)errorPtr {
+  GPBMessage *message = [[[self alloc] init] autorelease];
+  @try {
+    [message mergeDelimitedFromCodedInputStream:input
+                              extensionRegistry:extensionRegistry];
+    if (errorPtr) {
+      *errorPtr = nil;
+    }
+  }
+  @catch (NSException *exception) {
+    [message release];
+    message = nil;
+    if (errorPtr) {
+      *errorPtr = MessageErrorWithReason(GPBMessageErrorCodeMalformedData,
+                                         exception.reason);
+    }
+  }
+#ifdef DEBUG
+  if (message && !message.initialized) {
+    [message release];
+    message = nil;
+    if (errorPtr) {
+      *errorPtr = MessageError(GPBMessageErrorCodeMissingRequiredField, nil);
+    }
+  }
+#endif
+  return message;
+}
+
+#pragma mark - Unknown Field Support
+
+- (GPBUnknownFieldSet *)unknownFields {
+  return unknownFields_;
+}
+
+- (void)setUnknownFields:(GPBUnknownFieldSet *)unknownFields {
+  if (unknownFields != unknownFields_) {
+    [unknownFields_ release];
+    unknownFields_ = [unknownFields copy];
+    GPBBecomeVisibleToAutocreator(self);
+  }
+}
+
+- (void)parseMessageSet:(GPBCodedInputStream *)input
+      extensionRegistry:(GPBExtensionRegistry *)extensionRegistry {
+  uint32_t typeId = 0;
+  NSData *rawBytes = nil;
+  GPBExtensionDescriptor *extension = nil;
+  GPBCodedInputStreamState *state = &input->state_;
+  while (true) {
+    uint32_t tag = GPBCodedInputStreamReadTag(state);
+    if (tag == 0) {
+      break;
+    }
+
+    if (tag == GPBWireFormatMessageSetTypeIdTag) {
+      typeId = GPBCodedInputStreamReadUInt32(state);
+      if (typeId != 0) {
+        extension = [extensionRegistry extensionForDescriptor:[self descriptor]
+                                                  fieldNumber:typeId];
+      }
+    } else if (tag == GPBWireFormatMessageSetMessageTag) {
+      rawBytes =
+          [GPBCodedInputStreamReadRetainedBytesNoCopy(state) autorelease];
+    } else {
+      if (![input skipField:tag]) {
+        break;
+      }
+    }
+  }
+
+  [input checkLastTagWas:GPBWireFormatMessageSetItemEndTag];
+
+  if (rawBytes != nil && typeId != 0) {
+    if (extension != nil) {
+      GPBCodedInputStream *newInput =
+          [[GPBCodedInputStream alloc] initWithData:rawBytes];
+      GPBExtensionMergeFromInputStream(extension,
+                                       extension.packable,
+                                       newInput,
+                                       extensionRegistry,
+                                       self);
+      [newInput release];
+    } else {
+      GPBUnknownFieldSet *unknownFields = GetOrMakeUnknownFields(self);
+      [unknownFields mergeMessageSetMessage:typeId data:rawBytes];
+    }
+  }
+}
+
+- (BOOL)parseUnknownField:(GPBCodedInputStream *)input
+        extensionRegistry:(GPBExtensionRegistry *)extensionRegistry
+                      tag:(uint32_t)tag {
+  GPBWireFormat wireType = GPBWireFormatGetTagWireType(tag);
+  int32_t fieldNumber = GPBWireFormatGetTagFieldNumber(tag);
+
+  GPBDescriptor *descriptor = [self descriptor];
+  GPBExtensionDescriptor *extension =
+      [extensionRegistry extensionForDescriptor:descriptor
+                                    fieldNumber:fieldNumber];
+  if (extension == nil) {
+    if (descriptor.wireFormat && GPBWireFormatMessageSetItemTag == tag) {
+      [self parseMessageSet:input extensionRegistry:extensionRegistry];
+      return YES;
+    }
+  } else {
+    if (extension.wireType == wireType) {
+      GPBExtensionMergeFromInputStream(extension,
+                                       extension.packable,
+                                       input,
+                                       extensionRegistry,
+                                       self);
+      return YES;
+    }
+    // Primitive, repeated types can be packed on unpacked on the wire, and are
+    // parsed either way.
+    if ([extension isRepeated] &&
+        !GPBDataTypeIsObject(extension->description_->dataType) &&
+        (extension.alternateWireType == wireType)) {
+      GPBExtensionMergeFromInputStream(extension,
+                                       !extension.packable,
+                                       input,
+                                       extensionRegistry,
+                                       self);
+      return YES;
+    }
+  }
+  if ([GPBUnknownFieldSet isFieldTag:tag]) {
+    GPBUnknownFieldSet *unknownFields = GetOrMakeUnknownFields(self);
+    return [unknownFields mergeFieldFrom:tag input:input];
+  } else {
+    return NO;
+  }
+}
+
+- (void)addUnknownMapEntry:(int32_t)fieldNum value:(NSData *)data {
+  GPBUnknownFieldSet *unknownFields = GetOrMakeUnknownFields(self);
+  [unknownFields addUnknownMapEntry:fieldNum value:data];
+}
+
+#pragma mark - MergeFromCodedInputStream Support
+
+static void MergeSingleFieldFromCodedInputStream(
+    GPBMessage *self, GPBFieldDescriptor *field, GPBFileSyntax syntax,
+    GPBCodedInputStream *input, GPBExtensionRegistry *extensionRegistry) {
+  GPBDataType fieldDataType = GPBGetFieldDataType(field);
+  switch (fieldDataType) {
+#define CASE_SINGLE_POD(NAME, TYPE, FUNC_TYPE)                             \
+    case GPBDataType##NAME: {                                              \
+      TYPE val = GPBCodedInputStreamRead##NAME(&input->state_);            \
+      GPBSet##FUNC_TYPE##IvarWithFieldInternal(self, field, val, syntax);  \
+      break;                                                               \
+            }
+#define CASE_SINGLE_OBJECT(NAME)                                           \
+    case GPBDataType##NAME: {                                              \
+      id val = GPBCodedInputStreamReadRetained##NAME(&input->state_);      \
+      GPBSetRetainedObjectIvarWithFieldInternal(self, field, val, syntax); \
+      break;                                                               \
+    }
+      CASE_SINGLE_POD(Bool, BOOL, Bool)
+      CASE_SINGLE_POD(Fixed32, uint32_t, UInt32)
+      CASE_SINGLE_POD(SFixed32, int32_t, Int32)
+      CASE_SINGLE_POD(Float, float, Float)
+      CASE_SINGLE_POD(Fixed64, uint64_t, UInt64)
+      CASE_SINGLE_POD(SFixed64, int64_t, Int64)
+      CASE_SINGLE_POD(Double, double, Double)
+      CASE_SINGLE_POD(Int32, int32_t, Int32)
+      CASE_SINGLE_POD(Int64, int64_t, Int64)
+      CASE_SINGLE_POD(SInt32, int32_t, Int32)
+      CASE_SINGLE_POD(SInt64, int64_t, Int64)
+      CASE_SINGLE_POD(UInt32, uint32_t, UInt32)
+      CASE_SINGLE_POD(UInt64, uint64_t, UInt64)
+      CASE_SINGLE_OBJECT(Bytes)
+      CASE_SINGLE_OBJECT(String)
+#undef CASE_SINGLE_POD
+#undef CASE_SINGLE_OBJECT
+
+    case GPBDataTypeMessage: {
+      if (GPBGetHasIvarField(self, field)) {
+        // GPBGetObjectIvarWithFieldNoAutocreate() avoids doing the has
+        // check again.
+        GPBMessage *message =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [input readMessage:message extensionRegistry:extensionRegistry];
+      } else {
+        GPBMessage *message = [[field.msgClass alloc] init];
+        [input readMessage:message extensionRegistry:extensionRegistry];
+        GPBSetRetainedObjectIvarWithFieldInternal(self, field, message, syntax);
+      }
+      break;
+    }
+
+    case GPBDataTypeGroup: {
+      if (GPBGetHasIvarField(self, field)) {
+        // GPBGetObjectIvarWithFieldNoAutocreate() avoids doing the has
+        // check again.
+        GPBMessage *message =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+        [input readGroup:GPBFieldNumber(field)
+                      message:message
+            extensionRegistry:extensionRegistry];
+      } else {
+        GPBMessage *message = [[field.msgClass alloc] init];
+        [input readGroup:GPBFieldNumber(field)
+                      message:message
+            extensionRegistry:extensionRegistry];
+        GPBSetRetainedObjectIvarWithFieldInternal(self, field, message, syntax);
+      }
+      break;
+    }
+
+    case GPBDataTypeEnum: {
+      int32_t val = GPBCodedInputStreamReadEnum(&input->state_);
+      if (GPBHasPreservingUnknownEnumSemantics(syntax) ||
+          [field isValidEnumValue:val]) {
+        GPBSetInt32IvarWithFieldInternal(self, field, val, syntax);
+      } else {
+        GPBUnknownFieldSet *unknownFields = GetOrMakeUnknownFields(self);
+        [unknownFields mergeVarintField:GPBFieldNumber(field) value:val];
+      }
+    }
+  }  // switch
+}
+
+static void MergeRepeatedPackedFieldFromCodedInputStream(
+    GPBMessage *self, GPBFieldDescriptor *field, GPBFileSyntax syntax,
+    GPBCodedInputStream *input) {
+  GPBDataType fieldDataType = GPBGetFieldDataType(field);
+  GPBCodedInputStreamState *state = &input->state_;
+  id genericArray = GetOrCreateArrayIvarWithField(self, field, syntax);
+  int32_t length = GPBCodedInputStreamReadInt32(state);
+  size_t limit = GPBCodedInputStreamPushLimit(state, length);
+  while (GPBCodedInputStreamBytesUntilLimit(state) > 0) {
+    switch (fieldDataType) {
+#define CASE_REPEATED_PACKED_POD(NAME, TYPE, ARRAY_TYPE)      \
+     case GPBDataType##NAME: {                                \
+       TYPE val = GPBCodedInputStreamRead##NAME(state);       \
+       [(GPB##ARRAY_TYPE##Array *)genericArray addValue:val]; \
+       break;                                                 \
+     }
+        CASE_REPEATED_PACKED_POD(Bool, BOOL, Bool)
+        CASE_REPEATED_PACKED_POD(Fixed32, uint32_t, UInt32)
+        CASE_REPEATED_PACKED_POD(SFixed32, int32_t, Int32)
+        CASE_REPEATED_PACKED_POD(Float, float, Float)
+        CASE_REPEATED_PACKED_POD(Fixed64, uint64_t, UInt64)
+        CASE_REPEATED_PACKED_POD(SFixed64, int64_t, Int64)
+        CASE_REPEATED_PACKED_POD(Double, double, Double)
+        CASE_REPEATED_PACKED_POD(Int32, int32_t, Int32)
+        CASE_REPEATED_PACKED_POD(Int64, int64_t, Int64)
+        CASE_REPEATED_PACKED_POD(SInt32, int32_t, Int32)
+        CASE_REPEATED_PACKED_POD(SInt64, int64_t, Int64)
+        CASE_REPEATED_PACKED_POD(UInt32, uint32_t, UInt32)
+        CASE_REPEATED_PACKED_POD(UInt64, uint64_t, UInt64)
+#undef CASE_REPEATED_PACKED_POD
+
+      case GPBDataTypeBytes:
+      case GPBDataTypeString:
+      case GPBDataTypeMessage:
+      case GPBDataTypeGroup:
+        NSCAssert(NO, @"Non primitive types can't be packed");
+        break;
+
+      case GPBDataTypeEnum: {
+        int32_t val = GPBCodedInputStreamReadEnum(state);
+        if (GPBHasPreservingUnknownEnumSemantics(syntax) ||
+            [field isValidEnumValue:val]) {
+          [(GPBEnumArray*)genericArray addRawValue:val];
+        } else {
+          GPBUnknownFieldSet *unknownFields = GetOrMakeUnknownFields(self);
+          [unknownFields mergeVarintField:GPBFieldNumber(field) value:val];
+        }
+        break;
+      }
+    }  // switch
+  }  // while(BytesUntilLimit() > 0)
+  GPBCodedInputStreamPopLimit(state, limit);
+}
+
+static void MergeRepeatedNotPackedFieldFromCodedInputStream(
+    GPBMessage *self, GPBFieldDescriptor *field, GPBFileSyntax syntax,
+    GPBCodedInputStream *input, GPBExtensionRegistry *extensionRegistry) {
+  GPBCodedInputStreamState *state = &input->state_;
+  id genericArray = GetOrCreateArrayIvarWithField(self, field, syntax);
+  switch (GPBGetFieldDataType(field)) {
+#define CASE_REPEATED_NOT_PACKED_POD(NAME, TYPE, ARRAY_TYPE) \
+   case GPBDataType##NAME: {                                 \
+     TYPE val = GPBCodedInputStreamRead##NAME(state);        \
+     [(GPB##ARRAY_TYPE##Array *)genericArray addValue:val];  \
+     break;                                                  \
+   }
+#define CASE_REPEATED_NOT_PACKED_OBJECT(NAME)                \
+   case GPBDataType##NAME: {                                 \
+     id val = GPBCodedInputStreamReadRetained##NAME(state);  \
+     [(NSMutableArray*)genericArray addObject:val];          \
+     [val release];                                          \
+     break;                                                  \
+   }
+      CASE_REPEATED_NOT_PACKED_POD(Bool, BOOL, Bool)
+      CASE_REPEATED_NOT_PACKED_POD(Fixed32, uint32_t, UInt32)
+      CASE_REPEATED_NOT_PACKED_POD(SFixed32, int32_t, Int32)
+      CASE_REPEATED_NOT_PACKED_POD(Float, float, Float)
+      CASE_REPEATED_NOT_PACKED_POD(Fixed64, uint64_t, UInt64)
+      CASE_REPEATED_NOT_PACKED_POD(SFixed64, int64_t, Int64)
+      CASE_REPEATED_NOT_PACKED_POD(Double, double, Double)
+      CASE_REPEATED_NOT_PACKED_POD(Int32, int32_t, Int32)
+      CASE_REPEATED_NOT_PACKED_POD(Int64, int64_t, Int64)
+      CASE_REPEATED_NOT_PACKED_POD(SInt32, int32_t, Int32)
+      CASE_REPEATED_NOT_PACKED_POD(SInt64, int64_t, Int64)
+      CASE_REPEATED_NOT_PACKED_POD(UInt32, uint32_t, UInt32)
+      CASE_REPEATED_NOT_PACKED_POD(UInt64, uint64_t, UInt64)
+      CASE_REPEATED_NOT_PACKED_OBJECT(Bytes)
+      CASE_REPEATED_NOT_PACKED_OBJECT(String)
+#undef CASE_REPEATED_NOT_PACKED_POD
+#undef CASE_NOT_PACKED_OBJECT
+    case GPBDataTypeMessage: {
+      GPBMessage *message = [[field.msgClass alloc] init];
+      [input readMessage:message extensionRegistry:extensionRegistry];
+      [(NSMutableArray*)genericArray addObject:message];
+      [message release];
+      break;
+    }
+    case GPBDataTypeGroup: {
+      GPBMessage *message = [[field.msgClass alloc] init];
+      [input readGroup:GPBFieldNumber(field)
+                    message:message
+          extensionRegistry:extensionRegistry];
+      [(NSMutableArray*)genericArray addObject:message];
+      [message release];
+      break;
+    }
+    case GPBDataTypeEnum: {
+      int32_t val = GPBCodedInputStreamReadEnum(state);
+      if (GPBHasPreservingUnknownEnumSemantics(syntax) ||
+          [field isValidEnumValue:val]) {
+        [(GPBEnumArray*)genericArray addRawValue:val];
+      } else {
+        GPBUnknownFieldSet *unknownFields = GetOrMakeUnknownFields(self);
+        [unknownFields mergeVarintField:GPBFieldNumber(field) value:val];
+      }
+      break;
+    }
+  }  // switch
+}
+
+- (void)mergeFromCodedInputStream:(GPBCodedInputStream *)input
+                extensionRegistry:(GPBExtensionRegistry *)extensionRegistry {
+  GPBDescriptor *descriptor = [self descriptor];
+  GPBFileSyntax syntax = descriptor.file.syntax;
+  GPBCodedInputStreamState *state = &input->state_;
+  uint32_t tag = 0;
+  NSUInteger startingIndex = 0;
+  NSArray *fields = descriptor->fields_;
+  NSUInteger numFields = fields.count;
+  while (YES) {
+    BOOL merged = NO;
+    tag = GPBCodedInputStreamReadTag(state);
+    for (NSUInteger i = 0; i < numFields; ++i) {
+      if (startingIndex >= numFields) startingIndex = 0;
+      GPBFieldDescriptor *fieldDescriptor = fields[startingIndex];
+      if (GPBFieldTag(fieldDescriptor) == tag) {
+        GPBFieldType fieldType = fieldDescriptor.fieldType;
+        if (fieldType == GPBFieldTypeSingle) {
+          MergeSingleFieldFromCodedInputStream(self, fieldDescriptor, syntax,
+                                               input, extensionRegistry);
+          // Well formed protos will only have a single field once, advance
+          // the starting index to the next field.
+          startingIndex += 1;
+        } else if (fieldType == GPBFieldTypeRepeated) {
+          if (fieldDescriptor.isPackable) {
+            MergeRepeatedPackedFieldFromCodedInputStream(
+                self, fieldDescriptor, syntax, input);
+            // Well formed protos will only have a repeated field that is
+            // packed once, advance the starting index to the next field.
+            startingIndex += 1;
+          } else {
+            MergeRepeatedNotPackedFieldFromCodedInputStream(
+                self, fieldDescriptor, syntax, input, extensionRegistry);
+          }
+        } else {  // fieldType == GPBFieldTypeMap
+          // GPB*Dictionary or NSDictionary, exact type doesn't matter at this
+          // point.
+          id map = GetOrCreateMapIvarWithField(self, fieldDescriptor, syntax);
+          [input readMapEntry:map
+            extensionRegistry:extensionRegistry
+                        field:fieldDescriptor
+                parentMessage:self];
+        }
+        merged = YES;
+        break;
+      } else {
+        startingIndex += 1;
+      }
+    }  // for(i < numFields)
+
+    if (!merged) {
+      // Primitive, repeated types can be packed on unpacked on the wire, and
+      // are parsed either way.  The above loop covered tag in the preferred
+      // for, so this need to check the alternate form.
+      for (NSUInteger i = 0; i < numFields; ++i) {
+        if (startingIndex >= numFields) startingIndex = 0;
+        GPBFieldDescriptor *fieldDescriptor = fields[startingIndex];
+        if ((fieldDescriptor.fieldType == GPBFieldTypeRepeated) &&
+            !GPBFieldDataTypeIsObject(fieldDescriptor) &&
+            (GPBFieldAlternateTag(fieldDescriptor) == tag)) {
+          BOOL alternateIsPacked = !fieldDescriptor.isPackable;
+          if (alternateIsPacked) {
+            MergeRepeatedPackedFieldFromCodedInputStream(
+                self, fieldDescriptor, syntax, input);
+            // Well formed protos will only have a repeated field that is
+            // packed once, advance the starting index to the next field.
+            startingIndex += 1;
+          } else {
+            MergeRepeatedNotPackedFieldFromCodedInputStream(
+                self, fieldDescriptor, syntax, input, extensionRegistry);
+          }
+          merged = YES;
+          break;
+        } else {
+          startingIndex += 1;
+        }
+      }
+    }
+
+    if (!merged) {
+      if (tag == 0) {
+        // zero signals EOF / limit reached
+        return;
+      } else {
+        if (GPBPreserveUnknownFields(syntax)) {
+          if (![self parseUnknownField:input
+                     extensionRegistry:extensionRegistry
+                                   tag:tag]) {
+            // it's an endgroup tag
+            return;
+          }
+        } else {
+          if (![input skipField:tag]) {
+            return;
+          }
+        }
+      }
+    }  // if(!merged)
+
+  }  // while(YES)
+}
+
+#pragma mark - MergeFrom Support
+
+- (void)mergeFrom:(GPBMessage *)other {
+  Class selfClass = [self class];
+  Class otherClass = [other class];
+  if (!([selfClass isSubclassOfClass:otherClass] ||
+        [otherClass isSubclassOfClass:selfClass])) {
+    [NSException raise:NSInvalidArgumentException
+                format:@"Classes must match %@ != %@", selfClass, otherClass];
+  }
+
+  // We assume something will be done and become visible.
+  GPBBecomeVisibleToAutocreator(self);
+
+  GPBDescriptor *descriptor = [[self class] descriptor];
+  GPBFileSyntax syntax = descriptor.file.syntax;
+
+  for (GPBFieldDescriptor *field in descriptor->fields_) {
+    GPBFieldType fieldType = field.fieldType;
+    if (fieldType == GPBFieldTypeSingle) {
+      int32_t hasIndex = GPBFieldHasIndex(field);
+      uint32_t fieldNumber = GPBFieldNumber(field);
+      if (!GPBGetHasIvar(other, hasIndex, fieldNumber)) {
+        // Other doesn't have the field set, on to the next.
+        continue;
+      }
+      GPBDataType fieldDataType = GPBGetFieldDataType(field);
+      switch (fieldDataType) {
+        case GPBDataTypeBool:
+          GPBSetBoolIvarWithFieldInternal(
+              self, field, GPBGetMessageBoolField(other, field), syntax);
+          break;
+        case GPBDataTypeSFixed32:
+        case GPBDataTypeEnum:
+        case GPBDataTypeInt32:
+        case GPBDataTypeSInt32:
+          GPBSetInt32IvarWithFieldInternal(
+              self, field, GPBGetMessageInt32Field(other, field), syntax);
+          break;
+        case GPBDataTypeFixed32:
+        case GPBDataTypeUInt32:
+          GPBSetUInt32IvarWithFieldInternal(
+              self, field, GPBGetMessageUInt32Field(other, field), syntax);
+          break;
+        case GPBDataTypeSFixed64:
+        case GPBDataTypeInt64:
+        case GPBDataTypeSInt64:
+          GPBSetInt64IvarWithFieldInternal(
+              self, field, GPBGetMessageInt64Field(other, field), syntax);
+          break;
+        case GPBDataTypeFixed64:
+        case GPBDataTypeUInt64:
+          GPBSetUInt64IvarWithFieldInternal(
+              self, field, GPBGetMessageUInt64Field(other, field), syntax);
+          break;
+        case GPBDataTypeFloat:
+          GPBSetFloatIvarWithFieldInternal(
+              self, field, GPBGetMessageFloatField(other, field), syntax);
+          break;
+        case GPBDataTypeDouble:
+          GPBSetDoubleIvarWithFieldInternal(
+              self, field, GPBGetMessageDoubleField(other, field), syntax);
+          break;
+        case GPBDataTypeBytes:
+        case GPBDataTypeString: {
+          id otherVal = GPBGetObjectIvarWithFieldNoAutocreate(other, field);
+          GPBSetObjectIvarWithFieldInternal(self, field, otherVal, syntax);
+          break;
+        }
+        case GPBDataTypeMessage:
+        case GPBDataTypeGroup: {
+          id otherVal = GPBGetObjectIvarWithFieldNoAutocreate(other, field);
+          if (GPBGetHasIvar(self, hasIndex, fieldNumber)) {
+            GPBMessage *message =
+                GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+            [message mergeFrom:otherVal];
+          } else {
+            GPBMessage *message = [otherVal copy];
+            GPBSetRetainedObjectIvarWithFieldInternal(self, field, message,
+                                                      syntax);
+          }
+          break;
+        }
+      } // switch()
+    } else if (fieldType == GPBFieldTypeRepeated) {
+      // In the case of a list, they need to be appended, and there is no
+      // _hasIvar to worry about setting.
+      id otherArray =
+          GPBGetObjectIvarWithFieldNoAutocreate(other, field);
+      if (otherArray) {
+        GPBDataType fieldDataType = field->description_->dataType;
+        if (GPBDataTypeIsObject(fieldDataType)) {
+          NSMutableArray *resultArray =
+              GetOrCreateArrayIvarWithField(self, field, syntax);
+          [resultArray addObjectsFromArray:otherArray];
+        } else if (fieldDataType == GPBDataTypeEnum) {
+          GPBEnumArray *resultArray =
+              GetOrCreateArrayIvarWithField(self, field, syntax);
+          [resultArray addRawValuesFromArray:otherArray];
+        } else {
+          // The array type doesn't matter, that all implment
+          // -addValuesFromArray:.
+          GPBInt32Array *resultArray =
+              GetOrCreateArrayIvarWithField(self, field, syntax);
+          [resultArray addValuesFromArray:otherArray];
+        }
+      }
+    } else {  // fieldType = GPBFieldTypeMap
+      // In the case of a map, they need to be merged, and there is no
+      // _hasIvar to worry about setting.
+      id otherDict = GPBGetObjectIvarWithFieldNoAutocreate(other, field);
+      if (otherDict) {
+        GPBDataType keyDataType = field.mapKeyDataType;
+        GPBDataType valueDataType = field->description_->dataType;
+        if (GPBDataTypeIsObject(keyDataType) &&
+            GPBDataTypeIsObject(valueDataType)) {
+          NSMutableDictionary *resultDict =
+              GetOrCreateMapIvarWithField(self, field, syntax);
+          [resultDict addEntriesFromDictionary:otherDict];
+        } else if (valueDataType == GPBDataTypeEnum) {
+          // The exact type doesn't matter, just need to know it is a
+          // GPB*EnumDictionary.
+          GPBInt32EnumDictionary *resultDict =
+              GetOrCreateMapIvarWithField(self, field, syntax);
+          [resultDict addRawEntriesFromDictionary:otherDict];
+        } else {
+          // The exact type doesn't matter, they all implement
+          // -addEntriesFromDictionary:.
+          GPBInt32Int32Dictionary *resultDict =
+              GetOrCreateMapIvarWithField(self, field, syntax);
+          [resultDict addEntriesFromDictionary:otherDict];
+        }
+      }
+    }  // if (fieldType)..else if...else
+  }  // for(fields)
+
+  // Unknown fields.
+  if (!unknownFields_) {
+    [self setUnknownFields:other.unknownFields];
+  } else {
+    [unknownFields_ mergeUnknownFields:other.unknownFields];
+  }
+
+  // Extensions
+
+  if (other->extensionMap_.count == 0) {
+    return;
+  }
+
+  if (extensionMap_ == nil) {
+    extensionMap_ =
+        CloneExtensionMap(other->extensionMap_, NSZoneFromPointer(self));
+  } else {
+    for (GPBExtensionDescriptor *extension in other->extensionMap_) {
+      id otherValue = [other->extensionMap_ objectForKey:extension];
+      id value = [extensionMap_ objectForKey:extension];
+      BOOL isMessageExtension = GPBExtensionIsMessage(extension);
+
+      if (extension.repeated) {
+        NSMutableArray *list = value;
+        if (list == nil) {
+          list = [[NSMutableArray alloc] init];
+          [extensionMap_ setObject:list forKey:extension];
+          [list release];
+        }
+        if (isMessageExtension) {
+          for (GPBMessage *otherListValue in otherValue) {
+            GPBMessage *copiedValue = [otherListValue copy];
+            [list addObject:copiedValue];
+            [copiedValue release];
+          }
+        } else {
+          [list addObjectsFromArray:otherValue];
+        }
+      } else {
+        if (isMessageExtension) {
+          if (value) {
+            [(GPBMessage *)value mergeFrom:(GPBMessage *)otherValue];
+          } else {
+            GPBMessage *copiedValue = [otherValue copy];
+            [extensionMap_ setObject:copiedValue forKey:extension];
+            [copiedValue release];
+          }
+        } else {
+          [extensionMap_ setObject:otherValue forKey:extension];
+        }
+      }
+
+      if (isMessageExtension && !extension.isRepeated) {
+        GPBMessage *autocreatedValue =
+            [[autocreatedExtensionMap_ objectForKey:extension] retain];
+        // Must remove from the map before calling GPBClearMessageAutocreator()
+        // so that GPBClearMessageAutocreator() knows its safe to clear.
+        [autocreatedExtensionMap_ removeObjectForKey:extension];
+        GPBClearMessageAutocreator(autocreatedValue);
+        [autocreatedValue release];
+      }
+    }
+  }
+}
+
+#pragma mark - isEqual: & hash Support
+
+- (BOOL)isEqual:(GPBMessage *)other {
+  if (other == self) {
+    return YES;
+  }
+  if (![other isKindOfClass:[self class]] &&
+      ![self isKindOfClass:[other class]]) {
+    return NO;
+  }
+
+  GPBDescriptor *descriptor = [[self class] descriptor];
+  uint8_t *selfStorage = (uint8_t *)messageStorage_;
+  uint8_t *otherStorage = (uint8_t *)other->messageStorage_;
+
+  for (GPBFieldDescriptor *field in descriptor->fields_) {
+    if (GPBFieldIsMapOrArray(field)) {
+      // In the case of a list or map, there is no _hasIvar to worry about.
+      // NOTE: These are NSArray/GPB*Array or NSDictionary/GPB*Dictionary, but
+      // the type doesn't really matter as the objects all support -count and
+      // -isEqual:.
+      NSArray *resultMapOrArray =
+          GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+      NSArray *otherMapOrArray =
+          GPBGetObjectIvarWithFieldNoAutocreate(other, field);
+      // nil and empty are equal
+      if (resultMapOrArray.count != 0 || otherMapOrArray.count != 0) {
+        if (![resultMapOrArray isEqual:otherMapOrArray]) {
+          return NO;
+        }
+      }
+    } else {  // Single field
+      int32_t hasIndex = GPBFieldHasIndex(field);
+      uint32_t fieldNum = GPBFieldNumber(field);
+      BOOL selfHas = GPBGetHasIvar(self, hasIndex, fieldNum);
+      BOOL otherHas = GPBGetHasIvar(other, hasIndex, fieldNum);
+      if (selfHas != otherHas) {
+        return NO;  // Differing has values, not equal.
+      }
+      if (!selfHas) {
+        // Same has values, was no, nothing else to check for this field.
+        continue;
+      }
+      // Now compare the values.
+      GPBDataType fieldDataType = GPBGetFieldDataType(field);
+      size_t fieldOffset = field->description_->offset;
+      switch (fieldDataType) {
+        case GPBDataTypeBool: {
+          BOOL *selfValPtr = (BOOL *)&selfStorage[fieldOffset];
+          BOOL *otherValPtr = (BOOL *)&otherStorage[fieldOffset];
+          if (*selfValPtr != *otherValPtr) {
+            return NO;
+          }
+          break;
+        }
+        case GPBDataTypeSFixed32:
+        case GPBDataTypeInt32:
+        case GPBDataTypeSInt32:
+        case GPBDataTypeEnum:
+        case GPBDataTypeFixed32:
+        case GPBDataTypeUInt32:
+        case GPBDataTypeFloat: {
+          _GPBCompileAssert(sizeof(float) == sizeof(uint32_t), float_not_32_bits);
+          // These are all 32bit, signed/unsigned doesn't matter for equality.
+          uint32_t *selfValPtr = (uint32_t *)&selfStorage[fieldOffset];
+          uint32_t *otherValPtr = (uint32_t *)&otherStorage[fieldOffset];
+          if (*selfValPtr != *otherValPtr) {
+            return NO;
+          }
+          break;
+        }
+        case GPBDataTypeSFixed64:
+        case GPBDataTypeInt64:
+        case GPBDataTypeSInt64:
+        case GPBDataTypeFixed64:
+        case GPBDataTypeUInt64:
+        case GPBDataTypeDouble: {
+          _GPBCompileAssert(sizeof(double) == sizeof(uint64_t), double_not_64_bits);
+          // These are all 64bit, signed/unsigned doesn't matter for equality.
+          uint64_t *selfValPtr = (uint64_t *)&selfStorage[fieldOffset];
+          uint64_t *otherValPtr = (uint64_t *)&otherStorage[fieldOffset];
+          if (*selfValPtr != *otherValPtr) {
+            return NO;
+          }
+          break;
+        }
+        case GPBDataTypeBytes:
+        case GPBDataTypeString:
+        case GPBDataTypeMessage:
+        case GPBDataTypeGroup: {
+          // Type doesn't matter here, they all implement -isEqual:.
+          id *selfValPtr = (id *)&selfStorage[fieldOffset];
+          id *otherValPtr = (id *)&otherStorage[fieldOffset];
+          if (![*selfValPtr isEqual:*otherValPtr]) {
+            return NO;
+          }
+          break;
+        }
+      } // switch()
+    }   // if(mapOrArray)...else
+  }  // for(fields)
+
+  // nil and empty are equal
+  if (extensionMap_.count != 0 || other->extensionMap_.count != 0) {
+    if (![extensionMap_ isEqual:other->extensionMap_]) {
+      return NO;
+    }
+  }
+
+  // nil and empty are equal
+  GPBUnknownFieldSet *otherUnknowns = other->unknownFields_;
+  if ([unknownFields_ countOfFields] != 0 ||
+      [otherUnknowns countOfFields] != 0) {
+    if (![unknownFields_ isEqual:otherUnknowns]) {
+      return NO;
+    }
+  }
+
+  return YES;
+}
+
+// It is very difficult to implement a generic hash for ProtoBuf messages that
+// will perform well. If you need hashing on your ProtoBufs (eg you are using
+// them as dictionary keys) you will probably want to implement a ProtoBuf
+// message specific hash as a category on your protobuf class. Do not make it a
+// category on GPBMessage as you will conflict with this hash, and will possibly
+// override hash for all generated protobufs. A good implementation of hash will
+// be really fast, so we would recommend only hashing protobufs that have an
+// identifier field of some kind that you can easily hash. If you implement
+// hash, we would strongly recommend overriding isEqual: in your category as
+// well, as the default implementation of isEqual: is extremely slow, and may
+// drastically affect performance in large sets.
+- (NSUInteger)hash {
+  GPBDescriptor *descriptor = [[self class] descriptor];
+  const NSUInteger prime = 19;
+  uint8_t *storage = (uint8_t *)messageStorage_;
+
+  // Start with the descriptor and then mix it with some instance info.
+  // Hopefully that will give a spread based on classes and what fields are set.
+  NSUInteger result = (NSUInteger)descriptor;
+
+  for (GPBFieldDescriptor *field in descriptor->fields_) {
+    if (GPBFieldIsMapOrArray(field)) {
+      // Exact type doesn't matter, just check if there are any elements.
+      NSArray *mapOrArray = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+      NSUInteger count = mapOrArray.count;
+      if (count) {
+        // NSArray/NSDictionary use count, use the field number and the count.
+        result = prime * result + GPBFieldNumber(field);
+        result = prime * result + count;
+      }
+    } else if (GPBGetHasIvarField(self, field)) {
+      // Just using the field number seemed simple/fast, but then a small
+      // message class where all the same fields are always set (to different
+      // things would end up all with the same hash, so pull in some data).
+      GPBDataType fieldDataType = GPBGetFieldDataType(field);
+      size_t fieldOffset = field->description_->offset;
+      switch (fieldDataType) {
+        case GPBDataTypeBool: {
+          BOOL *valPtr = (BOOL *)&storage[fieldOffset];
+          result = prime * result + *valPtr;
+          break;
+        }
+        case GPBDataTypeSFixed32:
+        case GPBDataTypeInt32:
+        case GPBDataTypeSInt32:
+        case GPBDataTypeEnum:
+        case GPBDataTypeFixed32:
+        case GPBDataTypeUInt32:
+        case GPBDataTypeFloat: {
+          _GPBCompileAssert(sizeof(float) == sizeof(uint32_t), float_not_32_bits);
+          // These are all 32bit, just mix it in.
+          uint32_t *valPtr = (uint32_t *)&storage[fieldOffset];
+          result = prime * result + *valPtr;
+          break;
+        }
+        case GPBDataTypeSFixed64:
+        case GPBDataTypeInt64:
+        case GPBDataTypeSInt64:
+        case GPBDataTypeFixed64:
+        case GPBDataTypeUInt64:
+        case GPBDataTypeDouble: {
+          _GPBCompileAssert(sizeof(double) == sizeof(uint64_t), double_not_64_bits);
+          // These are all 64bit, just mix what fits into an NSUInteger in.
+          uint64_t *valPtr = (uint64_t *)&storage[fieldOffset];
+          result = prime * result + (NSUInteger)(*valPtr);
+          break;
+        }
+        case GPBDataTypeBytes:
+        case GPBDataTypeString: {
+          // Type doesn't matter here, they both implement -hash:.
+          id *valPtr = (id *)&storage[fieldOffset];
+          result = prime * result + [*valPtr hash];
+          break;
+        }
+
+        case GPBDataTypeMessage:
+        case GPBDataTypeGroup: {
+          GPBMessage **valPtr = (GPBMessage **)&storage[fieldOffset];
+          // Could call -hash on the sub message, but that could recurse pretty
+          // deep; follow the lead of NSArray/NSDictionary and don't really
+          // recurse for hash, instead use the field number and the descriptor
+          // of the sub message.  Yes, this could suck for a bunch of messages
+          // where they all only differ in the sub messages, but if you are
+          // using a message with sub messages for something that needs -hash,
+          // odds are you are also copying them as keys, and that deep copy
+          // will also suck.
+          result = prime * result + GPBFieldNumber(field);
+          result = prime * result + (NSUInteger)[[*valPtr class] descriptor];
+          break;
+        }
+      } // switch()
+    }
+  }
+
+  // Unknowns and extensions are not included.
+
+  return result;
+}
+
+#pragma mark - Description Support
+
+- (NSString *)description {
+  NSString *textFormat = GPBTextFormatForMessage(self, @"    ");
+  NSString *description = [NSString
+      stringWithFormat:@"<%@ %p>: {\n%@}", [self class], self, textFormat];
+  return description;
+}
+
+#if DEBUG
+
+// Xcode 5.1 added support for custom quick look info.
+// https://developer.apple.com/library/ios/documentation/IDEs/Conceptual/CustomClassDisplay_in_QuickLook/CH01-quick_look_for_custom_objects/CH01-quick_look_for_custom_objects.html#//apple_ref/doc/uid/TP40014001-CH2-SW1
+- (id)debugQuickLookObject {
+  return GPBTextFormatForMessage(self, nil);
+}
+
+#endif  // DEBUG
+
+#pragma mark - SerializedSize
+
+- (size_t)serializedSize {
+  GPBDescriptor *descriptor = [[self class] descriptor];
+  size_t result = 0;
+
+  // Has check is done explicitly, so GPBGetObjectIvarWithFieldNoAutocreate()
+  // avoids doing the has check again.
+
+  // Fields.
+  for (GPBFieldDescriptor *fieldDescriptor in descriptor->fields_) {
+    GPBFieldType fieldType = fieldDescriptor.fieldType;
+    GPBDataType fieldDataType = GPBGetFieldDataType(fieldDescriptor);
+
+    // Single Fields
+    if (fieldType == GPBFieldTypeSingle) {
+      BOOL selfHas = GPBGetHasIvarField(self, fieldDescriptor);
+      if (!selfHas) {
+        continue;  // Nothing to do.
+      }
+
+      uint32_t fieldNumber = GPBFieldNumber(fieldDescriptor);
+
+      switch (fieldDataType) {
+#define CASE_SINGLE_POD(NAME, TYPE, FUNC_TYPE)                                \
+        case GPBDataType##NAME: {                                             \
+          TYPE fieldVal = GPBGetMessage##FUNC_TYPE##Field(self, fieldDescriptor); \
+          result += GPBCompute##NAME##Size(fieldNumber, fieldVal);            \
+          break;                                                              \
+        }
+#define CASE_SINGLE_OBJECT(NAME)                                              \
+        case GPBDataType##NAME: {                                             \
+          id fieldVal = GPBGetObjectIvarWithFieldNoAutocreate(self, fieldDescriptor); \
+          result += GPBCompute##NAME##Size(fieldNumber, fieldVal);            \
+          break;                                                              \
+        }
+          CASE_SINGLE_POD(Bool, BOOL, Bool)
+          CASE_SINGLE_POD(Fixed32, uint32_t, UInt32)
+          CASE_SINGLE_POD(SFixed32, int32_t, Int32)
+          CASE_SINGLE_POD(Float, float, Float)
+          CASE_SINGLE_POD(Fixed64, uint64_t, UInt64)
+          CASE_SINGLE_POD(SFixed64, int64_t, Int64)
+          CASE_SINGLE_POD(Double, double, Double)
+          CASE_SINGLE_POD(Int32, int32_t, Int32)
+          CASE_SINGLE_POD(Int64, int64_t, Int64)
+          CASE_SINGLE_POD(SInt32, int32_t, Int32)
+          CASE_SINGLE_POD(SInt64, int64_t, Int64)
+          CASE_SINGLE_POD(UInt32, uint32_t, UInt32)
+          CASE_SINGLE_POD(UInt64, uint64_t, UInt64)
+          CASE_SINGLE_OBJECT(Bytes)
+          CASE_SINGLE_OBJECT(String)
+          CASE_SINGLE_OBJECT(Message)
+          CASE_SINGLE_OBJECT(Group)
+          CASE_SINGLE_POD(Enum, int32_t, Int32)
+#undef CASE_SINGLE_POD
+#undef CASE_SINGLE_OBJECT
+      }
+
+    // Repeated Fields
+    } else if (fieldType == GPBFieldTypeRepeated) {
+      id genericArray =
+          GPBGetObjectIvarWithFieldNoAutocreate(self, fieldDescriptor);
+      NSUInteger count = [genericArray count];
+      if (count == 0) {
+        continue;  // Nothing to add.
+      }
+      __block size_t dataSize = 0;
+
+      switch (fieldDataType) {
+#define CASE_REPEATED_POD(NAME, TYPE, ARRAY_TYPE)                             \
+    CASE_REPEATED_POD_EXTRA(NAME, TYPE, ARRAY_TYPE, )
+#define CASE_REPEATED_POD_EXTRA(NAME, TYPE, ARRAY_TYPE, ARRAY_ACCESSOR_NAME)  \
+        case GPBDataType##NAME: {                                             \
+          GPB##ARRAY_TYPE##Array *array = genericArray;                       \
+          [array enumerate##ARRAY_ACCESSOR_NAME##ValuesWithBlock:^(TYPE value, NSUInteger idx, BOOL *stop) { \
+            _Pragma("unused(idx, stop)");                                     \
+            dataSize += GPBCompute##NAME##SizeNoTag(value);                   \
+          }];                                                                 \
+          break;                                                              \
+        }
+#define CASE_REPEATED_OBJECT(NAME)                                            \
+        case GPBDataType##NAME: {                                             \
+          for (id value in genericArray) {                                    \
+            dataSize += GPBCompute##NAME##SizeNoTag(value);                   \
+          }                                                                   \
+          break;                                                              \
+        }
+          CASE_REPEATED_POD(Bool, BOOL, Bool)
+          CASE_REPEATED_POD(Fixed32, uint32_t, UInt32)
+          CASE_REPEATED_POD(SFixed32, int32_t, Int32)
+          CASE_REPEATED_POD(Float, float, Float)
+          CASE_REPEATED_POD(Fixed64, uint64_t, UInt64)
+          CASE_REPEATED_POD(SFixed64, int64_t, Int64)
+          CASE_REPEATED_POD(Double, double, Double)
+          CASE_REPEATED_POD(Int32, int32_t, Int32)
+          CASE_REPEATED_POD(Int64, int64_t, Int64)
+          CASE_REPEATED_POD(SInt32, int32_t, Int32)
+          CASE_REPEATED_POD(SInt64, int64_t, Int64)
+          CASE_REPEATED_POD(UInt32, uint32_t, UInt32)
+          CASE_REPEATED_POD(UInt64, uint64_t, UInt64)
+          CASE_REPEATED_OBJECT(Bytes)
+          CASE_REPEATED_OBJECT(String)
+          CASE_REPEATED_OBJECT(Message)
+          CASE_REPEATED_OBJECT(Group)
+          CASE_REPEATED_POD_EXTRA(Enum, int32_t, Enum, Raw)
+#undef CASE_REPEATED_POD
+#undef CASE_REPEATED_POD_EXTRA
+#undef CASE_REPEATED_OBJECT
+      }  // switch
+      result += dataSize;
+      size_t tagSize = GPBComputeTagSize(GPBFieldNumber(fieldDescriptor));
+      if (fieldDataType == GPBDataTypeGroup) {
+        // Groups have both a start and an end tag.
+        tagSize *= 2;
+      }
+      if (fieldDescriptor.isPackable) {
+        result += tagSize;
+        result += GPBComputeSizeTSizeAsInt32NoTag(dataSize);
+      } else {
+        result += count * tagSize;
+      }
+
+    // Map<> Fields
+    } else {  // fieldType == GPBFieldTypeMap
+      if (GPBDataTypeIsObject(fieldDataType) &&
+          (fieldDescriptor.mapKeyDataType == GPBDataTypeString)) {
+        // If key type was string, then the map is an NSDictionary.
+        NSDictionary *map =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, fieldDescriptor);
+        if (map) {
+          result += GPBDictionaryComputeSizeInternalHelper(map, fieldDescriptor);
+        }
+      } else {
+        // Type will be GPB*GroupDictionary, exact type doesn't matter.
+        GPBInt32Int32Dictionary *map =
+            GPBGetObjectIvarWithFieldNoAutocreate(self, fieldDescriptor);
+        result += [map computeSerializedSizeAsField:fieldDescriptor];
+      }
+    }
+  }  // for(fields)
+
+  // Add any unknown fields.
+  if (descriptor.wireFormat) {
+    result += [unknownFields_ serializedSizeAsMessageSet];
+  } else {
+    result += [unknownFields_ serializedSize];
+  }
+
+  // Add any extensions.
+  for (GPBExtensionDescriptor *extension in extensionMap_) {
+    id value = [extensionMap_ objectForKey:extension];
+    result += GPBComputeExtensionSerializedSizeIncludingTag(extension, value);
+  }
+
+  return result;
+}
+
+#pragma mark - Resolve Methods Support
+
+typedef struct ResolveIvarAccessorMethodResult {
+  IMP impToAdd;
+  SEL encodingSelector;
+} ResolveIvarAccessorMethodResult;
+
+static void ResolveIvarGet(GPBFieldDescriptor *field,
+                           ResolveIvarAccessorMethodResult *result) {
+  GPBDataType fieldDataType = GPBGetFieldDataType(field);
+  switch (fieldDataType) {
+#define CASE_GET(NAME, TYPE, TRUE_NAME)                          \
+    case GPBDataType##NAME: {                                    \
+      result->impToAdd = imp_implementationWithBlock(^(id obj) { \
+        return GPBGetMessage##TRUE_NAME##Field(obj, field);      \
+       });                                                       \
+      result->encodingSelector = @selector(get##NAME);           \
+      break;                                                     \
+    }
+#define CASE_GET_OBJECT(NAME, TYPE, TRUE_NAME)                   \
+    case GPBDataType##NAME: {                                    \
+      result->impToAdd = imp_implementationWithBlock(^(id obj) { \
+        return GPBGetObjectIvarWithField(obj, field);            \
+       });                                                       \
+      result->encodingSelector = @selector(get##NAME);           \
+      break;                                                     \
+    }
+      CASE_GET(Bool, BOOL, Bool)
+      CASE_GET(Fixed32, uint32_t, UInt32)
+      CASE_GET(SFixed32, int32_t, Int32)
+      CASE_GET(Float, float, Float)
+      CASE_GET(Fixed64, uint64_t, UInt64)
+      CASE_GET(SFixed64, int64_t, Int64)
+      CASE_GET(Double, double, Double)
+      CASE_GET(Int32, int32_t, Int32)
+      CASE_GET(Int64, int64_t, Int64)
+      CASE_GET(SInt32, int32_t, Int32)
+      CASE_GET(SInt64, int64_t, Int64)
+      CASE_GET(UInt32, uint32_t, UInt32)
+      CASE_GET(UInt64, uint64_t, UInt64)
+      CASE_GET_OBJECT(Bytes, id, Object)
+      CASE_GET_OBJECT(String, id, Object)
+      CASE_GET_OBJECT(Message, id, Object)
+      CASE_GET_OBJECT(Group, id, Object)
+      CASE_GET(Enum, int32_t, Enum)
+#undef CASE_GET
+  }
+}
+
+static void ResolveIvarSet(GPBFieldDescriptor *field,
+                           GPBFileSyntax syntax,
+                           ResolveIvarAccessorMethodResult *result) {
+  GPBDataType fieldDataType = GPBGetFieldDataType(field);
+  switch (fieldDataType) {
+#define CASE_SET(NAME, TYPE, TRUE_NAME)                                       \
+    case GPBDataType##NAME: {                                                 \
+      result->impToAdd = imp_implementationWithBlock(^(id obj, TYPE value) {  \
+        return GPBSet##TRUE_NAME##IvarWithFieldInternal(obj, field, value, syntax); \
+      });                                                                     \
+      result->encodingSelector = @selector(set##NAME:);                       \
+      break;                                                                  \
+    }
+      CASE_SET(Bool, BOOL, Bool)
+      CASE_SET(Fixed32, uint32_t, UInt32)
+      CASE_SET(SFixed32, int32_t, Int32)
+      CASE_SET(Float, float, Float)
+      CASE_SET(Fixed64, uint64_t, UInt64)
+      CASE_SET(SFixed64, int64_t, Int64)
+      CASE_SET(Double, double, Double)
+      CASE_SET(Int32, int32_t, Int32)
+      CASE_SET(Int64, int64_t, Int64)
+      CASE_SET(SInt32, int32_t, Int32)
+      CASE_SET(SInt64, int64_t, Int64)
+      CASE_SET(UInt32, uint32_t, UInt32)
+      CASE_SET(UInt64, uint64_t, UInt64)
+      CASE_SET(Bytes, id, Object)
+      CASE_SET(String, id, Object)
+      CASE_SET(Message, id, Object)
+      CASE_SET(Group, id, Object)
+      CASE_SET(Enum, int32_t, Enum)
+#undef CASE_SET
+  }
+}
+
++ (BOOL)resolveInstanceMethod:(SEL)sel {
+  const GPBDescriptor *descriptor = [self descriptor];
+  if (!descriptor) {
+    return NO;
+  }
+
+  // NOTE: hasOrCountSel_/setHasSel_ will be NULL if the field for the given
+  // message should not have has support (done in GPBDescriptor.m), so there is
+  // no need for checks here to see if has*/setHas* are allowed.
+
+  ResolveIvarAccessorMethodResult result = {NULL, NULL};
+  for (GPBFieldDescriptor *field in descriptor->fields_) {
+    BOOL isMapOrArray = GPBFieldIsMapOrArray(field);
+    if (!isMapOrArray) {
+      // Single fields.
+      if (sel == field->getSel_) {
+        ResolveIvarGet(field, &result);
+        break;
+      } else if (sel == field->setSel_) {
+        ResolveIvarSet(field, descriptor.file.syntax, &result);
+        break;
+      } else if (sel == field->hasOrCountSel_) {
+        int32_t index = GPBFieldHasIndex(field);
+        uint32_t fieldNum = GPBFieldNumber(field);
+        result.impToAdd = imp_implementationWithBlock(^(id obj) {
+          return GPBGetHasIvar(obj, index, fieldNum);
+        });
+        result.encodingSelector = @selector(getBool);
+        break;
+      } else if (sel == field->setHasSel_) {
+        result.impToAdd = imp_implementationWithBlock(^(id obj, BOOL value) {
+          if (value) {
+            [NSException raise:NSInvalidArgumentException
+                        format:@"%@: %@ can only be set to NO (to clear field).",
+                               [obj class],
+                               NSStringFromSelector(field->setHasSel_)];
+          }
+          GPBClearMessageField(obj, field);
+        });
+        result.encodingSelector = @selector(setBool:);
+        break;
+      } else {
+        GPBOneofDescriptor *oneof = field->containingOneof_;
+        if (oneof && (sel == oneof->caseSel_)) {
+          int32_t index = oneof->oneofDescription_->index;
+          result.impToAdd = imp_implementationWithBlock(^(id obj) {
+            return GPBGetHasOneof(obj, index);
+          });
+          result.encodingSelector = @selector(getEnum);
+          break;
+        }
+      }
+    } else {
+      // map<>/repeated fields.
+      if (sel == field->getSel_) {
+        if (field.fieldType == GPBFieldTypeRepeated) {
+          result.impToAdd = imp_implementationWithBlock(^(id obj) {
+            return GetArrayIvarWithField(obj, field);
+          });
+        } else {
+          result.impToAdd = imp_implementationWithBlock(^(id obj) {
+            return GetMapIvarWithField(obj, field);
+          });
+        }
+        result.encodingSelector = @selector(getArray);
+        break;
+      } else if (sel == field->setSel_) {
+        // Local for syntax so the block can directly capture it and not the
+        // full lookup.
+        const GPBFileSyntax syntax = descriptor.file.syntax;
+        result.impToAdd = imp_implementationWithBlock(^(id obj, id value) {
+          return GPBSetObjectIvarWithFieldInternal(obj, field, value, syntax);
+        });
+        result.encodingSelector = @selector(setArray:);
+        break;
+      } else if (sel == field->hasOrCountSel_) {
+        result.impToAdd = imp_implementationWithBlock(^(id obj) {
+          // Type doesn't matter, all *Array and *Dictionary types support
+          // -count.
+          NSArray *arrayOrMap =
+              GPBGetObjectIvarWithFieldNoAutocreate(obj, field);
+          return [arrayOrMap count];
+        });
+        result.encodingSelector = @selector(getArrayCount);
+        break;
+      }
+    }
+  }
+  if (result.impToAdd) {
+    const char *encoding =
+        GPBMessageEncodingForSelector(result.encodingSelector, YES);
+    BOOL methodAdded = class_addMethod(descriptor.messageClass, sel,
+                                       result.impToAdd, encoding);
+    return methodAdded;
+  }
+  return [super resolveInstanceMethod:sel];
+}
+
++ (BOOL)resolveClassMethod:(SEL)sel {
+  // Extensions scoped to a Message and looked up via class methods.
+  if (GPBResolveExtensionClassMethod(self, sel)) {
+    return YES;
+  }
+  return [super resolveClassMethod:sel];
+}
+
+#pragma mark - NSCoding Support
+
++ (BOOL)supportsSecureCoding {
+  return YES;
+}
+
+- (instancetype)initWithCoder:(NSCoder *)aDecoder {
+  self = [self init];
+  if (self) {
+    NSData *data =
+        [aDecoder decodeObjectOfClass:[NSData class] forKey:kGPBDataCoderKey];
+    if (data.length) {
+      [self mergeFromData:data extensionRegistry:nil];
+    }
+  }
+  return self;
+}
+
+- (void)encodeWithCoder:(NSCoder *)aCoder {
+  NSData *data = [self data];
+  if (data.length) {
+    [aCoder encodeObject:data forKey:kGPBDataCoderKey];
+  }
+}
+
+#pragma mark - KVC Support
+
++ (BOOL)accessInstanceVariablesDirectly {
+  // Make sure KVC doesn't use instance variables.
+  return NO;
+}
+
+@end