diff --git a/src/compiler/Tests/Descriptor.pb.h b/src/compiler/Tests/Descriptor.pb.h
index 2d3f8a9..b839a48 100644
--- a/src/compiler/Tests/Descriptor.pb.h
+++ b/src/compiler/Tests/Descriptor.pb.h
@@ -117,8 +117,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * file;
 - (PBFileDescriptorProto*)fileAtIndex:(NSUInteger)index;
 
-+ (PBFileDescriptorSet*) defaultInstance;
-- (PBFileDescriptorSet*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -200,8 +200,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 - (PBServiceDescriptorProto*)serviceAtIndex:(NSUInteger)index;
 - (PBFieldDescriptorProto*)extensionAtIndex:(NSUInteger)index;
 
-+ (PBFileDescriptorProto*) defaultInstance;
-- (PBFileDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -334,8 +334,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 - (PBDescriptorProtoExtensionRange*)extensionRangeAtIndex:(NSUInteger)index;
 - (PBOneofDescriptorProto*)oneofDeclAtIndex:(NSUInteger)index;
 
-+ (PBDescriptorProto*) defaultInstance;
-- (PBDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -364,8 +364,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly) SInt32 start;
 @property (readonly) SInt32 end;
 
-+ (PBDescriptorProtoExtensionRange*) defaultInstance;
-- (PBDescriptorProtoExtensionRange*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -516,8 +516,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly) SInt32 oneofIndex;
 @property (readonly, strong) PBFieldOptions* options;
 
-+ (PBFieldDescriptorProto*) defaultInstance;
-- (PBFieldDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -607,8 +607,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 - (BOOL) hasName;
 @property (readonly, strong) NSString* name;
 
-+ (PBOneofDescriptorProto*) defaultInstance;
-- (PBOneofDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -663,8 +663,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) PBEnumOptions* options;
 - (PBEnumValueDescriptorProto*)valueAtIndex:(NSUInteger)index;
 
-+ (PBEnumDescriptorProto*) defaultInstance;
-- (PBEnumDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -733,8 +733,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly) SInt32 number;
 @property (readonly, strong) PBEnumValueOptions* options;
 
-+ (PBEnumValueDescriptorProto*) defaultInstance;
-- (PBEnumValueDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -801,8 +801,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) PBServiceOptions* options;
 - (PBMethodDescriptorProto*)methodAtIndex:(NSUInteger)index;
 
-+ (PBServiceDescriptorProto*) defaultInstance;
-- (PBServiceDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -875,8 +875,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSString* outputType;
 @property (readonly, strong) PBMethodOptions* options;
 
-+ (PBMethodDescriptorProto*) defaultInstance;
-- (PBMethodDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -984,8 +984,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * uninterpretedOption;
 - (PBUninterpretedOption*)uninterpretedOptionAtIndex:(NSUInteger)index;
 
-+ (PBFileOptions*) defaultInstance;
-- (PBFileOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1100,8 +1100,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * uninterpretedOption;
 - (PBUninterpretedOption*)uninterpretedOptionAtIndex:(NSUInteger)index;
 
-+ (PBMessageOptions*) defaultInstance;
-- (PBMessageOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1188,8 +1188,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * uninterpretedOption;
 - (PBUninterpretedOption*)uninterpretedOptionAtIndex:(NSUInteger)index;
 
-+ (PBFieldOptions*) defaultInstance;
-- (PBFieldOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1275,8 +1275,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * uninterpretedOption;
 - (PBUninterpretedOption*)uninterpretedOptionAtIndex:(NSUInteger)index;
 
-+ (PBEnumOptions*) defaultInstance;
-- (PBEnumOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1338,8 +1338,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * uninterpretedOption;
 - (PBUninterpretedOption*)uninterpretedOptionAtIndex:(NSUInteger)index;
 
-+ (PBEnumValueOptions*) defaultInstance;
-- (PBEnumValueOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1396,8 +1396,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * uninterpretedOption;
 - (PBUninterpretedOption*)uninterpretedOptionAtIndex:(NSUInteger)index;
 
-+ (PBServiceOptions*) defaultInstance;
-- (PBServiceOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1454,8 +1454,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * uninterpretedOption;
 - (PBUninterpretedOption*)uninterpretedOptionAtIndex:(NSUInteger)index;
 
-+ (PBMethodOptions*) defaultInstance;
-- (PBMethodOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1532,8 +1532,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSString* aggregateValue;
 - (PBUninterpretedOptionNamePart*)nameAtIndex:(NSUInteger)index;
 
-+ (PBUninterpretedOption*) defaultInstance;
-- (PBUninterpretedOption*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1562,8 +1562,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSString* namePart;
 - (BOOL) isExtension;
 
-+ (PBUninterpretedOptionNamePart*) defaultInstance;
-- (PBUninterpretedOptionNamePart*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1669,8 +1669,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * location;
 - (PBSourceCodeInfoLocation*)locationAtIndex:(NSUInteger)index;
 
-+ (PBSourceCodeInfo*) defaultInstance;
-- (PBSourceCodeInfo*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1707,8 +1707,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 - (SInt32)pathAtIndex:(NSUInteger)index;
 - (SInt32)spanAtIndex:(NSUInteger)index;
 
-+ (PBSourceCodeInfoLocation*) defaultInstance;
-- (PBSourceCodeInfoLocation*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/compiler/Tests/Descriptor.pb.m b/src/compiler/Tests/Descriptor.pb.m
index 87031bd..e978640 100644
--- a/src/compiler/Tests/Descriptor.pb.m
+++ b/src/compiler/Tests/Descriptor.pb.m
@@ -39,10 +39,10 @@ + (void) initialize {
     defaultPBFileDescriptorSetInstance = [[PBFileDescriptorSet alloc] init];
   }
 }
-+ (PBFileDescriptorSet*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBFileDescriptorSetInstance;
 }
-- (PBFileDescriptorSet*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBFileDescriptorSetInstance;
 }
 - (NSArray *)file {
@@ -314,10 +314,10 @@ + (void) initialize {
     defaultPBFileDescriptorProtoInstance = [[PBFileDescriptorProto alloc] init];
   }
 }
-+ (PBFileDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBFileDescriptorProtoInstance;
 }
-- (PBFileDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBFileDescriptorProtoInstance;
 }
 - (NSArray *)dependency {
@@ -1146,10 +1146,10 @@ + (void) initialize {
     defaultPBDescriptorProtoInstance = [[PBDescriptorProto alloc] init];
   }
 }
-+ (PBDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBDescriptorProtoInstance;
 }
-- (PBDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBDescriptorProtoInstance;
 }
 - (NSArray *)field {
@@ -1454,10 +1454,10 @@ + (void) initialize {
     defaultPBDescriptorProtoExtensionRangeInstance = [[PBDescriptorProtoExtensionRange alloc] init];
   }
 }
-+ (PBDescriptorProtoExtensionRange*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBDescriptorProtoExtensionRangeInstance;
 }
-- (PBDescriptorProtoExtensionRange*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBDescriptorProtoExtensionRangeInstance;
 }
 - (BOOL) isInitialized {
@@ -2096,10 +2096,10 @@ + (void) initialize {
     defaultPBFieldDescriptorProtoInstance = [[PBFieldDescriptorProto alloc] init];
   }
 }
-+ (PBFieldDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBFieldDescriptorProtoInstance;
 }
-- (PBFieldDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBFieldDescriptorProtoInstance;
 }
 - (BOOL) isInitialized {
@@ -2664,10 +2664,10 @@ + (void) initialize {
     defaultPBOneofDescriptorProtoInstance = [[PBOneofDescriptorProto alloc] init];
   }
 }
-+ (PBOneofDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBOneofDescriptorProtoInstance;
 }
-- (PBOneofDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBOneofDescriptorProtoInstance;
 }
 - (BOOL) isInitialized {
@@ -2876,10 +2876,10 @@ + (void) initialize {
     defaultPBEnumDescriptorProtoInstance = [[PBEnumDescriptorProto alloc] init];
   }
 }
-+ (PBEnumDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBEnumDescriptorProtoInstance;
 }
-- (PBEnumDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBEnumDescriptorProtoInstance;
 }
 - (NSArray *)value {
@@ -3222,10 +3222,10 @@ + (void) initialize {
     defaultPBEnumValueDescriptorProtoInstance = [[PBEnumValueDescriptorProto alloc] init];
   }
 }
-+ (PBEnumValueDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBEnumValueDescriptorProtoInstance;
 }
-- (PBEnumValueDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBEnumValueDescriptorProtoInstance;
 }
 - (BOOL) isInitialized {
@@ -3535,10 +3535,10 @@ + (void) initialize {
     defaultPBServiceDescriptorProtoInstance = [[PBServiceDescriptorProto alloc] init];
   }
 }
-+ (PBServiceDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBServiceDescriptorProtoInstance;
 }
-- (PBServiceDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBServiceDescriptorProtoInstance;
 }
 - (NSArray *)method {
@@ -3890,10 +3890,10 @@ + (void) initialize {
     defaultPBMethodDescriptorProtoInstance = [[PBMethodDescriptorProto alloc] init];
   }
 }
-+ (PBMethodDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBMethodDescriptorProtoInstance;
 }
-- (PBMethodDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBMethodDescriptorProtoInstance;
 }
 - (BOOL) isInitialized {
@@ -4356,10 +4356,10 @@ + (void) initialize {
     defaultPBFileOptionsInstance = [[PBFileOptions alloc] init];
   }
 }
-+ (PBFileOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBFileOptionsInstance;
 }
-- (PBFileOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBFileOptionsInstance;
 }
 - (NSArray *)uninterpretedOption {
@@ -5056,10 +5056,10 @@ + (void) initialize {
     defaultPBMessageOptionsInstance = [[PBMessageOptions alloc] init];
   }
 }
-+ (PBMessageOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBMessageOptionsInstance;
 }
-- (PBMessageOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBMessageOptionsInstance;
 }
 - (NSArray *)uninterpretedOption {
@@ -5477,10 +5477,10 @@ + (void) initialize {
     defaultPBFieldOptionsInstance = [[PBFieldOptions alloc] init];
   }
 }
-+ (PBFieldOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBFieldOptionsInstance;
 }
-- (PBFieldOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBFieldOptionsInstance;
 }
 - (NSArray *)uninterpretedOption {
@@ -5978,10 +5978,10 @@ + (void) initialize {
     defaultPBEnumOptionsInstance = [[PBEnumOptions alloc] init];
   }
 }
-+ (PBEnumOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBEnumOptionsInstance;
 }
-- (PBEnumOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBEnumOptionsInstance;
 }
 - (NSArray *)uninterpretedOption {
@@ -6302,10 +6302,10 @@ + (void) initialize {
     defaultPBEnumValueOptionsInstance = [[PBEnumValueOptions alloc] init];
   }
 }
-+ (PBEnumValueOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBEnumValueOptionsInstance;
 }
-- (PBEnumValueOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBEnumValueOptionsInstance;
 }
 - (NSArray *)uninterpretedOption {
@@ -6589,10 +6589,10 @@ + (void) initialize {
     defaultPBServiceOptionsInstance = [[PBServiceOptions alloc] init];
   }
 }
-+ (PBServiceOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBServiceOptionsInstance;
 }
-- (PBServiceOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBServiceOptionsInstance;
 }
 - (NSArray *)uninterpretedOption {
@@ -6876,10 +6876,10 @@ + (void) initialize {
     defaultPBMethodOptionsInstance = [[PBMethodOptions alloc] init];
   }
 }
-+ (PBMethodOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBMethodOptionsInstance;
 }
-- (PBMethodOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBMethodOptionsInstance;
 }
 - (NSArray *)uninterpretedOption {
@@ -7203,10 +7203,10 @@ + (void) initialize {
     defaultPBUninterpretedOptionInstance = [[PBUninterpretedOption alloc] init];
   }
 }
-+ (PBUninterpretedOption*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBUninterpretedOptionInstance;
 }
-- (PBUninterpretedOption*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBUninterpretedOptionInstance;
 }
 - (NSArray *)name {
@@ -7430,10 +7430,10 @@ + (void) initialize {
     defaultPBUninterpretedOptionNamePartInstance = [[PBUninterpretedOptionNamePart alloc] init];
   }
 }
-+ (PBUninterpretedOptionNamePart*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBUninterpretedOptionNamePartInstance;
 }
-- (PBUninterpretedOptionNamePart*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBUninterpretedOptionNamePartInstance;
 }
 - (BOOL) isInitialized {
@@ -7903,10 +7903,10 @@ + (void) initialize {
     defaultPBSourceCodeInfoInstance = [[PBSourceCodeInfo alloc] init];
   }
 }
-+ (PBSourceCodeInfo*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBSourceCodeInfoInstance;
 }
-- (PBSourceCodeInfo*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBSourceCodeInfoInstance;
 }
 - (NSArray *)location {
@@ -8039,10 +8039,10 @@ + (void) initialize {
     defaultPBSourceCodeInfoLocationInstance = [[PBSourceCodeInfoLocation alloc] init];
   }
 }
-+ (PBSourceCodeInfoLocation*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBSourceCodeInfoLocationInstance;
 }
-- (PBSourceCodeInfoLocation*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBSourceCodeInfoLocationInstance;
 }
 - (PBArray *)path {
diff --git a/src/compiler/Tests/Unittest.pb.h b/src/compiler/Tests/Unittest.pb.h
index 6d3d564..014b880 100644
--- a/src/compiler/Tests/Unittest.pb.h
+++ b/src/compiler/Tests/Unittest.pb.h
@@ -605,8 +605,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (NSString*)repeatedCordAtIndex:(NSUInteger)index;
 - (TestAllTypesNestedMessage*)repeatedLazyMessageAtIndex:(NSUInteger)index;
 
-+ (TestAllTypes*) defaultInstance;
-- (TestAllTypes*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -631,8 +631,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasBb;
 @property (readonly) SInt32 bb;
 
-+ (TestAllTypesNestedMessage*) defaultInstance;
-- (TestAllTypesNestedMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -680,8 +680,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (TestAllTypesOptionalGroup*) defaultInstance;
-- (TestAllTypesOptionalGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -729,8 +729,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (TestAllTypesRepeatedGroup*) defaultInstance;
-- (TestAllTypesRepeatedGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1230,8 +1230,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) NestedTestAllTypes* child;
 @property (readonly, strong) TestAllTypes* payload;
 
-+ (NestedTestAllTypes*) defaultInstance;
-- (NestedTestAllTypes*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1288,8 +1288,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasDeprecatedInt32;
 @property (readonly) SInt32 deprecatedInt32;
 
-+ (TestDeprecatedFields*) defaultInstance;
-- (TestDeprecatedFields*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1337,8 +1337,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasC;
 @property (readonly) SInt32 c;
 
-+ (ForeignMessage*) defaultInstance;
-- (ForeignMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1382,8 +1382,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (TestAllExtensions*) defaultInstance;
-- (TestAllExtensions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1426,8 +1426,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (OptionalGroup_extension*) defaultInstance;
-- (OptionalGroup_extension*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1475,8 +1475,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (RepeatedGroup_extension*) defaultInstance;
-- (RepeatedGroup_extension*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1520,8 +1520,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (TestNestedExtension*) defaultInstance;
-- (TestNestedExtension*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) test;
 + (id<PBExtensionField>) nestedStringExtension;
@@ -1694,8 +1694,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt32 dummy32;
 @property (readonly) SInt32 c;
 
-+ (TestRequired*) defaultInstance;
-- (TestRequired*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) single;
 + (id<PBExtensionField>) multi;
@@ -1912,8 +1912,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt32 dummy;
 - (TestRequired*)repeatedMessageAtIndex:(NSUInteger)index;
 
-+ (TestRequiredForeign*) defaultInstance;
-- (TestRequiredForeign*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1974,8 +1974,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasForeignNested;
 @property (readonly, strong) TestAllTypesNestedMessage* foreignNested;
 
-+ (TestForeignNested*) defaultInstance;
-- (TestForeignNested*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2021,8 +2021,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (TestEmptyMessage*) defaultInstance;
-- (TestEmptyMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2061,8 +2061,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (TestEmptyMessageWithExtensions*) defaultInstance;
-- (TestEmptyMessageWithExtensions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2101,8 +2101,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (TestMultipleExtensionRanges*) defaultInstance;
-- (TestMultipleExtensionRanges*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2149,8 +2149,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt32 a;
 @property (readonly) SInt32 bb;
 
-+ (TestReallyLargeTagNumber*) defaultInstance;
-- (TestReallyLargeTagNumber*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2207,8 +2207,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) TestRecursiveMessage* a;
 @property (readonly) SInt32 i;
 
-+ (TestRecursiveMessage*) defaultInstance;
-- (TestRecursiveMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2263,8 +2263,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasBb;
 @property (readonly, strong) TestMutualRecursionB* bb;
 
-+ (TestMutualRecursionA*) defaultInstance;
-- (TestMutualRecursionA*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2318,8 +2318,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) TestMutualRecursionA* a;
 @property (readonly) SInt32 optionalInt32;
 
-+ (TestMutualRecursionB*) defaultInstance;
-- (TestMutualRecursionB*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2382,8 +2382,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) TestDupFieldNumberFoo* foo;
 @property (readonly, strong) TestDupFieldNumberBar* bar;
 
-+ (TestDupFieldNumber*) defaultInstance;
-- (TestDupFieldNumber*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2408,8 +2408,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (TestDupFieldNumberFoo*) defaultInstance;
-- (TestDupFieldNumberFoo*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2457,8 +2457,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (TestDupFieldNumberBar*) defaultInstance;
-- (TestDupFieldNumberBar*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2543,8 +2543,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasSubMessage;
 @property (readonly, strong) TestAllTypes* subMessage;
 
-+ (TestEagerMessage*) defaultInstance;
-- (TestEagerMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2594,8 +2594,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasSubMessage;
 @property (readonly, strong) TestAllTypes* subMessage;
 
-+ (TestLazyMessage*) defaultInstance;
-- (TestLazyMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2645,8 +2645,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasOptionalNestedMessage;
 @property (readonly, strong) TestNestedMessageHasBitsNestedMessage* optionalNestedMessage;
 
-+ (TestNestedMessageHasBits*) defaultInstance;
-- (TestNestedMessageHasBits*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2673,8 +2673,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (SInt32)nestedmessageRepeatedInt32AtIndex:(NSUInteger)index;
 - (ForeignMessage*)nestedmessageRepeatedForeignmessageAtIndex:(NSUInteger)index;
 
-+ (TestNestedMessageHasBitsNestedMessage*) defaultInstance;
-- (TestNestedMessageHasBitsNestedMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2793,8 +2793,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (NSString*)repeatedStringPieceFieldAtIndex:(NSUInteger)index;
 - (NSString*)repeatedCordFieldAtIndex:(NSUInteger)index;
 
-+ (TestCamelCaseFieldNames*) defaultInstance;
-- (TestCamelCaseFieldNames*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2915,8 +2915,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt64 myInt;
 @property (readonly) Float32 myFloat;
 
-+ (TestFieldOrderings*) defaultInstance;
-- (TestFieldOrderings*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3078,8 +3078,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) NSString* cordWithZero;
 @property (readonly, strong) NSString* replacementString;
 
-+ (TestExtremeDefaultValues*) defaultInstance;
-- (TestExtremeDefaultValues*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3257,8 +3257,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasSparseEnum;
 @property (readonly) TestSparseEnum sparseEnum;
 
-+ (SparseEnumMessage*) defaultInstance;
-- (SparseEnumMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3306,8 +3306,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasData;
 @property (readonly, strong) NSString* data;
 
-+ (OneString*) defaultInstance;
-- (OneString*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3354,8 +3354,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) NSArray * data;
 - (NSString*)dataAtIndex:(NSUInteger)index;
 
-+ (MoreString*) defaultInstance;
-- (MoreString*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3404,8 +3404,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasData;
 @property (readonly, strong) NSData* data;
 
-+ (OneBytes*) defaultInstance;
-- (OneBytes*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3452,8 +3452,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) NSArray * data;
 - (NSData*)dataAtIndex:(NSUInteger)index;
 
-+ (MoreBytes*) defaultInstance;
-- (MoreBytes*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3502,8 +3502,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasData;
 @property (readonly) SInt32 data;
 
-+ (Int32Message*) defaultInstance;
-- (Int32Message*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3551,8 +3551,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasData;
 @property (readonly) UInt32 data;
 
-+ (Uint32Message*) defaultInstance;
-- (Uint32Message*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3600,8 +3600,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasData;
 @property (readonly) SInt64 data;
 
-+ (Int64Message*) defaultInstance;
-- (Int64Message*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3649,8 +3649,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasData;
 @property (readonly) UInt64 data;
 
-+ (Uint64Message*) defaultInstance;
-- (Uint64Message*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3698,8 +3698,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasData;
 - (BOOL) data;
 
-+ (BoolMessage*) defaultInstance;
-- (BoolMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3759,8 +3759,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) TestAllTypes* fooMessage;
 @property (readonly, strong) TestOneofFooGroup* fooGroup;
 
-+ (TestOneof*) defaultInstance;
-- (TestOneof*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3789,8 +3789,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt32 a;
 @property (readonly, strong) NSString* b;
 
-+ (TestOneofFooGroup*) defaultInstance;
-- (TestOneofFooGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3897,8 +3897,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) TestAllTypes* fooMessage;
 @property (readonly, strong) TestOneofBackwardsCompatibleFooGroup* fooGroup;
 
-+ (TestOneofBackwardsCompatible*) defaultInstance;
-- (TestOneofBackwardsCompatible*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3927,8 +3927,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt32 a;
 @property (readonly, strong) NSString* b;
 
-+ (TestOneofBackwardsCompatibleFooGroup*) defaultInstance;
-- (TestOneofBackwardsCompatibleFooGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4087,8 +4087,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt32 bazInt;
 @property (readonly, strong) NSString* bazString;
 
-+ (TestOneof2*) defaultInstance;
-- (TestOneof2*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4117,8 +4117,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt32 a;
 @property (readonly, strong) NSString* b;
 
-+ (TestOneof2FooGroup*) defaultInstance;
-- (TestOneof2FooGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4174,8 +4174,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) PBArray * corgeInt;
 - (SInt32)corgeIntAtIndex:(NSUInteger)index;
 
-+ (TestOneof2NestedMessage*) defaultInstance;
-- (TestOneof2NestedMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4347,8 +4347,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) NSString* fooString;
 @property (readonly, strong) TestRequiredOneofNestedMessage* fooMessage;
 
-+ (TestRequiredOneof*) defaultInstance;
-- (TestRequiredOneof*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4373,8 +4373,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasRequiredDouble;
 @property (readonly) Float64 requiredDouble;
 
-+ (TestRequiredOneofNestedMessage*) defaultInstance;
-- (TestRequiredOneofNestedMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4509,8 +4509,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL)packedBoolAtIndex:(NSUInteger)index;
 - (ForeignEnum)packedEnumAtIndex:(NSUInteger)index;
 
-+ (TestPackedTypes*) defaultInstance;
-- (TestPackedTypes*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4689,8 +4689,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL)unpackedBoolAtIndex:(NSUInteger)index;
 - (ForeignEnum)unpackedEnumAtIndex:(NSUInteger)index;
 
-+ (TestUnpackedTypes*) defaultInstance;
-- (TestUnpackedTypes*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4827,8 +4827,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (TestPackedExtensions*) defaultInstance;
-- (TestPackedExtensions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4867,8 +4867,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (TestUnpackedExtensions*) defaultInstance;
-- (TestUnpackedExtensions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4934,8 +4934,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (NSString*)repeatedExtensionAtIndex:(NSUInteger)index;
 - (SInt32)packedExtensionAtIndex:(NSUInteger)index;
 
-+ (TestDynamicExtensions*) defaultInstance;
-- (TestDynamicExtensions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4960,8 +4960,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasDynamicField;
 @property (readonly) SInt32 dynamicField;
 
-+ (TestDynamicExtensionsDynamicMessageType*) defaultInstance;
-- (TestDynamicExtensionsDynamicMessageType*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5083,8 +5083,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (Float32)repeatedFloatAtIndex:(NSUInteger)index;
 - (UInt64)repeatedUint64AtIndex:(NSUInteger)index;
 
-+ (TestRepeatedScalarDifferentTagSizes*) defaultInstance;
-- (TestRepeatedScalarDifferentTagSizes*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5183,8 +5183,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (TestAllTypes*)repeatedAllTypesAtIndex:(NSUInteger)index;
 - (TestParsingMergeRepeatedGroup*)repeatedGroupAtIndex:(NSUInteger)index;
 
-+ (TestParsingMerge*) defaultInstance;
-- (TestParsingMerge*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) optionalExt;
 + (id<PBExtensionField>) repeatedExt;
@@ -5228,8 +5228,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (TestAllTypes*)ext1AtIndex:(NSUInteger)index;
 - (TestAllTypes*)ext2AtIndex:(NSUInteger)index;
 
-+ (TestParsingMergeRepeatedFieldsGenerator*) defaultInstance;
-- (TestParsingMergeRepeatedFieldsGenerator*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5254,8 +5254,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasField1;
 @property (readonly, strong) TestAllTypes* field1;
 
-+ (TestParsingMergeRepeatedFieldsGeneratorGroup1*) defaultInstance;
-- (TestParsingMergeRepeatedFieldsGeneratorGroup1*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5305,8 +5305,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasField1;
 @property (readonly, strong) TestAllTypes* field1;
 
-+ (TestParsingMergeRepeatedFieldsGeneratorGroup2*) defaultInstance;
-- (TestParsingMergeRepeatedFieldsGeneratorGroup2*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5416,8 +5416,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasOptionalGroupAllTypes;
 @property (readonly, strong) TestAllTypes* optionalGroupAllTypes;
 
-+ (TestParsingMergeOptionalGroup*) defaultInstance;
-- (TestParsingMergeOptionalGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5467,8 +5467,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasRepeatedGroupAllTypes;
 @property (readonly, strong) TestAllTypes* repeatedGroupAllTypes;
 
-+ (TestParsingMergeRepeatedGroup*) defaultInstance;
-- (TestParsingMergeRepeatedGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5569,8 +5569,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasA;
 @property (readonly, strong) NSString* a;
 
-+ (TestCommentInjectionMessage*) defaultInstance;
-- (TestCommentInjectionMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5614,8 +5614,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (FooRequest*) defaultInstance;
-- (FooRequest*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5654,8 +5654,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (FooResponse*) defaultInstance;
-- (FooResponse*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5694,8 +5694,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (FooClientMessage*) defaultInstance;
-- (FooClientMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5734,8 +5734,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (FooServerMessage*) defaultInstance;
-- (FooServerMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5774,8 +5774,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (BarRequest*) defaultInstance;
-- (BarRequest*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5814,8 +5814,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (BarResponse*) defaultInstance;
-- (BarResponse*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/compiler/Tests/Unittest.pb.m b/src/compiler/Tests/Unittest.pb.m
index f6adde7..231a729 100644
--- a/src/compiler/Tests/Unittest.pb.m
+++ b/src/compiler/Tests/Unittest.pb.m
@@ -2142,10 +2142,10 @@ + (void) initialize {
     defaultTestAllTypesInstance = [[TestAllTypes alloc] init];
   }
 }
-+ (TestAllTypes*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesInstance;
 }
-- (TestAllTypes*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesInstance;
 }
 - (PBArray *)repeatedInt32 {
@@ -3636,10 +3636,10 @@ + (void) initialize {
     defaultTestAllTypesNestedMessageInstance = [[TestAllTypesNestedMessage alloc] init];
   }
 }
-+ (TestAllTypesNestedMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesNestedMessageInstance;
 }
-- (TestAllTypesNestedMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesNestedMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -3836,10 +3836,10 @@ + (void) initialize {
     defaultTestAllTypesOptionalGroupInstance = [[TestAllTypesOptionalGroup alloc] init];
   }
 }
-+ (TestAllTypesOptionalGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesOptionalGroupInstance;
 }
-- (TestAllTypesOptionalGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesOptionalGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -4036,10 +4036,10 @@ + (void) initialize {
     defaultTestAllTypesRepeatedGroupInstance = [[TestAllTypesRepeatedGroup alloc] init];
   }
 }
-+ (TestAllTypesRepeatedGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesRepeatedGroupInstance;
 }
-- (TestAllTypesRepeatedGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesRepeatedGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -6511,10 +6511,10 @@ + (void) initialize {
     defaultNestedTestAllTypesInstance = [[NestedTestAllTypes alloc] init];
   }
 }
-+ (NestedTestAllTypes*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultNestedTestAllTypesInstance;
 }
-- (NestedTestAllTypes*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultNestedTestAllTypesInstance;
 }
 - (BOOL) isInitialized {
@@ -6792,10 +6792,10 @@ + (void) initialize {
     defaultTestDeprecatedFieldsInstance = [[TestDeprecatedFields alloc] init];
   }
 }
-+ (TestDeprecatedFields*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestDeprecatedFieldsInstance;
 }
-- (TestDeprecatedFields*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestDeprecatedFieldsInstance;
 }
 - (BOOL) isInitialized {
@@ -6992,10 +6992,10 @@ + (void) initialize {
     defaultForeignMessageInstance = [[ForeignMessage alloc] init];
   }
 }
-+ (ForeignMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultForeignMessageInstance;
 }
-- (ForeignMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultForeignMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -7183,10 +7183,10 @@ + (void) initialize {
     defaultTestAllExtensionsInstance = [[TestAllExtensions alloc] init];
   }
 }
-+ (TestAllExtensions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllExtensionsInstance;
 }
-- (TestAllExtensions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllExtensionsInstance;
 }
 - (BOOL) isInitialized {
@@ -7361,10 +7361,10 @@ + (void) initialize {
     defaultOptionalGroup_extensionInstance = [[OptionalGroup_extension alloc] init];
   }
 }
-+ (OptionalGroup_extension*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultOptionalGroup_extensionInstance;
 }
-- (OptionalGroup_extension*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultOptionalGroup_extensionInstance;
 }
 - (BOOL) isInitialized {
@@ -7561,10 +7561,10 @@ + (void) initialize {
     defaultRepeatedGroup_extensionInstance = [[RepeatedGroup_extension alloc] init];
   }
 }
-+ (RepeatedGroup_extension*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultRepeatedGroup_extensionInstance;
 }
-- (RepeatedGroup_extension*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultRepeatedGroup_extensionInstance;
 }
 - (BOOL) isInitialized {
@@ -7758,10 +7758,10 @@ + (void) initialize {
     defaultTestNestedExtensionInstance = [[TestNestedExtension alloc] init];
   }
 }
-+ (TestNestedExtension*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestNestedExtensionInstance;
 }
-- (TestNestedExtension*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestNestedExtensionInstance;
 }
 - (BOOL) isInitialized {
@@ -8215,10 +8215,10 @@ + (void) initialize {
     defaultTestRequiredInstance = [[TestRequired alloc] init];
   }
 }
-+ (TestRequired*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestRequiredInstance;
 }
-- (TestRequired*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestRequiredInstance;
 }
 - (BOOL) isInitialized {
@@ -9620,10 +9620,10 @@ + (void) initialize {
     defaultTestRequiredForeignInstance = [[TestRequiredForeign alloc] init];
   }
 }
-+ (TestRequiredForeign*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestRequiredForeignInstance;
 }
-- (TestRequiredForeign*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestRequiredForeignInstance;
 }
 - (NSArray *)repeatedMessage {
@@ -9948,10 +9948,10 @@ + (void) initialize {
     defaultTestForeignNestedInstance = [[TestForeignNested alloc] init];
   }
 }
-+ (TestForeignNested*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestForeignNestedInstance;
 }
-- (TestForeignNested*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestForeignNestedInstance;
 }
 - (BOOL) isInitialized {
@@ -10161,10 +10161,10 @@ + (void) initialize {
     defaultTestEmptyMessageInstance = [[TestEmptyMessage alloc] init];
   }
 }
-+ (TestEmptyMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestEmptyMessageInstance;
 }
-- (TestEmptyMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestEmptyMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -10315,10 +10315,10 @@ + (void) initialize {
     defaultTestEmptyMessageWithExtensionsInstance = [[TestEmptyMessageWithExtensions alloc] init];
   }
 }
-+ (TestEmptyMessageWithExtensions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestEmptyMessageWithExtensionsInstance;
 }
-- (TestEmptyMessageWithExtensions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestEmptyMessageWithExtensionsInstance;
 }
 - (BOOL) isInitialized {
@@ -10484,10 +10484,10 @@ + (void) initialize {
     defaultTestMultipleExtensionRangesInstance = [[TestMultipleExtensionRanges alloc] init];
   }
 }
-+ (TestMultipleExtensionRanges*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMultipleExtensionRangesInstance;
 }
-- (TestMultipleExtensionRanges*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMultipleExtensionRangesInstance;
 }
 - (BOOL) isInitialized {
@@ -10691,10 +10691,10 @@ + (void) initialize {
     defaultTestReallyLargeTagNumberInstance = [[TestReallyLargeTagNumber alloc] init];
   }
 }
-+ (TestReallyLargeTagNumber*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestReallyLargeTagNumberInstance;
 }
-- (TestReallyLargeTagNumber*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestReallyLargeTagNumberInstance;
 }
 - (BOOL) isInitialized {
@@ -10937,10 +10937,10 @@ + (void) initialize {
     defaultTestRecursiveMessageInstance = [[TestRecursiveMessage alloc] init];
   }
 }
-+ (TestRecursiveMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestRecursiveMessageInstance;
 }
-- (TestRecursiveMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestRecursiveMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -11196,10 +11196,10 @@ + (void) initialize {
     defaultTestMutualRecursionAInstance = [[TestMutualRecursionA alloc] init];
   }
 }
-+ (TestMutualRecursionA*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMutualRecursionAInstance;
 }
-- (TestMutualRecursionA*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMutualRecursionAInstance;
 }
 - (BOOL) isInitialized {
@@ -11427,10 +11427,10 @@ + (void) initialize {
     defaultTestMutualRecursionBInstance = [[TestMutualRecursionB alloc] init];
   }
 }
-+ (TestMutualRecursionB*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMutualRecursionBInstance;
 }
-- (TestMutualRecursionB*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMutualRecursionBInstance;
 }
 - (BOOL) isInitialized {
@@ -11704,10 +11704,10 @@ + (void) initialize {
     defaultTestDupFieldNumberInstance = [[TestDupFieldNumber alloc] init];
   }
 }
-+ (TestDupFieldNumber*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestDupFieldNumberInstance;
 }
-- (TestDupFieldNumber*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestDupFieldNumberInstance;
 }
 - (BOOL) isInitialized {
@@ -11851,10 +11851,10 @@ + (void) initialize {
     defaultTestDupFieldNumberFooInstance = [[TestDupFieldNumberFoo alloc] init];
   }
 }
-+ (TestDupFieldNumberFoo*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestDupFieldNumberFooInstance;
 }
-- (TestDupFieldNumberFoo*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestDupFieldNumberFooInstance;
 }
 - (BOOL) isInitialized {
@@ -12051,10 +12051,10 @@ + (void) initialize {
     defaultTestDupFieldNumberBarInstance = [[TestDupFieldNumberBar alloc] init];
   }
 }
-+ (TestDupFieldNumberBar*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestDupFieldNumberBarInstance;
 }
-- (TestDupFieldNumberBar*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestDupFieldNumberBarInstance;
 }
 - (BOOL) isInitialized {
@@ -12422,10 +12422,10 @@ + (void) initialize {
     defaultTestEagerMessageInstance = [[TestEagerMessage alloc] init];
   }
 }
-+ (TestEagerMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestEagerMessageInstance;
 }
-- (TestEagerMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestEagerMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -12644,10 +12644,10 @@ + (void) initialize {
     defaultTestLazyMessageInstance = [[TestLazyMessage alloc] init];
   }
 }
-+ (TestLazyMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestLazyMessageInstance;
 }
-- (TestLazyMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestLazyMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -12866,10 +12866,10 @@ + (void) initialize {
     defaultTestNestedMessageHasBitsInstance = [[TestNestedMessageHasBits alloc] init];
   }
 }
-+ (TestNestedMessageHasBits*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestNestedMessageHasBitsInstance;
 }
-- (TestNestedMessageHasBits*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestNestedMessageHasBitsInstance;
 }
 - (BOOL) isInitialized {
@@ -12979,10 +12979,10 @@ + (void) initialize {
     defaultTestNestedMessageHasBitsNestedMessageInstance = [[TestNestedMessageHasBitsNestedMessage alloc] init];
   }
 }
-+ (TestNestedMessageHasBitsNestedMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestNestedMessageHasBitsNestedMessageInstance;
 }
-- (TestNestedMessageHasBitsNestedMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestNestedMessageHasBitsNestedMessageInstance;
 }
 - (PBArray *)nestedmessageRepeatedInt32 {
@@ -13433,10 +13433,10 @@ + (void) initialize {
     defaultTestCamelCaseFieldNamesInstance = [[TestCamelCaseFieldNames alloc] init];
   }
 }
-+ (TestCamelCaseFieldNames*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestCamelCaseFieldNamesInstance;
 }
-- (TestCamelCaseFieldNames*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestCamelCaseFieldNamesInstance;
 }
 - (PBArray *)repeatedPrimitiveField {
@@ -14225,10 +14225,10 @@ + (void) initialize {
     defaultTestFieldOrderingsInstance = [[TestFieldOrderings alloc] init];
   }
 }
-+ (TestFieldOrderings*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestFieldOrderingsInstance;
 }
-- (TestFieldOrderings*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestFieldOrderingsInstance;
 }
 - (BOOL) isInitialized {
@@ -14758,10 +14758,10 @@ + (void) initialize {
     defaultTestExtremeDefaultValuesInstance = [[TestExtremeDefaultValues alloc] init];
   }
 }
-+ (TestExtremeDefaultValues*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestExtremeDefaultValuesInstance;
 }
-- (TestExtremeDefaultValues*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestExtremeDefaultValuesInstance;
 }
 - (BOOL) isInitialized {
@@ -15920,10 +15920,10 @@ + (void) initialize {
     defaultSparseEnumMessageInstance = [[SparseEnumMessage alloc] init];
   }
 }
-+ (SparseEnumMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultSparseEnumMessageInstance;
 }
-- (SparseEnumMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultSparseEnumMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -16125,10 +16125,10 @@ + (void) initialize {
     defaultOneStringInstance = [[OneString alloc] init];
   }
 }
-+ (OneString*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultOneStringInstance;
 }
-- (OneString*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultOneStringInstance;
 }
 - (BOOL) isInitialized {
@@ -16319,10 +16319,10 @@ + (void) initialize {
     defaultMoreStringInstance = [[MoreString alloc] init];
   }
 }
-+ (MoreString*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultMoreStringInstance;
 }
-- (MoreString*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultMoreStringInstance;
 }
 - (NSArray *)data {
@@ -16539,10 +16539,10 @@ + (void) initialize {
     defaultOneBytesInstance = [[OneBytes alloc] init];
   }
 }
-+ (OneBytes*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultOneBytesInstance;
 }
-- (OneBytes*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultOneBytesInstance;
 }
 - (BOOL) isInitialized {
@@ -16733,10 +16733,10 @@ + (void) initialize {
     defaultMoreBytesInstance = [[MoreBytes alloc] init];
   }
 }
-+ (MoreBytes*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultMoreBytesInstance;
 }
-- (MoreBytes*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultMoreBytesInstance;
 }
 - (NSArray *)data {
@@ -16953,10 +16953,10 @@ + (void) initialize {
     defaultInt32MessageInstance = [[Int32Message alloc] init];
   }
 }
-+ (Int32Message*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultInt32MessageInstance;
 }
-- (Int32Message*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultInt32MessageInstance;
 }
 - (BOOL) isInitialized {
@@ -17153,10 +17153,10 @@ + (void) initialize {
     defaultUint32MessageInstance = [[Uint32Message alloc] init];
   }
 }
-+ (Uint32Message*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultUint32MessageInstance;
 }
-- (Uint32Message*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultUint32MessageInstance;
 }
 - (BOOL) isInitialized {
@@ -17353,10 +17353,10 @@ + (void) initialize {
     defaultInt64MessageInstance = [[Int64Message alloc] init];
   }
 }
-+ (Int64Message*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultInt64MessageInstance;
 }
-- (Int64Message*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultInt64MessageInstance;
 }
 - (BOOL) isInitialized {
@@ -17553,10 +17553,10 @@ + (void) initialize {
     defaultUint64MessageInstance = [[Uint64Message alloc] init];
   }
 }
-+ (Uint64Message*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultUint64MessageInstance;
 }
-- (Uint64Message*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultUint64MessageInstance;
 }
 - (BOOL) isInitialized {
@@ -17758,10 +17758,10 @@ + (void) initialize {
     defaultBoolMessageInstance = [[BoolMessage alloc] init];
   }
 }
-+ (BoolMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultBoolMessageInstance;
 }
-- (BoolMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultBoolMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -17985,10 +17985,10 @@ + (void) initialize {
     defaultTestOneofInstance = [[TestOneof alloc] init];
   }
 }
-+ (TestOneof*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOneofInstance;
 }
-- (TestOneof*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOneofInstance;
 }
 - (BOOL) isInitialized {
@@ -18155,10 +18155,10 @@ + (void) initialize {
     defaultTestOneofFooGroupInstance = [[TestOneofFooGroup alloc] init];
   }
 }
-+ (TestOneofFooGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOneofFooGroupInstance;
 }
-- (TestOneofFooGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOneofFooGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -18613,10 +18613,10 @@ + (void) initialize {
     defaultTestOneofBackwardsCompatibleInstance = [[TestOneofBackwardsCompatible alloc] init];
   }
 }
-+ (TestOneofBackwardsCompatible*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOneofBackwardsCompatibleInstance;
 }
-- (TestOneofBackwardsCompatible*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOneofBackwardsCompatibleInstance;
 }
 - (BOOL) isInitialized {
@@ -18783,10 +18783,10 @@ + (void) initialize {
     defaultTestOneofBackwardsCompatibleFooGroupInstance = [[TestOneofBackwardsCompatibleFooGroup alloc] init];
   }
 }
-+ (TestOneofBackwardsCompatibleFooGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOneofBackwardsCompatibleFooGroupInstance;
 }
-- (TestOneofBackwardsCompatibleFooGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOneofBackwardsCompatibleFooGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -19358,10 +19358,10 @@ + (void) initialize {
     defaultTestOneof2Instance = [[TestOneof2 alloc] init];
   }
 }
-+ (TestOneof2*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOneof2Instance;
 }
-- (TestOneof2*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOneof2Instance;
 }
 - (BOOL) isInitialized {
@@ -19723,10 +19723,10 @@ + (void) initialize {
     defaultTestOneof2FooGroupInstance = [[TestOneof2FooGroup alloc] init];
   }
 }
-+ (TestOneof2FooGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOneof2FooGroupInstance;
 }
-- (TestOneof2FooGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOneof2FooGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -19963,10 +19963,10 @@ + (void) initialize {
     defaultTestOneof2NestedMessageInstance = [[TestOneof2NestedMessage alloc] init];
   }
 }
-+ (TestOneof2NestedMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOneof2NestedMessageInstance;
 }
-- (TestOneof2NestedMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOneof2NestedMessageInstance;
 }
 - (PBArray *)corgeInt {
@@ -20769,10 +20769,10 @@ + (void) initialize {
     defaultTestRequiredOneofInstance = [[TestRequiredOneof alloc] init];
   }
 }
-+ (TestRequiredOneof*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestRequiredOneofInstance;
 }
-- (TestRequiredOneof*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestRequiredOneofInstance;
 }
 - (BOOL) isInitialized {
@@ -20918,10 +20918,10 @@ + (void) initialize {
     defaultTestRequiredOneofNestedMessageInstance = [[TestRequiredOneofNestedMessage alloc] init];
   }
 }
-+ (TestRequiredOneofNestedMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestRequiredOneofNestedMessageInstance;
 }
-- (TestRequiredOneofNestedMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestRequiredOneofNestedMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -21306,10 +21306,10 @@ + (void) initialize {
     defaultTestPackedTypesInstance = [[TestPackedTypes alloc] init];
   }
 }
-+ (TestPackedTypes*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestPackedTypesInstance;
 }
-- (TestPackedTypes*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestPackedTypesInstance;
 }
 - (PBArray *)packedInt32 {
@@ -22603,10 +22603,10 @@ + (void) initialize {
     defaultTestUnpackedTypesInstance = [[TestUnpackedTypes alloc] init];
   }
 }
-+ (TestUnpackedTypes*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestUnpackedTypesInstance;
 }
-- (TestUnpackedTypes*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestUnpackedTypesInstance;
 }
 - (PBArray *)unpackedInt32 {
@@ -23663,10 +23663,10 @@ + (void) initialize {
     defaultTestPackedExtensionsInstance = [[TestPackedExtensions alloc] init];
   }
 }
-+ (TestPackedExtensions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestPackedExtensionsInstance;
 }
-- (TestPackedExtensions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestPackedExtensionsInstance;
 }
 - (BOOL) isInitialized {
@@ -23832,10 +23832,10 @@ + (void) initialize {
     defaultTestUnpackedExtensionsInstance = [[TestUnpackedExtensions alloc] init];
   }
 }
-+ (TestUnpackedExtensions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestUnpackedExtensionsInstance;
 }
-- (TestUnpackedExtensions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestUnpackedExtensionsInstance;
 }
 - (BOOL) isInitialized {
@@ -24052,10 +24052,10 @@ + (void) initialize {
     defaultTestDynamicExtensionsInstance = [[TestDynamicExtensions alloc] init];
   }
 }
-+ (TestDynamicExtensions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestDynamicExtensionsInstance;
 }
-- (TestDynamicExtensions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestDynamicExtensionsInstance;
 }
 - (NSArray *)repeatedExtension {
@@ -24298,10 +24298,10 @@ + (void) initialize {
     defaultTestDynamicExtensionsDynamicMessageTypeInstance = [[TestDynamicExtensionsDynamicMessageType alloc] init];
   }
 }
-+ (TestDynamicExtensionsDynamicMessageType*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestDynamicExtensionsDynamicMessageTypeInstance;
 }
-- (TestDynamicExtensionsDynamicMessageType*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestDynamicExtensionsDynamicMessageTypeInstance;
 }
 - (BOOL) isInitialized {
@@ -24810,10 +24810,10 @@ + (void) initialize {
     defaultTestRepeatedScalarDifferentTagSizesInstance = [[TestRepeatedScalarDifferentTagSizes alloc] init];
   }
 }
-+ (TestRepeatedScalarDifferentTagSizes*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestRepeatedScalarDifferentTagSizesInstance;
 }
-- (TestRepeatedScalarDifferentTagSizes*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestRepeatedScalarDifferentTagSizesInstance;
 }
 - (PBArray *)repeatedFixed32 {
@@ -25390,10 +25390,10 @@ + (void) initialize {
     defaultTestParsingMergeInstance = [[TestParsingMerge alloc] init];
   }
 }
-+ (TestParsingMerge*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeInstance;
 }
-- (TestParsingMerge*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeInstance;
 }
 - (NSArray *)repeatedAllTypes {
@@ -25613,10 +25613,10 @@ + (void) initialize {
     defaultTestParsingMergeRepeatedFieldsGeneratorInstance = [[TestParsingMergeRepeatedFieldsGenerator alloc] init];
   }
 }
-+ (TestParsingMergeRepeatedFieldsGenerator*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedFieldsGeneratorInstance;
 }
-- (TestParsingMergeRepeatedFieldsGenerator*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedFieldsGeneratorInstance;
 }
 - (NSArray *)field1 {
@@ -25866,10 +25866,10 @@ + (void) initialize {
     defaultTestParsingMergeRepeatedFieldsGeneratorGroup1Instance = [[TestParsingMergeRepeatedFieldsGeneratorGroup1 alloc] init];
   }
 }
-+ (TestParsingMergeRepeatedFieldsGeneratorGroup1*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedFieldsGeneratorGroup1Instance;
 }
-- (TestParsingMergeRepeatedFieldsGeneratorGroup1*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedFieldsGeneratorGroup1Instance;
 }
 - (BOOL) isInitialized {
@@ -26088,10 +26088,10 @@ + (void) initialize {
     defaultTestParsingMergeRepeatedFieldsGeneratorGroup2Instance = [[TestParsingMergeRepeatedFieldsGeneratorGroup2 alloc] init];
   }
 }
-+ (TestParsingMergeRepeatedFieldsGeneratorGroup2*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedFieldsGeneratorGroup2Instance;
 }
-- (TestParsingMergeRepeatedFieldsGeneratorGroup2*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedFieldsGeneratorGroup2Instance;
 }
 - (BOOL) isInitialized {
@@ -26612,10 +26612,10 @@ + (void) initialize {
     defaultTestParsingMergeOptionalGroupInstance = [[TestParsingMergeOptionalGroup alloc] init];
   }
 }
-+ (TestParsingMergeOptionalGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeOptionalGroupInstance;
 }
-- (TestParsingMergeOptionalGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeOptionalGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -26834,10 +26834,10 @@ + (void) initialize {
     defaultTestParsingMergeRepeatedGroupInstance = [[TestParsingMergeRepeatedGroup alloc] init];
   }
 }
-+ (TestParsingMergeRepeatedGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedGroupInstance;
 }
-- (TestParsingMergeRepeatedGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -27315,10 +27315,10 @@ + (void) initialize {
     defaultTestCommentInjectionMessageInstance = [[TestCommentInjectionMessage alloc] init];
   }
 }
-+ (TestCommentInjectionMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestCommentInjectionMessageInstance;
 }
-- (TestCommentInjectionMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestCommentInjectionMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -27506,10 +27506,10 @@ + (void) initialize {
     defaultFooRequestInstance = [[FooRequest alloc] init];
   }
 }
-+ (FooRequest*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultFooRequestInstance;
 }
-- (FooRequest*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultFooRequestInstance;
 }
 - (BOOL) isInitialized {
@@ -27660,10 +27660,10 @@ + (void) initialize {
     defaultFooResponseInstance = [[FooResponse alloc] init];
   }
 }
-+ (FooResponse*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultFooResponseInstance;
 }
-- (FooResponse*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultFooResponseInstance;
 }
 - (BOOL) isInitialized {
@@ -27814,10 +27814,10 @@ + (void) initialize {
     defaultFooClientMessageInstance = [[FooClientMessage alloc] init];
   }
 }
-+ (FooClientMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultFooClientMessageInstance;
 }
-- (FooClientMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultFooClientMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -27968,10 +27968,10 @@ + (void) initialize {
     defaultFooServerMessageInstance = [[FooServerMessage alloc] init];
   }
 }
-+ (FooServerMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultFooServerMessageInstance;
 }
-- (FooServerMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultFooServerMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -28122,10 +28122,10 @@ + (void) initialize {
     defaultBarRequestInstance = [[BarRequest alloc] init];
   }
 }
-+ (BarRequest*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultBarRequestInstance;
 }
-- (BarRequest*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultBarRequestInstance;
 }
 - (BOOL) isInitialized {
@@ -28276,10 +28276,10 @@ + (void) initialize {
     defaultBarResponseInstance = [[BarResponse alloc] init];
   }
 }
-+ (BarResponse*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultBarResponseInstance;
 }
-- (BarResponse*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultBarResponseInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/compiler/Tests/Unittest_custom_options.pb.h b/src/compiler/Tests/Unittest_custom_options.pb.h
index 8c40a41..a1bf4ec 100644
--- a/src/compiler/Tests/Unittest_custom_options.pb.h
+++ b/src/compiler/Tests/Unittest_custom_options.pb.h
@@ -197,8 +197,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 - (BOOL) hasField1;
 @property (readonly, strong) NSString* field1;
 
-+ (TestMessageWithCustomOptions*) defaultInstance;
-- (TestMessageWithCustomOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -242,8 +242,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (CustomOptionFooRequest*) defaultInstance;
-- (CustomOptionFooRequest*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -282,8 +282,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (CustomOptionFooResponse*) defaultInstance;
-- (CustomOptionFooResponse*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -322,8 +322,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (CustomOptionFooClientMessage*) defaultInstance;
-- (CustomOptionFooClientMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -362,8 +362,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (CustomOptionFooServerMessage*) defaultInstance;
-- (CustomOptionFooServerMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -402,8 +402,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (DummyMessageContainingEnum*) defaultInstance;
-- (DummyMessageContainingEnum*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -442,8 +442,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (DummyMessageInvalidAsOptionType*) defaultInstance;
-- (DummyMessageInvalidAsOptionType*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -482,8 +482,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (CustomOptionMinIntegerValues*) defaultInstance;
-- (CustomOptionMinIntegerValues*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -522,8 +522,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (CustomOptionMaxIntegerValues*) defaultInstance;
-- (CustomOptionMaxIntegerValues*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -562,8 +562,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (CustomOptionOtherValues*) defaultInstance;
-- (CustomOptionOtherValues*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -602,8 +602,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (SettingRealsFromPositiveInts*) defaultInstance;
-- (SettingRealsFromPositiveInts*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -642,8 +642,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (SettingRealsFromNegativeInts*) defaultInstance;
-- (SettingRealsFromNegativeInts*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -697,8 +697,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @property (readonly, strong) PBArray * foo4;
 - (SInt32)foo4AtIndex:(NSUInteger)index;
 
-+ (ComplexOptionType1*) defaultInstance;
-- (ComplexOptionType1*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -774,8 +774,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @property (readonly, strong) NSArray * barney;
 - (ComplexOptionType2ComplexOptionType4*)barneyAtIndex:(NSUInteger)index;
 
-+ (ComplexOptionType2*) defaultInstance;
-- (ComplexOptionType2*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -800,8 +800,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 - (BOOL) hasWaldo;
 @property (readonly) SInt32 waldo;
 
-+ (ComplexOptionType2ComplexOptionType4*) defaultInstance;
-- (ComplexOptionType2ComplexOptionType4*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) complexOpt4;
 - (BOOL) isInitialized;
@@ -897,8 +897,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @property (readonly) SInt32 qux;
 @property (readonly, strong) ComplexOptionType3ComplexOptionType5* complexOptionType5;
 
-+ (ComplexOptionType3*) defaultInstance;
-- (ComplexOptionType3*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -923,8 +923,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 - (BOOL) hasPlugh;
 @property (readonly) SInt32 plugh;
 
-+ (ComplexOptionType3ComplexOptionType5*) defaultInstance;
-- (ComplexOptionType3ComplexOptionType5*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1002,8 +1002,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 - (BOOL) hasXyzzy;
 @property (readonly) SInt32 xyzzy;
 
-+ (ComplexOpt6*) defaultInstance;
-- (ComplexOpt6*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1047,8 +1047,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (VariousComplexOptions*) defaultInstance;
-- (VariousComplexOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1087,8 +1087,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (AggregateMessageSet*) defaultInstance;
-- (AggregateMessageSet*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1131,8 +1131,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 - (BOOL) hasS;
 @property (readonly, strong) NSString* s;
 
-+ (AggregateMessageSetElement*) defaultInstance;
-- (AggregateMessageSetElement*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) messageSetExtension;
 - (BOOL) isInitialized;
@@ -1197,8 +1197,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @property (readonly, strong) PBFileOptions* file;
 @property (readonly, strong) AggregateMessageSet* mset;
 
-+ (Aggregate*) defaultInstance;
-- (Aggregate*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) nested;
 - (BOOL) isInitialized;
@@ -1273,8 +1273,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 - (BOOL) hasFieldname;
 @property (readonly) SInt32 fieldname;
 
-+ (AggregateMessage*) defaultInstance;
-- (AggregateMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1318,8 +1318,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (NestedOptionType*) defaultInstance;
-- (NestedOptionType*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) nestedExtension;
 - (BOOL) isInitialized;
@@ -1345,8 +1345,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 - (BOOL) hasNestedField;
 @property (readonly) SInt32 nestedField;
 
-+ (NestedOptionTypeNestedMessage*) defaultInstance;
-- (NestedOptionTypeNestedMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/compiler/Tests/Unittest_custom_options.pb.m b/src/compiler/Tests/Unittest_custom_options.pb.m
index 0b28148..bd5c51b 100644
--- a/src/compiler/Tests/Unittest_custom_options.pb.m
+++ b/src/compiler/Tests/Unittest_custom_options.pb.m
@@ -667,10 +667,10 @@ + (void) initialize {
     defaultTestMessageWithCustomOptionsInstance = [[TestMessageWithCustomOptions alloc] init];
   }
 }
-+ (TestMessageWithCustomOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMessageWithCustomOptionsInstance;
 }
-- (TestMessageWithCustomOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMessageWithCustomOptionsInstance;
 }
 - (BOOL) isInitialized {
@@ -867,10 +867,10 @@ + (void) initialize {
     defaultCustomOptionFooRequestInstance = [[CustomOptionFooRequest alloc] init];
   }
 }
-+ (CustomOptionFooRequest*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultCustomOptionFooRequestInstance;
 }
-- (CustomOptionFooRequest*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultCustomOptionFooRequestInstance;
 }
 - (BOOL) isInitialized {
@@ -1021,10 +1021,10 @@ + (void) initialize {
     defaultCustomOptionFooResponseInstance = [[CustomOptionFooResponse alloc] init];
   }
 }
-+ (CustomOptionFooResponse*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultCustomOptionFooResponseInstance;
 }
-- (CustomOptionFooResponse*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultCustomOptionFooResponseInstance;
 }
 - (BOOL) isInitialized {
@@ -1175,10 +1175,10 @@ + (void) initialize {
     defaultCustomOptionFooClientMessageInstance = [[CustomOptionFooClientMessage alloc] init];
   }
 }
-+ (CustomOptionFooClientMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultCustomOptionFooClientMessageInstance;
 }
-- (CustomOptionFooClientMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultCustomOptionFooClientMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -1329,10 +1329,10 @@ + (void) initialize {
     defaultCustomOptionFooServerMessageInstance = [[CustomOptionFooServerMessage alloc] init];
   }
 }
-+ (CustomOptionFooServerMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultCustomOptionFooServerMessageInstance;
 }
-- (CustomOptionFooServerMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultCustomOptionFooServerMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -1483,10 +1483,10 @@ + (void) initialize {
     defaultDummyMessageContainingEnumInstance = [[DummyMessageContainingEnum alloc] init];
   }
 }
-+ (DummyMessageContainingEnum*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultDummyMessageContainingEnumInstance;
 }
-- (DummyMessageContainingEnum*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultDummyMessageContainingEnumInstance;
 }
 - (BOOL) isInitialized {
@@ -1646,10 +1646,10 @@ + (void) initialize {
     defaultDummyMessageInvalidAsOptionTypeInstance = [[DummyMessageInvalidAsOptionType alloc] init];
   }
 }
-+ (DummyMessageInvalidAsOptionType*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultDummyMessageInvalidAsOptionTypeInstance;
 }
-- (DummyMessageInvalidAsOptionType*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultDummyMessageInvalidAsOptionTypeInstance;
 }
 - (BOOL) isInitialized {
@@ -1800,10 +1800,10 @@ + (void) initialize {
     defaultCustomOptionMinIntegerValuesInstance = [[CustomOptionMinIntegerValues alloc] init];
   }
 }
-+ (CustomOptionMinIntegerValues*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultCustomOptionMinIntegerValuesInstance;
 }
-- (CustomOptionMinIntegerValues*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultCustomOptionMinIntegerValuesInstance;
 }
 - (BOOL) isInitialized {
@@ -1954,10 +1954,10 @@ + (void) initialize {
     defaultCustomOptionMaxIntegerValuesInstance = [[CustomOptionMaxIntegerValues alloc] init];
   }
 }
-+ (CustomOptionMaxIntegerValues*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultCustomOptionMaxIntegerValuesInstance;
 }
-- (CustomOptionMaxIntegerValues*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultCustomOptionMaxIntegerValuesInstance;
 }
 - (BOOL) isInitialized {
@@ -2108,10 +2108,10 @@ + (void) initialize {
     defaultCustomOptionOtherValuesInstance = [[CustomOptionOtherValues alloc] init];
   }
 }
-+ (CustomOptionOtherValues*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultCustomOptionOtherValuesInstance;
 }
-- (CustomOptionOtherValues*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultCustomOptionOtherValuesInstance;
 }
 - (BOOL) isInitialized {
@@ -2262,10 +2262,10 @@ + (void) initialize {
     defaultSettingRealsFromPositiveIntsInstance = [[SettingRealsFromPositiveInts alloc] init];
   }
 }
-+ (SettingRealsFromPositiveInts*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultSettingRealsFromPositiveIntsInstance;
 }
-- (SettingRealsFromPositiveInts*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultSettingRealsFromPositiveIntsInstance;
 }
 - (BOOL) isInitialized {
@@ -2416,10 +2416,10 @@ + (void) initialize {
     defaultSettingRealsFromNegativeIntsInstance = [[SettingRealsFromNegativeInts alloc] init];
   }
 }
-+ (SettingRealsFromNegativeInts*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultSettingRealsFromNegativeIntsInstance;
 }
-- (SettingRealsFromNegativeInts*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultSettingRealsFromNegativeIntsInstance;
 }
 - (BOOL) isInitialized {
@@ -2600,10 +2600,10 @@ + (void) initialize {
     defaultComplexOptionType1Instance = [[ComplexOptionType1 alloc] init];
   }
 }
-+ (ComplexOptionType1*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultComplexOptionType1Instance;
 }
-- (ComplexOptionType1*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultComplexOptionType1Instance;
 }
 - (PBArray *)foo4 {
@@ -2976,10 +2976,10 @@ + (void) initialize {
     defaultComplexOptionType2Instance = [[ComplexOptionType2 alloc] init];
   }
 }
-+ (ComplexOptionType2*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultComplexOptionType2Instance;
 }
-- (ComplexOptionType2*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultComplexOptionType2Instance;
 }
 - (NSArray *)barney {
@@ -3167,10 +3167,10 @@ + (void) initialize {
     defaultComplexOptionType2ComplexOptionType4Instance = [[ComplexOptionType2ComplexOptionType4 alloc] init];
   }
 }
-+ (ComplexOptionType2ComplexOptionType4*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultComplexOptionType2ComplexOptionType4Instance;
 }
-- (ComplexOptionType2ComplexOptionType4*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultComplexOptionType2ComplexOptionType4Instance;
 }
 - (BOOL) isInitialized {
@@ -3582,10 +3582,10 @@ + (void) initialize {
     defaultComplexOptionType3Instance = [[ComplexOptionType3 alloc] init];
   }
 }
-+ (ComplexOptionType3*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultComplexOptionType3Instance;
 }
-- (ComplexOptionType3*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultComplexOptionType3Instance;
 }
 - (BOOL) isInitialized {
@@ -3712,10 +3712,10 @@ + (void) initialize {
     defaultComplexOptionType3ComplexOptionType5Instance = [[ComplexOptionType3ComplexOptionType5 alloc] init];
   }
 }
-+ (ComplexOptionType3ComplexOptionType5*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultComplexOptionType3ComplexOptionType5Instance;
 }
-- (ComplexOptionType3ComplexOptionType5*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultComplexOptionType3ComplexOptionType5Instance;
 }
 - (BOOL) isInitialized {
@@ -4041,10 +4041,10 @@ + (void) initialize {
     defaultComplexOpt6Instance = [[ComplexOpt6 alloc] init];
   }
 }
-+ (ComplexOpt6*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultComplexOpt6Instance;
 }
-- (ComplexOpt6*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultComplexOpt6Instance;
 }
 - (BOOL) isInitialized {
@@ -4232,10 +4232,10 @@ + (void) initialize {
     defaultVariousComplexOptionsInstance = [[VariousComplexOptions alloc] init];
   }
 }
-+ (VariousComplexOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultVariousComplexOptionsInstance;
 }
-- (VariousComplexOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultVariousComplexOptionsInstance;
 }
 - (BOOL) isInitialized {
@@ -4386,10 +4386,10 @@ + (void) initialize {
     defaultAggregateMessageSetInstance = [[AggregateMessageSet alloc] init];
   }
 }
-+ (AggregateMessageSet*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultAggregateMessageSetInstance;
 }
-- (AggregateMessageSet*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultAggregateMessageSetInstance;
 }
 - (BOOL) isInitialized {
@@ -4567,10 +4567,10 @@ + (void) initialize {
     defaultAggregateMessageSetElementInstance = [[AggregateMessageSetElement alloc] init];
   }
 }
-+ (AggregateMessageSetElement*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultAggregateMessageSetElementInstance;
 }
-- (AggregateMessageSetElement*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultAggregateMessageSetElementInstance;
 }
 - (BOOL) isInitialized {
@@ -4806,10 +4806,10 @@ + (void) initialize {
     defaultAggregateInstance = [[Aggregate alloc] init];
   }
 }
-+ (Aggregate*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultAggregateInstance;
 }
-- (Aggregate*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultAggregateInstance;
 }
 - (BOOL) isInitialized {
@@ -5235,10 +5235,10 @@ + (void) initialize {
     defaultAggregateMessageInstance = [[AggregateMessage alloc] init];
   }
 }
-+ (AggregateMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultAggregateMessageInstance;
 }
-- (AggregateMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultAggregateMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -5429,10 +5429,10 @@ + (void) initialize {
     defaultNestedOptionTypeInstance = [[NestedOptionType alloc] init];
   }
 }
-+ (NestedOptionType*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultNestedOptionTypeInstance;
 }
-- (NestedOptionType*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultNestedOptionTypeInstance;
 }
 - (BOOL) isInitialized {
@@ -5536,10 +5536,10 @@ + (void) initialize {
     defaultNestedOptionTypeNestedMessageInstance = [[NestedOptionTypeNestedMessage alloc] init];
   }
 }
-+ (NestedOptionTypeNestedMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultNestedOptionTypeNestedMessageInstance;
 }
-- (NestedOptionTypeNestedMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultNestedOptionTypeNestedMessageInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/compiler/Tests/Unittest_embed_optimize_for.pb.h b/src/compiler/Tests/Unittest_embed_optimize_for.pb.h
index 84e486b..7d59bb7 100644
--- a/src/compiler/Tests/Unittest_embed_optimize_for.pb.h
+++ b/src/compiler/Tests/Unittest_embed_optimize_for.pb.h
@@ -187,8 +187,8 @@
 @property (readonly, strong) NSArray * repeatedMessage;
 - (TestOptimizedForSize*)repeatedMessageAtIndex:(NSUInteger)index;
 
-+ (TestEmbedOptimizedForSize*) defaultInstance;
-- (TestEmbedOptimizedForSize*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/compiler/Tests/Unittest_embed_optimize_for.pb.m b/src/compiler/Tests/Unittest_embed_optimize_for.pb.m
index 941e720..a7a4f18 100644
--- a/src/compiler/Tests/Unittest_embed_optimize_for.pb.m
+++ b/src/compiler/Tests/Unittest_embed_optimize_for.pb.m
@@ -49,10 +49,10 @@ + (void) initialize {
     defaultTestEmbedOptimizedForSizeInstance = [[TestEmbedOptimizedForSize alloc] init];
   }
 }
-+ (TestEmbedOptimizedForSize*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestEmbedOptimizedForSizeInstance;
 }
-- (TestEmbedOptimizedForSize*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestEmbedOptimizedForSizeInstance;
 }
 - (NSArray *)repeatedMessage {
diff --git a/src/compiler/Tests/Unittest_enormous_descriptor.pb.h b/src/compiler/Tests/Unittest_enormous_descriptor.pb.h
index 26820ab..a37ab49 100644
--- a/src/compiler/Tests/Unittest_enormous_descriptor.pb.h
+++ b/src/compiler/Tests/Unittest_enormous_descriptor.pb.h
@@ -4029,8 +4029,8 @@
 @property (readonly, strong) NSString* longFieldNameIsLooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong999;
 @property (readonly, strong) NSString* longFieldNameIsLooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong1000;
 
-+ (TestEnormousDescriptor*) defaultInstance;
-- (TestEnormousDescriptor*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/compiler/Tests/Unittest_enormous_descriptor.pb.m b/src/compiler/Tests/Unittest_enormous_descriptor.pb.m
index 81db84a..5710a7f 100644
--- a/src/compiler/Tests/Unittest_enormous_descriptor.pb.m
+++ b/src/compiler/Tests/Unittest_enormous_descriptor.pb.m
@@ -9036,10 +9036,10 @@ + (void) initialize {
     defaultTestEnormousDescriptorInstance = [[TestEnormousDescriptor alloc] init];
   }
 }
-+ (TestEnormousDescriptor*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestEnormousDescriptorInstance;
 }
-- (TestEnormousDescriptor*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestEnormousDescriptorInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/compiler/Tests/Unittest_import.pb.h b/src/compiler/Tests/Unittest_import.pb.h
index 6be12ba..29cb422 100644
--- a/src/compiler/Tests/Unittest_import.pb.h
+++ b/src/compiler/Tests/Unittest_import.pb.h
@@ -44,8 +44,8 @@ BOOL ImportEnumIsValidValue(ImportEnum value);
 - (BOOL) hasD;
 @property (readonly) SInt32 d;
 
-+ (ImportMessage*) defaultInstance;
-- (ImportMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/compiler/Tests/Unittest_import.pb.m b/src/compiler/Tests/Unittest_import.pb.m
index f2bd993..ddab0e1 100644
--- a/src/compiler/Tests/Unittest_import.pb.m
+++ b/src/compiler/Tests/Unittest_import.pb.m
@@ -56,10 +56,10 @@ + (void) initialize {
     defaultImportMessageInstance = [[ImportMessage alloc] init];
   }
 }
-+ (ImportMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultImportMessageInstance;
 }
-- (ImportMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultImportMessageInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/compiler/Tests/Unittest_import_lite.pb.h b/src/compiler/Tests/Unittest_import_lite.pb.h
index b75c3d6..cadbdd1 100644
--- a/src/compiler/Tests/Unittest_import_lite.pb.h
+++ b/src/compiler/Tests/Unittest_import_lite.pb.h
@@ -44,8 +44,8 @@ BOOL ImportEnumLiteIsValidValue(ImportEnumLite value);
 - (BOOL) hasD;
 @property (readonly) SInt32 d;
 
-+ (ImportMessageLite*) defaultInstance;
-- (ImportMessageLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/compiler/Tests/Unittest_import_lite.pb.m b/src/compiler/Tests/Unittest_import_lite.pb.m
index f8598dc..f48d4f0 100644
--- a/src/compiler/Tests/Unittest_import_lite.pb.m
+++ b/src/compiler/Tests/Unittest_import_lite.pb.m
@@ -56,10 +56,10 @@ + (void) initialize {
     defaultImportMessageLiteInstance = [[ImportMessageLite alloc] init];
   }
 }
-+ (ImportMessageLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultImportMessageLiteInstance;
 }
-- (ImportMessageLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultImportMessageLiteInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/compiler/Tests/Unittest_import_public.pb.h b/src/compiler/Tests/Unittest_import_public.pb.h
index 9b2e8f4..76b7fba 100644
--- a/src/compiler/Tests/Unittest_import_public.pb.h
+++ b/src/compiler/Tests/Unittest_import_public.pb.h
@@ -33,8 +33,8 @@
 - (BOOL) hasE;
 @property (readonly) SInt32 e;
 
-+ (PublicImportMessage*) defaultInstance;
-- (PublicImportMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/compiler/Tests/Unittest_import_public.pb.m b/src/compiler/Tests/Unittest_import_public.pb.m
index 5ffaab4..d803de4 100644
--- a/src/compiler/Tests/Unittest_import_public.pb.m
+++ b/src/compiler/Tests/Unittest_import_public.pb.m
@@ -45,10 +45,10 @@ + (void) initialize {
     defaultPublicImportMessageInstance = [[PublicImportMessage alloc] init];
   }
 }
-+ (PublicImportMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPublicImportMessageInstance;
 }
-- (PublicImportMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPublicImportMessageInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/compiler/Tests/Unittest_import_public_lite.pb.h b/src/compiler/Tests/Unittest_import_public_lite.pb.h
index 126c19f..9eaf053 100644
--- a/src/compiler/Tests/Unittest_import_public_lite.pb.h
+++ b/src/compiler/Tests/Unittest_import_public_lite.pb.h
@@ -33,8 +33,8 @@
 - (BOOL) hasE;
 @property (readonly) SInt32 e;
 
-+ (PublicImportMessageLite*) defaultInstance;
-- (PublicImportMessageLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/compiler/Tests/Unittest_import_public_lite.pb.m b/src/compiler/Tests/Unittest_import_public_lite.pb.m
index f50d302..c300354 100644
--- a/src/compiler/Tests/Unittest_import_public_lite.pb.m
+++ b/src/compiler/Tests/Unittest_import_public_lite.pb.m
@@ -45,10 +45,10 @@ + (void) initialize {
     defaultPublicImportMessageLiteInstance = [[PublicImportMessageLite alloc] init];
   }
 }
-+ (PublicImportMessageLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPublicImportMessageLiteInstance;
 }
-- (PublicImportMessageLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPublicImportMessageLiteInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/compiler/Tests/Unittest_lite.pb.h b/src/compiler/Tests/Unittest_lite.pb.h
index 2ca613c..ed3d81f 100644
--- a/src/compiler/Tests/Unittest_lite.pb.h
+++ b/src/compiler/Tests/Unittest_lite.pb.h
@@ -452,8 +452,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (NSString*)repeatedCordAtIndex:(NSUInteger)index;
 - (TestAllTypesLiteNestedMessage*)repeatedLazyMessageAtIndex:(NSUInteger)index;
 
-+ (TestAllTypesLite*) defaultInstance;
-- (TestAllTypesLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -478,8 +478,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasBb;
 @property (readonly) SInt32 bb;
 
-+ (TestAllTypesLiteNestedMessage*) defaultInstance;
-- (TestAllTypesLiteNestedMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -527,8 +527,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (TestAllTypesLiteOptionalGroup*) defaultInstance;
-- (TestAllTypesLiteOptionalGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -576,8 +576,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (TestAllTypesLiteRepeatedGroup*) defaultInstance;
-- (TestAllTypesLiteRepeatedGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1073,8 +1073,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasC;
 @property (readonly) SInt32 c;
 
-+ (ForeignMessageLite*) defaultInstance;
-- (ForeignMessageLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1174,8 +1174,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL)packedBoolAtIndex:(NSUInteger)index;
 - (ForeignEnumLite)packedEnumAtIndex:(NSUInteger)index;
 
-+ (TestPackedTypesLite*) defaultInstance;
-- (TestPackedTypesLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1312,8 +1312,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 @private
 }
 
-+ (TestAllExtensionsLite*) defaultInstance;
-- (TestAllExtensionsLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1356,8 +1356,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (OptionalGroup_extension_lite*) defaultInstance;
-- (OptionalGroup_extension_lite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1405,8 +1405,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (RepeatedGroup_extension_lite*) defaultInstance;
-- (RepeatedGroup_extension_lite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1450,8 +1450,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 @private
 }
 
-+ (TestPackedExtensionsLite*) defaultInstance;
-- (TestPackedExtensionsLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1490,8 +1490,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 @private
 }
 
-+ (TestNestedExtensionLite*) defaultInstance;
-- (TestNestedExtensionLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) nestedExtension;
 - (BOOL) isInitialized;
@@ -1535,8 +1535,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasDeprecatedField;
 @property (readonly) SInt32 deprecatedField;
 
-+ (TestDeprecatedLite*) defaultInstance;
-- (TestDeprecatedLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1598,8 +1598,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (TestAllTypesLite*)repeatedAllTypesAtIndex:(NSUInteger)index;
 - (TestParsingMergeLiteRepeatedGroup*)repeatedGroupAtIndex:(NSUInteger)index;
 
-+ (TestParsingMergeLite*) defaultInstance;
-- (TestParsingMergeLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) optionalExt;
 + (id<PBExtensionField>) repeatedExt;
@@ -1643,8 +1643,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (TestAllTypesLite*)ext1AtIndex:(NSUInteger)index;
 - (TestAllTypesLite*)ext2AtIndex:(NSUInteger)index;
 
-+ (TestParsingMergeLiteRepeatedFieldsGenerator*) defaultInstance;
-- (TestParsingMergeLiteRepeatedFieldsGenerator*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1669,8 +1669,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasField1;
 @property (readonly, strong) TestAllTypesLite* field1;
 
-+ (TestParsingMergeLiteRepeatedFieldsGeneratorGroup1*) defaultInstance;
-- (TestParsingMergeLiteRepeatedFieldsGeneratorGroup1*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1720,8 +1720,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasField1;
 @property (readonly, strong) TestAllTypesLite* field1;
 
-+ (TestParsingMergeLiteRepeatedFieldsGeneratorGroup2*) defaultInstance;
-- (TestParsingMergeLiteRepeatedFieldsGeneratorGroup2*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1831,8 +1831,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasOptionalGroupAllTypes;
 @property (readonly, strong) TestAllTypesLite* optionalGroupAllTypes;
 
-+ (TestParsingMergeLiteOptionalGroup*) defaultInstance;
-- (TestParsingMergeLiteOptionalGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1882,8 +1882,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasRepeatedGroupAllTypes;
 @property (readonly, strong) TestAllTypesLite* repeatedGroupAllTypes;
 
-+ (TestParsingMergeLiteRepeatedGroup*) defaultInstance;
-- (TestParsingMergeLiteRepeatedGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1980,8 +1980,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 @private
 }
 
-+ (TestEmptyMessageLite*) defaultInstance;
-- (TestEmptyMessageLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2020,8 +2020,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 @private
 }
 
-+ (TestEmptyMessageWithExtensionsLite*) defaultInstance;
-- (TestEmptyMessageWithExtensionsLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/compiler/Tests/Unittest_lite.pb.m b/src/compiler/Tests/Unittest_lite.pb.m
index a9147e1..29b51d3 100644
--- a/src/compiler/Tests/Unittest_lite.pb.m
+++ b/src/compiler/Tests/Unittest_lite.pb.m
@@ -1861,10 +1861,10 @@ + (void) initialize {
     defaultTestAllTypesLiteInstance = [[TestAllTypesLite alloc] init];
   }
 }
-+ (TestAllTypesLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesLiteInstance;
 }
-- (TestAllTypesLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesLiteInstance;
 }
 - (PBArray *)repeatedInt32 {
@@ -3354,10 +3354,10 @@ + (void) initialize {
     defaultTestAllTypesLiteNestedMessageInstance = [[TestAllTypesLiteNestedMessage alloc] init];
   }
 }
-+ (TestAllTypesLiteNestedMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesLiteNestedMessageInstance;
 }
-- (TestAllTypesLiteNestedMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesLiteNestedMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -3554,10 +3554,10 @@ + (void) initialize {
     defaultTestAllTypesLiteOptionalGroupInstance = [[TestAllTypesLiteOptionalGroup alloc] init];
   }
 }
-+ (TestAllTypesLiteOptionalGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesLiteOptionalGroupInstance;
 }
-- (TestAllTypesLiteOptionalGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesLiteOptionalGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -3754,10 +3754,10 @@ + (void) initialize {
     defaultTestAllTypesLiteRepeatedGroupInstance = [[TestAllTypesLiteRepeatedGroup alloc] init];
   }
 }
-+ (TestAllTypesLiteRepeatedGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesLiteRepeatedGroupInstance;
 }
-- (TestAllTypesLiteRepeatedGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesLiteRepeatedGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -6220,10 +6220,10 @@ + (void) initialize {
     defaultForeignMessageLiteInstance = [[ForeignMessageLite alloc] init];
   }
 }
-+ (ForeignMessageLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultForeignMessageLiteInstance;
 }
-- (ForeignMessageLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultForeignMessageLiteInstance;
 }
 - (BOOL) isInitialized {
@@ -6453,10 +6453,10 @@ + (void) initialize {
     defaultTestPackedTypesLiteInstance = [[TestPackedTypesLite alloc] init];
   }
 }
-+ (TestPackedTypesLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestPackedTypesLiteInstance;
 }
-- (TestPackedTypesLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestPackedTypesLiteInstance;
 }
 - (PBArray *)packedInt32 {
@@ -7708,10 +7708,10 @@ + (void) initialize {
     defaultTestAllExtensionsLiteInstance = [[TestAllExtensionsLite alloc] init];
   }
 }
-+ (TestAllExtensionsLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllExtensionsLiteInstance;
 }
-- (TestAllExtensionsLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllExtensionsLiteInstance;
 }
 - (BOOL) isInitialized {
@@ -7886,10 +7886,10 @@ + (void) initialize {
     defaultOptionalGroup_extension_liteInstance = [[OptionalGroup_extension_lite alloc] init];
   }
 }
-+ (OptionalGroup_extension_lite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultOptionalGroup_extension_liteInstance;
 }
-- (OptionalGroup_extension_lite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultOptionalGroup_extension_liteInstance;
 }
 - (BOOL) isInitialized {
@@ -8086,10 +8086,10 @@ + (void) initialize {
     defaultRepeatedGroup_extension_liteInstance = [[RepeatedGroup_extension_lite alloc] init];
   }
 }
-+ (RepeatedGroup_extension_lite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultRepeatedGroup_extension_liteInstance;
 }
-- (RepeatedGroup_extension_lite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultRepeatedGroup_extension_liteInstance;
 }
 - (BOOL) isInitialized {
@@ -8277,10 +8277,10 @@ + (void) initialize {
     defaultTestPackedExtensionsLiteInstance = [[TestPackedExtensionsLite alloc] init];
   }
 }
-+ (TestPackedExtensionsLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestPackedExtensionsLiteInstance;
 }
-- (TestPackedExtensionsLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestPackedExtensionsLiteInstance;
 }
 - (BOOL) isInitialized {
@@ -8449,10 +8449,10 @@ + (void) initialize {
     defaultTestNestedExtensionLiteInstance = [[TestNestedExtensionLite alloc] init];
   }
 }
-+ (TestNestedExtensionLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestNestedExtensionLiteInstance;
 }
-- (TestNestedExtensionLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestNestedExtensionLiteInstance;
 }
 - (BOOL) isInitialized {
@@ -8612,10 +8612,10 @@ + (void) initialize {
     defaultTestDeprecatedLiteInstance = [[TestDeprecatedLite alloc] init];
   }
 }
-+ (TestDeprecatedLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestDeprecatedLiteInstance;
 }
-- (TestDeprecatedLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestDeprecatedLiteInstance;
 }
 - (BOOL) isInitialized {
@@ -8842,10 +8842,10 @@ + (void) initialize {
     defaultTestParsingMergeLiteInstance = [[TestParsingMergeLite alloc] init];
   }
 }
-+ (TestParsingMergeLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteInstance;
 }
-- (TestParsingMergeLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteInstance;
 }
 - (NSArray *)repeatedAllTypes {
@@ -9065,10 +9065,10 @@ + (void) initialize {
     defaultTestParsingMergeLiteRepeatedFieldsGeneratorInstance = [[TestParsingMergeLiteRepeatedFieldsGenerator alloc] init];
   }
 }
-+ (TestParsingMergeLiteRepeatedFieldsGenerator*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedFieldsGeneratorInstance;
 }
-- (TestParsingMergeLiteRepeatedFieldsGenerator*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedFieldsGeneratorInstance;
 }
 - (NSArray *)field1 {
@@ -9318,10 +9318,10 @@ + (void) initialize {
     defaultTestParsingMergeLiteRepeatedFieldsGeneratorGroup1Instance = [[TestParsingMergeLiteRepeatedFieldsGeneratorGroup1 alloc] init];
   }
 }
-+ (TestParsingMergeLiteRepeatedFieldsGeneratorGroup1*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedFieldsGeneratorGroup1Instance;
 }
-- (TestParsingMergeLiteRepeatedFieldsGeneratorGroup1*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedFieldsGeneratorGroup1Instance;
 }
 - (BOOL) isInitialized {
@@ -9540,10 +9540,10 @@ + (void) initialize {
     defaultTestParsingMergeLiteRepeatedFieldsGeneratorGroup2Instance = [[TestParsingMergeLiteRepeatedFieldsGeneratorGroup2 alloc] init];
   }
 }
-+ (TestParsingMergeLiteRepeatedFieldsGeneratorGroup2*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedFieldsGeneratorGroup2Instance;
 }
-- (TestParsingMergeLiteRepeatedFieldsGeneratorGroup2*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedFieldsGeneratorGroup2Instance;
 }
 - (BOOL) isInitialized {
@@ -10064,10 +10064,10 @@ + (void) initialize {
     defaultTestParsingMergeLiteOptionalGroupInstance = [[TestParsingMergeLiteOptionalGroup alloc] init];
   }
 }
-+ (TestParsingMergeLiteOptionalGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteOptionalGroupInstance;
 }
-- (TestParsingMergeLiteOptionalGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteOptionalGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -10286,10 +10286,10 @@ + (void) initialize {
     defaultTestParsingMergeLiteRepeatedGroupInstance = [[TestParsingMergeLiteRepeatedGroup alloc] init];
   }
 }
-+ (TestParsingMergeLiteRepeatedGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedGroupInstance;
 }
-- (TestParsingMergeLiteRepeatedGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -10758,10 +10758,10 @@ + (void) initialize {
     defaultTestEmptyMessageLiteInstance = [[TestEmptyMessageLite alloc] init];
   }
 }
-+ (TestEmptyMessageLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestEmptyMessageLiteInstance;
 }
-- (TestEmptyMessageLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestEmptyMessageLiteInstance;
 }
 - (BOOL) isInitialized {
@@ -10912,10 +10912,10 @@ + (void) initialize {
     defaultTestEmptyMessageWithExtensionsLiteInstance = [[TestEmptyMessageWithExtensionsLite alloc] init];
   }
 }
-+ (TestEmptyMessageWithExtensionsLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestEmptyMessageWithExtensionsLiteInstance;
 }
-- (TestEmptyMessageWithExtensionsLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestEmptyMessageWithExtensionsLiteInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/compiler/Tests/Unittest_lite_imports_nonlite.pb.h b/src/compiler/Tests/Unittest_lite_imports_nonlite.pb.h
index 1d80409..86d13b5 100644
--- a/src/compiler/Tests/Unittest_lite_imports_nonlite.pb.h
+++ b/src/compiler/Tests/Unittest_lite_imports_nonlite.pb.h
@@ -178,8 +178,8 @@
 - (BOOL) hasMessage;
 @property (readonly, strong) TestAllTypes* message;
 
-+ (TestLiteImportsNonlite*) defaultInstance;
-- (TestLiteImportsNonlite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/compiler/Tests/Unittest_lite_imports_nonlite.pb.m b/src/compiler/Tests/Unittest_lite_imports_nonlite.pb.m
index b7a8293..c4b4bfe 100644
--- a/src/compiler/Tests/Unittest_lite_imports_nonlite.pb.m
+++ b/src/compiler/Tests/Unittest_lite_imports_nonlite.pb.m
@@ -46,10 +46,10 @@ + (void) initialize {
     defaultTestLiteImportsNonliteInstance = [[TestLiteImportsNonlite alloc] init];
   }
 }
-+ (TestLiteImportsNonlite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestLiteImportsNonliteInstance;
 }
-- (TestLiteImportsNonlite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestLiteImportsNonliteInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/compiler/Tests/Unittest_mset.pb.h b/src/compiler/Tests/Unittest_mset.pb.h
index 26e3859..af892e6 100644
--- a/src/compiler/Tests/Unittest_mset.pb.h
+++ b/src/compiler/Tests/Unittest_mset.pb.h
@@ -39,8 +39,8 @@
 @private
 }
 
-+ (TestMessageSet*) defaultInstance;
-- (TestMessageSet*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -83,8 +83,8 @@
 - (BOOL) hasMessageSet;
 @property (readonly, strong) TestMessageSet* messageSet;
 
-+ (TestMessageSetContainer*) defaultInstance;
-- (TestMessageSetContainer*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -134,8 +134,8 @@
 - (BOOL) hasI;
 @property (readonly) SInt32 i;
 
-+ (TestMessageSetExtension1*) defaultInstance;
-- (TestMessageSetExtension1*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) messageSetExtension;
 - (BOOL) isInitialized;
@@ -184,8 +184,8 @@
 - (BOOL) hasStr;
 @property (readonly, strong) NSString* str;
 
-+ (TestMessageSetExtension2*) defaultInstance;
-- (TestMessageSetExtension2*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) messageSetExtension;
 - (BOOL) isInitialized;
@@ -233,8 +233,8 @@
 @property (readonly, strong) NSArray * item;
 - (RawMessageSetItem*)itemAtIndex:(NSUInteger)index;
 
-+ (RawMessageSet*) defaultInstance;
-- (RawMessageSet*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -263,8 +263,8 @@
 @property (readonly) SInt32 typeId;
 @property (readonly, strong) NSData* message;
 
-+ (RawMessageSetItem*) defaultInstance;
-- (RawMessageSetItem*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/compiler/Tests/Unittest_mset.pb.m b/src/compiler/Tests/Unittest_mset.pb.m
index f2607c4..8be5a74 100644
--- a/src/compiler/Tests/Unittest_mset.pb.m
+++ b/src/compiler/Tests/Unittest_mset.pb.m
@@ -58,10 +58,10 @@ + (void) initialize {
     defaultTestMessageSetInstance = [[TestMessageSet alloc] init];
   }
 }
-+ (TestMessageSet*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMessageSetInstance;
 }
-- (TestMessageSet*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMessageSetInstance;
 }
 - (BOOL) isInitialized {
@@ -236,10 +236,10 @@ + (void) initialize {
     defaultTestMessageSetContainerInstance = [[TestMessageSetContainer alloc] init];
   }
 }
-+ (TestMessageSetContainer*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMessageSetContainerInstance;
 }
-- (TestMessageSetContainer*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMessageSetContainerInstance;
 }
 - (BOOL) isInitialized {
@@ -466,10 +466,10 @@ + (void) initialize {
     defaultTestMessageSetExtension1Instance = [[TestMessageSetExtension1 alloc] init];
   }
 }
-+ (TestMessageSetExtension1*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMessageSetExtension1Instance;
 }
-- (TestMessageSetExtension1*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMessageSetExtension1Instance;
 }
 - (BOOL) isInitialized {
@@ -669,10 +669,10 @@ + (void) initialize {
     defaultTestMessageSetExtension2Instance = [[TestMessageSetExtension2 alloc] init];
   }
 }
-+ (TestMessageSetExtension2*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMessageSetExtension2Instance;
 }
-- (TestMessageSetExtension2*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMessageSetExtension2Instance;
 }
 - (BOOL) isInitialized {
@@ -863,10 +863,10 @@ + (void) initialize {
     defaultRawMessageSetInstance = [[RawMessageSet alloc] init];
   }
 }
-+ (RawMessageSet*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultRawMessageSetInstance;
 }
-- (RawMessageSet*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultRawMessageSetInstance;
 }
 - (NSArray *)item {
@@ -1001,10 +1001,10 @@ + (void) initialize {
     defaultRawMessageSetItemInstance = [[RawMessageSetItem alloc] init];
   }
 }
-+ (RawMessageSetItem*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultRawMessageSetItemInstance;
 }
-- (RawMessageSetItem*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultRawMessageSetItemInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/compiler/Tests/Unittest_no_generic_services.pb.h b/src/compiler/Tests/Unittest_no_generic_services.pb.h
index 2acfd20..8250396 100644
--- a/src/compiler/Tests/Unittest_no_generic_services.pb.h
+++ b/src/compiler/Tests/Unittest_no_generic_services.pb.h
@@ -40,8 +40,8 @@ BOOL TestEnumIsValidValue(TestEnum value);
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (TestMessage*) defaultInstance;
-- (TestMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/compiler/Tests/Unittest_no_generic_services.pb.m b/src/compiler/Tests/Unittest_no_generic_services.pb.m
index 858f5c0..dc868e2 100644
--- a/src/compiler/Tests/Unittest_no_generic_services.pb.m
+++ b/src/compiler/Tests/Unittest_no_generic_services.pb.m
@@ -67,10 +67,10 @@ + (void) initialize {
     defaultTestMessageInstance = [[TestMessage alloc] init];
   }
 }
-+ (TestMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMessageInstance;
 }
-- (TestMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMessageInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/compiler/Tests/Unittest_optimize_for.pb.h b/src/compiler/Tests/Unittest_optimize_for.pb.h
index 1c125b8..b2403de 100644
--- a/src/compiler/Tests/Unittest_optimize_for.pb.h
+++ b/src/compiler/Tests/Unittest_optimize_for.pb.h
@@ -194,8 +194,8 @@
 @property (readonly) SInt32 integerField;
 @property (readonly, strong) NSString* stringField;
 
-+ (TestOptimizedForSize*) defaultInstance;
-- (TestOptimizedForSize*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) testExtension;
 + (id<PBExtensionField>) testExtension2;
@@ -262,8 +262,8 @@
 - (BOOL) hasX;
 @property (readonly) SInt32 x;
 
-+ (TestRequiredOptimizedForSize*) defaultInstance;
-- (TestRequiredOptimizedForSize*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -311,8 +311,8 @@
 - (BOOL) hasO;
 @property (readonly, strong) TestRequiredOptimizedForSize* o;
 
-+ (TestOptionalOptimizedForSize*) defaultInstance;
-- (TestOptionalOptimizedForSize*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/compiler/Tests/Unittest_optimize_for.pb.m b/src/compiler/Tests/Unittest_optimize_for.pb.m
index 91c4e09..57cdf24 100644
--- a/src/compiler/Tests/Unittest_optimize_for.pb.m
+++ b/src/compiler/Tests/Unittest_optimize_for.pb.m
@@ -101,10 +101,10 @@ + (void) initialize {
     defaultTestOptimizedForSizeInstance = [[TestOptimizedForSize alloc] init];
   }
 }
-+ (TestOptimizedForSize*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOptimizedForSizeInstance;
 }
-- (TestOptimizedForSize*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOptimizedForSizeInstance;
 }
 - (BOOL) isInitialized {
@@ -449,10 +449,10 @@ + (void) initialize {
     defaultTestRequiredOptimizedForSizeInstance = [[TestRequiredOptimizedForSize alloc] init];
   }
 }
-+ (TestRequiredOptimizedForSize*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestRequiredOptimizedForSizeInstance;
 }
-- (TestRequiredOptimizedForSize*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestRequiredOptimizedForSizeInstance;
 }
 - (BOOL) isInitialized {
@@ -652,10 +652,10 @@ + (void) initialize {
     defaultTestOptionalOptimizedForSizeInstance = [[TestOptionalOptimizedForSize alloc] init];
   }
 }
-+ (TestOptionalOptimizedForSize*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOptionalOptimizedForSizeInstance;
 }
-- (TestOptionalOptimizedForSize*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOptionalOptimizedForSizeInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/compiler/objc_message.cc b/src/compiler/objc_message.cc
index e44958b..e0f2e23 100644
--- a/src/compiler/objc_message.cc
+++ b/src/compiler/objc_message.cc
@@ -284,8 +284,8 @@ namespace google { namespace protobuf { namespace compiler { namespace objective
         
         printer->Print(
                        "\n"
-                       "+ ($classname$*) defaultInstance;\n"
-                       "- ($classname$*) defaultInstance;\n",
+                       "+ (instancetype) defaultInstance;\n"
+                       "- (instancetype) defaultInstance;\n",
                        "classname", ClassName(descriptor_));
         printer->Print(
                        "\n",
@@ -363,10 +363,10 @@ namespace google { namespace protobuf { namespace compiler { namespace objective
         printer->Print(
                        "  }\n"
                        "}\n"
-                       "+ ($classname$*) defaultInstance {\n"
+                       "+ (instancetype) defaultInstance {\n"
                        "  return default$classname$Instance;\n"
                        "}\n"
-                       "- ($classname$*) defaultInstance {\n"
+                       "- (instancetype) defaultInstance {\n"
                        "  return default$classname$Instance;\n"
                        "}\n",
                        "classname", ClassName(descriptor_));
diff --git a/src/runtime/Classes/AbstractMessage.m b/src/runtime/Classes/AbstractMessage.m
index 7e4774f..a9ee874 100644
--- a/src/runtime/Classes/AbstractMessage.m
+++ b/src/runtime/Classes/AbstractMessage.m
@@ -59,7 +59,7 @@ - (void) writeToOutputStream:(NSOutputStream*) output {
 }
 
 
-- (id<PBMessage>) defaultInstance {
+- (instancetype) defaultInstance {
   @throw [NSException exceptionWithName:@"ImproperSubclassing" reason:@"" userInfo:nil];
 }
 
diff --git a/src/runtime/Classes/AbstractMessageBuilder.m b/src/runtime/Classes/AbstractMessageBuilder.m
index 1d162ef..bedbc69 100644
--- a/src/runtime/Classes/AbstractMessageBuilder.m
+++ b/src/runtime/Classes/AbstractMessageBuilder.m
@@ -106,7 +106,7 @@ - (BOOL) isInitialized {
 }
 
 
-- (id<PBMessage>) defaultInstance {
+- (instancetype) defaultInstance {
   @throw [NSException exceptionWithName:@"ImproperSubclassing" reason:@"" userInfo:nil];
 }
 
diff --git a/src/runtime/Classes/Descriptor.pb.h b/src/runtime/Classes/Descriptor.pb.h
index ac299f5..13d9a36 100644
--- a/src/runtime/Classes/Descriptor.pb.h
+++ b/src/runtime/Classes/Descriptor.pb.h
@@ -118,8 +118,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * file;
 - (PBFileDescriptorProto*)fileAtIndex:(NSUInteger)index;
 
-+ (PBFileDescriptorSet*) defaultInstance;
-- (PBFileDescriptorSet*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -201,8 +201,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 - (PBServiceDescriptorProto*)serviceAtIndex:(NSUInteger)index;
 - (PBFieldDescriptorProto*)extensionAtIndex:(NSUInteger)index;
 
-+ (PBFileDescriptorProto*) defaultInstance;
-- (PBFileDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -335,8 +335,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 - (PBDescriptorProtoExtensionRange*)extensionRangeAtIndex:(NSUInteger)index;
 - (PBOneofDescriptorProto*)oneofDeclAtIndex:(NSUInteger)index;
 
-+ (PBDescriptorProto*) defaultInstance;
-- (PBDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -365,8 +365,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly) SInt32 start;
 @property (readonly) SInt32 end;
 
-+ (PBDescriptorProtoExtensionRange*) defaultInstance;
-- (PBDescriptorProtoExtensionRange*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -517,8 +517,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly) SInt32 oneofIndex;
 @property (readonly, strong) PBFieldOptions* options;
 
-+ (PBFieldDescriptorProto*) defaultInstance;
-- (PBFieldDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -608,8 +608,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 - (BOOL) hasName;
 @property (readonly, strong) NSString* name;
 
-+ (PBOneofDescriptorProto*) defaultInstance;
-- (PBOneofDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -664,8 +664,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) PBEnumOptions* options;
 - (PBEnumValueDescriptorProto*)valueAtIndex:(NSUInteger)index;
 
-+ (PBEnumDescriptorProto*) defaultInstance;
-- (PBEnumDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -734,8 +734,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly) SInt32 number;
 @property (readonly, strong) PBEnumValueOptions* options;
 
-+ (PBEnumValueDescriptorProto*) defaultInstance;
-- (PBEnumValueDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -802,8 +802,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) PBServiceOptions* options;
 - (PBMethodDescriptorProto*)methodAtIndex:(NSUInteger)index;
 
-+ (PBServiceDescriptorProto*) defaultInstance;
-- (PBServiceDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -876,8 +876,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSString* outputType;
 @property (readonly, strong) PBMethodOptions* options;
 
-+ (PBMethodDescriptorProto*) defaultInstance;
-- (PBMethodDescriptorProto*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -985,8 +985,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * uninterpretedOption;
 - (PBUninterpretedOption*)uninterpretedOptionAtIndex:(NSUInteger)index;
 
-+ (PBFileOptions*) defaultInstance;
-- (PBFileOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1101,8 +1101,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * uninterpretedOption;
 - (PBUninterpretedOption*)uninterpretedOptionAtIndex:(NSUInteger)index;
 
-+ (PBMessageOptions*) defaultInstance;
-- (PBMessageOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1189,8 +1189,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * uninterpretedOption;
 - (PBUninterpretedOption*)uninterpretedOptionAtIndex:(NSUInteger)index;
 
-+ (PBFieldOptions*) defaultInstance;
-- (PBFieldOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1276,8 +1276,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * uninterpretedOption;
 - (PBUninterpretedOption*)uninterpretedOptionAtIndex:(NSUInteger)index;
 
-+ (PBEnumOptions*) defaultInstance;
-- (PBEnumOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1339,8 +1339,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * uninterpretedOption;
 - (PBUninterpretedOption*)uninterpretedOptionAtIndex:(NSUInteger)index;
 
-+ (PBEnumValueOptions*) defaultInstance;
-- (PBEnumValueOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1397,8 +1397,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * uninterpretedOption;
 - (PBUninterpretedOption*)uninterpretedOptionAtIndex:(NSUInteger)index;
 
-+ (PBServiceOptions*) defaultInstance;
-- (PBServiceOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1455,8 +1455,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * uninterpretedOption;
 - (PBUninterpretedOption*)uninterpretedOptionAtIndex:(NSUInteger)index;
 
-+ (PBMethodOptions*) defaultInstance;
-- (PBMethodOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1533,8 +1533,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSString* aggregateValue;
 - (PBUninterpretedOptionNamePart*)nameAtIndex:(NSUInteger)index;
 
-+ (PBUninterpretedOption*) defaultInstance;
-- (PBUninterpretedOption*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1563,8 +1563,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSString* namePart;
 - (BOOL) isExtension;
 
-+ (PBUninterpretedOptionNamePart*) defaultInstance;
-- (PBUninterpretedOptionNamePart*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1670,8 +1670,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 @property (readonly, strong) NSArray * location;
 - (PBSourceCodeInfoLocation*)locationAtIndex:(NSUInteger)index;
 
-+ (PBSourceCodeInfo*) defaultInstance;
-- (PBSourceCodeInfo*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1708,8 +1708,8 @@ BOOL PBFieldOptionsCTypeIsValidValue(PBFieldOptionsCType value);
 - (SInt32)pathAtIndex:(NSUInteger)index;
 - (SInt32)spanAtIndex:(NSUInteger)index;
 
-+ (PBSourceCodeInfoLocation*) defaultInstance;
-- (PBSourceCodeInfoLocation*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/runtime/Classes/Descriptor.pb.m b/src/runtime/Classes/Descriptor.pb.m
index 87031bd..e978640 100644
--- a/src/runtime/Classes/Descriptor.pb.m
+++ b/src/runtime/Classes/Descriptor.pb.m
@@ -39,10 +39,10 @@ + (void) initialize {
     defaultPBFileDescriptorSetInstance = [[PBFileDescriptorSet alloc] init];
   }
 }
-+ (PBFileDescriptorSet*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBFileDescriptorSetInstance;
 }
-- (PBFileDescriptorSet*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBFileDescriptorSetInstance;
 }
 - (NSArray *)file {
@@ -314,10 +314,10 @@ + (void) initialize {
     defaultPBFileDescriptorProtoInstance = [[PBFileDescriptorProto alloc] init];
   }
 }
-+ (PBFileDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBFileDescriptorProtoInstance;
 }
-- (PBFileDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBFileDescriptorProtoInstance;
 }
 - (NSArray *)dependency {
@@ -1146,10 +1146,10 @@ + (void) initialize {
     defaultPBDescriptorProtoInstance = [[PBDescriptorProto alloc] init];
   }
 }
-+ (PBDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBDescriptorProtoInstance;
 }
-- (PBDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBDescriptorProtoInstance;
 }
 - (NSArray *)field {
@@ -1454,10 +1454,10 @@ + (void) initialize {
     defaultPBDescriptorProtoExtensionRangeInstance = [[PBDescriptorProtoExtensionRange alloc] init];
   }
 }
-+ (PBDescriptorProtoExtensionRange*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBDescriptorProtoExtensionRangeInstance;
 }
-- (PBDescriptorProtoExtensionRange*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBDescriptorProtoExtensionRangeInstance;
 }
 - (BOOL) isInitialized {
@@ -2096,10 +2096,10 @@ + (void) initialize {
     defaultPBFieldDescriptorProtoInstance = [[PBFieldDescriptorProto alloc] init];
   }
 }
-+ (PBFieldDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBFieldDescriptorProtoInstance;
 }
-- (PBFieldDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBFieldDescriptorProtoInstance;
 }
 - (BOOL) isInitialized {
@@ -2664,10 +2664,10 @@ + (void) initialize {
     defaultPBOneofDescriptorProtoInstance = [[PBOneofDescriptorProto alloc] init];
   }
 }
-+ (PBOneofDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBOneofDescriptorProtoInstance;
 }
-- (PBOneofDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBOneofDescriptorProtoInstance;
 }
 - (BOOL) isInitialized {
@@ -2876,10 +2876,10 @@ + (void) initialize {
     defaultPBEnumDescriptorProtoInstance = [[PBEnumDescriptorProto alloc] init];
   }
 }
-+ (PBEnumDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBEnumDescriptorProtoInstance;
 }
-- (PBEnumDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBEnumDescriptorProtoInstance;
 }
 - (NSArray *)value {
@@ -3222,10 +3222,10 @@ + (void) initialize {
     defaultPBEnumValueDescriptorProtoInstance = [[PBEnumValueDescriptorProto alloc] init];
   }
 }
-+ (PBEnumValueDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBEnumValueDescriptorProtoInstance;
 }
-- (PBEnumValueDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBEnumValueDescriptorProtoInstance;
 }
 - (BOOL) isInitialized {
@@ -3535,10 +3535,10 @@ + (void) initialize {
     defaultPBServiceDescriptorProtoInstance = [[PBServiceDescriptorProto alloc] init];
   }
 }
-+ (PBServiceDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBServiceDescriptorProtoInstance;
 }
-- (PBServiceDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBServiceDescriptorProtoInstance;
 }
 - (NSArray *)method {
@@ -3890,10 +3890,10 @@ + (void) initialize {
     defaultPBMethodDescriptorProtoInstance = [[PBMethodDescriptorProto alloc] init];
   }
 }
-+ (PBMethodDescriptorProto*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBMethodDescriptorProtoInstance;
 }
-- (PBMethodDescriptorProto*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBMethodDescriptorProtoInstance;
 }
 - (BOOL) isInitialized {
@@ -4356,10 +4356,10 @@ + (void) initialize {
     defaultPBFileOptionsInstance = [[PBFileOptions alloc] init];
   }
 }
-+ (PBFileOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBFileOptionsInstance;
 }
-- (PBFileOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBFileOptionsInstance;
 }
 - (NSArray *)uninterpretedOption {
@@ -5056,10 +5056,10 @@ + (void) initialize {
     defaultPBMessageOptionsInstance = [[PBMessageOptions alloc] init];
   }
 }
-+ (PBMessageOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBMessageOptionsInstance;
 }
-- (PBMessageOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBMessageOptionsInstance;
 }
 - (NSArray *)uninterpretedOption {
@@ -5477,10 +5477,10 @@ + (void) initialize {
     defaultPBFieldOptionsInstance = [[PBFieldOptions alloc] init];
   }
 }
-+ (PBFieldOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBFieldOptionsInstance;
 }
-- (PBFieldOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBFieldOptionsInstance;
 }
 - (NSArray *)uninterpretedOption {
@@ -5978,10 +5978,10 @@ + (void) initialize {
     defaultPBEnumOptionsInstance = [[PBEnumOptions alloc] init];
   }
 }
-+ (PBEnumOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBEnumOptionsInstance;
 }
-- (PBEnumOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBEnumOptionsInstance;
 }
 - (NSArray *)uninterpretedOption {
@@ -6302,10 +6302,10 @@ + (void) initialize {
     defaultPBEnumValueOptionsInstance = [[PBEnumValueOptions alloc] init];
   }
 }
-+ (PBEnumValueOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBEnumValueOptionsInstance;
 }
-- (PBEnumValueOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBEnumValueOptionsInstance;
 }
 - (NSArray *)uninterpretedOption {
@@ -6589,10 +6589,10 @@ + (void) initialize {
     defaultPBServiceOptionsInstance = [[PBServiceOptions alloc] init];
   }
 }
-+ (PBServiceOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBServiceOptionsInstance;
 }
-- (PBServiceOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBServiceOptionsInstance;
 }
 - (NSArray *)uninterpretedOption {
@@ -6876,10 +6876,10 @@ + (void) initialize {
     defaultPBMethodOptionsInstance = [[PBMethodOptions alloc] init];
   }
 }
-+ (PBMethodOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBMethodOptionsInstance;
 }
-- (PBMethodOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBMethodOptionsInstance;
 }
 - (NSArray *)uninterpretedOption {
@@ -7203,10 +7203,10 @@ + (void) initialize {
     defaultPBUninterpretedOptionInstance = [[PBUninterpretedOption alloc] init];
   }
 }
-+ (PBUninterpretedOption*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBUninterpretedOptionInstance;
 }
-- (PBUninterpretedOption*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBUninterpretedOptionInstance;
 }
 - (NSArray *)name {
@@ -7430,10 +7430,10 @@ + (void) initialize {
     defaultPBUninterpretedOptionNamePartInstance = [[PBUninterpretedOptionNamePart alloc] init];
   }
 }
-+ (PBUninterpretedOptionNamePart*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBUninterpretedOptionNamePartInstance;
 }
-- (PBUninterpretedOptionNamePart*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBUninterpretedOptionNamePartInstance;
 }
 - (BOOL) isInitialized {
@@ -7903,10 +7903,10 @@ + (void) initialize {
     defaultPBSourceCodeInfoInstance = [[PBSourceCodeInfo alloc] init];
   }
 }
-+ (PBSourceCodeInfo*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBSourceCodeInfoInstance;
 }
-- (PBSourceCodeInfo*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBSourceCodeInfoInstance;
 }
 - (NSArray *)location {
@@ -8039,10 +8039,10 @@ + (void) initialize {
     defaultPBSourceCodeInfoLocationInstance = [[PBSourceCodeInfoLocation alloc] init];
   }
 }
-+ (PBSourceCodeInfoLocation*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPBSourceCodeInfoLocationInstance;
 }
-- (PBSourceCodeInfoLocation*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPBSourceCodeInfoLocationInstance;
 }
 - (PBArray *)path {
diff --git a/src/runtime/ProtocolBuffers.xcodeproj/project.xcworkspace/xcuserdata/alexeyxo.xcuserdatad/UserInterfaceState.xcuserstate b/src/runtime/ProtocolBuffers.xcodeproj/project.xcworkspace/xcuserdata/alexeyxo.xcuserdatad/UserInterfaceState.xcuserstate
index 0d2c973..7c8ee8a 100644
Binary files a/src/runtime/ProtocolBuffers.xcodeproj/project.xcworkspace/xcuserdata/alexeyxo.xcuserdatad/UserInterfaceState.xcuserstate and b/src/runtime/ProtocolBuffers.xcodeproj/project.xcworkspace/xcuserdata/alexeyxo.xcuserdatad/UserInterfaceState.xcuserstate differ
diff --git a/src/runtime/Tests/Unittest.pb.h b/src/runtime/Tests/Unittest.pb.h
index 6d3d564..014b880 100644
--- a/src/runtime/Tests/Unittest.pb.h
+++ b/src/runtime/Tests/Unittest.pb.h
@@ -605,8 +605,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (NSString*)repeatedCordAtIndex:(NSUInteger)index;
 - (TestAllTypesNestedMessage*)repeatedLazyMessageAtIndex:(NSUInteger)index;
 
-+ (TestAllTypes*) defaultInstance;
-- (TestAllTypes*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -631,8 +631,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasBb;
 @property (readonly) SInt32 bb;
 
-+ (TestAllTypesNestedMessage*) defaultInstance;
-- (TestAllTypesNestedMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -680,8 +680,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (TestAllTypesOptionalGroup*) defaultInstance;
-- (TestAllTypesOptionalGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -729,8 +729,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (TestAllTypesRepeatedGroup*) defaultInstance;
-- (TestAllTypesRepeatedGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1230,8 +1230,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) NestedTestAllTypes* child;
 @property (readonly, strong) TestAllTypes* payload;
 
-+ (NestedTestAllTypes*) defaultInstance;
-- (NestedTestAllTypes*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1288,8 +1288,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasDeprecatedInt32;
 @property (readonly) SInt32 deprecatedInt32;
 
-+ (TestDeprecatedFields*) defaultInstance;
-- (TestDeprecatedFields*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1337,8 +1337,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasC;
 @property (readonly) SInt32 c;
 
-+ (ForeignMessage*) defaultInstance;
-- (ForeignMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1382,8 +1382,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (TestAllExtensions*) defaultInstance;
-- (TestAllExtensions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1426,8 +1426,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (OptionalGroup_extension*) defaultInstance;
-- (OptionalGroup_extension*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1475,8 +1475,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (RepeatedGroup_extension*) defaultInstance;
-- (RepeatedGroup_extension*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1520,8 +1520,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (TestNestedExtension*) defaultInstance;
-- (TestNestedExtension*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) test;
 + (id<PBExtensionField>) nestedStringExtension;
@@ -1694,8 +1694,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt32 dummy32;
 @property (readonly) SInt32 c;
 
-+ (TestRequired*) defaultInstance;
-- (TestRequired*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) single;
 + (id<PBExtensionField>) multi;
@@ -1912,8 +1912,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt32 dummy;
 - (TestRequired*)repeatedMessageAtIndex:(NSUInteger)index;
 
-+ (TestRequiredForeign*) defaultInstance;
-- (TestRequiredForeign*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1974,8 +1974,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasForeignNested;
 @property (readonly, strong) TestAllTypesNestedMessage* foreignNested;
 
-+ (TestForeignNested*) defaultInstance;
-- (TestForeignNested*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2021,8 +2021,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (TestEmptyMessage*) defaultInstance;
-- (TestEmptyMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2061,8 +2061,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (TestEmptyMessageWithExtensions*) defaultInstance;
-- (TestEmptyMessageWithExtensions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2101,8 +2101,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (TestMultipleExtensionRanges*) defaultInstance;
-- (TestMultipleExtensionRanges*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2149,8 +2149,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt32 a;
 @property (readonly) SInt32 bb;
 
-+ (TestReallyLargeTagNumber*) defaultInstance;
-- (TestReallyLargeTagNumber*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2207,8 +2207,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) TestRecursiveMessage* a;
 @property (readonly) SInt32 i;
 
-+ (TestRecursiveMessage*) defaultInstance;
-- (TestRecursiveMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2263,8 +2263,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasBb;
 @property (readonly, strong) TestMutualRecursionB* bb;
 
-+ (TestMutualRecursionA*) defaultInstance;
-- (TestMutualRecursionA*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2318,8 +2318,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) TestMutualRecursionA* a;
 @property (readonly) SInt32 optionalInt32;
 
-+ (TestMutualRecursionB*) defaultInstance;
-- (TestMutualRecursionB*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2382,8 +2382,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) TestDupFieldNumberFoo* foo;
 @property (readonly, strong) TestDupFieldNumberBar* bar;
 
-+ (TestDupFieldNumber*) defaultInstance;
-- (TestDupFieldNumber*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2408,8 +2408,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (TestDupFieldNumberFoo*) defaultInstance;
-- (TestDupFieldNumberFoo*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2457,8 +2457,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (TestDupFieldNumberBar*) defaultInstance;
-- (TestDupFieldNumberBar*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2543,8 +2543,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasSubMessage;
 @property (readonly, strong) TestAllTypes* subMessage;
 
-+ (TestEagerMessage*) defaultInstance;
-- (TestEagerMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2594,8 +2594,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasSubMessage;
 @property (readonly, strong) TestAllTypes* subMessage;
 
-+ (TestLazyMessage*) defaultInstance;
-- (TestLazyMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2645,8 +2645,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasOptionalNestedMessage;
 @property (readonly, strong) TestNestedMessageHasBitsNestedMessage* optionalNestedMessage;
 
-+ (TestNestedMessageHasBits*) defaultInstance;
-- (TestNestedMessageHasBits*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2673,8 +2673,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (SInt32)nestedmessageRepeatedInt32AtIndex:(NSUInteger)index;
 - (ForeignMessage*)nestedmessageRepeatedForeignmessageAtIndex:(NSUInteger)index;
 
-+ (TestNestedMessageHasBitsNestedMessage*) defaultInstance;
-- (TestNestedMessageHasBitsNestedMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2793,8 +2793,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (NSString*)repeatedStringPieceFieldAtIndex:(NSUInteger)index;
 - (NSString*)repeatedCordFieldAtIndex:(NSUInteger)index;
 
-+ (TestCamelCaseFieldNames*) defaultInstance;
-- (TestCamelCaseFieldNames*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2915,8 +2915,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt64 myInt;
 @property (readonly) Float32 myFloat;
 
-+ (TestFieldOrderings*) defaultInstance;
-- (TestFieldOrderings*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3078,8 +3078,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) NSString* cordWithZero;
 @property (readonly, strong) NSString* replacementString;
 
-+ (TestExtremeDefaultValues*) defaultInstance;
-- (TestExtremeDefaultValues*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3257,8 +3257,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasSparseEnum;
 @property (readonly) TestSparseEnum sparseEnum;
 
-+ (SparseEnumMessage*) defaultInstance;
-- (SparseEnumMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3306,8 +3306,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasData;
 @property (readonly, strong) NSString* data;
 
-+ (OneString*) defaultInstance;
-- (OneString*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3354,8 +3354,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) NSArray * data;
 - (NSString*)dataAtIndex:(NSUInteger)index;
 
-+ (MoreString*) defaultInstance;
-- (MoreString*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3404,8 +3404,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasData;
 @property (readonly, strong) NSData* data;
 
-+ (OneBytes*) defaultInstance;
-- (OneBytes*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3452,8 +3452,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) NSArray * data;
 - (NSData*)dataAtIndex:(NSUInteger)index;
 
-+ (MoreBytes*) defaultInstance;
-- (MoreBytes*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3502,8 +3502,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasData;
 @property (readonly) SInt32 data;
 
-+ (Int32Message*) defaultInstance;
-- (Int32Message*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3551,8 +3551,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasData;
 @property (readonly) UInt32 data;
 
-+ (Uint32Message*) defaultInstance;
-- (Uint32Message*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3600,8 +3600,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasData;
 @property (readonly) SInt64 data;
 
-+ (Int64Message*) defaultInstance;
-- (Int64Message*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3649,8 +3649,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasData;
 @property (readonly) UInt64 data;
 
-+ (Uint64Message*) defaultInstance;
-- (Uint64Message*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3698,8 +3698,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasData;
 - (BOOL) data;
 
-+ (BoolMessage*) defaultInstance;
-- (BoolMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3759,8 +3759,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) TestAllTypes* fooMessage;
 @property (readonly, strong) TestOneofFooGroup* fooGroup;
 
-+ (TestOneof*) defaultInstance;
-- (TestOneof*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3789,8 +3789,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt32 a;
 @property (readonly, strong) NSString* b;
 
-+ (TestOneofFooGroup*) defaultInstance;
-- (TestOneofFooGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3897,8 +3897,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) TestAllTypes* fooMessage;
 @property (readonly, strong) TestOneofBackwardsCompatibleFooGroup* fooGroup;
 
-+ (TestOneofBackwardsCompatible*) defaultInstance;
-- (TestOneofBackwardsCompatible*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -3927,8 +3927,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt32 a;
 @property (readonly, strong) NSString* b;
 
-+ (TestOneofBackwardsCompatibleFooGroup*) defaultInstance;
-- (TestOneofBackwardsCompatibleFooGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4087,8 +4087,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt32 bazInt;
 @property (readonly, strong) NSString* bazString;
 
-+ (TestOneof2*) defaultInstance;
-- (TestOneof2*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4117,8 +4117,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly) SInt32 a;
 @property (readonly, strong) NSString* b;
 
-+ (TestOneof2FooGroup*) defaultInstance;
-- (TestOneof2FooGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4174,8 +4174,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) PBArray * corgeInt;
 - (SInt32)corgeIntAtIndex:(NSUInteger)index;
 
-+ (TestOneof2NestedMessage*) defaultInstance;
-- (TestOneof2NestedMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4347,8 +4347,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @property (readonly, strong) NSString* fooString;
 @property (readonly, strong) TestRequiredOneofNestedMessage* fooMessage;
 
-+ (TestRequiredOneof*) defaultInstance;
-- (TestRequiredOneof*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4373,8 +4373,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasRequiredDouble;
 @property (readonly) Float64 requiredDouble;
 
-+ (TestRequiredOneofNestedMessage*) defaultInstance;
-- (TestRequiredOneofNestedMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4509,8 +4509,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL)packedBoolAtIndex:(NSUInteger)index;
 - (ForeignEnum)packedEnumAtIndex:(NSUInteger)index;
 
-+ (TestPackedTypes*) defaultInstance;
-- (TestPackedTypes*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4689,8 +4689,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL)unpackedBoolAtIndex:(NSUInteger)index;
 - (ForeignEnum)unpackedEnumAtIndex:(NSUInteger)index;
 
-+ (TestUnpackedTypes*) defaultInstance;
-- (TestUnpackedTypes*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4827,8 +4827,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (TestPackedExtensions*) defaultInstance;
-- (TestPackedExtensions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4867,8 +4867,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (TestUnpackedExtensions*) defaultInstance;
-- (TestUnpackedExtensions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4934,8 +4934,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (NSString*)repeatedExtensionAtIndex:(NSUInteger)index;
 - (SInt32)packedExtensionAtIndex:(NSUInteger)index;
 
-+ (TestDynamicExtensions*) defaultInstance;
-- (TestDynamicExtensions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -4960,8 +4960,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasDynamicField;
 @property (readonly) SInt32 dynamicField;
 
-+ (TestDynamicExtensionsDynamicMessageType*) defaultInstance;
-- (TestDynamicExtensionsDynamicMessageType*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5083,8 +5083,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (Float32)repeatedFloatAtIndex:(NSUInteger)index;
 - (UInt64)repeatedUint64AtIndex:(NSUInteger)index;
 
-+ (TestRepeatedScalarDifferentTagSizes*) defaultInstance;
-- (TestRepeatedScalarDifferentTagSizes*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5183,8 +5183,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (TestAllTypes*)repeatedAllTypesAtIndex:(NSUInteger)index;
 - (TestParsingMergeRepeatedGroup*)repeatedGroupAtIndex:(NSUInteger)index;
 
-+ (TestParsingMerge*) defaultInstance;
-- (TestParsingMerge*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) optionalExt;
 + (id<PBExtensionField>) repeatedExt;
@@ -5228,8 +5228,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (TestAllTypes*)ext1AtIndex:(NSUInteger)index;
 - (TestAllTypes*)ext2AtIndex:(NSUInteger)index;
 
-+ (TestParsingMergeRepeatedFieldsGenerator*) defaultInstance;
-- (TestParsingMergeRepeatedFieldsGenerator*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5254,8 +5254,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasField1;
 @property (readonly, strong) TestAllTypes* field1;
 
-+ (TestParsingMergeRepeatedFieldsGeneratorGroup1*) defaultInstance;
-- (TestParsingMergeRepeatedFieldsGeneratorGroup1*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5305,8 +5305,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasField1;
 @property (readonly, strong) TestAllTypes* field1;
 
-+ (TestParsingMergeRepeatedFieldsGeneratorGroup2*) defaultInstance;
-- (TestParsingMergeRepeatedFieldsGeneratorGroup2*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5416,8 +5416,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasOptionalGroupAllTypes;
 @property (readonly, strong) TestAllTypes* optionalGroupAllTypes;
 
-+ (TestParsingMergeOptionalGroup*) defaultInstance;
-- (TestParsingMergeOptionalGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5467,8 +5467,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasRepeatedGroupAllTypes;
 @property (readonly, strong) TestAllTypes* repeatedGroupAllTypes;
 
-+ (TestParsingMergeRepeatedGroup*) defaultInstance;
-- (TestParsingMergeRepeatedGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5569,8 +5569,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 - (BOOL) hasA;
 @property (readonly, strong) NSString* a;
 
-+ (TestCommentInjectionMessage*) defaultInstance;
-- (TestCommentInjectionMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5614,8 +5614,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (FooRequest*) defaultInstance;
-- (FooRequest*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5654,8 +5654,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (FooResponse*) defaultInstance;
-- (FooResponse*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5694,8 +5694,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (FooClientMessage*) defaultInstance;
-- (FooClientMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5734,8 +5734,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (FooServerMessage*) defaultInstance;
-- (FooServerMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5774,8 +5774,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (BarRequest*) defaultInstance;
-- (BarRequest*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -5814,8 +5814,8 @@ BOOL TestDynamicExtensionsDynamicEnumTypeIsValidValue(TestDynamicExtensionsDynam
 @private
 }
 
-+ (BarResponse*) defaultInstance;
-- (BarResponse*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/runtime/Tests/Unittest.pb.m b/src/runtime/Tests/Unittest.pb.m
index f6adde7..231a729 100644
--- a/src/runtime/Tests/Unittest.pb.m
+++ b/src/runtime/Tests/Unittest.pb.m
@@ -2142,10 +2142,10 @@ + (void) initialize {
     defaultTestAllTypesInstance = [[TestAllTypes alloc] init];
   }
 }
-+ (TestAllTypes*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesInstance;
 }
-- (TestAllTypes*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesInstance;
 }
 - (PBArray *)repeatedInt32 {
@@ -3636,10 +3636,10 @@ + (void) initialize {
     defaultTestAllTypesNestedMessageInstance = [[TestAllTypesNestedMessage alloc] init];
   }
 }
-+ (TestAllTypesNestedMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesNestedMessageInstance;
 }
-- (TestAllTypesNestedMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesNestedMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -3836,10 +3836,10 @@ + (void) initialize {
     defaultTestAllTypesOptionalGroupInstance = [[TestAllTypesOptionalGroup alloc] init];
   }
 }
-+ (TestAllTypesOptionalGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesOptionalGroupInstance;
 }
-- (TestAllTypesOptionalGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesOptionalGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -4036,10 +4036,10 @@ + (void) initialize {
     defaultTestAllTypesRepeatedGroupInstance = [[TestAllTypesRepeatedGroup alloc] init];
   }
 }
-+ (TestAllTypesRepeatedGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesRepeatedGroupInstance;
 }
-- (TestAllTypesRepeatedGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesRepeatedGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -6511,10 +6511,10 @@ + (void) initialize {
     defaultNestedTestAllTypesInstance = [[NestedTestAllTypes alloc] init];
   }
 }
-+ (NestedTestAllTypes*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultNestedTestAllTypesInstance;
 }
-- (NestedTestAllTypes*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultNestedTestAllTypesInstance;
 }
 - (BOOL) isInitialized {
@@ -6792,10 +6792,10 @@ + (void) initialize {
     defaultTestDeprecatedFieldsInstance = [[TestDeprecatedFields alloc] init];
   }
 }
-+ (TestDeprecatedFields*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestDeprecatedFieldsInstance;
 }
-- (TestDeprecatedFields*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestDeprecatedFieldsInstance;
 }
 - (BOOL) isInitialized {
@@ -6992,10 +6992,10 @@ + (void) initialize {
     defaultForeignMessageInstance = [[ForeignMessage alloc] init];
   }
 }
-+ (ForeignMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultForeignMessageInstance;
 }
-- (ForeignMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultForeignMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -7183,10 +7183,10 @@ + (void) initialize {
     defaultTestAllExtensionsInstance = [[TestAllExtensions alloc] init];
   }
 }
-+ (TestAllExtensions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllExtensionsInstance;
 }
-- (TestAllExtensions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllExtensionsInstance;
 }
 - (BOOL) isInitialized {
@@ -7361,10 +7361,10 @@ + (void) initialize {
     defaultOptionalGroup_extensionInstance = [[OptionalGroup_extension alloc] init];
   }
 }
-+ (OptionalGroup_extension*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultOptionalGroup_extensionInstance;
 }
-- (OptionalGroup_extension*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultOptionalGroup_extensionInstance;
 }
 - (BOOL) isInitialized {
@@ -7561,10 +7561,10 @@ + (void) initialize {
     defaultRepeatedGroup_extensionInstance = [[RepeatedGroup_extension alloc] init];
   }
 }
-+ (RepeatedGroup_extension*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultRepeatedGroup_extensionInstance;
 }
-- (RepeatedGroup_extension*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultRepeatedGroup_extensionInstance;
 }
 - (BOOL) isInitialized {
@@ -7758,10 +7758,10 @@ + (void) initialize {
     defaultTestNestedExtensionInstance = [[TestNestedExtension alloc] init];
   }
 }
-+ (TestNestedExtension*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestNestedExtensionInstance;
 }
-- (TestNestedExtension*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestNestedExtensionInstance;
 }
 - (BOOL) isInitialized {
@@ -8215,10 +8215,10 @@ + (void) initialize {
     defaultTestRequiredInstance = [[TestRequired alloc] init];
   }
 }
-+ (TestRequired*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestRequiredInstance;
 }
-- (TestRequired*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestRequiredInstance;
 }
 - (BOOL) isInitialized {
@@ -9620,10 +9620,10 @@ + (void) initialize {
     defaultTestRequiredForeignInstance = [[TestRequiredForeign alloc] init];
   }
 }
-+ (TestRequiredForeign*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestRequiredForeignInstance;
 }
-- (TestRequiredForeign*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestRequiredForeignInstance;
 }
 - (NSArray *)repeatedMessage {
@@ -9948,10 +9948,10 @@ + (void) initialize {
     defaultTestForeignNestedInstance = [[TestForeignNested alloc] init];
   }
 }
-+ (TestForeignNested*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestForeignNestedInstance;
 }
-- (TestForeignNested*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestForeignNestedInstance;
 }
 - (BOOL) isInitialized {
@@ -10161,10 +10161,10 @@ + (void) initialize {
     defaultTestEmptyMessageInstance = [[TestEmptyMessage alloc] init];
   }
 }
-+ (TestEmptyMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestEmptyMessageInstance;
 }
-- (TestEmptyMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestEmptyMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -10315,10 +10315,10 @@ + (void) initialize {
     defaultTestEmptyMessageWithExtensionsInstance = [[TestEmptyMessageWithExtensions alloc] init];
   }
 }
-+ (TestEmptyMessageWithExtensions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestEmptyMessageWithExtensionsInstance;
 }
-- (TestEmptyMessageWithExtensions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestEmptyMessageWithExtensionsInstance;
 }
 - (BOOL) isInitialized {
@@ -10484,10 +10484,10 @@ + (void) initialize {
     defaultTestMultipleExtensionRangesInstance = [[TestMultipleExtensionRanges alloc] init];
   }
 }
-+ (TestMultipleExtensionRanges*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMultipleExtensionRangesInstance;
 }
-- (TestMultipleExtensionRanges*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMultipleExtensionRangesInstance;
 }
 - (BOOL) isInitialized {
@@ -10691,10 +10691,10 @@ + (void) initialize {
     defaultTestReallyLargeTagNumberInstance = [[TestReallyLargeTagNumber alloc] init];
   }
 }
-+ (TestReallyLargeTagNumber*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestReallyLargeTagNumberInstance;
 }
-- (TestReallyLargeTagNumber*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestReallyLargeTagNumberInstance;
 }
 - (BOOL) isInitialized {
@@ -10937,10 +10937,10 @@ + (void) initialize {
     defaultTestRecursiveMessageInstance = [[TestRecursiveMessage alloc] init];
   }
 }
-+ (TestRecursiveMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestRecursiveMessageInstance;
 }
-- (TestRecursiveMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestRecursiveMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -11196,10 +11196,10 @@ + (void) initialize {
     defaultTestMutualRecursionAInstance = [[TestMutualRecursionA alloc] init];
   }
 }
-+ (TestMutualRecursionA*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMutualRecursionAInstance;
 }
-- (TestMutualRecursionA*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMutualRecursionAInstance;
 }
 - (BOOL) isInitialized {
@@ -11427,10 +11427,10 @@ + (void) initialize {
     defaultTestMutualRecursionBInstance = [[TestMutualRecursionB alloc] init];
   }
 }
-+ (TestMutualRecursionB*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMutualRecursionBInstance;
 }
-- (TestMutualRecursionB*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMutualRecursionBInstance;
 }
 - (BOOL) isInitialized {
@@ -11704,10 +11704,10 @@ + (void) initialize {
     defaultTestDupFieldNumberInstance = [[TestDupFieldNumber alloc] init];
   }
 }
-+ (TestDupFieldNumber*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestDupFieldNumberInstance;
 }
-- (TestDupFieldNumber*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestDupFieldNumberInstance;
 }
 - (BOOL) isInitialized {
@@ -11851,10 +11851,10 @@ + (void) initialize {
     defaultTestDupFieldNumberFooInstance = [[TestDupFieldNumberFoo alloc] init];
   }
 }
-+ (TestDupFieldNumberFoo*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestDupFieldNumberFooInstance;
 }
-- (TestDupFieldNumberFoo*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestDupFieldNumberFooInstance;
 }
 - (BOOL) isInitialized {
@@ -12051,10 +12051,10 @@ + (void) initialize {
     defaultTestDupFieldNumberBarInstance = [[TestDupFieldNumberBar alloc] init];
   }
 }
-+ (TestDupFieldNumberBar*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestDupFieldNumberBarInstance;
 }
-- (TestDupFieldNumberBar*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestDupFieldNumberBarInstance;
 }
 - (BOOL) isInitialized {
@@ -12422,10 +12422,10 @@ + (void) initialize {
     defaultTestEagerMessageInstance = [[TestEagerMessage alloc] init];
   }
 }
-+ (TestEagerMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestEagerMessageInstance;
 }
-- (TestEagerMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestEagerMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -12644,10 +12644,10 @@ + (void) initialize {
     defaultTestLazyMessageInstance = [[TestLazyMessage alloc] init];
   }
 }
-+ (TestLazyMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestLazyMessageInstance;
 }
-- (TestLazyMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestLazyMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -12866,10 +12866,10 @@ + (void) initialize {
     defaultTestNestedMessageHasBitsInstance = [[TestNestedMessageHasBits alloc] init];
   }
 }
-+ (TestNestedMessageHasBits*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestNestedMessageHasBitsInstance;
 }
-- (TestNestedMessageHasBits*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestNestedMessageHasBitsInstance;
 }
 - (BOOL) isInitialized {
@@ -12979,10 +12979,10 @@ + (void) initialize {
     defaultTestNestedMessageHasBitsNestedMessageInstance = [[TestNestedMessageHasBitsNestedMessage alloc] init];
   }
 }
-+ (TestNestedMessageHasBitsNestedMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestNestedMessageHasBitsNestedMessageInstance;
 }
-- (TestNestedMessageHasBitsNestedMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestNestedMessageHasBitsNestedMessageInstance;
 }
 - (PBArray *)nestedmessageRepeatedInt32 {
@@ -13433,10 +13433,10 @@ + (void) initialize {
     defaultTestCamelCaseFieldNamesInstance = [[TestCamelCaseFieldNames alloc] init];
   }
 }
-+ (TestCamelCaseFieldNames*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestCamelCaseFieldNamesInstance;
 }
-- (TestCamelCaseFieldNames*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestCamelCaseFieldNamesInstance;
 }
 - (PBArray *)repeatedPrimitiveField {
@@ -14225,10 +14225,10 @@ + (void) initialize {
     defaultTestFieldOrderingsInstance = [[TestFieldOrderings alloc] init];
   }
 }
-+ (TestFieldOrderings*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestFieldOrderingsInstance;
 }
-- (TestFieldOrderings*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestFieldOrderingsInstance;
 }
 - (BOOL) isInitialized {
@@ -14758,10 +14758,10 @@ + (void) initialize {
     defaultTestExtremeDefaultValuesInstance = [[TestExtremeDefaultValues alloc] init];
   }
 }
-+ (TestExtremeDefaultValues*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestExtremeDefaultValuesInstance;
 }
-- (TestExtremeDefaultValues*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestExtremeDefaultValuesInstance;
 }
 - (BOOL) isInitialized {
@@ -15920,10 +15920,10 @@ + (void) initialize {
     defaultSparseEnumMessageInstance = [[SparseEnumMessage alloc] init];
   }
 }
-+ (SparseEnumMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultSparseEnumMessageInstance;
 }
-- (SparseEnumMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultSparseEnumMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -16125,10 +16125,10 @@ + (void) initialize {
     defaultOneStringInstance = [[OneString alloc] init];
   }
 }
-+ (OneString*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultOneStringInstance;
 }
-- (OneString*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultOneStringInstance;
 }
 - (BOOL) isInitialized {
@@ -16319,10 +16319,10 @@ + (void) initialize {
     defaultMoreStringInstance = [[MoreString alloc] init];
   }
 }
-+ (MoreString*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultMoreStringInstance;
 }
-- (MoreString*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultMoreStringInstance;
 }
 - (NSArray *)data {
@@ -16539,10 +16539,10 @@ + (void) initialize {
     defaultOneBytesInstance = [[OneBytes alloc] init];
   }
 }
-+ (OneBytes*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultOneBytesInstance;
 }
-- (OneBytes*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultOneBytesInstance;
 }
 - (BOOL) isInitialized {
@@ -16733,10 +16733,10 @@ + (void) initialize {
     defaultMoreBytesInstance = [[MoreBytes alloc] init];
   }
 }
-+ (MoreBytes*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultMoreBytesInstance;
 }
-- (MoreBytes*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultMoreBytesInstance;
 }
 - (NSArray *)data {
@@ -16953,10 +16953,10 @@ + (void) initialize {
     defaultInt32MessageInstance = [[Int32Message alloc] init];
   }
 }
-+ (Int32Message*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultInt32MessageInstance;
 }
-- (Int32Message*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultInt32MessageInstance;
 }
 - (BOOL) isInitialized {
@@ -17153,10 +17153,10 @@ + (void) initialize {
     defaultUint32MessageInstance = [[Uint32Message alloc] init];
   }
 }
-+ (Uint32Message*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultUint32MessageInstance;
 }
-- (Uint32Message*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultUint32MessageInstance;
 }
 - (BOOL) isInitialized {
@@ -17353,10 +17353,10 @@ + (void) initialize {
     defaultInt64MessageInstance = [[Int64Message alloc] init];
   }
 }
-+ (Int64Message*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultInt64MessageInstance;
 }
-- (Int64Message*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultInt64MessageInstance;
 }
 - (BOOL) isInitialized {
@@ -17553,10 +17553,10 @@ + (void) initialize {
     defaultUint64MessageInstance = [[Uint64Message alloc] init];
   }
 }
-+ (Uint64Message*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultUint64MessageInstance;
 }
-- (Uint64Message*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultUint64MessageInstance;
 }
 - (BOOL) isInitialized {
@@ -17758,10 +17758,10 @@ + (void) initialize {
     defaultBoolMessageInstance = [[BoolMessage alloc] init];
   }
 }
-+ (BoolMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultBoolMessageInstance;
 }
-- (BoolMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultBoolMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -17985,10 +17985,10 @@ + (void) initialize {
     defaultTestOneofInstance = [[TestOneof alloc] init];
   }
 }
-+ (TestOneof*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOneofInstance;
 }
-- (TestOneof*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOneofInstance;
 }
 - (BOOL) isInitialized {
@@ -18155,10 +18155,10 @@ + (void) initialize {
     defaultTestOneofFooGroupInstance = [[TestOneofFooGroup alloc] init];
   }
 }
-+ (TestOneofFooGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOneofFooGroupInstance;
 }
-- (TestOneofFooGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOneofFooGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -18613,10 +18613,10 @@ + (void) initialize {
     defaultTestOneofBackwardsCompatibleInstance = [[TestOneofBackwardsCompatible alloc] init];
   }
 }
-+ (TestOneofBackwardsCompatible*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOneofBackwardsCompatibleInstance;
 }
-- (TestOneofBackwardsCompatible*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOneofBackwardsCompatibleInstance;
 }
 - (BOOL) isInitialized {
@@ -18783,10 +18783,10 @@ + (void) initialize {
     defaultTestOneofBackwardsCompatibleFooGroupInstance = [[TestOneofBackwardsCompatibleFooGroup alloc] init];
   }
 }
-+ (TestOneofBackwardsCompatibleFooGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOneofBackwardsCompatibleFooGroupInstance;
 }
-- (TestOneofBackwardsCompatibleFooGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOneofBackwardsCompatibleFooGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -19358,10 +19358,10 @@ + (void) initialize {
     defaultTestOneof2Instance = [[TestOneof2 alloc] init];
   }
 }
-+ (TestOneof2*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOneof2Instance;
 }
-- (TestOneof2*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOneof2Instance;
 }
 - (BOOL) isInitialized {
@@ -19723,10 +19723,10 @@ + (void) initialize {
     defaultTestOneof2FooGroupInstance = [[TestOneof2FooGroup alloc] init];
   }
 }
-+ (TestOneof2FooGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOneof2FooGroupInstance;
 }
-- (TestOneof2FooGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOneof2FooGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -19963,10 +19963,10 @@ + (void) initialize {
     defaultTestOneof2NestedMessageInstance = [[TestOneof2NestedMessage alloc] init];
   }
 }
-+ (TestOneof2NestedMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOneof2NestedMessageInstance;
 }
-- (TestOneof2NestedMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOneof2NestedMessageInstance;
 }
 - (PBArray *)corgeInt {
@@ -20769,10 +20769,10 @@ + (void) initialize {
     defaultTestRequiredOneofInstance = [[TestRequiredOneof alloc] init];
   }
 }
-+ (TestRequiredOneof*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestRequiredOneofInstance;
 }
-- (TestRequiredOneof*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestRequiredOneofInstance;
 }
 - (BOOL) isInitialized {
@@ -20918,10 +20918,10 @@ + (void) initialize {
     defaultTestRequiredOneofNestedMessageInstance = [[TestRequiredOneofNestedMessage alloc] init];
   }
 }
-+ (TestRequiredOneofNestedMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestRequiredOneofNestedMessageInstance;
 }
-- (TestRequiredOneofNestedMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestRequiredOneofNestedMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -21306,10 +21306,10 @@ + (void) initialize {
     defaultTestPackedTypesInstance = [[TestPackedTypes alloc] init];
   }
 }
-+ (TestPackedTypes*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestPackedTypesInstance;
 }
-- (TestPackedTypes*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestPackedTypesInstance;
 }
 - (PBArray *)packedInt32 {
@@ -22603,10 +22603,10 @@ + (void) initialize {
     defaultTestUnpackedTypesInstance = [[TestUnpackedTypes alloc] init];
   }
 }
-+ (TestUnpackedTypes*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestUnpackedTypesInstance;
 }
-- (TestUnpackedTypes*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestUnpackedTypesInstance;
 }
 - (PBArray *)unpackedInt32 {
@@ -23663,10 +23663,10 @@ + (void) initialize {
     defaultTestPackedExtensionsInstance = [[TestPackedExtensions alloc] init];
   }
 }
-+ (TestPackedExtensions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestPackedExtensionsInstance;
 }
-- (TestPackedExtensions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestPackedExtensionsInstance;
 }
 - (BOOL) isInitialized {
@@ -23832,10 +23832,10 @@ + (void) initialize {
     defaultTestUnpackedExtensionsInstance = [[TestUnpackedExtensions alloc] init];
   }
 }
-+ (TestUnpackedExtensions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestUnpackedExtensionsInstance;
 }
-- (TestUnpackedExtensions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestUnpackedExtensionsInstance;
 }
 - (BOOL) isInitialized {
@@ -24052,10 +24052,10 @@ + (void) initialize {
     defaultTestDynamicExtensionsInstance = [[TestDynamicExtensions alloc] init];
   }
 }
-+ (TestDynamicExtensions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestDynamicExtensionsInstance;
 }
-- (TestDynamicExtensions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestDynamicExtensionsInstance;
 }
 - (NSArray *)repeatedExtension {
@@ -24298,10 +24298,10 @@ + (void) initialize {
     defaultTestDynamicExtensionsDynamicMessageTypeInstance = [[TestDynamicExtensionsDynamicMessageType alloc] init];
   }
 }
-+ (TestDynamicExtensionsDynamicMessageType*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestDynamicExtensionsDynamicMessageTypeInstance;
 }
-- (TestDynamicExtensionsDynamicMessageType*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestDynamicExtensionsDynamicMessageTypeInstance;
 }
 - (BOOL) isInitialized {
@@ -24810,10 +24810,10 @@ + (void) initialize {
     defaultTestRepeatedScalarDifferentTagSizesInstance = [[TestRepeatedScalarDifferentTagSizes alloc] init];
   }
 }
-+ (TestRepeatedScalarDifferentTagSizes*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestRepeatedScalarDifferentTagSizesInstance;
 }
-- (TestRepeatedScalarDifferentTagSizes*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestRepeatedScalarDifferentTagSizesInstance;
 }
 - (PBArray *)repeatedFixed32 {
@@ -25390,10 +25390,10 @@ + (void) initialize {
     defaultTestParsingMergeInstance = [[TestParsingMerge alloc] init];
   }
 }
-+ (TestParsingMerge*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeInstance;
 }
-- (TestParsingMerge*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeInstance;
 }
 - (NSArray *)repeatedAllTypes {
@@ -25613,10 +25613,10 @@ + (void) initialize {
     defaultTestParsingMergeRepeatedFieldsGeneratorInstance = [[TestParsingMergeRepeatedFieldsGenerator alloc] init];
   }
 }
-+ (TestParsingMergeRepeatedFieldsGenerator*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedFieldsGeneratorInstance;
 }
-- (TestParsingMergeRepeatedFieldsGenerator*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedFieldsGeneratorInstance;
 }
 - (NSArray *)field1 {
@@ -25866,10 +25866,10 @@ + (void) initialize {
     defaultTestParsingMergeRepeatedFieldsGeneratorGroup1Instance = [[TestParsingMergeRepeatedFieldsGeneratorGroup1 alloc] init];
   }
 }
-+ (TestParsingMergeRepeatedFieldsGeneratorGroup1*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedFieldsGeneratorGroup1Instance;
 }
-- (TestParsingMergeRepeatedFieldsGeneratorGroup1*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedFieldsGeneratorGroup1Instance;
 }
 - (BOOL) isInitialized {
@@ -26088,10 +26088,10 @@ + (void) initialize {
     defaultTestParsingMergeRepeatedFieldsGeneratorGroup2Instance = [[TestParsingMergeRepeatedFieldsGeneratorGroup2 alloc] init];
   }
 }
-+ (TestParsingMergeRepeatedFieldsGeneratorGroup2*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedFieldsGeneratorGroup2Instance;
 }
-- (TestParsingMergeRepeatedFieldsGeneratorGroup2*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedFieldsGeneratorGroup2Instance;
 }
 - (BOOL) isInitialized {
@@ -26612,10 +26612,10 @@ + (void) initialize {
     defaultTestParsingMergeOptionalGroupInstance = [[TestParsingMergeOptionalGroup alloc] init];
   }
 }
-+ (TestParsingMergeOptionalGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeOptionalGroupInstance;
 }
-- (TestParsingMergeOptionalGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeOptionalGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -26834,10 +26834,10 @@ + (void) initialize {
     defaultTestParsingMergeRepeatedGroupInstance = [[TestParsingMergeRepeatedGroup alloc] init];
   }
 }
-+ (TestParsingMergeRepeatedGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedGroupInstance;
 }
-- (TestParsingMergeRepeatedGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeRepeatedGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -27315,10 +27315,10 @@ + (void) initialize {
     defaultTestCommentInjectionMessageInstance = [[TestCommentInjectionMessage alloc] init];
   }
 }
-+ (TestCommentInjectionMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestCommentInjectionMessageInstance;
 }
-- (TestCommentInjectionMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestCommentInjectionMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -27506,10 +27506,10 @@ + (void) initialize {
     defaultFooRequestInstance = [[FooRequest alloc] init];
   }
 }
-+ (FooRequest*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultFooRequestInstance;
 }
-- (FooRequest*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultFooRequestInstance;
 }
 - (BOOL) isInitialized {
@@ -27660,10 +27660,10 @@ + (void) initialize {
     defaultFooResponseInstance = [[FooResponse alloc] init];
   }
 }
-+ (FooResponse*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultFooResponseInstance;
 }
-- (FooResponse*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultFooResponseInstance;
 }
 - (BOOL) isInitialized {
@@ -27814,10 +27814,10 @@ + (void) initialize {
     defaultFooClientMessageInstance = [[FooClientMessage alloc] init];
   }
 }
-+ (FooClientMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultFooClientMessageInstance;
 }
-- (FooClientMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultFooClientMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -27968,10 +27968,10 @@ + (void) initialize {
     defaultFooServerMessageInstance = [[FooServerMessage alloc] init];
   }
 }
-+ (FooServerMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultFooServerMessageInstance;
 }
-- (FooServerMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultFooServerMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -28122,10 +28122,10 @@ + (void) initialize {
     defaultBarRequestInstance = [[BarRequest alloc] init];
   }
 }
-+ (BarRequest*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultBarRequestInstance;
 }
-- (BarRequest*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultBarRequestInstance;
 }
 - (BOOL) isInitialized {
@@ -28276,10 +28276,10 @@ + (void) initialize {
     defaultBarResponseInstance = [[BarResponse alloc] init];
   }
 }
-+ (BarResponse*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultBarResponseInstance;
 }
-- (BarResponse*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultBarResponseInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/runtime/Tests/Unittest_custom_options.pb.h b/src/runtime/Tests/Unittest_custom_options.pb.h
index 8c40a41..a1bf4ec 100644
--- a/src/runtime/Tests/Unittest_custom_options.pb.h
+++ b/src/runtime/Tests/Unittest_custom_options.pb.h
@@ -197,8 +197,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 - (BOOL) hasField1;
 @property (readonly, strong) NSString* field1;
 
-+ (TestMessageWithCustomOptions*) defaultInstance;
-- (TestMessageWithCustomOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -242,8 +242,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (CustomOptionFooRequest*) defaultInstance;
-- (CustomOptionFooRequest*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -282,8 +282,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (CustomOptionFooResponse*) defaultInstance;
-- (CustomOptionFooResponse*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -322,8 +322,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (CustomOptionFooClientMessage*) defaultInstance;
-- (CustomOptionFooClientMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -362,8 +362,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (CustomOptionFooServerMessage*) defaultInstance;
-- (CustomOptionFooServerMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -402,8 +402,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (DummyMessageContainingEnum*) defaultInstance;
-- (DummyMessageContainingEnum*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -442,8 +442,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (DummyMessageInvalidAsOptionType*) defaultInstance;
-- (DummyMessageInvalidAsOptionType*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -482,8 +482,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (CustomOptionMinIntegerValues*) defaultInstance;
-- (CustomOptionMinIntegerValues*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -522,8 +522,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (CustomOptionMaxIntegerValues*) defaultInstance;
-- (CustomOptionMaxIntegerValues*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -562,8 +562,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (CustomOptionOtherValues*) defaultInstance;
-- (CustomOptionOtherValues*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -602,8 +602,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (SettingRealsFromPositiveInts*) defaultInstance;
-- (SettingRealsFromPositiveInts*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -642,8 +642,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (SettingRealsFromNegativeInts*) defaultInstance;
-- (SettingRealsFromNegativeInts*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -697,8 +697,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @property (readonly, strong) PBArray * foo4;
 - (SInt32)foo4AtIndex:(NSUInteger)index;
 
-+ (ComplexOptionType1*) defaultInstance;
-- (ComplexOptionType1*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -774,8 +774,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @property (readonly, strong) NSArray * barney;
 - (ComplexOptionType2ComplexOptionType4*)barneyAtIndex:(NSUInteger)index;
 
-+ (ComplexOptionType2*) defaultInstance;
-- (ComplexOptionType2*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -800,8 +800,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 - (BOOL) hasWaldo;
 @property (readonly) SInt32 waldo;
 
-+ (ComplexOptionType2ComplexOptionType4*) defaultInstance;
-- (ComplexOptionType2ComplexOptionType4*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) complexOpt4;
 - (BOOL) isInitialized;
@@ -897,8 +897,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @property (readonly) SInt32 qux;
 @property (readonly, strong) ComplexOptionType3ComplexOptionType5* complexOptionType5;
 
-+ (ComplexOptionType3*) defaultInstance;
-- (ComplexOptionType3*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -923,8 +923,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 - (BOOL) hasPlugh;
 @property (readonly) SInt32 plugh;
 
-+ (ComplexOptionType3ComplexOptionType5*) defaultInstance;
-- (ComplexOptionType3ComplexOptionType5*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1002,8 +1002,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 - (BOOL) hasXyzzy;
 @property (readonly) SInt32 xyzzy;
 
-+ (ComplexOpt6*) defaultInstance;
-- (ComplexOpt6*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1047,8 +1047,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (VariousComplexOptions*) defaultInstance;
-- (VariousComplexOptions*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1087,8 +1087,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (AggregateMessageSet*) defaultInstance;
-- (AggregateMessageSet*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1131,8 +1131,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 - (BOOL) hasS;
 @property (readonly, strong) NSString* s;
 
-+ (AggregateMessageSetElement*) defaultInstance;
-- (AggregateMessageSetElement*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) messageSetExtension;
 - (BOOL) isInitialized;
@@ -1197,8 +1197,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @property (readonly, strong) PBFileOptions* file;
 @property (readonly, strong) AggregateMessageSet* mset;
 
-+ (Aggregate*) defaultInstance;
-- (Aggregate*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) nested;
 - (BOOL) isInitialized;
@@ -1273,8 +1273,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 - (BOOL) hasFieldname;
 @property (readonly) SInt32 fieldname;
 
-+ (AggregateMessage*) defaultInstance;
-- (AggregateMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1318,8 +1318,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 @private
 }
 
-+ (NestedOptionType*) defaultInstance;
-- (NestedOptionType*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) nestedExtension;
 - (BOOL) isInitialized;
@@ -1345,8 +1345,8 @@ BOOL NestedOptionTypeNestedEnumIsValidValue(NestedOptionTypeNestedEnum value);
 - (BOOL) hasNestedField;
 @property (readonly) SInt32 nestedField;
 
-+ (NestedOptionTypeNestedMessage*) defaultInstance;
-- (NestedOptionTypeNestedMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/runtime/Tests/Unittest_custom_options.pb.m b/src/runtime/Tests/Unittest_custom_options.pb.m
index 0b28148..bd5c51b 100644
--- a/src/runtime/Tests/Unittest_custom_options.pb.m
+++ b/src/runtime/Tests/Unittest_custom_options.pb.m
@@ -667,10 +667,10 @@ + (void) initialize {
     defaultTestMessageWithCustomOptionsInstance = [[TestMessageWithCustomOptions alloc] init];
   }
 }
-+ (TestMessageWithCustomOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMessageWithCustomOptionsInstance;
 }
-- (TestMessageWithCustomOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMessageWithCustomOptionsInstance;
 }
 - (BOOL) isInitialized {
@@ -867,10 +867,10 @@ + (void) initialize {
     defaultCustomOptionFooRequestInstance = [[CustomOptionFooRequest alloc] init];
   }
 }
-+ (CustomOptionFooRequest*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultCustomOptionFooRequestInstance;
 }
-- (CustomOptionFooRequest*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultCustomOptionFooRequestInstance;
 }
 - (BOOL) isInitialized {
@@ -1021,10 +1021,10 @@ + (void) initialize {
     defaultCustomOptionFooResponseInstance = [[CustomOptionFooResponse alloc] init];
   }
 }
-+ (CustomOptionFooResponse*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultCustomOptionFooResponseInstance;
 }
-- (CustomOptionFooResponse*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultCustomOptionFooResponseInstance;
 }
 - (BOOL) isInitialized {
@@ -1175,10 +1175,10 @@ + (void) initialize {
     defaultCustomOptionFooClientMessageInstance = [[CustomOptionFooClientMessage alloc] init];
   }
 }
-+ (CustomOptionFooClientMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultCustomOptionFooClientMessageInstance;
 }
-- (CustomOptionFooClientMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultCustomOptionFooClientMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -1329,10 +1329,10 @@ + (void) initialize {
     defaultCustomOptionFooServerMessageInstance = [[CustomOptionFooServerMessage alloc] init];
   }
 }
-+ (CustomOptionFooServerMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultCustomOptionFooServerMessageInstance;
 }
-- (CustomOptionFooServerMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultCustomOptionFooServerMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -1483,10 +1483,10 @@ + (void) initialize {
     defaultDummyMessageContainingEnumInstance = [[DummyMessageContainingEnum alloc] init];
   }
 }
-+ (DummyMessageContainingEnum*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultDummyMessageContainingEnumInstance;
 }
-- (DummyMessageContainingEnum*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultDummyMessageContainingEnumInstance;
 }
 - (BOOL) isInitialized {
@@ -1646,10 +1646,10 @@ + (void) initialize {
     defaultDummyMessageInvalidAsOptionTypeInstance = [[DummyMessageInvalidAsOptionType alloc] init];
   }
 }
-+ (DummyMessageInvalidAsOptionType*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultDummyMessageInvalidAsOptionTypeInstance;
 }
-- (DummyMessageInvalidAsOptionType*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultDummyMessageInvalidAsOptionTypeInstance;
 }
 - (BOOL) isInitialized {
@@ -1800,10 +1800,10 @@ + (void) initialize {
     defaultCustomOptionMinIntegerValuesInstance = [[CustomOptionMinIntegerValues alloc] init];
   }
 }
-+ (CustomOptionMinIntegerValues*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultCustomOptionMinIntegerValuesInstance;
 }
-- (CustomOptionMinIntegerValues*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultCustomOptionMinIntegerValuesInstance;
 }
 - (BOOL) isInitialized {
@@ -1954,10 +1954,10 @@ + (void) initialize {
     defaultCustomOptionMaxIntegerValuesInstance = [[CustomOptionMaxIntegerValues alloc] init];
   }
 }
-+ (CustomOptionMaxIntegerValues*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultCustomOptionMaxIntegerValuesInstance;
 }
-- (CustomOptionMaxIntegerValues*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultCustomOptionMaxIntegerValuesInstance;
 }
 - (BOOL) isInitialized {
@@ -2108,10 +2108,10 @@ + (void) initialize {
     defaultCustomOptionOtherValuesInstance = [[CustomOptionOtherValues alloc] init];
   }
 }
-+ (CustomOptionOtherValues*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultCustomOptionOtherValuesInstance;
 }
-- (CustomOptionOtherValues*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultCustomOptionOtherValuesInstance;
 }
 - (BOOL) isInitialized {
@@ -2262,10 +2262,10 @@ + (void) initialize {
     defaultSettingRealsFromPositiveIntsInstance = [[SettingRealsFromPositiveInts alloc] init];
   }
 }
-+ (SettingRealsFromPositiveInts*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultSettingRealsFromPositiveIntsInstance;
 }
-- (SettingRealsFromPositiveInts*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultSettingRealsFromPositiveIntsInstance;
 }
 - (BOOL) isInitialized {
@@ -2416,10 +2416,10 @@ + (void) initialize {
     defaultSettingRealsFromNegativeIntsInstance = [[SettingRealsFromNegativeInts alloc] init];
   }
 }
-+ (SettingRealsFromNegativeInts*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultSettingRealsFromNegativeIntsInstance;
 }
-- (SettingRealsFromNegativeInts*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultSettingRealsFromNegativeIntsInstance;
 }
 - (BOOL) isInitialized {
@@ -2600,10 +2600,10 @@ + (void) initialize {
     defaultComplexOptionType1Instance = [[ComplexOptionType1 alloc] init];
   }
 }
-+ (ComplexOptionType1*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultComplexOptionType1Instance;
 }
-- (ComplexOptionType1*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultComplexOptionType1Instance;
 }
 - (PBArray *)foo4 {
@@ -2976,10 +2976,10 @@ + (void) initialize {
     defaultComplexOptionType2Instance = [[ComplexOptionType2 alloc] init];
   }
 }
-+ (ComplexOptionType2*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultComplexOptionType2Instance;
 }
-- (ComplexOptionType2*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultComplexOptionType2Instance;
 }
 - (NSArray *)barney {
@@ -3167,10 +3167,10 @@ + (void) initialize {
     defaultComplexOptionType2ComplexOptionType4Instance = [[ComplexOptionType2ComplexOptionType4 alloc] init];
   }
 }
-+ (ComplexOptionType2ComplexOptionType4*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultComplexOptionType2ComplexOptionType4Instance;
 }
-- (ComplexOptionType2ComplexOptionType4*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultComplexOptionType2ComplexOptionType4Instance;
 }
 - (BOOL) isInitialized {
@@ -3582,10 +3582,10 @@ + (void) initialize {
     defaultComplexOptionType3Instance = [[ComplexOptionType3 alloc] init];
   }
 }
-+ (ComplexOptionType3*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultComplexOptionType3Instance;
 }
-- (ComplexOptionType3*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultComplexOptionType3Instance;
 }
 - (BOOL) isInitialized {
@@ -3712,10 +3712,10 @@ + (void) initialize {
     defaultComplexOptionType3ComplexOptionType5Instance = [[ComplexOptionType3ComplexOptionType5 alloc] init];
   }
 }
-+ (ComplexOptionType3ComplexOptionType5*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultComplexOptionType3ComplexOptionType5Instance;
 }
-- (ComplexOptionType3ComplexOptionType5*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultComplexOptionType3ComplexOptionType5Instance;
 }
 - (BOOL) isInitialized {
@@ -4041,10 +4041,10 @@ + (void) initialize {
     defaultComplexOpt6Instance = [[ComplexOpt6 alloc] init];
   }
 }
-+ (ComplexOpt6*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultComplexOpt6Instance;
 }
-- (ComplexOpt6*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultComplexOpt6Instance;
 }
 - (BOOL) isInitialized {
@@ -4232,10 +4232,10 @@ + (void) initialize {
     defaultVariousComplexOptionsInstance = [[VariousComplexOptions alloc] init];
   }
 }
-+ (VariousComplexOptions*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultVariousComplexOptionsInstance;
 }
-- (VariousComplexOptions*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultVariousComplexOptionsInstance;
 }
 - (BOOL) isInitialized {
@@ -4386,10 +4386,10 @@ + (void) initialize {
     defaultAggregateMessageSetInstance = [[AggregateMessageSet alloc] init];
   }
 }
-+ (AggregateMessageSet*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultAggregateMessageSetInstance;
 }
-- (AggregateMessageSet*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultAggregateMessageSetInstance;
 }
 - (BOOL) isInitialized {
@@ -4567,10 +4567,10 @@ + (void) initialize {
     defaultAggregateMessageSetElementInstance = [[AggregateMessageSetElement alloc] init];
   }
 }
-+ (AggregateMessageSetElement*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultAggregateMessageSetElementInstance;
 }
-- (AggregateMessageSetElement*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultAggregateMessageSetElementInstance;
 }
 - (BOOL) isInitialized {
@@ -4806,10 +4806,10 @@ + (void) initialize {
     defaultAggregateInstance = [[Aggregate alloc] init];
   }
 }
-+ (Aggregate*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultAggregateInstance;
 }
-- (Aggregate*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultAggregateInstance;
 }
 - (BOOL) isInitialized {
@@ -5235,10 +5235,10 @@ + (void) initialize {
     defaultAggregateMessageInstance = [[AggregateMessage alloc] init];
   }
 }
-+ (AggregateMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultAggregateMessageInstance;
 }
-- (AggregateMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultAggregateMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -5429,10 +5429,10 @@ + (void) initialize {
     defaultNestedOptionTypeInstance = [[NestedOptionType alloc] init];
   }
 }
-+ (NestedOptionType*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultNestedOptionTypeInstance;
 }
-- (NestedOptionType*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultNestedOptionTypeInstance;
 }
 - (BOOL) isInitialized {
@@ -5536,10 +5536,10 @@ + (void) initialize {
     defaultNestedOptionTypeNestedMessageInstance = [[NestedOptionTypeNestedMessage alloc] init];
   }
 }
-+ (NestedOptionTypeNestedMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultNestedOptionTypeNestedMessageInstance;
 }
-- (NestedOptionTypeNestedMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultNestedOptionTypeNestedMessageInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/runtime/Tests/Unittest_embed_optimize_for.pb.h b/src/runtime/Tests/Unittest_embed_optimize_for.pb.h
index 84e486b..7d59bb7 100644
--- a/src/runtime/Tests/Unittest_embed_optimize_for.pb.h
+++ b/src/runtime/Tests/Unittest_embed_optimize_for.pb.h
@@ -187,8 +187,8 @@
 @property (readonly, strong) NSArray * repeatedMessage;
 - (TestOptimizedForSize*)repeatedMessageAtIndex:(NSUInteger)index;
 
-+ (TestEmbedOptimizedForSize*) defaultInstance;
-- (TestEmbedOptimizedForSize*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/runtime/Tests/Unittest_embed_optimize_for.pb.m b/src/runtime/Tests/Unittest_embed_optimize_for.pb.m
index 941e720..a7a4f18 100644
--- a/src/runtime/Tests/Unittest_embed_optimize_for.pb.m
+++ b/src/runtime/Tests/Unittest_embed_optimize_for.pb.m
@@ -49,10 +49,10 @@ + (void) initialize {
     defaultTestEmbedOptimizedForSizeInstance = [[TestEmbedOptimizedForSize alloc] init];
   }
 }
-+ (TestEmbedOptimizedForSize*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestEmbedOptimizedForSizeInstance;
 }
-- (TestEmbedOptimizedForSize*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestEmbedOptimizedForSizeInstance;
 }
 - (NSArray *)repeatedMessage {
diff --git a/src/runtime/Tests/Unittest_enormous_descriptor.pb.h b/src/runtime/Tests/Unittest_enormous_descriptor.pb.h
index 26820ab..a37ab49 100644
--- a/src/runtime/Tests/Unittest_enormous_descriptor.pb.h
+++ b/src/runtime/Tests/Unittest_enormous_descriptor.pb.h
@@ -4029,8 +4029,8 @@
 @property (readonly, strong) NSString* longFieldNameIsLooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong999;
 @property (readonly, strong) NSString* longFieldNameIsLooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong1000;
 
-+ (TestEnormousDescriptor*) defaultInstance;
-- (TestEnormousDescriptor*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/runtime/Tests/Unittest_enormous_descriptor.pb.m b/src/runtime/Tests/Unittest_enormous_descriptor.pb.m
index 81db84a..5710a7f 100644
--- a/src/runtime/Tests/Unittest_enormous_descriptor.pb.m
+++ b/src/runtime/Tests/Unittest_enormous_descriptor.pb.m
@@ -9036,10 +9036,10 @@ + (void) initialize {
     defaultTestEnormousDescriptorInstance = [[TestEnormousDescriptor alloc] init];
   }
 }
-+ (TestEnormousDescriptor*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestEnormousDescriptorInstance;
 }
-- (TestEnormousDescriptor*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestEnormousDescriptorInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/runtime/Tests/Unittest_import.pb.h b/src/runtime/Tests/Unittest_import.pb.h
index 6be12ba..29cb422 100644
--- a/src/runtime/Tests/Unittest_import.pb.h
+++ b/src/runtime/Tests/Unittest_import.pb.h
@@ -44,8 +44,8 @@ BOOL ImportEnumIsValidValue(ImportEnum value);
 - (BOOL) hasD;
 @property (readonly) SInt32 d;
 
-+ (ImportMessage*) defaultInstance;
-- (ImportMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/runtime/Tests/Unittest_import.pb.m b/src/runtime/Tests/Unittest_import.pb.m
index f2bd993..ddab0e1 100644
--- a/src/runtime/Tests/Unittest_import.pb.m
+++ b/src/runtime/Tests/Unittest_import.pb.m
@@ -56,10 +56,10 @@ + (void) initialize {
     defaultImportMessageInstance = [[ImportMessage alloc] init];
   }
 }
-+ (ImportMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultImportMessageInstance;
 }
-- (ImportMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultImportMessageInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/runtime/Tests/Unittest_import_lite.pb.h b/src/runtime/Tests/Unittest_import_lite.pb.h
index b75c3d6..cadbdd1 100644
--- a/src/runtime/Tests/Unittest_import_lite.pb.h
+++ b/src/runtime/Tests/Unittest_import_lite.pb.h
@@ -44,8 +44,8 @@ BOOL ImportEnumLiteIsValidValue(ImportEnumLite value);
 - (BOOL) hasD;
 @property (readonly) SInt32 d;
 
-+ (ImportMessageLite*) defaultInstance;
-- (ImportMessageLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/runtime/Tests/Unittest_import_lite.pb.m b/src/runtime/Tests/Unittest_import_lite.pb.m
index f8598dc..f48d4f0 100644
--- a/src/runtime/Tests/Unittest_import_lite.pb.m
+++ b/src/runtime/Tests/Unittest_import_lite.pb.m
@@ -56,10 +56,10 @@ + (void) initialize {
     defaultImportMessageLiteInstance = [[ImportMessageLite alloc] init];
   }
 }
-+ (ImportMessageLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultImportMessageLiteInstance;
 }
-- (ImportMessageLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultImportMessageLiteInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/runtime/Tests/Unittest_import_public.pb.h b/src/runtime/Tests/Unittest_import_public.pb.h
index 9b2e8f4..76b7fba 100644
--- a/src/runtime/Tests/Unittest_import_public.pb.h
+++ b/src/runtime/Tests/Unittest_import_public.pb.h
@@ -33,8 +33,8 @@
 - (BOOL) hasE;
 @property (readonly) SInt32 e;
 
-+ (PublicImportMessage*) defaultInstance;
-- (PublicImportMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/runtime/Tests/Unittest_import_public.pb.m b/src/runtime/Tests/Unittest_import_public.pb.m
index 5ffaab4..d803de4 100644
--- a/src/runtime/Tests/Unittest_import_public.pb.m
+++ b/src/runtime/Tests/Unittest_import_public.pb.m
@@ -45,10 +45,10 @@ + (void) initialize {
     defaultPublicImportMessageInstance = [[PublicImportMessage alloc] init];
   }
 }
-+ (PublicImportMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPublicImportMessageInstance;
 }
-- (PublicImportMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPublicImportMessageInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/runtime/Tests/Unittest_import_public_lite.pb.h b/src/runtime/Tests/Unittest_import_public_lite.pb.h
index 126c19f..9eaf053 100644
--- a/src/runtime/Tests/Unittest_import_public_lite.pb.h
+++ b/src/runtime/Tests/Unittest_import_public_lite.pb.h
@@ -33,8 +33,8 @@
 - (BOOL) hasE;
 @property (readonly) SInt32 e;
 
-+ (PublicImportMessageLite*) defaultInstance;
-- (PublicImportMessageLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/runtime/Tests/Unittest_import_public_lite.pb.m b/src/runtime/Tests/Unittest_import_public_lite.pb.m
index f50d302..c300354 100644
--- a/src/runtime/Tests/Unittest_import_public_lite.pb.m
+++ b/src/runtime/Tests/Unittest_import_public_lite.pb.m
@@ -45,10 +45,10 @@ + (void) initialize {
     defaultPublicImportMessageLiteInstance = [[PublicImportMessageLite alloc] init];
   }
 }
-+ (PublicImportMessageLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultPublicImportMessageLiteInstance;
 }
-- (PublicImportMessageLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultPublicImportMessageLiteInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/runtime/Tests/Unittest_lite.pb.h b/src/runtime/Tests/Unittest_lite.pb.h
index 2ca613c..ed3d81f 100644
--- a/src/runtime/Tests/Unittest_lite.pb.h
+++ b/src/runtime/Tests/Unittest_lite.pb.h
@@ -452,8 +452,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (NSString*)repeatedCordAtIndex:(NSUInteger)index;
 - (TestAllTypesLiteNestedMessage*)repeatedLazyMessageAtIndex:(NSUInteger)index;
 
-+ (TestAllTypesLite*) defaultInstance;
-- (TestAllTypesLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -478,8 +478,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasBb;
 @property (readonly) SInt32 bb;
 
-+ (TestAllTypesLiteNestedMessage*) defaultInstance;
-- (TestAllTypesLiteNestedMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -527,8 +527,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (TestAllTypesLiteOptionalGroup*) defaultInstance;
-- (TestAllTypesLiteOptionalGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -576,8 +576,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (TestAllTypesLiteRepeatedGroup*) defaultInstance;
-- (TestAllTypesLiteRepeatedGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1073,8 +1073,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasC;
 @property (readonly) SInt32 c;
 
-+ (ForeignMessageLite*) defaultInstance;
-- (ForeignMessageLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1174,8 +1174,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL)packedBoolAtIndex:(NSUInteger)index;
 - (ForeignEnumLite)packedEnumAtIndex:(NSUInteger)index;
 
-+ (TestPackedTypesLite*) defaultInstance;
-- (TestPackedTypesLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1312,8 +1312,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 @private
 }
 
-+ (TestAllExtensionsLite*) defaultInstance;
-- (TestAllExtensionsLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1356,8 +1356,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (OptionalGroup_extension_lite*) defaultInstance;
-- (OptionalGroup_extension_lite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1405,8 +1405,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (RepeatedGroup_extension_lite*) defaultInstance;
-- (RepeatedGroup_extension_lite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1450,8 +1450,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 @private
 }
 
-+ (TestPackedExtensionsLite*) defaultInstance;
-- (TestPackedExtensionsLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1490,8 +1490,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 @private
 }
 
-+ (TestNestedExtensionLite*) defaultInstance;
-- (TestNestedExtensionLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) nestedExtension;
 - (BOOL) isInitialized;
@@ -1535,8 +1535,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasDeprecatedField;
 @property (readonly) SInt32 deprecatedField;
 
-+ (TestDeprecatedLite*) defaultInstance;
-- (TestDeprecatedLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1598,8 +1598,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (TestAllTypesLite*)repeatedAllTypesAtIndex:(NSUInteger)index;
 - (TestParsingMergeLiteRepeatedGroup*)repeatedGroupAtIndex:(NSUInteger)index;
 
-+ (TestParsingMergeLite*) defaultInstance;
-- (TestParsingMergeLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) optionalExt;
 + (id<PBExtensionField>) repeatedExt;
@@ -1643,8 +1643,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (TestAllTypesLite*)ext1AtIndex:(NSUInteger)index;
 - (TestAllTypesLite*)ext2AtIndex:(NSUInteger)index;
 
-+ (TestParsingMergeLiteRepeatedFieldsGenerator*) defaultInstance;
-- (TestParsingMergeLiteRepeatedFieldsGenerator*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1669,8 +1669,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasField1;
 @property (readonly, strong) TestAllTypesLite* field1;
 
-+ (TestParsingMergeLiteRepeatedFieldsGeneratorGroup1*) defaultInstance;
-- (TestParsingMergeLiteRepeatedFieldsGeneratorGroup1*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1720,8 +1720,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasField1;
 @property (readonly, strong) TestAllTypesLite* field1;
 
-+ (TestParsingMergeLiteRepeatedFieldsGeneratorGroup2*) defaultInstance;
-- (TestParsingMergeLiteRepeatedFieldsGeneratorGroup2*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1831,8 +1831,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasOptionalGroupAllTypes;
 @property (readonly, strong) TestAllTypesLite* optionalGroupAllTypes;
 
-+ (TestParsingMergeLiteOptionalGroup*) defaultInstance;
-- (TestParsingMergeLiteOptionalGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1882,8 +1882,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 - (BOOL) hasRepeatedGroupAllTypes;
 @property (readonly, strong) TestAllTypesLite* repeatedGroupAllTypes;
 
-+ (TestParsingMergeLiteRepeatedGroup*) defaultInstance;
-- (TestParsingMergeLiteRepeatedGroup*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -1980,8 +1980,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 @private
 }
 
-+ (TestEmptyMessageLite*) defaultInstance;
-- (TestEmptyMessageLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -2020,8 +2020,8 @@ BOOL TestAllTypesLiteNestedEnumIsValidValue(TestAllTypesLiteNestedEnum value);
 @private
 }
 
-+ (TestEmptyMessageWithExtensionsLite*) defaultInstance;
-- (TestEmptyMessageWithExtensionsLite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/runtime/Tests/Unittest_lite.pb.m b/src/runtime/Tests/Unittest_lite.pb.m
index a9147e1..29b51d3 100644
--- a/src/runtime/Tests/Unittest_lite.pb.m
+++ b/src/runtime/Tests/Unittest_lite.pb.m
@@ -1861,10 +1861,10 @@ + (void) initialize {
     defaultTestAllTypesLiteInstance = [[TestAllTypesLite alloc] init];
   }
 }
-+ (TestAllTypesLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesLiteInstance;
 }
-- (TestAllTypesLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesLiteInstance;
 }
 - (PBArray *)repeatedInt32 {
@@ -3354,10 +3354,10 @@ + (void) initialize {
     defaultTestAllTypesLiteNestedMessageInstance = [[TestAllTypesLiteNestedMessage alloc] init];
   }
 }
-+ (TestAllTypesLiteNestedMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesLiteNestedMessageInstance;
 }
-- (TestAllTypesLiteNestedMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesLiteNestedMessageInstance;
 }
 - (BOOL) isInitialized {
@@ -3554,10 +3554,10 @@ + (void) initialize {
     defaultTestAllTypesLiteOptionalGroupInstance = [[TestAllTypesLiteOptionalGroup alloc] init];
   }
 }
-+ (TestAllTypesLiteOptionalGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesLiteOptionalGroupInstance;
 }
-- (TestAllTypesLiteOptionalGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesLiteOptionalGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -3754,10 +3754,10 @@ + (void) initialize {
     defaultTestAllTypesLiteRepeatedGroupInstance = [[TestAllTypesLiteRepeatedGroup alloc] init];
   }
 }
-+ (TestAllTypesLiteRepeatedGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllTypesLiteRepeatedGroupInstance;
 }
-- (TestAllTypesLiteRepeatedGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllTypesLiteRepeatedGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -6220,10 +6220,10 @@ + (void) initialize {
     defaultForeignMessageLiteInstance = [[ForeignMessageLite alloc] init];
   }
 }
-+ (ForeignMessageLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultForeignMessageLiteInstance;
 }
-- (ForeignMessageLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultForeignMessageLiteInstance;
 }
 - (BOOL) isInitialized {
@@ -6453,10 +6453,10 @@ + (void) initialize {
     defaultTestPackedTypesLiteInstance = [[TestPackedTypesLite alloc] init];
   }
 }
-+ (TestPackedTypesLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestPackedTypesLiteInstance;
 }
-- (TestPackedTypesLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestPackedTypesLiteInstance;
 }
 - (PBArray *)packedInt32 {
@@ -7708,10 +7708,10 @@ + (void) initialize {
     defaultTestAllExtensionsLiteInstance = [[TestAllExtensionsLite alloc] init];
   }
 }
-+ (TestAllExtensionsLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestAllExtensionsLiteInstance;
 }
-- (TestAllExtensionsLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestAllExtensionsLiteInstance;
 }
 - (BOOL) isInitialized {
@@ -7886,10 +7886,10 @@ + (void) initialize {
     defaultOptionalGroup_extension_liteInstance = [[OptionalGroup_extension_lite alloc] init];
   }
 }
-+ (OptionalGroup_extension_lite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultOptionalGroup_extension_liteInstance;
 }
-- (OptionalGroup_extension_lite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultOptionalGroup_extension_liteInstance;
 }
 - (BOOL) isInitialized {
@@ -8086,10 +8086,10 @@ + (void) initialize {
     defaultRepeatedGroup_extension_liteInstance = [[RepeatedGroup_extension_lite alloc] init];
   }
 }
-+ (RepeatedGroup_extension_lite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultRepeatedGroup_extension_liteInstance;
 }
-- (RepeatedGroup_extension_lite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultRepeatedGroup_extension_liteInstance;
 }
 - (BOOL) isInitialized {
@@ -8277,10 +8277,10 @@ + (void) initialize {
     defaultTestPackedExtensionsLiteInstance = [[TestPackedExtensionsLite alloc] init];
   }
 }
-+ (TestPackedExtensionsLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestPackedExtensionsLiteInstance;
 }
-- (TestPackedExtensionsLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestPackedExtensionsLiteInstance;
 }
 - (BOOL) isInitialized {
@@ -8449,10 +8449,10 @@ + (void) initialize {
     defaultTestNestedExtensionLiteInstance = [[TestNestedExtensionLite alloc] init];
   }
 }
-+ (TestNestedExtensionLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestNestedExtensionLiteInstance;
 }
-- (TestNestedExtensionLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestNestedExtensionLiteInstance;
 }
 - (BOOL) isInitialized {
@@ -8612,10 +8612,10 @@ + (void) initialize {
     defaultTestDeprecatedLiteInstance = [[TestDeprecatedLite alloc] init];
   }
 }
-+ (TestDeprecatedLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestDeprecatedLiteInstance;
 }
-- (TestDeprecatedLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestDeprecatedLiteInstance;
 }
 - (BOOL) isInitialized {
@@ -8842,10 +8842,10 @@ + (void) initialize {
     defaultTestParsingMergeLiteInstance = [[TestParsingMergeLite alloc] init];
   }
 }
-+ (TestParsingMergeLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteInstance;
 }
-- (TestParsingMergeLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteInstance;
 }
 - (NSArray *)repeatedAllTypes {
@@ -9065,10 +9065,10 @@ + (void) initialize {
     defaultTestParsingMergeLiteRepeatedFieldsGeneratorInstance = [[TestParsingMergeLiteRepeatedFieldsGenerator alloc] init];
   }
 }
-+ (TestParsingMergeLiteRepeatedFieldsGenerator*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedFieldsGeneratorInstance;
 }
-- (TestParsingMergeLiteRepeatedFieldsGenerator*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedFieldsGeneratorInstance;
 }
 - (NSArray *)field1 {
@@ -9318,10 +9318,10 @@ + (void) initialize {
     defaultTestParsingMergeLiteRepeatedFieldsGeneratorGroup1Instance = [[TestParsingMergeLiteRepeatedFieldsGeneratorGroup1 alloc] init];
   }
 }
-+ (TestParsingMergeLiteRepeatedFieldsGeneratorGroup1*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedFieldsGeneratorGroup1Instance;
 }
-- (TestParsingMergeLiteRepeatedFieldsGeneratorGroup1*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedFieldsGeneratorGroup1Instance;
 }
 - (BOOL) isInitialized {
@@ -9540,10 +9540,10 @@ + (void) initialize {
     defaultTestParsingMergeLiteRepeatedFieldsGeneratorGroup2Instance = [[TestParsingMergeLiteRepeatedFieldsGeneratorGroup2 alloc] init];
   }
 }
-+ (TestParsingMergeLiteRepeatedFieldsGeneratorGroup2*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedFieldsGeneratorGroup2Instance;
 }
-- (TestParsingMergeLiteRepeatedFieldsGeneratorGroup2*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedFieldsGeneratorGroup2Instance;
 }
 - (BOOL) isInitialized {
@@ -10064,10 +10064,10 @@ + (void) initialize {
     defaultTestParsingMergeLiteOptionalGroupInstance = [[TestParsingMergeLiteOptionalGroup alloc] init];
   }
 }
-+ (TestParsingMergeLiteOptionalGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteOptionalGroupInstance;
 }
-- (TestParsingMergeLiteOptionalGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteOptionalGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -10286,10 +10286,10 @@ + (void) initialize {
     defaultTestParsingMergeLiteRepeatedGroupInstance = [[TestParsingMergeLiteRepeatedGroup alloc] init];
   }
 }
-+ (TestParsingMergeLiteRepeatedGroup*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedGroupInstance;
 }
-- (TestParsingMergeLiteRepeatedGroup*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestParsingMergeLiteRepeatedGroupInstance;
 }
 - (BOOL) isInitialized {
@@ -10758,10 +10758,10 @@ + (void) initialize {
     defaultTestEmptyMessageLiteInstance = [[TestEmptyMessageLite alloc] init];
   }
 }
-+ (TestEmptyMessageLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestEmptyMessageLiteInstance;
 }
-- (TestEmptyMessageLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestEmptyMessageLiteInstance;
 }
 - (BOOL) isInitialized {
@@ -10912,10 +10912,10 @@ + (void) initialize {
     defaultTestEmptyMessageWithExtensionsLiteInstance = [[TestEmptyMessageWithExtensionsLite alloc] init];
   }
 }
-+ (TestEmptyMessageWithExtensionsLite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestEmptyMessageWithExtensionsLiteInstance;
 }
-- (TestEmptyMessageWithExtensionsLite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestEmptyMessageWithExtensionsLiteInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/runtime/Tests/Unittest_lite_imports_nonlite.pb.h b/src/runtime/Tests/Unittest_lite_imports_nonlite.pb.h
index 1d80409..86d13b5 100644
--- a/src/runtime/Tests/Unittest_lite_imports_nonlite.pb.h
+++ b/src/runtime/Tests/Unittest_lite_imports_nonlite.pb.h
@@ -178,8 +178,8 @@
 - (BOOL) hasMessage;
 @property (readonly, strong) TestAllTypes* message;
 
-+ (TestLiteImportsNonlite*) defaultInstance;
-- (TestLiteImportsNonlite*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/runtime/Tests/Unittest_lite_imports_nonlite.pb.m b/src/runtime/Tests/Unittest_lite_imports_nonlite.pb.m
index b7a8293..c4b4bfe 100644
--- a/src/runtime/Tests/Unittest_lite_imports_nonlite.pb.m
+++ b/src/runtime/Tests/Unittest_lite_imports_nonlite.pb.m
@@ -46,10 +46,10 @@ + (void) initialize {
     defaultTestLiteImportsNonliteInstance = [[TestLiteImportsNonlite alloc] init];
   }
 }
-+ (TestLiteImportsNonlite*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestLiteImportsNonliteInstance;
 }
-- (TestLiteImportsNonlite*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestLiteImportsNonliteInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/runtime/Tests/Unittest_mset.pb.h b/src/runtime/Tests/Unittest_mset.pb.h
index 26e3859..af892e6 100644
--- a/src/runtime/Tests/Unittest_mset.pb.h
+++ b/src/runtime/Tests/Unittest_mset.pb.h
@@ -39,8 +39,8 @@
 @private
 }
 
-+ (TestMessageSet*) defaultInstance;
-- (TestMessageSet*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -83,8 +83,8 @@
 - (BOOL) hasMessageSet;
 @property (readonly, strong) TestMessageSet* messageSet;
 
-+ (TestMessageSetContainer*) defaultInstance;
-- (TestMessageSetContainer*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -134,8 +134,8 @@
 - (BOOL) hasI;
 @property (readonly) SInt32 i;
 
-+ (TestMessageSetExtension1*) defaultInstance;
-- (TestMessageSetExtension1*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) messageSetExtension;
 - (BOOL) isInitialized;
@@ -184,8 +184,8 @@
 - (BOOL) hasStr;
 @property (readonly, strong) NSString* str;
 
-+ (TestMessageSetExtension2*) defaultInstance;
-- (TestMessageSetExtension2*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) messageSetExtension;
 - (BOOL) isInitialized;
@@ -233,8 +233,8 @@
 @property (readonly, strong) NSArray * item;
 - (RawMessageSetItem*)itemAtIndex:(NSUInteger)index;
 
-+ (RawMessageSet*) defaultInstance;
-- (RawMessageSet*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -263,8 +263,8 @@
 @property (readonly) SInt32 typeId;
 @property (readonly, strong) NSData* message;
 
-+ (RawMessageSetItem*) defaultInstance;
-- (RawMessageSetItem*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/runtime/Tests/Unittest_mset.pb.m b/src/runtime/Tests/Unittest_mset.pb.m
index f2607c4..8be5a74 100644
--- a/src/runtime/Tests/Unittest_mset.pb.m
+++ b/src/runtime/Tests/Unittest_mset.pb.m
@@ -58,10 +58,10 @@ + (void) initialize {
     defaultTestMessageSetInstance = [[TestMessageSet alloc] init];
   }
 }
-+ (TestMessageSet*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMessageSetInstance;
 }
-- (TestMessageSet*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMessageSetInstance;
 }
 - (BOOL) isInitialized {
@@ -236,10 +236,10 @@ + (void) initialize {
     defaultTestMessageSetContainerInstance = [[TestMessageSetContainer alloc] init];
   }
 }
-+ (TestMessageSetContainer*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMessageSetContainerInstance;
 }
-- (TestMessageSetContainer*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMessageSetContainerInstance;
 }
 - (BOOL) isInitialized {
@@ -466,10 +466,10 @@ + (void) initialize {
     defaultTestMessageSetExtension1Instance = [[TestMessageSetExtension1 alloc] init];
   }
 }
-+ (TestMessageSetExtension1*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMessageSetExtension1Instance;
 }
-- (TestMessageSetExtension1*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMessageSetExtension1Instance;
 }
 - (BOOL) isInitialized {
@@ -669,10 +669,10 @@ + (void) initialize {
     defaultTestMessageSetExtension2Instance = [[TestMessageSetExtension2 alloc] init];
   }
 }
-+ (TestMessageSetExtension2*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMessageSetExtension2Instance;
 }
-- (TestMessageSetExtension2*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMessageSetExtension2Instance;
 }
 - (BOOL) isInitialized {
@@ -863,10 +863,10 @@ + (void) initialize {
     defaultRawMessageSetInstance = [[RawMessageSet alloc] init];
   }
 }
-+ (RawMessageSet*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultRawMessageSetInstance;
 }
-- (RawMessageSet*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultRawMessageSetInstance;
 }
 - (NSArray *)item {
@@ -1001,10 +1001,10 @@ + (void) initialize {
     defaultRawMessageSetItemInstance = [[RawMessageSetItem alloc] init];
   }
 }
-+ (RawMessageSetItem*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultRawMessageSetItemInstance;
 }
-- (RawMessageSetItem*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultRawMessageSetItemInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/runtime/Tests/Unittest_no_generic_services.pb.h b/src/runtime/Tests/Unittest_no_generic_services.pb.h
index 2acfd20..8250396 100644
--- a/src/runtime/Tests/Unittest_no_generic_services.pb.h
+++ b/src/runtime/Tests/Unittest_no_generic_services.pb.h
@@ -40,8 +40,8 @@ BOOL TestEnumIsValidValue(TestEnum value);
 - (BOOL) hasA;
 @property (readonly) SInt32 a;
 
-+ (TestMessage*) defaultInstance;
-- (TestMessage*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/runtime/Tests/Unittest_no_generic_services.pb.m b/src/runtime/Tests/Unittest_no_generic_services.pb.m
index 858f5c0..dc868e2 100644
--- a/src/runtime/Tests/Unittest_no_generic_services.pb.m
+++ b/src/runtime/Tests/Unittest_no_generic_services.pb.m
@@ -67,10 +67,10 @@ + (void) initialize {
     defaultTestMessageInstance = [[TestMessage alloc] init];
   }
 }
-+ (TestMessage*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestMessageInstance;
 }
-- (TestMessage*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestMessageInstance;
 }
 - (BOOL) isInitialized {
diff --git a/src/runtime/Tests/Unittest_optimize_for.pb.h b/src/runtime/Tests/Unittest_optimize_for.pb.h
index 1c125b8..b2403de 100644
--- a/src/runtime/Tests/Unittest_optimize_for.pb.h
+++ b/src/runtime/Tests/Unittest_optimize_for.pb.h
@@ -194,8 +194,8 @@
 @property (readonly) SInt32 integerField;
 @property (readonly, strong) NSString* stringField;
 
-+ (TestOptimizedForSize*) defaultInstance;
-- (TestOptimizedForSize*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 + (id<PBExtensionField>) testExtension;
 + (id<PBExtensionField>) testExtension2;
@@ -262,8 +262,8 @@
 - (BOOL) hasX;
 @property (readonly) SInt32 x;
 
-+ (TestRequiredOptimizedForSize*) defaultInstance;
-- (TestRequiredOptimizedForSize*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
@@ -311,8 +311,8 @@
 - (BOOL) hasO;
 @property (readonly, strong) TestRequiredOptimizedForSize* o;
 
-+ (TestOptionalOptimizedForSize*) defaultInstance;
-- (TestOptionalOptimizedForSize*) defaultInstance;
++ (instancetype) defaultInstance;
+- (instancetype) defaultInstance;
 
 - (BOOL) isInitialized;
 - (void) writeToCodedOutputStream:(PBCodedOutputStream*) output;
diff --git a/src/runtime/Tests/Unittest_optimize_for.pb.m b/src/runtime/Tests/Unittest_optimize_for.pb.m
index 91c4e09..57cdf24 100644
--- a/src/runtime/Tests/Unittest_optimize_for.pb.m
+++ b/src/runtime/Tests/Unittest_optimize_for.pb.m
@@ -101,10 +101,10 @@ + (void) initialize {
     defaultTestOptimizedForSizeInstance = [[TestOptimizedForSize alloc] init];
   }
 }
-+ (TestOptimizedForSize*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOptimizedForSizeInstance;
 }
-- (TestOptimizedForSize*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOptimizedForSizeInstance;
 }
 - (BOOL) isInitialized {
@@ -449,10 +449,10 @@ + (void) initialize {
     defaultTestRequiredOptimizedForSizeInstance = [[TestRequiredOptimizedForSize alloc] init];
   }
 }
-+ (TestRequiredOptimizedForSize*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestRequiredOptimizedForSizeInstance;
 }
-- (TestRequiredOptimizedForSize*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestRequiredOptimizedForSizeInstance;
 }
 - (BOOL) isInitialized {
@@ -652,10 +652,10 @@ + (void) initialize {
     defaultTestOptionalOptimizedForSizeInstance = [[TestOptionalOptimizedForSize alloc] init];
   }
 }
-+ (TestOptionalOptimizedForSize*) defaultInstance {
++ (instancetype) defaultInstance {
   return defaultTestOptionalOptimizedForSizeInstance;
 }
-- (TestOptionalOptimizedForSize*) defaultInstance {
+- (instancetype) defaultInstance {
   return defaultTestOptionalOptimizedForSizeInstance;
 }
 - (BOOL) isInitialized {