[ObjC] Remove the need to tracking MessageSet on extension field descriptors

The flag is still set, but the runtime doesn't need to check it, instead it uses
the bit set on the message. It also streamlines some of the serialization since
we aren't checking the bit at some of the lower levels.

PiperOrigin-RevId: 725208757

objectivec/GPBDescriptor_PackagePrivate.h

@@ -300,10 +300,6 @@ GPB_INLINE BOOL GPBExtensionIsPacked(GPBExtensionDescription *description) {
   return (description->options & GPBExtensionPacked) != 0;
 }
 
-GPB_INLINE BOOL GPBExtensionIsWireFormat(GPBExtensionDescription *description) {
-  return (description->options & GPBExtensionSetWireFormat) != 0;
-}
-
 // Helper for compile time assets.
 #ifndef GPBInternalCompileAssert
 #define GPBInternalCompileAssert(test, msg) _Static_assert((test), #msg)

objectivec/GPBExtensionInternals.m

@@ -97,12 +97,7 @@ static size_t ComputeSerializedSizeIncludingTagOfObject(GPBExtensionDescription
     FIELD_CASE2(Bytes)
     FIELD_CASE2(String)
     FIELD_CASE2(Group)
-    case GPBDataTypeMessage:
-      if (GPBExtensionIsWireFormat(description)) {
-        return GPBComputeMessageSetExtensionSize(description->fieldNumber, object);
-      } else {
-        return GPBComputeMessageSize(description->fieldNumber, object);
-      }
+    FIELD_CASE2(Message)
   }
 #undef FIELD_CASE
 #undef FIELD_CASE2
@@ -160,13 +155,7 @@ static void WriteObjectIncludingTagToCodedOutputStream(id object,
     FIELD_CASE2(Bytes)
     FIELD_CASE2(String)
     FIELD_CASE2(Group)
-    case GPBDataTypeMessage:
-      if (GPBExtensionIsWireFormat(description)) {
-        [output writeMessageSetExtension:description->fieldNumber value:object];
-      } else {
-        [output writeMessage:description->fieldNumber value:object];
-      }
-      return;
+    FIELD_CASE2(Message)
   }
 #undef FIELD_CASE
 #undef FIELD_CASE2

objectivec/GPBMessage.m

@@ -894,38 +894,30 @@ static void DecodeSingleValueFromInputStream(GPBExtensionDescriptor *extension,
         nsValue = [[NSNumber alloc] initWithInt:val];
       } else {
         AddUnknownFieldVarint32(messageToGetExtension, extension->description_->fieldNumber, val);
-        nsValue = nil;
+        return;
       }
       break;
     }
-    case GPBDataTypeGroup:
+    case GPBDataTypeGroup: {
+      [input readGroup:description->fieldNumber
+                    message:targetMessage
+          extensionRegistry:extensionRegistry];
+      // Nothing to add below since the caller provided the message (and added it).
+      return;
+    }
     case GPBDataTypeMessage: {
-      if (description->dataType == GPBDataTypeGroup) {
-        [input readGroup:description->fieldNumber
-                      message:targetMessage
-            extensionRegistry:extensionRegistry];
-      } else {
-// description->dataType == GPBDataTypeMessage
-#if defined(DEBUG) && DEBUG && !defined(NS_BLOCK_ASSERTIONS)
-        NSCAssert(!GPBExtensionIsWireFormat(description),
-                  @"Internal error: got a MessageSet extension when not expected.");
-#endif
-        [input readMessage:targetMessage extensionRegistry:extensionRegistry];
-      }
+      [input readMessage:targetMessage extensionRegistry:extensionRegistry];
       // Nothing to add below since the caller provided the message (and added it).
-      nsValue = nil;
-      break;
+      return;
     }
   }  // switch
 
-  if (nsValue) {
-    if (isRepeated) {
-      [messageToGetExtension addExtension:extension value:nsValue];
-    } else {
-      [messageToGetExtension setExtension:extension value:nsValue];
-    }
-    [nsValue release];
+  if (isRepeated) {
+    [messageToGetExtension addExtension:extension value:nsValue];
+  } else {
+    [messageToGetExtension setExtension:extension value:nsValue];
   }
+  [nsValue release];
 }
 
 static void ExtensionMergeFromInputStream(GPBExtensionDescriptor *extension, BOOL isPackedOnStream,
@@ -1576,24 +1568,41 @@ void GPBClearMessageAutocreator(GPBMessage *self) {
 
 - (void)writeToCodedOutputStream:(GPBCodedOutputStream *)output {
   GPBDescriptor *descriptor = [self descriptor];
+  BOOL isMessageSetWireFormat = descriptor.isWireFormat;
   NSArray *fieldsArray = descriptor->fields_;
   NSUInteger fieldCount = fieldsArray.count;
-  const GPBExtensionRange *extensionRanges = descriptor.extensionRanges;
-  NSUInteger extensionRangesCount = descriptor.extensionRangesCount;
   NSArray *sortedExtensions =
       [[extensionMap_ allKeys] sortedArrayUsingSelector:@selector(compareByFieldNumber:)];
-  for (NSUInteger i = 0, j = 0; i < fieldCount || j < extensionRangesCount;) {
-    if (i == fieldCount) {
-      [self writeExtensionsToCodedOutputStream:output
-                                         range:extensionRanges[j++]
-                              sortedExtensions:sortedExtensions];
-    } else if (j == extensionRangesCount ||
-               GPBFieldNumber(fieldsArray[i]) < extensionRanges[j].start) {
-      [self writeField:fieldsArray[i++] toCodedOutputStream:output];
-    } else {
-      [self writeExtensionsToCodedOutputStream:output
-                                         range:extensionRanges[j++]
-                              sortedExtensions:sortedExtensions];
+  if (isMessageSetWireFormat) {
+#if defined(DEBUG) && DEBUG && !defined(NS_BLOCK_ASSERTIONS)
+    NSAssert(fieldCount == 0, @"MessageSet wire format messages must have no fields.");
+#endif
+    for (GPBExtensionDescriptor *extension in sortedExtensions) {
+#if defined(DEBUG) && DEBUG && !defined(NS_BLOCK_ASSERTIONS)
+      NSAssert(extension.dataType == GPBDataTypeMessage,
+               @"Internal Error: MessageSet extension must be a message field.");
+      NSAssert(!GPBExtensionIsRepeated(extension->description_),
+               @"Internal Error: MessageSet extension can't be repeated.");
+#endif
+      id value = [extensionMap_ objectForKey:extension];
+      [output writeMessageSetExtension:(int32_t)extension.fieldNumber value:value];
+    }
+  } else {
+    const GPBExtensionRange *extensionRanges = descriptor.extensionRanges;
+    NSUInteger extensionRangesCount = descriptor.extensionRangesCount;
+    for (NSUInteger i = 0, j = 0; i < fieldCount || j < extensionRangesCount;) {
+      if (i == fieldCount) {
+        [self writeExtensionsToCodedOutputStream:output
+                                           range:extensionRanges[j++]
+                                sortedExtensions:sortedExtensions];
+      } else if (j == extensionRangesCount ||
+                 GPBFieldNumber(fieldsArray[i]) < extensionRanges[j].start) {
+        [self writeField:fieldsArray[i++] toCodedOutputStream:output];
+      } else {
+        [self writeExtensionsToCodedOutputStream:output
+                                           range:extensionRanges[j++]
+                                sortedExtensions:sortedExtensions];
+      }
     }
   }
   if (unknownFieldData_) {
@@ -2359,8 +2368,6 @@ void GPBClearMessageAutocreator(GPBMessage *self) {
 #if defined(DEBUG) && DEBUG && !defined(NS_BLOCK_ASSERTIONS)
     NSAssert(extension.dataType == GPBDataTypeMessage,
              @"Internal Error: MessageSet extension must be a message field.");
-    NSAssert(GPBExtensionIsWireFormat(extension->description_),
-             @"Internal Error: MessageSet extension must have message_set_wire_format set.");
     NSAssert(!GPBExtensionIsRepeated(extension->description_),
              @"Internal Error: MessageSet extension can't be repeated.");
 #endif
@@ -3280,9 +3287,22 @@ static void MergeRepeatedNotPackedFieldFromCodedInputStream(
   result += [unknownFieldData_ length];
 
   // Add any extensions.
-  for (GPBExtensionDescriptor *extension in extensionMap_) {
-    id value = [extensionMap_ objectForKey:extension];
-    result += GPBComputeExtensionSerializedSizeIncludingTag(extension, value);
+  if (descriptor.isWireFormat) {
+    for (GPBExtensionDescriptor *extension in extensionMap_) {
+#if defined(DEBUG) && DEBUG && !defined(NS_BLOCK_ASSERTIONS)
+      NSAssert(extension.dataType == GPBDataTypeMessage,
+               @"Internal Error: MessageSet extension must be a message field.");
+      NSAssert(!GPBExtensionIsRepeated(extension->description_),
+               @"Internal Error: MessageSet extension can't be repeated.");
+#endif
+      id value = [extensionMap_ objectForKey:extension];
+      result += GPBComputeMessageSetExtensionSize((int32_t)extension.fieldNumber, value);
+    }
+  } else {
+    for (GPBExtensionDescriptor *extension in extensionMap_) {
+      id value = [extensionMap_ objectForKey:extension];
+      result += GPBComputeExtensionSerializedSizeIncludingTag(extension, value);
+    }
   }
 
   return result;