Strange build error: "MacPlatformCompilerSetup.h(15): [C2065] '__clang_major__': undeclared identifier"

I’ve been adding a lot of code to an actor. Finally finished adding a big section and hit build… it gives me

  MacPlatformCompilerSetup.h(15): [C2065] '__clang_major__': undeclared identifier
  MacPlatformCompilerSetup.h(15): [C2065] '__clang_major__': undeclared identifier
  MacPlatformCompilerSetup.h(15): [C2065] '__clang_minor__': undeclared identifier
  MacSystemIncludes.h(11): [C1083] Cannot open include file: 'Carbon/Carbon.h': No such file or directory
  Microsoft.MakeFile.targets(44, 5): [MSB3075] The command ""C:\Program Files\Epic Games\UE_4.23\Engine\Build\BatchFiles\Build.bat" DemoEditor Win64 Development -Project="C:\Users\Administrator\Documents\Unreal Projects\Demo\Demo.uproject" -WaitMutex -FromMsBuild" exited with code 5. Please verify that you have sufficient rights to run this command.

No idea what this means or why it’s suddenly coming up. I even commented out all the code I added and the error still happens. This is completely blocking me from doing anything - anything I can try here? I must have accidentally changed something but I have no idea what. The code was building just fine before I added more stuff. Does the error give any hints as to what to look for?

Probably important to note I’m on a Windows machine and the config is set to Development Editor | Win64

Nevermind, somehow
#include “Mac/MacSystemIncludes.h”
got added to my includes.

Thank you very much for posting the solution. I was extremely confused and your answer helped fix the problem instantly!