Editor won't build if a source file is modified and the unmodified

[anonymous_user_5e9d0e71]

It happened the same to me, the problem was because I was including an external library (boost), and the header file I was using was including windows.h so I fix it including the unreal windows headers

#include "AllowWindowsPlatformTypes.h"

//The external headers and defines goes here

#include "HideWindowsPlatformTypes.h"