Incredible! This was caused when I created a class
template<class T>
class Stack
{
}
in a file called ‘Stack.h’. The mere presence of that file in the game source folder breaks the entire build!
Dear Epic. this is a very unpleasant feature of your engine. I can’t help but notice the lack of namespacing (both logical and physical) and this sort of painful, Saturday-wasting stupidity, could have been avoided. Also, not having a TStack class of your own is a bit of an omission!