Takeaways. Try to use "friend" on functions/operators that are frequently overloaded EXCEPT if they are in a templated type that is frequently instantiated. So do not put friends in TMap, TSet, TObjectPtr etc, this will slow down compile times. There is a break-even somewhere and hard to tell where it is but taking a class that is templatized on character type probably don't matter either way and then it is nicer to use a friend since that simplies error messages when compiler can't resolve functions/operators.
If it is possible to use member functions instead of friend that is the best option in terms of compile time performance. With c++20 you only have to write operator==(Foo, Bar) and the compiler will automatically provide operator==(Bar, Foo), operator!=(Foo, Bar) and operator!=(Bar, Foo).
Changes in this changelist involes
* Making operator<< friends in non-template types and not friends in template types
* Making operator==/!= members where possible and if not possible moved out if type is a frequently instantiated templated type.
#preflight 636970f5376a9cd6a80da54a
#rb steve.robb
[CL 23038965 by henrik karlsson in ue5-main branch]
