@robinm @Conan_Kudo @pinskia @scherzog @lina C++ has some really deep ends that you'll only be able to resolve by looking at the standard. I think the most obscure one I helped answer was a guy trying to disable a copy constructor but allow construction via an implicit cast operator on the same type--or something...weird thing to do, but why wasn't the compiler allowing it?? It's this weird rule in the standard language that tosses every other possible resolution BUT copy out of even lookup.