I would argue that's just "knowledge" not "arcane knowledge". To me arcane knowledge is stuff like the xvalues, prvalues, etc... Where it's both complex and obs

I would argue that's just "knowledge" not "arcane knowledge". To me arcane knowledge is stuff like the xvalues, prvalues, etc... Where it's both complex and obscure. Where you can go down a headache-inducing rabbit hole. This isn't really that, it's pretty simple, and really only does that single thing. It doesn't have complex interactions with anything else: https://en.cppreference.com/w/cpp/language/function#Deleted_functions https://en.cppreference.com/w/cpp/language/function#Deleted_... As a sibling mentioned, it's not even a new syntax as '= 0' has always been there.