[makecheck]

I sort of want a file-by-file language upgrade like Objective-C seems to have. For instance, if you add something like “nullable” to an Objective-C header, then the compiler will require similar directives throughout the file; otherwise, it doesn’t.

C++ needs a new strict set of rules that (ideally for individual files, to start) prohibits some set of older/deprecated features from even compiling. That way, you know where the language is going and you adapt.