This in theory reduce some kind of bugs, when one forget to mark
method as virtual.
It doesn't reduce bugs, it introduces noticeable bugs and
slightly lowers performance. All at the benefit of not having to
write' virtual'.
/pedantic
As for the actual DIP, I don't like final(false). It's simply far
too verbose, and a double negative (not not overridable), same
for @nogc(false). I slightly prefer !final (though it's again a
double negative, but at least it's more consistent with bools and
not function invocation), but even then it's not a nice solution.
Only decent one I can think of though, short of adding virtual.
