You're right. But I've given up "language lawyering" a long time ago: I have a set of "rules of thumb" (like the one I just wrote) that exclude some technically

You're right. But I've given up "language lawyering" a long time ago: I have a set of "rules of thumb" (like the one I just wrote) that exclude some technically valid programs, (but so be it) and that let me write robust code quickly without spending time on digging through the documentation for special cases. Even if I did know every single edge case in the language and library, the developers next to me might not. Then they decide to emulate me (many learn by example) and catastrophe ensues.