In addition to “conditionally supported”?
Interesting. Conditional support applies to features, but I essentially suggested the same semantics for *mis*features. Casual readers would probably be better off with a separate term for it, if we do eventually go the route of “hard” static analysis.
In general, yeah, hard static analysis would turn into a portability mess; the status quo is better. Perhaps the real problem is giving users the ability to increase tolerance on (third-party) library headers while still applying strict rules to their own development.