On Tue, Jul 24, 2018 at 5:26 AM Jeff King <peff@xxxxxxxx> wrote: > 1. We'll only trigger with -Wimplicit-function-declaration > (and only stop compilation with -Werror). These are > generally enabled by DEVELOPER=1. If you _don't_ have > that set, we'll still catch the problem, but only at > link-time, with a slightly less useful message: > > If instead we convert this to a reference to an > undefined variable, that always dies immediately. But > gcc seems to print the set of errors twice, which > clutters things up. The above does a pretty good job of convincing me that this ought to be implemented via an undefined variable rather than undefined function, exactly because it is the newcomer or casual contributor who is most likely to trip over a banned function, and almost certainly won't have DEVELOPER=1 set. The gcc clutter seems a minor point against the benefit this provides to that audience.