On Sat, Apr 23, 2016 at 9:29 AM, Nicholas Nethercote <[email protected]> wrote: > > one thing I've been thinking about is using > MOZ_WARN_UNUSED_RESULT more. > It isn't useful for the "return null on failure" case, because the > result will always be used even if you forget the check. But it is > useful for the "return false on failure" case. I count 113 uses of it > currently in js/src/, the majority of which are for functions > returning bool. I suspect the number could/should be at least 10x > higher than that. > > I would be happy to try to add more uses of it if people think it's > worthwhile.
I've started doing this in bug 1267551. (Taking over from bug 606349, where this idea was first suggested.) Having added quite a few MOZ_MUST_USE annotations now I can't help but wonder if it would be better to have some kind of result type (JSResult?), as an alternative to bool. A bit like nsresult but without the zillion different failure values. With that in place, bool would be used for the return type of functions to indicate true/false or yes/no, and JSResult would be used in fallible functions to indicate success/failure. And then we could use MOZ_MUST_USE_TYPE on JSResult, which would give us assurance (via static analysis) that all functions that return this type are checked, and then we wouldn't need all these MOZ_MUST_USE annotations everywhere. (We might also need a JSResultUnchecked variant, because for some fallible functions not checking the return value is reasonable.) Nick _______________________________________________ dev-tech-js-engine-internals mailing list [email protected] https://lists.mozilla.org/listinfo/dev-tech-js-engine-internals
