[cfe-commits] [PATCH] Implicit fall-through between switch labels

[Matthieu Monrocq]

Le 21 avril 2012 18:17, Jordy Rose <jediknil at belkadan.com> a écrit :

> I feel like the common case here is not actually fall-through but a
> missing break, though like David said there are many other ways to exit a
> switch. I would expect something like this instead:
>
> warning: fall-through to subsequent switch case
> note: use 'break' to prevent fall-through
>  [fixit]
> note: use 'fallthrough' attribute to silence this warning
>  [fixit]
>
> If we really want to go crazy, we could look and see if 'return' is more
> appropriate than 'break', but I think probably these would cover the common
> cases.
>
> Also, the attribute fixit would have to only use square-bracket syntax if
> it's supported, and possibly disabled altogether if the current language
> options don't support attributes at all, i.e. non-GNU. (The warning could
> still be disabled with pragmas, after all.)
>
> Jordy
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>

Two remarks:

> if there is no statement between two cases, then fallthrough is most
probable
> otherwise it is not possible to actually distinguish between a possible
fallthrough or break

I don't think that providing a fixit is reasonable, because fixit should be
provided only when they are right, taking chances is risking miscompilation.

-- Matthieu
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