alexfh added a comment. In http://reviews.llvm.org/D17043#348569, @sidney wrote:
> In http://reviews.llvm.org/D17043#348525, @alexfh wrote: > > > I'd like to note that there is a library-side way to mitigate this issue > > using the `[[clang::warn_unused_result]]` attribute on `vector::empty()` > > and similar methods: > > > Using an attribute sounds much better than this kind of check and I'd be fine > with throwing this patch out completely. IMHO the diagnostic is bad, though. > A message like this: > > > q.cc:17:3: warning: ignoring return value of function declared with > > warn_unused_result attribute [-Wunused-result] > > > v.empty(); > > > ^~~~~~~ > > > > > > …is way too literal. It could indicate two completely different issues: > > 1. `empty()` just tells you whether the container is empty. > 2. `empty()` has side effects and returns a value which should never be > ignored (like recv, send, and scanf). > > Searching for this warning > (https://www.google.com/search?q="Wunused-result";) turns up tons of confusion. > > I'm not an expert on attributes. Is there a way to attach metadata (like a > subtype, or a string description), so that calls without side effects could > have a diagnostic more like the one I wrote, and things like `recv(2)` and > `scanf(3)` could have rich messages? The attribute can have arguments (e.g. `[[deprecated("use some other API")]] void f();`), so if there is a good reason, an argument (e.g. a custom message) can be added to the `warn_unused_result` attribute. Richard might have thoughts on the matter. > I'm going to hold of on addressing any of your other comments until I hear > back. Thanks for the review! http://reviews.llvm.org/D17043 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
