Zach - looks like you're right, GCC seems to allow the second syntax only on function forward declarations, not definitions.
On Mon, Jan 9, 2017 at 10:11 AM, Zachary Amsden <[email protected]> wrote: > Maybe I'm just being dense but I couldn't get it to work with syntax 2 on a > function definition without having a separate forward declaration: > > https://godbolt.org/g/ODtoQC vs. https://godbolt.org/g/WCxDZv > (non-functional) > > - Zach > > On Mon, Jan 9, 2017 at 10:00 AM, Jim Apple <[email protected]> wrote: > > > That's applying it to the type definition. At the type use: > > > > https://godbolt.org/g/RMYVW7 > > > > On Mon, Jan 9, 2017 at 9:56 AM, Zachary Amsden <[email protected]> > > wrote: > > > GCC doesn't catch this when optimization is enabled and the result is > > > discarded: > > > > > > https://godbolt.org/g/4b0BQC > > > > > > I think that means a type wrapper approach is needed, which probably > > > necessitates option 1. > > > > > > - Zach > > > > > > On Mon, Jan 9, 2017 at 9:17 AM, Jim Apple <[email protected]> > wrote: > > > > > >> My vote, as I mentioned on the patch, is option 1. I see MUST_USE(T) > > >> as a property of T, like const T or volatile T. I think it is dual to > > >> move semantics or to Rust's ability to temporarily or permanently > > >> consume values so that /only/ one copy is in use rather than > > >> MUST_USE's /at least one/. > > >> > > >> https://en.wikipedia.org/wiki/Substructural_type_system > > >> > > >> On Fri, Jan 6, 2017 at 4:05 PM, Taras Bobrovytsky > > >> <[email protected]> wrote: > > >> > I'd vote for #2. I think it's better to have less important > > information > > >> > (such as qualifiers) towards the end of lines. (I think it would be > > nice > > >> if > > >> > modifiers such as public and private were at the end of method > > >> declarations > > >> > in Java, for example: void myMethod() private static {...}) > > >> > > > >> > On Fri, Jan 6, 2017 at 3:38 PM, Daniel Hecht <[email protected]> > > >> wrote: > > >> > > > >> >> As I indicated in the original review, my preference is #2 but I > > don't > > >> feel > > >> >> too strongly. > > >> >> > > >> >> On Fri, Jan 6, 2017 at 2:59 PM, Tim Armstrong < > > [email protected]> > > >> >> wrote: > > >> >> > > >> >> > Hi All, > > >> >> > I wanted to poll the Impala community for opinions about style > > for > > >> >> > declaring functions where the caller is expected to do something > > with > > >> the > > >> >> > return value. > > >> >> > > > >> >> > Ideally we'd be able to declare Status with an attribute that > made > > >> this > > >> >> > take effect globally, but unfortunately that's not available > until > > >> C++17. > > >> >> > > > >> >> > So we need to annotate each Status-returning function. The two > > >> >> alternatives > > >> >> > we discussed on this CR (https://gerrit.cloudera.org/#/c/4878/) > > were: > > >> >> > > > >> >> > #1 - a special macro wrapping Status > > >> >> > > > >> >> > MUST_USE(Status) DoSomethingThatCanFail(int64_t foo, Bar* bar); > > >> >> > > > >> >> > Pros: > > >> >> > * Closely connected to the return type that it affects > > >> >> > * It's easier to search/replace Status with MUST_USE(Status) > > >> >> > > > >> >> > Cons: > > >> >> > * Could get visually noisy if we use it everywhere > > >> >> > > > >> >> > #2 - a macro that gets appended to the declaration: > > >> >> > > > >> >> > Status DoSomethingThatCanFail(int64_t foo, Bar* bar) > > >> WARN_UNUSED_RESULT; > > >> >> > > > >> >> > Pros: > > >> >> > * Macro is slightly > > >> >> > * Less visually noisy since it's at the end of the declaration > > >> >> > > > >> >> > What do people think? > > >> >> > > > >> >> > > >> > > >
