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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/112349] ranges::max makes unnecessary copies Date: Thu, 02 Nov 2023 18:02:29 +0000 [thread overview] Message-ID: <bug-112349-4-vSaM1ftGMA@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-112349-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112349 Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 Last reconfirmed| |2023-11-02 Status|UNCONFIRMED |NEW --- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to Ted Lyngmo from comment #0) > auto& __tmp = *__first; That won't compile for a move_iterator or a proxy reference. I think auto&& would be OK. But we'd need to restore the value category: auto __result = *__first; while (++__first != __last) { auto&& __tmp = *__first; if (std::__invoke(__comp, std::__invoke(__proj, __result), std::__invoke(__proj, __tmp))) __result = std::forward<decltype(*__first)>(__tmp); } return __result; > ...or just supplying `*__first` to `std::__invoke` it doesn't do copies in > OP's example but it may have other consequences. Worth looking in to anyway. I think that would be OK too. auto __result = *__first; while (++__first != __last) { if (std::__invoke(__comp, std::__invoke(__proj, __result), std::__invoke(__proj, *__first))) __result = *__first; } return __result;
next prev parent reply other threads:[~2023-11-02 18:02 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-11-02 13:31 [Bug c++/112349] New: ranges::max makes unecessary copies ted at lyncon dot se 2023-11-02 18:02 ` redi at gcc dot gnu.org [this message] 2023-11-04 12:05 ` [Bug libstdc++/112349] ranges::max makes unnecessary copies hewillk at gmail dot com
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