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From: "hewillk at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/100287] New: Using iterator after std::move in
 ranges::partition
Date: Tue, 27 Apr 2021 10:18:17 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100287

            Bug ID: 100287
           Summary: Using iterator after std::move in ranges::partition
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

Hi, in ranges::partition in ranges_algo.h#L2540:

  if (__first =3D=3D __last)
    return {std::move(__first), std::move(__first)};

  while (std::__invoke(__pred, std::__invoke(__proj, *__first)))
    if (++__first =3D=3D __last)
      return {std::move(__first), std::move(__first)};

The above two return statements std::move on __first twice. If the previous=
 one
changes the original state of the __first, it may cause a problem.=