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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++/108556] std::sort changes objects' member values
Date: Thu, 26 Jan 2023 10:23:01 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108556

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
  std::sort(items.begin(), items.end(), [](const Item &i, const Item &j) {
    return i.getHeight() >=3D j.getHeight();
  });

The bug is here. For a strict weak ordering cmp(x, x) must be false, becaus=
e an
object must no be ordered before/after itself. Your lambda fails that
requirement, because it returns true when called with equivalent values.=