https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108556
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() >= j.getHeight(); }); The bug is here. For a strict weak ordering cmp(x, x) must be false, because an object must no be ordered before/after itself. Your lambda fails that requirement, because it returns true when called with equivalent values.