[Bug libstdc++/125220] std::priority_queue move constructs twice and move assigns upon emplace

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125220

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2026-05-07
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
This fixes it:

--- a/libstdc++-v3/include/bits/stl_heap.h
+++ b/libstdc++-v3/include/bits/stl_heap.h
@@ -180,6 +180,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       __glibcxx_requires_irreflexive(__first, __last);
       __glibcxx_requires_heap(__first, __last - _DistanceType(1));

+      if ((__last - __first) < 2)
+       return;
+
       __gnu_cxx::__ops::less __comp;
       _ValueType __value = _GLIBCXX_MOVE(*(__last - _DistanceType(1)));
       std::__push_heap(__first, _DistanceType((__last - __first) - 1),
@@ -216,6 +219,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       __glibcxx_requires_irreflexive_pred(__first, __last, __comp);
       __glibcxx_requires_heap_pred(__first, __last - _DistanceType(1),
__comp);

+      if ((__last - __first) < 2)
+       return;
+
       _ValueType __value = _GLIBCXX_MOVE(*(__last - _DistanceType(1)));
       std::__push_heap(__first, _DistanceType((__last - __first) - 1),
                       _DistanceType(0), _GLIBCXX_MOVE(__value), __comp);