[Bug libstdc++/104561] New: std::ranges::sort, std::ranges::stable_sort and std::ranges::partial_sort do not support proxy references

[Bug libstdc++/104561] New: std::ranges::sort, std::ranges::stable_sort and std::ranges::partial_sort do not support proxy references

[Berenger.Berthoul at onera dot fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104561

            Bug ID: 104561
           Summary: std::ranges::sort, std::ranges::stable_sort and
                    std::ranges::partial_sort do not support proxy
                    references
           Product: gcc
           Version: og11 (devel/omp/gcc-11)
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Berenger.Berthoul at onera dot fr
  Target Milestone: ---

std::ranges::sort, std::ranges::stable_sort and std::ranges::partial_sort are
implemented by calls to the old std::sort, std::stable_sort and
std::partial_sort

This is wrong because the non-range algorithms assume that the reference type
of the iterator is a true C++ reference, so it does not work with proxy
references.

I have some code with a proxy reference type that (I think) demonstrates the
problem. However it would be non-trivial to extract in a complete compilable
example... I can do it if necessary, but I don't think this is needed, I am
sure libstdc++ devs know the problem since most other std::ranges:: algorithms
were implemented without the use of the non-range equivalent. (As a side-note,
using std::ranges::partition, it is pretty easy to come up with a quicksort
that works with proxy references)

So my guess would be that the developpers know the problem but did not have
time to implement a correct std::ranges::sort (and the like). But I was unable
to find anything (bug report, standard conformance limitation...). The page
https://en.cppreference.com/w/cpp/compiler_support says that C++20 ranges are
completely implemented since GCC 10.

I am understanding things correcly here?

[Bug libstdc++/104561] std::ranges::sort, std::ranges::stable_sort and std::ranges::partial_sort do not support proxy references

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104561

康桓瑋 <hewillk at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hewillk at gmail dot com

--- Comment #1 from 康桓瑋 <hewillk at gmail dot com> ---
Dup of PR100795

[Bug libstdc++/104561] std::ranges::sort, std::ranges::stable_sort and std::ranges::partial_sort do not support proxy references

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104561

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

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

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Dup of bug 100795.

*** This bug has been marked as a duplicate of bug 100795 ***