[Bug libstdc++/86537] New: std::less specialization for std::shared_ptr

[d at ilvokhin dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86537

            Bug ID: 86537
           Summary: std::less specialization for std::shared_ptr
           Product: gcc
           Version: 4.8.5
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: d at ilvokhin dot com
  Target Milestone: ---

Created attachment 44401
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44401&action=edit
problem demonstration

There is a specialization for std::less for std::shared_ptr in
bits/shared_ptr.h. I'm not sure it is really should be there. If user defines
operator < for std::shared_ptr<user_type> some inconsistent behaviour may
occurs depending on is operator < uses directly or through std::less. There is
a reference to 20.8.13.2.7 in this header file, but I can't found nothing about
std::less specialization for std::shared_ptr in standart.

I attach a simple example.cpp file, which illustrates problem.
(I use pretty old gcc version, but this behaviour persist in most recent
versions as well)