[Bug libstdc++/78956] New: std::thread doesn't fully meet LWG 2097 requirement

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78956

            Bug ID: 78956
           Summary: std::thread doesn't fully meet LWG 2097 requirement
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---

#include <thread>
static_assert( !std::is_constructible_v<std::thread, const std::thread> );

This assertion should pass according to LWG 2097. We only get it right for
lvalues and non-const rvalues.

We also need:

  thread(const thread&&) = delete;