[Bug libstdc++/71301] New: std::tuple move constructor

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71301

            Bug ID: 71301
           Summary: std::tuple move constructor
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Keywords: ABI
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: glisse at gcc dot gnu.org
  Target Milestone: ---

#include <tuple>
#include <type_traits>
struct A { A(A&&)=delete; };
static_assert(std::is_trivially_move_constructible<std::tuple<int>>::value);
static_assert(!std::is_move_constructible<std::tuple<A>>::value);

Both assertions fail, the move constructor should be better constrained, and
trivial when it can be. But that breaks the ABI.

Discussion (in 3 parts in the archives):
https://gcc.gnu.org/ml/libstdc++/2016-04/msg00039.html
https://gcc.gnu.org/ml/libstdc++/2016-05/msg00007.html
https://gcc.gnu.org/ml/libstdc++/2016-05/msg00050.html