[Bug libstdc++/114147] New: tuple allocator-extended constructor requires non-explicit default constructor

["victor.dyachenko at protonmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114147

            Bug ID: 114147
           Summary: tuple allocator-extended constructor requires
                    non-explicit default constructor
           Product: gcc
           Version: 10.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: victor.dyachenko at protonmail dot com
  Target Milestone: ---

GCC 10.1 fails to compile this code (GCC 9.1 is OK):

#include <tuple>
#include <memory>

struct C {
    explicit C() = default;
};

int main()
{
    std::tuple<C, int> t(std::allocator_arg, std::allocator<char>{});
}