[Bug libstdc++/118087] New: std::deque::emplace does not do uses-allocator construction

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118087

            Bug ID: 118087
           Summary: std::deque::emplace does not do uses-allocator
                    construction
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---

#include <deque>
#include <scoped_allocator>
#include <cassert>

template<typename T>
struct Alloc
{
  Alloc(int i) : id(i) { }
  template<typename U>
    Alloc(const Alloc<U>& a) : id(a.id) { }

  using value_type = T;
  using propagate_on_container_copy_assignment = std::true_type;
  using propagate_on_container_move_assignment = std::true_type;
  using propagate_on_container_swap = std::true_type;

  using Base = std::allocator<T>;

  T* allocate(std::size_t n) { return Base().allocate(n); }
  void deallocate(T* p, std::size_t n) { return Base().deallocate(p, n); }

  int id;

  bool operator==(const Alloc& a) const { return id == a.id; }
  bool operator!=(const Alloc& a) const { return id != a.id; }
};

struct X
{
  using allocator_type = Alloc<int>;
  X() { }
  X(const X&) { }
  X(X&&) { }
  X(const allocator_type& a) : alloc(a) { }
  X(const X&, const allocator_type& a) : alloc(a) { }
  X(X&&, const allocator_type& a) : alloc(a) { }

  X& operator=(const X&) = default;

  allocator_type alloc{-1};
};

int main()
{
  std::deque<X, std::scoped_allocator_adaptor<Alloc<X>>> d(2, Alloc<X>(50));
  d.emplace(d.begin() + 1);
  assert( d[1].alloc.id == 50 );
}


d: d.cc:47: int main(): Assertion `d[1].alloc.id == 50' failed.