struct S1 {
  int * __ptrauth(1,1,50) p_;
};
static_assert(!__is_bitwise_cloneable(S1));

This test case fails. I apologise for missing this trait at the time that I filed #137473 and #137474.
The purpose of __is_bitwise_cloneable is not clear, libc++ does not use it, but ptrauth types are surely not bitwise copyable.