https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114479
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> --- [dcl.array] says that for T[N] the value "N specifies the array bound, i.e., the number of elements in the array; N shall be greater than zero." So T[0] is not a valid array type. And std::is_array<T[0]> has never been true for any traditional implementation based on partial specialization of class templates, only when switching to an intrinsic __is_array that fails to accurately give the same behaviour as the std::is_array trait. Since the purpose of the __is_array intrinsic is to optimize the std::is_array trait, it should have the same behaviour. For the optimization to change the behaviour of the trait seems like the tail wagging the dog.
