[Bug fortran/121425] Invalid derived type constructor using polymorphic variable

[federico.perini at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121425

--- Comment #1 from federico <federico.perini at gmail dot com> ---
This slightly better example shows that the same error also shows up if the
variable is typed, but from an allocatable polymorphic:
https://godbolt.org/z/3j6zKPnK5

```
module types
   use iso_fortran_env, only: rp => real64
   type :: vec
      real(rp) :: xyz(3) = 0
   end type vec
   type :: ax
      type(vec) :: p
      type(vec) :: n
   end type ax

   contains

   subroutine use_class(v)
      class(vec), intent(in) :: v ! no error if `type(vec)`

      class(vec), allocatable :: w
      type(ax) :: aa

      allocate(vec :: w); w%xyz = [1,2,3]

      aa = ax(p=w,n=vec([1,0,0])); call check_a(aa,'with polymorphic variable')
      aa = ax(p=v,n=vec([1,0,0])); call check_a(aa,'with `CLASS(),
intent(in)`')

      contains

      subroutine check_a(aa,msg)
         type(ax), intent(in) :: aa
         character(*), intent(in) :: msg
         if (any(nint(aa%p%xyz)/=[1,2,3])) then 
            print *, 'n=',aa%n%xyz
            print *, 'p=',aa%p%xyz
            error stop 'invalid default constructor '//msg
         endif  
      end subroutine check_a
   end subroutine use_class
end module types

program t
   use types
   type(vec) :: x
   x = vec([1,2,3])
   call use_class(x)
end program t   

```