[Bug fortran/101658] New: Bogus message for declaration of polymorphic dummy argument

["longb at cray dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101658

            Bug ID: 101658
           Summary: Bogus message for declaration of polymorphic dummy
                    argument
           Product: gcc
           Version: 10.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: longb at cray dot com
  Target Milestone: ---

For this code:

> cat test2.f90
module test_module
  use, intrinsic:: iso_fortran_env, only: int32
  implicit none

  type, abstract :: hash_base_t
  contains
    procedure, nopass:: hash => dhash
  end type

  type, extends(hash_base_t), public:: hash_t(len)
    integer(kind=int32), len:: len=1
  contains
    procedure:: get_len
    final:: finalise_hash
  end type

contains

  pure elemental integer function dhash(key, start)
    character(len=*), intent(in):: key
    integer(kind=int32), intent(in), optional:: start
    dhash = 1
  end function dhash

  pure integer function get_len(this)
    class(hash_t( * )), intent(in):: this
    get_len = this%len
  end function get_len

  subroutine finalise_hash(this)
    class(hash_t( * )), intent(inout):: this
  end subroutine finalise_hash

end module test_module

gfortran give this set of errors:

> gfortran -c test2.f90
test2.f90:30:31:

   30 |   subroutine finalise_hash(this)
      |                               1
Error: Argument of FINAL procedure at (1) must be of type 'hash_t'
test2.f90:26:22:

   26 |     class(hash_t( * )), intent(in):: this
      |                      1
Error: 'hash_base_t' at (1) is of the ABSTRACT type 'hash_base_t'
test2.f90:26:22:

   26 |     class(hash_t( * )), intent(in):: this
      |                      1
Error: 'hash_base_t' at (1) is of the ABSTRACT type 'hash_base_t'
test2.f90:26:22:

   26 |     class(hash_t( * )), intent(in):: this
      |                      1
Error: 'hash_base_t' at (1) is of the ABSTRACT type 'hash_base_t'

> gfortran --version
GNU Fortran (GCC) 10.3.0 20210408 (Cray Inc.)
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

The type of the argument is hash_t, and not hash_base_t. Maybe getting confused
because hash_t is parameterized??