[Bug fortran/57217] New: [4.7/4.8/4.9 Regression][OOP] Accepts invalid TBP overriding - lacking arguments check

["burnus at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57217

             Bug #: 57217
           Summary: [4.7/4.8/4.9 Regression][OOP] Accepts invalid TBP
                    overriding - lacking arguments check
    Classification: Unclassified
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Keywords: accepts-invalid
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: burnus@gcc.gnu.org
                CC: janus@gcc.gnu.org, salvatore.filippone@uniroma2.it


Reported by Salvatore; very vaguely related to PR47978.

In the following program, "clone" is overridden. The overridden procedure shall
use for the dummy arguments "CLASS(base_type)" instead of "CLASS(r_type)" as in
the original TBP - except for the PASS argument, which may be different.


GCC 4.6 prints:
    procedure, pass(map)  :: clone    => r_clone
             1
Error: Types mismatch for dummy argument 'mapout' of 'clone' (1) in respect to
the overridden procedure


F2008, "4.5.7.3 Type-bound procedure overriding":
"The overriding and overridden type-bound procedures shall satisfy the
following conditions.
[...] * Dummy arguments that correspond by position shall have the same names
and characteristics, except for the type of the passed-object dummy arguments."


module base_mod
  type base_type
    integer :: kind
  contains
    procedure, pass(map)  :: clone    => base_clone
  end type base_type
contains
  subroutine  base_clone(map,mapout,info)
    implicit none
    class(base_type), intent(inout) :: map
    class(base_type), intent(inout) :: mapout
    integer     :: info
  end subroutine base_clone
end module base_mod

module r_mod
  use base_mod
  type, extends(base_type) :: r_type
    real  :: dat
  contains
    procedure, pass(map)  :: clone    => r_clone
  end type r_type
contains
  subroutine  r_clone(map,mapout,info)
    implicit none
    class(r_type), intent(inout) :: map
    class(r_type), intent(inout) :: mapout
    integer     :: info
  end subroutine r_clone
end module r_mod