https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78737
--- Comment #18 from janus at gcc dot gnu.org ---
(In reply to Paul Thomas from comment #15)
> See this further example, which works with the last version of the patch.
Here is another runtime example, which in contrast to comment #15 does not
utilize any SELECT TYPE workaround:
module object_interface
type :: object
contains
procedure :: write_formatted => write_formatted1
generic :: write(formatted) => write_formatted
end type
type, extends(object) :: child
integer :: i
contains
procedure :: write_formatted => write_formatted2
end type
contains
subroutine write_formatted1(this,unit,iotype,vlist,iostat,iomsg)
class(object), intent(in) :: this
integer, intent(in) :: unit
character (len=*), intent(in) :: iotype
integer, intent(in) :: vlist(:)
integer, intent(out) :: iostat
character (len=*), intent(inout) :: iomsg
print '(a)', "write_formatted1"
end subroutine
subroutine write_formatted2(this,unit,iotype,vlist,iostat,iomsg)
class(child), intent(in) :: this
integer, intent(in) :: unit
character (len=*), intent(in) :: iotype
integer, intent(in) :: vlist(:)
integer, intent(out) :: iostat
character (len=*), intent(inout) :: iomsg
print '(a,i4/)', "write_formatted2 => ", this%i
end subroutine
subroutine assert(a)
class(object):: a
write(*,*) a
end subroutine
end module
use object_interface
call assert (object ())
call assert (child (99))
end
It currently prints (i.e. with Paul's latest patch and probably also with a
clean trunk):
write_formatted1
write_formatted1
I.e. both calls to assert result in the same DTIO procedure, although the type
of the argument differs (and the extended type overrides the DTIO procedure).
In my opinion the output should be:
write_formatted1
write_formatted2 => 99
When looking at the dump of the generated code for the assert routine, one
currently sees:
assert (struct __class_object_interface_Object_t & restrict a)
{
[...]
_gfortran_transfer_derived (&dt_parm.0, (struct
__class_object_interface_Object_t *) a, write_formatted1);
[...]
}
That is, we always call the DTIO procedure of the base type (write_formatted1).
IMHO this is wrong and the second argument of _gfortran_transfer_derived
should rather be "a->_vptr->write_formatted", in order to call the correct DTIO
procedure of the dynamic type.
