[flang] Failed at runtime when handling user-defined `v_list` with `DT` edit descriptor.

[DanielCChen]

Consider the following code:

module m
   type base
      integer :: i
   end type

   interface write(formatted)
      subroutine writeformatted(dtv, unit, iotype, v_list, iostat, iomsg )
         import base
         class(base), intent(in) :: dtv
         integer,  intent(in) :: unit
         character(*), intent(in) :: iotype
         integer, intent(in)     :: v_list(:)
         integer,  intent(out) :: iostat
         character(*),  intent(inout) :: iomsg
      end subroutine
   end interface

end module

program fdtedit105kl
use m

   type(base) :: b1 = base(100)
   type(base) :: b2 = base(200)

   integer :: stat
   character(150) :: msg = 'original'
   open (1, file = 'fdtedit105kl.1', form='formatted', access='sequential' )

10 format (DT'write'(-1,+2,3,-4,+5,6))

   write ( 1, 10, iostat = stat, iomsg = msg )   b1
print*, stat
print*, msg
   if ( stat /= 0 ) ERROR STOP 1

   close ( 1, status='delete' )

end program

subroutine writeformatted (dtv, unit, iotype, v_list, iostat, iomsg)
use m, only: base

   class(base), intent(in) :: dtv
   integer, intent(in) :: unit
   character(*), intent(in) :: iotype
   integer, intent(in)     :: v_list(:)
   integer, intent(out) :: iostat
   character(*), intent(inout) :: iomsg

   write ( unit, "(I4)", iostat = iostat ) dtv%i

end subroutine

Flang failed at the runtime as:

> a.out
 1005
 Excessive DT(v_list) in FORMAT; at offset 1 in format '(dt'write'(1,+2,3,-4,+5
 ,6))'
Fortran ERROR STOP: code 1

The test case is testing if the v_list that the main program defined via the DT edit descriptor gets passed to the DTIO procedure correctly.

[llvmbot]

@llvm/issue-subscribers-flang-runtime

Author: Daniel Chen (DanielCChen)

Consider the following code: ``` module m type base integer :: i end type

interface write(formatted)
subroutine writeformatted(dtv, unit, iotype, v_list, iostat, iomsg )
import base
class(base), intent(in) :: dtv
integer, intent(in) :: unit
character(), intent(in) :: iotype
integer, intent(in) :: v_list(:)
integer, intent(out) :: iostat
character(), intent(inout) :: iomsg
end subroutine
end interface

end module

program fdtedit105kl
use m

type(base) :: b1 = base(100)
type(base) :: b2 = base(200)

integer :: stat
character(150) :: msg = 'original'
open (1, file = 'fdtedit105kl.1', form='formatted', access='sequential' )

10 format (DT'write'(-1,+2,3,-4,+5,6))

write ( 1, 10, iostat = stat, iomsg = msg ) b1
print*, stat
print*, msg
if ( stat /= 0 ) ERROR STOP 1

close ( 1, status='delete' )

end program

subroutine writeformatted (dtv, unit, iotype, v_list, iostat, iomsg)
use m, only: base

class(base), intent(in) :: dtv
integer, intent(in) :: unit
character(), intent(in) :: iotype
integer, intent(in) :: v_list(:)
integer, intent(out) :: iostat
character(), intent(inout) :: iomsg

write ( unit, "(I4)", iostat = iostat ) dtv%i

end subroutine

Flang failed at the runtime as:

> a.out
1005
Excessive DT(v_list) in FORMAT; at offset 1 in format '(dt'write'(1,+2,3,-4,+5
,6))'
Fortran ERROR STOP: code 1

The test case is testing if the `v_list` that the main program defined via the `DT` edit descriptor gets passed to the DTIO procedure correctly.
</details>

[akuhlens]

This is bad error message, but what it is trying to say is that there is a maximum of four v_list elements allowed currently. We should be able to extend this limit as long as it doesn't cause undue overhead.

[DanielCChen]

This is bad error message, but what it is trying to say is that there is a maximum of four v_list elements allowed currently. We should be able to extend this limit as long as it doesn't cause undue overhead.

I see. I can change this to a feature if that is more appropriate?
XLF goes by the supported array size as it is an assumed-shape array dummy argument.