Re: [patch, libgfortran] Fix PR27304 Data descriptors exhausted

[Jerry DeLisle <jvdelisle at verizon dot net>]

Jerry DeLisle wrote:
> Brooks Moses wrote:
>
> > Brooks Moses wrote:
> >
> > > Thus, I'm a bit baffled: is it possible for this error to occur 
> > > except in the case (from your test program) where there are no data 
> > > descriptors in the format at all?  If not, perhaps an error message 
> > > of "No data descriptors found in format" would be better.
> >
> >
> >
> > And, of course, just as I hit send, I thought of a better wording (I 
> > think): "Format for nonempty I/O list contains no data descriptors"
> >
> > - Brooks
> The error occurs if there has been a reversion and no descriptors 
> available. There is a data descriptor available in the following example 
> so the above message just doesn't quite fit.
>
>       program test
>       implicit none
>       integer :: n
>       n = 1
>       write(*,"(i7,(' abcd'))") n, n
>       end program test
>
>
> So I would like to propose the error say:
>
> At line 5 of file fmt_exhaust.f90
> Fortran runtime error: Missing data descriptor in format after reversion
>
> I will amend the patch accordingly unless anyone has grief with this.  I 
> just wanted to come up with something brief and to the point.
>
> Is this OK to commit?
>
> Regarding a test case.  See my thread on "Testing for run-time errors"

Attached is a revised patch and a testcase that just verifies that we do throw a 
runtime error.

Hope this is final.  OK for trunk and 4.1 a bit later?  (I also fixed the typo 
in the ChangeLog entry)  If I hear nothing I will commit this weekend.

Jerry




Index: io/transfer.c
===================================================================
*** io/transfer.c	(revision 113213)
--- io/transfer.c	(working copy)
*************** formatted_transfer_scalar (st_parameter_
*** 670,676 ****
  
        f = next_format (dtp);
        if (f == NULL)
! 	return;	      /* No data descriptors left (already raised).  */
  
        /* Now discharge T, TR and X movements to the right.  This is delayed
  	 until a data producing format to suppress trailing spaces.  */
--- 670,682 ----
  
        f = next_format (dtp);
        if (f == NULL)
! 	{
! 	  /* No data descriptors left.  */
! 	  if (n > 0)
! 	    generate_error (&dtp->common, ERROR_FORMAT,
! 		"Missing data descriptor in format after reversion");
! 	  return;
! 	}
  
        /* Now discharge T, TR and X movements to the right.  This is delayed
  	 until a data producing format to suppress trailing spaces.  */

Attachment: fmt_exhaust.f90
Description: application/extension-f90