[Gretl-devel] bug which is new in 1.7.4

[Riccardo (Jack) Lucchetti]

On Thu, 3 Apr 2008, Riccardo (Jack) Lucchetti wrote:

> Somehow, the problem lies with the fact that the return type is a list. If 
> you modify the big file as per:
>
> --- permaconfbackend.inp        2008-04-03 16:21:27.000000000 +0200
> +++ permaconfbackend_2.inp      2008-04-03 16:23:35.000000000 +0200
> @@ -725,5 +725,7 @@
>     list results = results GGlownaive GGupnaive SWPlownaive SWPupnaive
>     list results = results GGlowHall GGupHall SWPlowHall SWPupHall
>   end if
> -  return list results
> +
> +  matrix ret = { results }
> +  return matrix ret
> end function
>
> and modify kpsw_testfrontend.inp accordingly, it runs fine.

More details: gretl gets stuck while trying to delete all the temporary 
variables created inside the function. It looks like we run into an 
infinite loop in this section of lib/src/gretl_func.c (line numbers added 
for clarity):

3536:	    for (i=orig_v; i<pdinfo->v; i++) {
3537:		fprintf(stderr, "i = %d\n", i);
3538:		if (STACK_LEVEL(pdinfo, i) == d) {
3539:		    anyerr = dataset_drop_variable(i--, pZ, pdinfo);
3540:		    if (anyerr && !err) {
3541:			err = anyerr;
3542:		    }
3543:		}
3544:	    }

The "i--" operation smells bad, but I'm not familiar enough with this 
region of the source to pin down what's wrong with it.


Riccardo (Jack) Lucchetti
Dipartimento di Economia
Università Politecnica delle Marche

r.lucchetti at univpm.it
http://www.econ.univpm.it/lucchetti