[Bug fortran/77505] Negative character length not treated as LEN=0

[elizebethp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77505

--- Comment #9 from Elizebeth Punnoose <elizebethp at gmail dot com> ---
(In reply to Janne Blomqvist from comment #8)
> (In reply to Elizebeth Punnoose from comment #6)
> > Modified code with the warning message moved behind -fcheck=bounds.
> > 
> > Index: trans-array.c
> > ===================================================================
> > --- trans-array.c	(revision 241960)
> > +++ trans-array.c	(working copy)
> > @@ -2226,6 +2226,8 @@
> >    gfc_ss_info *ss_info;
> >    gfc_expr *expr;
> >    gfc_ss *s;
> > +  tree neg_len;
> > +  char *msg;
> >  
> >    /* Save the old values for nested checking.  */
> >    old_first_len = first_len;
> > @@ -2271,6 +2273,27 @@
> >  	  gfc_conv_expr_type (&length_se, expr->ts.u.cl->length,
> >  			      gfc_charlen_type_node);
> >  	  ss_info->string_length = length_se.expr;
> > +
> > +	  /* Check if the character length is negative, 
> > +	     if so consider it as LEN=0. */
> > +	  neg_len = fold_build2_loc (input_location, LT_EXPR,
> > +		    boolean_type_node, ss_info->string_length,
> > +		    build_int_cst (gfc_charlen_type_node, 0));
> > +	  /* Print a warning if bounds checking is enabled. */
> > +	  if (gfc_option.rtcheck & GFC_RTCHECK_BOUNDS)
> > +	  {
> > +	    msg = xasprintf ("Negative character length will be treated as LEN=0");
> > +	    gfc_trans_runtime_check (false, true, neg_len, 
> > +				     &length_se.pre, where, msg);
> > +	    free(msg);
> > +	  }
> > +	  ss_info->string_length = fold_build3_loc (input_location, 
> > +				   COND_EXPR, gfc_charlen_type_node, 
> > +				   neg_len, gfc_index_zero_node, 
> > +				   ss_info->string_length);
> > +	  ss_info->string_length = gfc_evaluate_now (ss_info->string_length,
> > +						     &length_se.pre);
> > +
> >  	  gfc_add_block_to_block (&outer_loop->pre, &length_se.pre);
> >  	  gfc_add_block_to_block (&outer_loop->post, &length_se.post);
> >  	}
> 
> 
> Shouldn't you have build_int_cst (gfc_charlen_type_node, 0) instead of
> gfc_index_zero_node?

Thank you for your comment. I will make the necessary changes and re-post.