🚀 go-pugleaf

This is to  let you  know that all  is  not perfectly well with  bison
generated grammars. I'm  using 1.18,   on a  sparcstation  2,  running
4.1.1.

I have a grammar that looks something like this:

%{
#ifndef LINT
static char rcs_edifmapb_id[] = "$Id: edif_map.b,v 1.10 1992/05/15 20:56:37 murf Exp $";
#endif
#include <stdio.h>
#include "structure.h"
#include "edif_rp_struct.h"
#if defined(EDI) || defined(BERK)

#include "form_edif_interface.h"

#endif
char *re_comp();
struct map *reading,*writing,**current;
#define Calloc(x)  (x *)calloc(sizeof (x),1)
extern double edif_grid_divisor;
extern int page_spacing;
struct path *pptr;
extern struct namefilter *netfilt, *instfilt;
%}

%union {
	struct map *mapstructptr;
	struct position pos;
	struct placement place;
	char string[100];
	double dval;
	int orientation;
	struct pathlist *plist;
	struct path *pathptr;
	struct userwindow userwindow;
       }

%token ON READING WRITING MAP CELL TO SYMBOL MODULE PARAM FORGET SET COMMA SEMI HAS VIA BUNVIA GRIDRES R0 R90 R180 R270 MX MY MYR90 MXR90 OFFSET
%token BUNINPIN BUNOUTPIN BUNIOPIN INPIN OUTPIN IOPIN PICBUNINPIN PICBUNOUTPIN PICBUNIOPIN PICINPIN PICOUTPIN PICIOPIN WIRE FROM DIRMAG WINDOW
%token DIRLESSPINS PAGESPACING EXTRACT EXTRACTNUMBER NET SCHEM FILTER NETNAMES INSTNAMES XSCALE YSCALE
%token <string> STRING
%token <dval> NUM
%type <pos> offset
%type <place> xform
%type <orientation> orient
%type <mapstructptr> readmaplist writemaplist readmapitem writemapitem readmapintro 
         writemapintro paramlist paramobject object paramitem value
%type <pathptr> path
%type <plist> pathlist
%type <userwindow> window
%%

file : statlist {}
     ;

statlist : statitem {}
		| statlist statitem {}
        ;

statitem : reading {}
         | writing {}
         ;

reading: ON READING COMMA {/*current = &reading;*/} readmaplist {} 
       ;

readmaplist : readmapitem {reading=$1;}     /* Will crash here ---v   */
            | readmaplist readmapitem {struct map *x; x=$2; if( $2) {$2->next = $1; reading = $2;
                                         $$ = $2;} else $$ = $1;} 
            ;

readmapitem : readmapintro SEMI {$$ = $1;}
            | paramlist SEMI {$$ = $1;}
			| readmapintro pathlist xform SEMI { $$=$1; $$->place = $3; $$->pathlist = $2; }
			| readmapintro xform pathlist SEMI { $$=$1; $$->place = $2; $$->pathlist = $3; }
			| readmapintro pathlist xform COMMA window SEMI { $$=$1; $$->place = $3; $$->pathlist = $2; $$->win = $5; }
            | readmapintro pathlist xform COMMA paramlist SEMI {$$=$1; $$->parammaplist = $5; $$->pathlist = $2; $$->place = $3; } 
            | readmapintro pathlist xform COMMA window COMMA paramlist SEMI {$$=$1; $$->parammaplist = $7; $$->pathlist = $2; $$->place = $3; $$->win = $5; } 
            | readmapintro xform pathlist COMMA window COMMA paramlist SEMI {$$=$1; $$->parammaplist = $7; $$->pathlist = $3; $$->place = $2; $$->win = $5; } 
            | readmapintro xform pathlist COMMA paramlist SEMI {$$=$1; $$->parammaplist = $5; $$->pathlist = $3; $$->place = $2; } 
			| readmapintro xform pathlist COMMA window SEMI { $$=$1; $$->place = $2; $$->pathlist = $3; $$->win = $5;}
            | readmapintro pathlist COMMA window COMMA paramlist SEMI {$$=$1; $$->parammaplist = $6; $$->pathlist  = $2; $$->win = $4; } 
            | readmapintro pathlist COMMA paramlist SEMI {$$=$1; $$->parammaplist = $4; $$->pathlist  = $2; } 
            | readmapintro xform COMMA window COMMA paramlist SEMI {$$=$1; $$->parammaplist = $6; $$->place = $2; $$->win = $4; } 
            | readmapintro xform COMMA paramlist SEMI {$$=$1; $$->parammaplist = $4; $$->place = $2; } 
            | readmapintro xform SEMI {$$=$1; $$->place = $2; } 
            | readmapintro pathlist SEMI {$$=$1; $$->pathlist  = $2; } 
            | readmapintro paramlist SEMI {$$=$1; $$->parammaplist = $2;} 
			| readmapintro window SEMI {$$=$1; $$->win = $2; }
            | readmapintro window COMMA paramlist SEMI {$$=$1; $$->parammaplist = $4; $$->win = $2;} 
			| MAP paramobject paramlist SEMI {$$ = $2; $$->parammaplist = $3;}
			| SET GRIDRES TO NUM SEMI {edif_grid_divisor = $4; $$=0; 
                edif_print(1,"<<edif_grid_divisor = %f>>\n",edif_grid_divisor);} 
			| SET DIRLESSPINS  SEMI { setDirlessPins(1); $$=0; }
            | SET XSCALE TO NUM SEMI {set_x_scale_factor($4); $$=0;}
            | SET YSCALE TO NUM SEMI {set_y_scale_factor($4); $$=0;}
			| SET PAGESPACING TO NUM SEMI {page_spacing = $4; $$=0;
                edif_print(1,"<<page_spacing = %d>>\n",page_spacing);} 
			| FILTER NETNAMES STRING TO STRING SEMI 
				{struct namefilter *x,*y; x = (struct namefilter *)calloc(sizeof(struct namefilter),1);
					$$=0;strcpy(x->from,$3); strcpy(x->to,$5);
					if( !netfilt ) netfilt =x;
					else{ y=netfilt; while( y->next) y = y->next; y->next = x; }}
			| FILTER INSTNAMES STRING TO STRING SEMI 
				{struct namefilter *x,*y; x = (struct namefilter *)calloc(sizeof(struct namefilter),1);
					$$=0;strcpy(x->from,$3); strcpy(x->to,$5);
					if( !instfilt ) instfilt =x;
					else{ y=instfilt; while( y->next) y = y->next; y->next = x; }}
            ;


anyway, if I move the actions in before  the SEMI, especially the ones
that zero out $$, I will often get crashes when  I try to evaluate the
second rule of  readmaplist. $2 is garbage,  and results in  a segment
fault. We've been fixing this by moving around where  the actions are,
for instance, last time I compiled (probably under 1.16),  this seemed
to make things work better:

			| readmapintro window SEMI {$$=$1; $$->win = $2; }
            | readmapintro window COMMA paramlist SEMI {$$=$1; $$->parammaplist = $4; $$->win = $2;} 
			| MAP paramobject paramlist SEMI {$$ = $2; $$->parammaplist = $3;}
			| SET GRIDRES TO NUM {edif_grid_divisor = $4; $$=0; 
                edif_print(1,"<<edif_grid_divisor = %f>>\n",edif_grid_divisor);} SEMI 
			| SET DIRLESSPINS  { setDirlessPins(1); $$=0; } SEMI
            | SET XSCALE TO NUM {set_x_scale_factor($4); $$=0;} SEMI 
            | SET YSCALE TO NUM {set_y_scale_factor($4); $$=0;} SEMI
			| SET PAGESPACING TO NUM {page_spacing = $4; $$=0;
                edif_print(1,"<<page_spacing = %d>>\n",page_spacing);} SEMI 
			| FILTER NETNAMES STRING TO STRING SEMI 

Now it doesn't. If this kind  of clue doesn't help  you, perhaps I can
rip out some example files and the complete  source to this chunk, and
you can quickly construct a test  executable. The yyvsp stack seems to
be getting mixed up.

murf