Re: push parser

[Paul Eggert]

Bob Rossi <address@hidden> writes:

> I have absolutly no idea what yymsgbuf is used for.

It's used to construct an error message that is passed to
yysyntax_error.  yysyntax_error is not supposed to assume that the
message is in static storage, so it's OK to make it auto.

> What do you think?

That looks good, except there's a memory leak if the push
parser outputs a long diagnostic (thus calling malloc for
yymsg), and then exits.  I installed the following patch
instead; I hope it works for you (at least, "make check"
passes).

2006-10-11  Paul Eggert  <address@hidden>

        * data/push.c (yypushparse): Fix memory leak if yymsg is malloced
        in a push parser.  Reindent slightly to match yacc.c better.

2006-10-11  Bob Rossi  <address@hidden>

        * data/push.c (struct yypvars): Remove yymsgbuf, yymsgbuf_ptr, yymsg,
        yymsg_alloc fields.
        (yypvarsinit, yypushparse): Remove init of removed fields.
        (yypushparse): Use yymsgbuf instead of yymsgbuf_ptr.

--- data/push.c 21 Sep 2006 17:45:21 -0000      1.3
+++ data/push.c 11 Oct 2006 16:35:22 -0000
@@ -1017,14 +1017,6 @@ m4_define([b4_declare_yyparse_variables]
     /* Look-ahead token as an internal (translated) token number.  */
     int yytoken;
 
-#if YYERROR_VERBOSE
-    /* Buffer for error messages, and its allocated size.  */
-    char yymsgbuf[128];
-    char *yymsgbuf_ptr;
-    char *yymsg;
-    YYSIZE_T yymsg_alloc;
-#endif
-
     /* Three stacks and their tools:
        `yyss': related to states,
        `yyvs': related to semantic values,
@@ -1070,12 +1062,6 @@ yypvarsinit (void)
   pv->yyerrstatus = 0;
   pv->yytoken = 0;
 
-#if YYERROR_VERBOSE
-  pv->yymsgbuf_ptr = pv->yymsgbuf;
-  pv->yymsg = pv->yymsgbuf;
-  pv->yymsg_alloc = sizeof pv->yymsgbuf;
-#endif
-
   pv->yyssa_ptr = pv->yyssa;
   pv->yyss = pv->yyssa;
   pv->yyvs = pv->yyvsa;
@@ -1153,7 +1139,6 @@ b4_c_function_def([yyparse], [int], b4_p
 #if YYERROR_VERBOSE
   /* Buffer for error messages, and its allocated size.  */
   char yymsgbuf[128];
-  char *yymsgbuf_ptr = yymsgbuf;
   char *yymsg = yymsgbuf;
   YYSIZE_T yymsg_alloc = sizeof yymsgbuf;
 #endif
@@ -1248,11 +1233,7 @@ m4_ifdef([b4_at_dollar_used], [[  yylsp[
        yyresult = pv->yyresult;
        yyerrstatus = pv->yyerrstatus;
        yytoken = pv->yytoken;
-#if YYERROR_VERBOSE
-       yymsgbuf_ptr = pv->yymsgbuf_ptr;
-       yymsg = pv->yymsg;;
-       yymsg_alloc = pv->yymsg_alloc;
-#endif
+
        yyssa_ptr = pv->yyssa_ptr;
        yyss = pv->yyss;
        yyssp = pv->yyssp;
@@ -1390,14 +1371,9 @@ yybackup:
 
        pv->yystate = yystate;
        pv->yyn = yyn;
-       pv->yyresult = yyresult;
        pv->yyerrstatus = yyerrstatus;
        pv->yytoken = yytoken;
-#if YYERROR_VERBOSE
-       pv->yymsgbuf_ptr = yymsgbuf_ptr;
-       pv->yymsg = yymsg;;
-       pv->yymsg_alloc = yymsg_alloc;
-#endif
+
        pv->yyssa_ptr = yyssa_ptr;
        pv->yyss = yyss;
        pv->yyssp = yyssp;
@@ -1414,11 +1390,10 @@ yybackup:
        pv->yylen = yylen;
        pv->yyval = yyval;
        ]b4_locations_if([pv->yyloc = yyloc;])[
-       return yyresult;
-gottoken:
-       YYDPRINTF((stderr, "Reading a token: "));],[
-       YYDPRINTF ((stderr, "Reading a token: "));
-       yychar = YYLEX;])[
+       goto yypushreturn;
+gottoken:])
+      YYDPRINTF ((stderr, "Reading a token: "));
+      ]b4_push_if([], [yychar = YYLEX;])[
     }
 
   if (yychar <= YYEOF)
@@ -1541,14 +1516,14 @@ yyerrlab:
            YYSIZE_T yyalloc = 2 * yysize;
            if (! (yysize <= yyalloc && yyalloc <= YYSTACK_ALLOC_MAXIMUM))
              yyalloc = YYSTACK_ALLOC_MAXIMUM;
-           if (yymsg != yymsgbuf_ptr)
+           if (yymsg != yymsgbuf)
              YYSTACK_FREE (yymsg);
            yymsg = (char *) YYSTACK_ALLOC (yyalloc);
            if (yymsg)
              yymsg_alloc = yyalloc;
            else
              {
-               yymsg = yymsgbuf_ptr;
+               yymsg = yymsgbuf;
                yymsg_alloc = sizeof yymsgbuf;
              }
          }
@@ -1704,13 +1679,14 @@ yyreturn:
   if (yyss != yyssa_ptr)
     YYSTACK_FREE (yyss);
 #endif
+]b4_push_if([yypushreturn:])[
 #if YYERROR_VERBOSE
-  if (yymsg != yymsgbuf_ptr)
+  if (yymsg != yymsgbuf)
     YYSTACK_FREE (yymsg);
 #endif
   ]b4_push_if([pv->yyresult = YYID (yyresult);])[
-    /* Make sure YYID is used.  */
-    return YYID (yyresult);
+  /* Make sure YYID is used.  */
+  return YYID (yyresult);
 ]}
 
 b4_push_if([