From 660bc8dd090bbdbcac3b3d01945aa4c515ed8041 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Fri, 24 May 2002 12:37:12 +0000
Subject: [PATCH] (yyparse): Correct error handling to conform to POSIX and
 yacc.  Specifically, after syntax error is discovered, do not reduce further
 before shifting the error token. Clean up the code a bit by removing the
 labels yyerrdefault, yyerrhandle, yyerrpop.

---
 data/bison.simple | 85 +++++++++++++++--------------------------------
 1 file changed, 27 insertions(+), 58 deletions(-)

diff --git a/data/bison.simple b/data/bison.simple
index ad42a919..7a491feb 100644
--- a/data/bison.simple
+++ b/data/bison.simple
@@ -1120,71 +1120,40 @@ yyerrlab1:
 
   yyerrstatus = 3;	/* Each real token shifted decrements this.  */
 
-  goto yyerrhandle;
-
-
-/*-------------------------------------------------------------------.
-| yyerrdefault -- current state does not do anything special for the |
-| error token.                                                       |
-`-------------------------------------------------------------------*/
-yyerrdefault:
-#if 0
-  /* This is wrong; only states that explicitly want error tokens
-     should shift them.  */
-
-  /* If its default is to accept any token, ok.  Otherwise pop it.  */
-  yyn = yydefact[yystate];
-  if (yyn)
-    goto yydefault;
-#endif
-
+  for (;;)
+    {
+      yyn = yypact[yystate];
+      if (yyn != YYFLAG)
+	{
+	  yyn += YYTERROR;
+	  if (0 <= yyn && yyn <= YYLAST && yycheck[yyn] == YYTERROR)
+	    {
+	      yyn = yytable[yyn];
+	      if (0 < yyn)
+		break;
+	    }
+	}
 
-/*---------------------------------------------------------------.
-| yyerrpop -- pop the current state because it cannot handle the |
-| error token.                                                   |
-`---------------------------------------------------------------*/
-yyerrpop:
-  if (yyssp == yyss)
-    YYABORT;
-  yyvsp--;
-  yystate = *--yyssp;
+      /* Pop the current state because it cannot handle the error token.  */
+      if (yyssp == yyss)
+	YYABORT;
+      yyvsp--;
+      yystate = *--yyssp;
 #if YYLSP_NEEDED
-  yylsp--;
+      yylsp--;
 #endif
 
 #if YYDEBUG
-  if (yydebug)
-    {
-      short *yyssp1 = yyss - 1;
-      YYFPRINTF (stderr, "Error: state stack now");
-      while (yyssp1 != yyssp)
-	YYFPRINTF (stderr, " %d", *++yyssp1);
-      YYFPRINTF (stderr, "\n");
-    }
+      if (yydebug)
+	{
+	  short *yyssp1 = yyss - 1;
+	  YYFPRINTF (stderr, "Error: state stack now");
+	  while (yyssp1 != yyssp)
+	    YYFPRINTF (stderr, " %d", *++yyssp1);
+	  YYFPRINTF (stderr, "\n");
+	}
 #endif
-
-/*--------------.
-| yyerrhandle.  |
-`--------------*/
-yyerrhandle:
-  yyn = yypact[yystate];
-  if (yyn == YYFLAG)
-    goto yyerrdefault;
-
-  yyn += YYTERROR;
-  if (yyn < 0 || yyn > YYLAST || yycheck[yyn] != YYTERROR)
-    goto yyerrdefault;
-
-  yyn = yytable[yyn];
-  if (yyn < 0)
-    {
-      if (yyn == YYFLAG)
-	goto yyerrpop;
-      yyn = -yyn;
-      goto yyreduce;
     }
-  else if (yyn == 0)
-    goto yyerrpop;
 
   if (yyn == YYFINAL)
     YYACCEPT;
-- 
2.45.2