* data/glr.c (yyreportSyntaxError): Fix off-by-one error in

checking against YYLAST that caused the parser to miss a potential
alternative in its diagnostic.
Problem reported by Maria Jose Moron Fernandez in
<http://lists.gnu.org/archive/html/bug-bison/2006-05/msg00024.html>.
* data/lalr1.cc (yysyntax_error_): Likewise.
* data/yacc.c (yysyntax_error): Likewise.
* tests/regression.at (_AT_DATA_DANCER_Y): Use static array for
tokens, in case we run into an older C compiler.
(_AT_DATA_EXPECT2_Y, AT_CHECK_EXPECT2): New macros.
Use them to check for the off-by-one error fixed above.

ChangeLog

@@ -1,5 +1,17 @@
 2006-05-14  Paul Eggert  <eggert@cs.ucla.edu>
 
+	* data/glr.c (yyreportSyntaxError): Fix off-by-one error in
+	checking against YYLAST that caused the parser to miss a potential
+	alternative in its diagnostic.
+	Problem reported by Maria Jose Moron Fernandez in
+	<http://lists.gnu.org/archive/html/bug-bison/2006-05/msg00024.html>.
+	* data/lalr1.cc (yysyntax_error_): Likewise.
+	* data/yacc.c (yysyntax_error): Likewise.
+	* tests/regression.at (_AT_DATA_DANCER_Y): Use static array for
+	tokens, in case we run into an older C compiler.
+	(_AT_DATA_EXPECT2_Y, AT_CHECK_EXPECT2): New macros.
+	Use them to check for the off-by-one error fixed above.
+
 	* data/yacc.c (yytnamerr): Fix typo: local var should be of type
 	YYSIZE_T, not size_t.
 	* tests/regression.at (Trivial grammars): New test, to catch

data/glr.c

@@ -2077,7 +2077,7 @@ yyreportSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
 #if YYERROR_VERBOSE
       int yyn;
       yyn = yypact[yystackp->yytops.yystates[0]->yylrState];
-      if (YYPACT_NINF < yyn && yyn < YYLAST)
+      if (YYPACT_NINF < yyn && yyn <= YYLAST)
 	{
 	  yySymbol yytoken = YYTRANSLATE (yychar);
 	  size_t yysize0 = yytnamerr (NULL, yytokenName (yytoken));
@@ -2104,7 +2104,7 @@ yyreportSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
 	  int yyxbegin = yyn < 0 ? -yyn : 0;
 
 	  /* Stay within bounds of both yycheck and yytname.  */
-	  int yychecklim = YYLAST - yyn;
+	  int yychecklim = YYLAST - yyn + 1;
 	  int yyxend = yychecklim < YYNTOKENS ? yychecklim : YYNTOKENS;
 	  int yycount = 1;
 

data/lalr1.cc

@@ -838,14 +838,14 @@ b4_error_verbose_if([, int tok])[)
     YYUSE (yystate);
 #if YYERROR_VERBOSE
     int yyn = yypact_[yystate];
-    if (yypact_ninf_ < yyn && yyn < yylast_)
+    if (yypact_ninf_ < yyn && yyn <= yylast_)
       {
 	/* Start YYX at -YYN if negative to avoid negative indexes in
 	   YYCHECK.  */
 	int yyxbegin = yyn < 0 ? -yyn : 0;
 
 	/* Stay within bounds of both yycheck and yytname.  */
-	int yychecklim = yylast_ - yyn;
+	int yychecklim = yylast_ - yyn + 1;
 	int yyxend = yychecklim < yyntokens_ ? yychecklim : yyntokens_;
 	int count = 0;
 	for (int x = yyxbegin; x < yyxend; ++x)

data/yacc.c

@@ -847,7 +847,7 @@ yysyntax_error (char *yyresult, int yystate, int yychar)
 {
   int yyn = yypact[yystate];
 
-  if (! (YYPACT_NINF < yyn && yyn < YYLAST))
+  if (! (YYPACT_NINF < yyn && yyn <= YYLAST))
     return 0;
   else
     {
@@ -885,7 +885,7 @@ yysyntax_error (char *yyresult, int yystate, int yychar)
       int yyxbegin = yyn < 0 ? -yyn : 0;
 
       /* Stay within bounds of both yycheck and yytname.  */
-      int yychecklim = YYLAST - yyn;
+      int yychecklim = YYLAST - yyn + 1;
       int yyxend = yychecklim < YYNTOKENS ? yychecklim : YYNTOKENS;
       int yycount = 1;
 

tests/regression.at

@@ -824,7 +824,7 @@ static int
 yylex (AT_LALR1_CC_IF([int *lval], [void]))
 [{
   static int toknum = 0;
-  int tokens[] =
+  static int tokens[] =
     {
       ':', -1
     };
@@ -864,3 +864,100 @@ AT_CLEANUP
 AT_CHECK_DANCER()
 AT_CHECK_DANCER([%glr-parser])
 AT_CHECK_DANCER([%skeleton "lalr1.cc"])
+
+
+## ------------------------------------------ ##
+## Diagnostic that expects two alternatives.  ##
+## ------------------------------------------ ##
+
+
+# _AT_DATA_EXPECT2_Y(BISON-OPTIONS)
+# --------------------------------
+m4_define([_AT_DATA_EXPECT2_Y],
+[AT_DATA_GRAMMAR([expect2.y],
+[%{
+static int yylex (AT_LALR1_CC_IF([int *], [void]));
+AT_LALR1_CC_IF([],
+[#include <stdio.h>
+static void yyerror (const char *);])
+%}
+$1
+%defines
+%error-verbose
+%token A 1000
+%token B
+
+%%
+program: /* empty */
+ | program e ';'
+ | program error ';';
+
+e: e '+' t | t;
+t: A | B;
+
+%%
+AT_LALR1_CC_IF(
+[/* A C++ error reporting function. */
+void
+yy::parser::error (const location&, const std::string& m)
+{
+  std::cerr << m << std::endl;
+}
+
+int
+yyparse ()
+{
+  yy::parser parser;
+  return parser.parse ();
+}
+],
+[static void
+yyerror (const char *s)
+{
+  fprintf (stderr, "%s\n", s);
+}])
+
+static int
+yylex (AT_LALR1_CC_IF([int *lval], [void]))
+[{
+  static int toknum = 0;
+  static int tokens[] =
+    {
+      1000, '+', '+', -1
+    };
+  ]AT_LALR1_CC_IF([*lval = 0; /* Pacify GCC.  */])[
+  return tokens[toknum++];
+}]
+
+int
+main (void)
+{
+  return yyparse ();
+}
+])
+])# _AT_DATA_EXPECT2_Y
+
+
+# AT_CHECK_EXPECT2(BISON-OPTIONS)
+# ------------------------------
+# Generate the grammar, compile it, run it.
+m4_define([AT_CHECK_EXPECT2],
+[AT_SETUP([Expecting two tokens $1])
+AT_BISON_OPTION_PUSHDEFS([$1])
+_AT_DATA_EXPECT2_Y([$1])
+AT_CHECK([bison -o expect2.c expect2.y])
+AT_LALR1_CC_IF(
+  [AT_CHECK([bison -o expect2.cc expect2.y])
+   AT_COMPILE_CXX([expect2])],
+  [AT_CHECK([bison -o expect2.c expect2.y])
+   AT_COMPILE([expect2])])
+AT_PARSER_CHECK([./expect2], 1, [],
+[syntax error, unexpected '+', expecting A or B
+])
+AT_BISON_OPTION_POPDEFS
+AT_CLEANUP
+])
+
+AT_CHECK_EXPECT2()
+AT_CHECK_EXPECT2([%glr-parser])
+AT_CHECK_EXPECT2([%skeleton "lalr1.cc"])