data/glr.c (yyfill): Adjust comment.

(yyresolveAction): Initialize default location properly for empty right-hand
 sides.
 (yydoAction): Ditto.  Add comment explaining apparently dead code.
* tests/glr-regression.at
 (Incorrectly initialized location for empty right-hand side in GLR): New test.

ChangeLog

@@ -1,3 +1,14 @@
+2005-10-30  Paul Hilfinger  <hilfingr@tully.CS.Berkeley.EDU>
+
+	* data/glr.c (yyfill): Adjust comment.
+	(yyresolveAction): Initialize default location properly 
+	for empty right-hand sides.
+	(yydoAction): Ditto.
+	Add comment explaining apparently dead code.
+	* tests/glr-regression.at 
+	(Incorrectly initialized location for empty right-hand side in GLR): 
+	New test.
+	
 2005-10-30  Paul Eggert  <eggert@cs.ucla.edu>
 
 	* bootstrap (cleanup_gnulib): New function.  Use it to clean up

data/glr.c

@@ -782,8 +782,7 @@ yytokenName (yySymbol yytoken)
 
 /** Fill in YYVSP[YYLOW1 .. YYLOW0-1] from the chain of states starting
  *  at YYVSP[YYLOW0].yystate.yypred.  Leaves YYVSP[YYLOW1].yystate.yypred
- *  containing the pointer to the next state in the chain. Assumes
+ *  containing the pointer to the next state in the chain. */
- *  YYLOW1 < YYLOW0.  */
 static void yyfillin (yyGLRStackItem *, int, int) __attribute__ ((__unused__));
 static void
 yyfillin (yyGLRStackItem *yyvsp, int yylow0, int yylow1)
@@ -802,8 +801,8 @@ yyfillin (yyGLRStackItem *yyvsp, int yylow0, int yylow1)
 }
 
 /* Do nothing if YYNORMAL or if *YYLOW <= YYLOW1.  Otherwise, fill in
-   YYVSP[YYLOW1 .. *YYLOW-1] as in yyfillin and set *YYLOW = YYLOW1.
+ * YYVSP[YYLOW1 .. *YYLOW-1] as in yyfillin and set *YYLOW = YYLOW1.
-   For convenience, always return YYLOW1.  */
+ * For convenience, always return YYLOW1.  */
 static inline int yyfill (yyGLRStackItem *, int *, int, yybool)
      __attribute__ ((__unused__));
 static inline int
@@ -1286,11 +1285,18 @@ yydoAction (yyGLRStack* yystack, size_t yyk, yyRuleNum yyrule,
     }
   else
     {
+      /* At present, doAction is never called in nondeterministic
+       * mode, so this branch is never taken.  It is here in
+       * anticipation of a future feature that will allow immediate
+       * evaluation of selected actions in nondeterministic mode. */
       int yyi;
       yyGLRState* yys;
       yyGLRStackItem yyrhsVals[YYMAXRHS + YYMAXLEFT + 1];
       yys = yyrhsVals[YYMAXRHS + YYMAXLEFT].yystate.yypred
-	= yystack->yytops.yystates[yyk];
+	= yystack->yytops.yystates[yyk];]b4_location_if([[
+      if (yynrhs == 0)
+	/* Set default location. */
+        yyrhsVals[YYMAXRHS + YYMAXLEFT - 1].yystate.yyloc = yys->yyloc;]])[
       for (yyi = 0; yyi < yynrhs; yyi += 1)
 	{
 	  yys = yys->yypred;
@@ -1564,7 +1570,10 @@ yyresolveAction (yySemanticOption* yyopt, yyGLRStack* yystack,
 
   yynrhs = yyrhsLength (yyopt->yyrule);
   YYCHK (yyresolveStates (yyopt->yystate, yynrhs, yystack]b4_user_args[));
-  yyrhsVals[YYMAXRHS + YYMAXLEFT].yystate.yypred = yyopt->yystate;
+  yyrhsVals[YYMAXRHS + YYMAXLEFT].yystate.yypred = yyopt->yystate;]b4_location_if([[
+  if (yynrhs == 0)
+    /* Set default location. */
+    yyrhsVals[YYMAXRHS + YYMAXLEFT - 1].yystate.yyloc = yyopt->yystate->yyloc;]])[
   return yyuserAction (yyopt->yyrule, yynrhs,
 		       yyrhsVals + YYMAXRHS + YYMAXLEFT - 1,
 		       yyvalp, yylocp, yystack]b4_user_args[);

tests/glr-regression.at

@@ -636,3 +636,100 @@ AT_CHECK([[./glr-regr7]], 2, [],
 AT_XFAIL_IF(:)
 
 AT_CLEANUP
+
+
+## ------------------------------------------------------------------------- ##
+## Incorrect default location for empty right-hand sides.  Adapted from bug  ##
+## report by Claudia Hermann.						     ##
+## See http://lists.gnu.org/archive/html/bug-bison/2005-10/msg00069.html and ##
+## http://lists.gnu.org/archive/html/bug-bison/2005-10/msg00072.html         ##
+## ------------------------------------------------------------------------- ##
+
+AT_SETUP([Incorrectly initialized location for empty right-hand side in GLR])
+
+AT_DATA_GRAMMAR([glr-regr8.y],
+[[
+%{
+  #include <stdio.h>
+  #include <stdlib.h>
+  static void yyerror (char const *);
+  static int yylex (void);
+  static void yyerror(const char *msg);
+%}
+
+%token T_CONSTANT
+%token T_PORT
+%token T_SIGNAL
+
+%glr-parser
+
+%%
+
+
+PortClause	: T_PORT InterfaceDeclaration T_PORT
+		{ printf("%d/%d - %d/%d - %d/%d\n", 
+			 @1.first_column, @1.last_column, 
+			 @2.first_column, @2.last_column, 
+			 @3.first_column, @3.last_column); }
+	;
+
+InterfaceDeclaration	: OptConstantWord	%dprec 1
+	| OptSignalWord	%dprec 2
+	;
+
+OptConstantWord	: /* empty */
+	| T_CONSTANT
+	;
+
+OptSignalWord	: /* empty */
+		{ printf("empty: %d/%d\n", @$.first_column, @$.last_column); }
+	| T_SIGNAL
+	;
+
+%%
+
+void yyerror(const char *msg)
+{
+  fprintf (stderr, "error\n");
+}
+
+static int lexIndex;
+
+int yylex() 
+{
+  lexIndex += 1;
+  switch (lexIndex)
+    {
+    case 1:
+      yylloc.first_column = 1;
+      yylloc.last_column = 9;
+      return T_PORT;
+    case 2:
+      yylloc.first_column = 13;
+      yylloc.last_column = 17;
+      return T_PORT;
+    default:
+      return 0;
+    }
+}
+
+int
+main (void) 
+{
+  yyparse();
+  return 0;
+}
+]])
+
+AT_CHECK([[bison -o glr-regr8.c glr-regr8.y]], 0, [],
+[glr-regr8.y: conflicts: 1 reduce/reduce
+])
+AT_COMPILE([glr-regr8])
+
+AT_CHECK([[./glr-regr8]], 0, 
+[empty: 9/9
+1/9 - 9/9 - 13/17
+],
+[])
+
+AT_CLEANUP