* src/LR0.c (new_state): Display `nstates' as the name of the

newly created state.
Adjust to initialize first_state and last_state if needed.
Be sure to distinguish the initial from the final state.
(new_states): Create the itemset of the initial state, and use
new_state.
* src/closure.c (closure): Now that the initial state has its
items properly set, there is no need for a special case when
creating `ruleset'.
As a result, now the rule 0, reducing to $axiom, is visible in the
outputs.  Adjust the test suite.
* tests/conflicts.at (Solved SR Conflicts)
(Unresolved SR Conflicts): Adjust.
* tests/regression.at (Web2c Report, Rule Line Numbers): Idem.
* tests/conflicts.at (S/R in initial): New.

ChangeLog

@@ -1,3 +1,23 @@
+2002-04-07  Akim Demaille  <akim@epita.fr>
+
+	* src/LR0.c (new_state): Display `nstates' as the name of the
+	newly created state.
+	Adjust to initialize first_state and last_state if needed.
+	Be sure to distinguish the initial from the final state.
+	(new_states): Create the itemset of the initial state, and use
+	new_state.
+	* src/closure.c (closure): Now that the initial state has its
+	items properly set, there is no need for a special case when
+	creating `ruleset'.
+
+	As a result, now the rule 0, reducing to $axiom, is visible in the
+	outputs.  Adjust the test suite.
+
+	* tests/conflicts.at (Solved SR Conflicts)
+	(Unresolved SR Conflicts): Adjust.
+	* tests/regression.at (Web2c Report, Rule Line Numbers): Idem.
+	* tests/conflicts.at (S/R in initial): New.
+
 2002-04-07  Akim Demaille  <akim@epita.fr>
 
 	* src/LR0.c (allocate_itemsets): Don't loop over ritem: loop over

NEWS

@@ -3,6 +3,15 @@ Bison News
 
 Changes in version 1.49a:
 
+* The initial rule is explicit.
+  Bison used to play hacks with the initial rule, which the user does
+  not write.  It is now explicit, and visible in the reports and
+  graphs as rule 0.
+      
+* Useless rules are actually removed.
+  Before, Bison reported the useless rules, but, although not used,
+  included them in the parsers.
+	 
 * False `Token not used' report fixed.
   On a grammar such as
 

src/LR0.c

@@ -35,7 +35,7 @@
 #include "lalr.h"
 #include "reduce.h"
 
-unsigned int nstates;
+unsigned int nstates = 0;
 /* Initialize the final state to -1, otherwise, it might be set to 0
    by default, and since we don't compute the reductions of the final
    state, we end up not computing the reductions of the initial state,
@@ -190,7 +190,7 @@ new_state (int symbol)
 
   if (trace_flag)
     fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n",
-	     this_state->number, symbol, symbols[symbol]->tag);
+	     nstates, symbol, symbols[symbol]->tag);
 
   if (nstates >= MAXSHORT)
     fatal (_("too many states (max %d)"), MAXSHORT);
@@ -202,14 +202,19 @@ new_state (int symbol)
 
   shortcpy (p->items, kernel_base[symbol], kernel_size[symbol]);
 
-  last_state->next = p;
+  /* If this is the eoftoken, and this is not the initial state, then
-  last_state = p;
+     this is the final state.  */
-  nstates++;
+  if (symbol == 0 && first_state)
-
-  /* If this is the eoftoken, then this is the final state. */
-  if (symbol == 0)
     final_state = p->number;
 
+  if (!first_state)
+    first_state = p;
+  if (last_state)
+    last_state->next = p;
+  last_state = p;
+
+  nstates++;
+
   return p;
 }
 
@@ -317,8 +322,10 @@ append_states (void)
 static void
 new_states (void)
 {
-  first_state = last_state = this_state = STATE_ALLOC (0);
+  /* The 0 at the lhs is the index of the item of this initial rule.  */
-  nstates = 1;
+  kernel_base[0][0] = 0;
+  kernel_size[0] = 1;
+  this_state = new_state (0);
 }
 
 

src/closure.c

@@ -244,18 +244,11 @@ closure (short *core, int n)
   if (trace_flag)
     print_closure ("input", core, n);
 
-  if (n == 0)
+  bitset_zero (ruleset);
-    {
-      bitset_copy (ruleset, FDERIVES (start_symbol));
-    }
-  else
-    {
-      bitset_zero (ruleset);
 
-      for (c = 0; c < n; ++c)
+  for (c = 0; c < n; ++c)
-	if (ISVAR (ritem[core[c]]))
+    if (ISVAR (ritem[core[c]]))
-	  bitset_or (ruleset, ruleset, FDERIVES (ritem[core[c]]));
+      bitset_or (ruleset, ruleset, FDERIVES (ritem[core[c]]));
-    }
 
   nitemset = 0;
   c = 0;

tests/Makefile.am

@@ -55,7 +55,7 @@ TESTSUITE_AT = \
 TESTSUITE = $(srcdir)/testsuite
 
 AUTOTEST = $(AUTOM4TE) --language=autotest
-$(srcdir)/$(TESTSUITE): package.m4 $(TESTSUITE_AT)
+$(TESTSUITE): package.m4 $(TESTSUITE_AT)
 	$(AUTOTEST) -I $(srcdir) testsuite.at -o $@.tmp
 	mv $@.tmp $@
 

tests/conflicts.at

@@ -1,5 +1,5 @@
 # Exercising Bison on conflicts.                         -*- Autotest -*-
-# Copyright 2002 Free Software Foundation, Inc.
+# Copyright (C) 2002 Free Software Foundation, Inc.
 
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -19,6 +19,28 @@
 AT_BANNER([[Conflicts.]])
 
 
+## ---------------- ##
+## S/R in initial.  ##
+## ---------------- ##
+
+# I once hacked Bison in such a way that it lost its reductions on the
+# initial state (because it was confusing it with the last state).  It
+# took me a while to strip down my failures to this simple case.  So
+# make sure it finds the s/r conflict below.
+
+AT_SETUP([S/R in initial])
+
+AT_DATA([[input.y]],
+[[%expect 1
+%%
+exp: e 'e';
+e: 'e' | /* Nothing. */;
+]])
+
+AT_CHECK([bison input.y -o input.c])
+
+AT_CLEANUP
+
 ## ------------------- ##
 ## %nonassoc and eof.  ##
 ## ------------------- ##
@@ -143,6 +165,8 @@ exp (6)
 
 state 0
 
+    $axiom  ->  . exp $   (rule 0)
+
     NUM 	shift, and go to state 1
 
     exp 	go to state 2
@@ -247,6 +271,8 @@ exp (6)
 
 state 0
 
+    $axiom  ->  . exp $   (rule 0)
+
     NUM 	shift, and go to state 1
 
     exp 	go to state 2

tests/regression.at

@@ -139,6 +139,8 @@ expr (7)
 
 state 0
 
+    $axiom  ->  . expr $   (rule 0)
+
     'a' 	shift, and go to state 1
 
     $default	reduce using rule 3 (@2)
@@ -348,6 +350,7 @@ CONST_DEC (10)
 @1 (11)
     on left: 4, on right: 5
 state 0
+    $axiom  ->  . CONST_DEC_PART $   (rule 0)
     $default	reduce using rule 4 (@1)
     CONST_DEC_PART	go to state 1
     CONST_DEC_LIST	go to state 2