Between Bison releases, manually append `+' to the previous Bison

[bison.git] / src / reader.c

diff --git a/src/reader.c b/src/reader.c
index 0e0a8c21bebecb0588e8b20fdd628f00f0ea7452..d07ce5caa9e9c18b96bc989cfaf70cbbc07ae156 100644 (file)
--- a/src/reader.c
+++ b/src/reader.c
@@ -1,7 +1,7 @@
 /* Input parser for Bison
 
    Copyright (C) 1984, 1986, 1989, 1992, 1998, 2000, 2001, 2002, 2003,
-   2005 Free Software Foundation, Inc.
+   2005, 2006 Free Software Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
@@ -31,11 +31,12 @@
 #include "getargs.h"
 #include "gram.h"
 #include "muscle_tab.h"
-#include "output.h"
 #include "reader.h"
 #include "symlist.h"
 #include "symtab.h"
 
+static void check_and_convert_grammar (void);
+
 static symbol_list *grammar = NULL;
 static bool start_flag = false;
 merger_list *merge_functions;
@@ -210,6 +211,19 @@ grammar_current_rule_begin (symbol *lhs, location loc)
 }
 
 
+/*----------------------------------------------------------------------.
+| A symbol should be used if it has a destructor, or if it is a         |
+| mid-rule symbol (i.e., the generated LHS replacing a mid-rule         |
+| action) that was assigned to, as in "exp: { $$ = 1; } { $$ = $1; }".  |
+`----------------------------------------------------------------------*/
+
+static bool
+symbol_should_be_used (symbol_list const *s)
+{
+  return (s->sym->destructor
+         || (s->midrule && s->midrule->used));
+}
+
 /*----------------------------------------------------------------.
 | Check that the rule R is properly defined.  For instance, there |
 | should be no type clash on the default action.                  |
@@ -245,13 +259,13 @@ grammar_rule_check (const symbol_list *r)
                 _("empty rule for typed nonterminal, and no action"));
     }
 
-  /* Check that typed symbol values are used.  */
+  /* Check that symbol values that should be used are in fact used.  */
   {
     symbol_list const *l = r;
     int n = 0;
     for (; l && l->sym; l = l->next, ++n)
       if (! (l->used
-            || !l->sym->type_name
+            || !symbol_should_be_used (l)
             /* The default action, $$ = $1, `uses' both.  */
             || (!r->action && (n == 0 || n == 1))))
        {
@@ -285,7 +299,7 @@ grammar_current_rule_end (location loc)
 | rule.                                                              |
 `-------------------------------------------------------------------*/
 
-static void
+void
 grammar_midrule_action (void)
 {
   /* Since the action was written out with this rule's number, we must
@@ -307,6 +321,10 @@ grammar_midrule_action (void)
   midrule->action = current_rule->action;
   midrule->action_location = dummy_location;
   current_rule->action = NULL;
+  /* If $$ was used in the action, the LHS of the enclosing rule was
+     incorrectly flagged as used.  */
+  midrule->used = current_rule->used;
+  current_rule->used = false;
 
   if (previous_rule_end)
     previous_rule_end->next = midrule;
@@ -314,14 +332,16 @@ grammar_midrule_action (void)
     grammar = midrule;
 
   /* End the dummy's rule.  */
-  previous_rule_end = symbol_list_new (NULL, dummy_location);
-  previous_rule_end->next = current_rule;
+  midrule->next = symbol_list_new (NULL, dummy_location);
+  grammar_rule_check (midrule);
+  midrule->next->next = current_rule;
 
-  midrule->next = previous_rule_end;
+  previous_rule_end = midrule->next;
 
   /* Insert the dummy nonterminal replacing the midrule action into
-     the current rule.  */
+     the current rule.  Bind it to its dedicated rule.  */
   grammar_current_rule_symbol_append (dummy, dummy_location);
+  grammar_end->midrule = midrule;
 }
 
 /* Set the precedence symbol of the current rule to PRECSYM. */
@@ -373,14 +393,13 @@ grammar_current_rule_symbol_append (symbol *sym, location loc)
   grammar_symbol_append (sym, loc);
 }
 
-/* Attach an ACTION to the current rule.  If needed, move the previous
-   action as a mid-rule action.  */
+/* Attach an ACTION to the current rule.  */
 
 void
 grammar_current_rule_action_append (const char *action, location loc)
 {
-  if (current_rule->action)
-    grammar_midrule_action ();
+  /* There's no need to invoke grammar_midrule_action here, since the
+     scanner already did it if necessary.  */
   current_rule->action = action;
   current_rule->action_location = loc;
 }
@@ -398,7 +417,11 @@ packgram (void)
   rule_number ruleno = 0;
   symbol_list *p = grammar;
 
-  ritem = xnmalloc (nritems, sizeof *ritem);
+  ritem = xnmalloc (nritems + 1, sizeof *ritem);
+
+  /* This sentinel is used by build_relations in gram.c.  */
+  *ritem++ = 0;
+
   rules = xnmalloc (nrules, sizeof *rules);
 
   while (p)
@@ -445,8 +468,7 @@ packgram (void)
        p = p->next;
     }
 
-  if (itemno != nritems)
-    abort ();
+  assert (itemno == nritems);
 
   if (trace_flag & trace_sets)
     ritem_print (stderr);
@@ -492,12 +514,22 @@ reader (void)
   scanner_initialize ();
   gram_parse ();
 
-  /* If something went wrong during the parsing, don't try to
-     continue.  */
-  if (complaint_issued)
-    return;
+  if (! complaint_issued)
+    check_and_convert_grammar ();
+
+  xfclose (gram_in);
+}
+
 
-  /* Grammar has been read.  Do some checking */
+/*-------------------------------------------------------------.
+| Check the grammar that has just been read, and convert it to |
+| internal form.                                              |
+`-------------------------------------------------------------*/
+
+static void
+check_and_convert_grammar (void)
+{
+  /* Grammar has been read.  Do some checking.  */
   if (nrules == 0)
     fatal (_("no rules in the input grammar"));
 
@@ -514,7 +546,7 @@ reader (void)
       endtoken->user_token_number = 0;
     }
 
-  /* Insert the initial rule, which line is that of the first rule
+  /* Insert the initial rule, whose line is that of the first rule
      (not that of the start symbol):
 
      accept: %start EOF.  */
@@ -530,10 +562,7 @@ reader (void)
     grammar = p;
   }
 
-  if (! (nsyms <= SYMBOL_NUMBER_MAXIMUM && nsyms == ntokens + nvars))
-    abort ();
-
-  xfclose (gram_in);
+  assert (nsyms <= SYMBOL_NUMBER_MAXIMUM && nsyms == ntokens + nvars);
 
   /* Assign the symbols their symbol numbers.  Write #defines for the
      token symbols into FDEFINES if requested.  */