tests: use %empty

[bison.git] / src / reader.c

diff --git a/src/reader.c b/src/reader.c
index fb17b0186c41c6b24fa3bb1712d53aac4d5db15b..a83f11c1a8da97973efceeb873e62792d4b17027 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, 2000-2003, 2005-2007,
-   2009-2012 Free Software Foundation, Inc.
+   2009-2013 Free Software Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
@@ -267,9 +267,9 @@ symbol_should_be_used (symbol_list const *s, bool *midrule_warning)
     return true;
   if ((s->midrule && s->midrule->action_props.is_value_used)
       || (s->midrule_parent_rule
-          && symbol_list_n_get (s->midrule_parent_rule,
-                                s->midrule_parent_rhs_index)
-               ->action_props.is_value_used))
+          && (symbol_list_n_get (s->midrule_parent_rule,
+                                 s->midrule_parent_rhs_index)
+              ->action_props.is_value_used)))
     {
       *midrule_warning = true;
       return true;
@@ -326,13 +326,19 @@ grammar_rule_check (const symbol_list *r)
           {
             warnings warn_flag = midrule_warning ? Wmidrule_values : Wother;
             if (n)
-              complain (&r->location, warn_flag, _("unused value: $%d"), n);
+              complain (&l->location, warn_flag, _("unused value: $%d"), n);
             else
-              complain (&r->location, warn_flag, _("unset value: $$"));
+              complain (&l->location, warn_flag, _("unset value: $$"));
           }
       }
   }
 
+  /* Check that %empty => empty rule.  */
+  if (r->percent_empty_loc.start.file
+      && r->next && r->next->content.sym)
+    complain (&r->percent_empty_loc, complaint,
+              _("%%empty on non-empty rule"));
+
   /* See comments in grammar_current_rule_prec_set for how POSIX
      mandates this complaint.  It's only for identifiers, so skip
      it for char literals and strings, which are always tokens.  */
@@ -434,6 +440,17 @@ grammar_current_rule_prec_set (symbol *precsym, location loc)
   current_rule->ruleprec = precsym;
 }
 
+/* Set %empty for the current rule. */
+
+void
+grammar_current_rule_empty_set (location loc)
+{
+  if (current_rule->percent_empty_loc.start.file)
+    complain (&loc, complaint, _("only one %s allowed per rule"), "%empty");
+  else
+    current_rule->percent_empty_loc = loc;
+}
+
 /* Attach dynamic precedence DPREC to the current rule. */
 
 void
@@ -507,7 +524,7 @@ packgram (void)
 {
   unsigned int itemno = 0;
   rule_number ruleno = 0;
-  symbol_list *p = grammar;
+  symbol_list *p;
 
   ritem = xnmalloc (nritems + 1, sizeof *ritem);
 
@@ -516,9 +533,8 @@ packgram (void)
 
   rules = xnmalloc (nrules, sizeof *rules);
 
-  while (p)
+  for (p = grammar; p; p = p->next)
     {
-      int rule_length = 0;
       symbol *ruleprec = p->ruleprec;
       record_merge_function_type (p->merger, p->content.sym->type_name,
                                   p->merger_declaration_location);
@@ -541,9 +557,9 @@ packgram (void)
          %destructor and %printer apply.  */
       if (p->midrule_parent_rule
           && (p->action_props.is_value_used
-              || symbol_list_n_get (p->midrule_parent_rule,
-                                    p->midrule_parent_rhs_index)
-                   ->action_props.is_value_used))
+              || (symbol_list_n_get (p->midrule_parent_rule,
+                                     p->midrule_parent_rhs_index)
+                  ->action_props.is_value_used)))
         p->content.sym->tag += 1;
 
       /* Don't check the generated rule 0.  It has no action, so some rhs
@@ -552,24 +568,27 @@ packgram (void)
       if (p != grammar)
         grammar_rule_check (p);
 
-      for (p = p->next; p && p->content.sym; p = p->next)
-        {
-          ++rule_length;
-
-          /* Don't allow rule_length == INT_MAX, since that might
-             cause confusion with strtol if INT_MAX == LONG_MAX.  */
-          if (rule_length == INT_MAX)
-            complain (&rules[ruleno].location, fatal, _("rule is too long"));
-
-          /* item_number = symbol_number.
-             But the former needs to contain more: negative rule numbers. */
-          ritem[itemno++] =
-            symbol_number_as_item_number (p->content.sym->number);
-          /* A rule gets by default the precedence and associativity
-             of its last token.  */
-          if (p->content.sym->class == token_sym && default_prec)
-            rules[ruleno].prec = p->content.sym;
-        }
+      {
+        size_t rule_length = 0;
+        for (p = p->next; p->content.sym; p = p->next)
+          {
+            ++rule_length;
+
+            /* Don't allow rule_length == INT_MAX, since that might
+               cause confusion with strtol if INT_MAX == LONG_MAX.  */
+            if (rule_length == INT_MAX)
+              complain (&rules[ruleno].location, fatal, _("rule is too long"));
+
+            /* item_number = symbol_number.
+               But the former needs to contain more: negative rule numbers. */
+            ritem[itemno++] =
+              symbol_number_as_item_number (p->content.sym->number);
+            /* A rule gets by default the precedence and associativity
+               of its last token.  */
+            if (p->content.sym->class == token_sym && default_prec)
+              rules[ruleno].prec = p->content.sym;
+          }
+      }
 
       /* If this rule has a %prec,
          the specified symbol's precedence replaces the default.  */
@@ -583,9 +602,6 @@ packgram (void)
       aver (itemno < ITEM_NUMBER_MAX);
       ++ruleno;
       aver (ruleno < RULE_NUMBER_MAX);
-
-      if (p)
-        p = p->next;
     }
 
   aver (itemno == nritems);
@@ -713,7 +729,7 @@ check_and_convert_grammar (void)
   /* Insert the initial rule, whose line is that of the first rule
      (not that of the start symbol):
 
-     accept: %start EOF.  */
+     $accept: %start $end.  */
   {
     symbol_list *p = symbol_list_sym_new (accept, empty_location);
     p->location = grammar->location;
@@ -726,7 +742,8 @@ check_and_convert_grammar (void)
     grammar = p;
   }
 
-  aver (nsyms <= SYMBOL_NUMBER_MAXIMUM && nsyms == ntokens + nvars);
+  aver (nsyms <= SYMBOL_NUMBER_MAXIMUM);
+  aver (nsyms == ntokens + nvars);
 
   /* Assign the symbols their symbol numbers.  Write #defines for the
      token symbols into FDEFINES if requested.  */