Allow specification of semantic predicates.

[bison.git] / src / reader.c

diff --git a/src/reader.c b/src/reader.c
index 800ecc227876b0b060551ca804c3152a67e13c55..e64741cb2389b1a03cb809254255631a80ca93a9 100644 (file)
--- a/src/reader.c
+++ b/src/reader.c
@@ -1,29 +1,27 @@
 /* Input parser for Bison
 
    Copyright (C) 1984, 1986, 1989, 1992, 1998, 2000, 2001, 2002, 2003,
 /* Input parser for Bison
 
    Copyright (C) 1984, 1986, 1989, 1992, 1998, 2000, 2001, 2002, 2003,

-   2005, 2006 Free Software Foundation, Inc.
+   2005, 2006, 2007, 2009, 2010 Free Software Foundation, Inc.

 
    This file is part of Bison, the GNU Compiler Compiler.
 
 
    This file is part of Bison, the GNU Compiler Compiler.
 

-   Bison is free software; you can redistribute it and/or modify
+   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
    it under the terms of the GNU General Public License as published by

-   the Free Software Foundation; either version 2, or (at your option)
-   any later version.
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.

 
 

-   Bison is distributed in the hope that it will be useful,
+   This program is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License

-   along with Bison; see the file COPYING.  If not, write to
-   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
-   Boston, MA 02110-1301, USA.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

 
 #include <config.h>
 #include "system.h"
 
 #include <config.h>
 #include "system.h"

-#include <assert.h>

 
 

+#include <quote.h>

 #include <quotearg.h>
 
 #include "complain.h"
 #include <quotearg.h>
 
 #include "complain.h"


@@ -31,13 +29,14 @@
 #include "files.h"
 #include "getargs.h"
 #include "gram.h"
 #include "files.h"
 #include "getargs.h"
 #include "gram.h"

-#include "muscle_tab.h"
+#include "muscle-tab.h"

 #include "reader.h"
 #include "symlist.h"
 #include "symtab.h"
 #include "scan-gram.h"
 #include "scan-code.h"
 
 #include "reader.h"
 #include "symlist.h"
 #include "symtab.h"
 #include "scan-gram.h"
 #include "scan-code.h"
 

+static void prepare_percent_define_front_end_variables (void);

 static void check_and_convert_grammar (void);
 
 static symbol_list *grammar = NULL;
 static void check_and_convert_grammar (void);
 
 static symbol_list *grammar = NULL;


@@ -70,27 +69,6 @@ grammar_start_symbol_set (symbol *sym, location loc)
     }
 }
 
     }
 }
 

-
-/*---------------------------------------------------------------------.
-| There are two prologues: one before the first %union and one after.  |
-|  Augment the one specified by POST.                                  |
-`---------------------------------------------------------------------*/
-
-void
-prologue_augment (const char *prologue, location loc, bool post)
-{
-  struct obstack *oout =
-    !post ? &pre_prologue_obstack : &post_prologue_obstack;
-
-  obstack_fgrow1 (oout, "]b4_syncline(%d, [[", loc.start.line);
-  /* FIXME: Protection of M4 characters missing here.  See
-     output.c:escaped_output.  */
-  MUSCLE_OBSTACK_SGROW (oout,
-                       quotearg_style (c_quoting_style, loc.start.file));
-  obstack_sgrow (oout, "]])[\n");
-  obstack_sgrow (oout, prologue);
-}
-

 \f
 
 /*------------------------------------------------------------------------.
 \f
 
 /*------------------------------------------------------------------------.


@@ -148,7 +126,7 @@ record_merge_function_type (int merger, uniqstr type, location declaration_loc)
        merge_function != NULL && merger_find != merger;
        merge_function = merge_function->next)
     merger_find += 1;
        merge_function != NULL && merger_find != merger;
        merge_function = merge_function->next)
     merger_find += 1;

-  assert (merge_function != NULL && merger_find == merger);
+  aver (merge_function != NULL && merger_find == merger);

   if (merge_function->type != NULL && !UNIQSTR_EQ (merge_function->type, type))
     {
       complain_at (declaration_loc,
   if (merge_function->type != NULL && !UNIQSTR_EQ (merge_function->type, type))
     {
       complain_at (declaration_loc,


@@ -193,10 +171,10 @@ free_merger_functions (void)
 static symbol_list *grammar_end = NULL;
 
 /* Append SYM to the grammar.  */
 static symbol_list *grammar_end = NULL;
 
 /* Append SYM to the grammar.  */

-static void
+static symbol_list *

 grammar_symbol_append (symbol *sym, location loc)
 {
 grammar_symbol_append (symbol *sym, location loc)
 {

-  symbol_list *p = symbol_list_new (sym, loc);
+  symbol_list *p = symbol_list_sym_new (sym, loc);

 
   if (grammar_end)
     grammar_end->next = p;
 
   if (grammar_end)
     grammar_end->next = p;


@@ -209,8 +187,27 @@ grammar_symbol_append (symbol *sym, location loc)
      part of it.  */
   if (sym)
     ++nritems;
      part of it.  */
   if (sym)
     ++nritems;

+
+  return p;
+}
+
+static void
+assign_named_ref (symbol_list *p, named_ref *name)
+{
+  symbol *sym = p->content.sym;
+
+  if (name->id == sym->tag)
+    {
+      warn_at (name->loc,
+              _("duplicated symbol name for %s ignored"),
+              quote (sym->tag));
+      named_ref_free (name);
+    }
+  else
+    p->named_ref = name;

 }
 
 }
 

+

 /* The rule currently being defined, and the previous rule.
    CURRENT_RULE points to the first LHS of the current rule, while
    PREVIOUS_RULE_END points to the *end* of the previous rule (NULL).  */
 /* The rule currently being defined, and the previous rule.
    CURRENT_RULE points to the first LHS of the current rule, while
    PREVIOUS_RULE_END points to the *end* of the previous rule (NULL).  */


@@ -223,19 +220,19 @@ static symbol_list *previous_rule_end = NULL;
 `----------------------------------------------*/
 
 void
 `----------------------------------------------*/
 
 void

-grammar_current_rule_begin (symbol *lhs, location loc)
+grammar_current_rule_begin (symbol *lhs, location loc,
+                           named_ref *lhs_name)

 {
 {

-  if (!start_flag)
-    {
-      startsymbol = lhs;
-      startsymbol_location = loc;
-      start_flag = true;
-    }
+  symbol_list* p;

 
   /* Start a new rule and record its lhs.  */
   ++nrules;
   previous_rule_end = grammar_end;
 
   /* Start a new rule and record its lhs.  */
   ++nrules;
   previous_rule_end = grammar_end;

-  grammar_symbol_append (lhs, loc);
+
+  p = grammar_symbol_append (lhs, loc);
+  if (lhs_name)
+    assign_named_ref(p, lhs_name);
+

   current_rule = grammar_end;
 
   /* Mark the rule's lhs as a nonterminal if not already so.  */
   current_rule = grammar_end;
 
   /* Mark the rule's lhs as a nonterminal if not already so.  */


@@ -251,16 +248,25 @@ 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; }".  |
+| A symbol should be used if either:                                    |
+|   1. It has a destructor.                                             |
+|   2. --warnings=midrule-values and the symbol is a mid-rule symbol    |
+|      (i.e., the generated LHS replacing a mid-rule action) that was   |
+|      assigned to or used, as in "exp: { $$ = 1; } { $$ = $1; }".      |

 `----------------------------------------------------------------------*/
 
 static bool
 symbol_should_be_used (symbol_list const *s)
 {
 `----------------------------------------------------------------------*/
 
 static bool
 symbol_should_be_used (symbol_list const *s)
 {

-  return (s->sym->destructor
-         || (s->midrule && s->midrule->used));
+  if (symbol_destructor_get (s->content.sym)->code)
+    return true;
+  if (warnings_flag & warnings_midrule_values)
+    return ((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));
+  return false;

 }
 
 /*----------------------------------------------------------------.
 }
 
 /*----------------------------------------------------------------.


@@ -278,13 +284,13 @@ grammar_rule_check (const symbol_list *r)
 
      Don't worry about the default action if $$ is untyped, since $$'s
      value can't be used.  */
 
      Don't worry about the default action if $$ is untyped, since $$'s
      value can't be used.  */

-  if (!r->action && r->sym->type_name)
+  if (!r->action_props.code && r->content.sym->type_name)

     {
     {

-      symbol *first_rhs = r->next->sym;
+      symbol *first_rhs = r->next->content.sym;

       /* If $$ is being set in default way, report if any type mismatch.  */
       if (first_rhs)
        {
       /* If $$ is being set in default way, report if any type mismatch.  */
       if (first_rhs)
        {

-         char const *lhs_type = r->sym->type_name;
+         char const *lhs_type = r->content.sym->type_name;

          const char *rhs_type =
            first_rhs->type_name ? first_rhs->type_name : "";
          if (!UNIQSTR_EQ (lhs_type, rhs_type))
          const char *rhs_type =
            first_rhs->type_name ? first_rhs->type_name : "";
          if (!UNIQSTR_EQ (lhs_type, rhs_type))


@@ -302,11 +308,11 @@ grammar_rule_check (const symbol_list *r)
   {
     symbol_list const *l = r;
     int n = 0;
   {
     symbol_list const *l = r;
     int n = 0;

-    for (; l && l->sym; l = l->next, ++n)
-      if (! (l->used
+    for (; l && l->content.sym; l = l->next, ++n)
+      if (! (l->action_props.is_value_used

             || !symbol_should_be_used (l)
             /* The default action, $$ = $1, `uses' both.  */
             || !symbol_should_be_used (l)
             /* The default action, $$ = $1, `uses' both.  */

-            || (!r->action && (n == 0 || n == 1))))
+            || (!r->action_props.code && (n == 0 || n == 1))))

        {
          if (n)
            warn_at (r->location, _("unused value: $%d"), n);
        {
          if (n)
            warn_at (r->location, _("unused value: $%d"), n);


@@ -314,6 +320,15 @@ grammar_rule_check (const symbol_list *r)
            warn_at (r->location, _("unset value: $$"));
        }
   }
            warn_at (r->location, _("unset value: $$"));
        }
   }

+
+  /* 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.  */
+  if (r->ruleprec
+      && r->ruleprec->tag[0] != '\'' && r->ruleprec->tag[0] != '"'
+      && !r->ruleprec->declared && !r->ruleprec->prec)
+    warn_at (r->location, _("token for %%prec is not defined: %s"),
+             r->ruleprec->tag);

 }
 
 
 }
 
 


@@ -346,9 +361,12 @@ grammar_midrule_action (void)
 
   /* Make a DUMMY nonterminal, whose location is that of the midrule
      action.  Create the MIDRULE.  */
 
   /* Make a DUMMY nonterminal, whose location is that of the midrule
      action.  Create the MIDRULE.  */

-  location dummy_location = current_rule->action_location;
+  location dummy_location = current_rule->action_props.location;

   symbol *dummy = dummy_symbol_get (dummy_location);
   symbol *dummy = dummy_symbol_get (dummy_location);

-  symbol_list *midrule = symbol_list_new (dummy, dummy_location);
+  symbol_list *midrule = symbol_list_sym_new (dummy, dummy_location);
+
+  /* Remember named_ref of previous action. */
+  named_ref *action_name = current_rule->action_props.named_ref;

 
   /* Make a new rule, whose body is empty, before the current one, so
      that the action just read can belong to it.  */
 
   /* Make a new rule, whose body is empty, before the current one, so
      that the action just read can belong to it.  */


@@ -356,12 +374,12 @@ grammar_midrule_action (void)
   ++nritems;
   /* Attach its location and actions to that of the DUMMY.  */
   midrule->location = dummy_location;
   ++nritems;
   /* Attach its location and actions to that of the DUMMY.  */
   midrule->location = dummy_location;

-  midrule->action = current_rule->action;
-  midrule->action_location = dummy_location;
-  current_rule->action = NULL;
-  /* The action has not been translated yet, so $$ use hasn't been
-     detected yet.  */
-  midrule->used = false;
+  code_props_rule_action_init (&midrule->action_props,
+                               current_rule->action_props.code,
+                               current_rule->action_props.location,
+                               midrule, 0,
+                              current_rule->action_props.is_predicate);
+  code_props_none_init (&current_rule->action_props);

 
   if (previous_rule_end)
     previous_rule_end->next = midrule;
 
   if (previous_rule_end)
     previous_rule_end->next = midrule;


@@ -369,14 +387,15 @@ grammar_midrule_action (void)
     grammar = midrule;
 
   /* End the dummy's rule.  */
     grammar = midrule;
 
   /* End the dummy's rule.  */

-  midrule->next = symbol_list_new (NULL, dummy_location);
+  midrule->next = symbol_list_sym_new (NULL, dummy_location);

   midrule->next->next = current_rule;
 
   previous_rule_end = midrule->next;
 
   /* Insert the dummy nonterminal replacing the midrule action into
      the current rule.  Bind it to its dedicated rule.  */
   midrule->next->next = current_rule;
 
   previous_rule_end = midrule->next;
 
   /* Insert the dummy nonterminal replacing the midrule action into
      the current rule.  Bind it to its dedicated rule.  */

-  grammar_current_rule_symbol_append (dummy, dummy_location);
+  grammar_current_rule_symbol_append (dummy, dummy_location,
+                                      action_name);

   grammar_end->midrule = midrule;
   midrule->midrule_parent_rule = current_rule;
   midrule->midrule_parent_rhs_index = symbol_list_length (current_rule->next);
   grammar_end->midrule = midrule;
   midrule->midrule_parent_rule = current_rule;
   midrule->midrule_parent_rhs_index = symbol_list_length (current_rule->next);


@@ -387,6 +406,17 @@ grammar_midrule_action (void)
 void
 grammar_current_rule_prec_set (symbol *precsym, location loc)
 {
 void
 grammar_current_rule_prec_set (symbol *precsym, location loc)
 {

+  /* POSIX says that any identifier is a nonterminal if it does not
+     appear on the LHS of a grammar rule and is not defined by %token
+     or by one of the directives that assigns precedence to a token.  We
+     ignore this here because the only kind of identifier that POSIX
+     allows to follow a %prec is a token and because assuming it's a
+     token now can produce more logical error messages.  Nevertheless,
+     grammar_rule_check does obey what we believe is the real intent of
+     POSIX here: that an error be reported for any identifier that
+     appears after %prec but that is not defined separately as a
+     token.  */
+  symbol_class_set (precsym, token_sym, loc, false);

   if (current_rule->ruleprec)
     complain_at (loc, _("only one %s allowed per rule"), "%prec");
   current_rule->ruleprec = precsym;
   if (current_rule->ruleprec)
     complain_at (loc, _("only one %s allowed per rule"), "%prec");
   current_rule->ruleprec = precsym;


@@ -424,24 +454,29 @@ grammar_current_rule_merge_set (uniqstr name, location loc)
    action as a mid-rule action.  */
 
 void
    action as a mid-rule action.  */
 
 void

-grammar_current_rule_symbol_append (symbol *sym, location loc)
+grammar_current_rule_symbol_append (symbol *sym, location loc,
+                                   named_ref *name)

 {
 {

-  if (current_rule->action)
+  symbol_list *p;
+  if (current_rule->action_props.code)

     grammar_midrule_action ();
     grammar_midrule_action ();

-  grammar_symbol_append (sym, loc);
+  p = grammar_symbol_append (sym, loc);
+  if (name)
+    assign_named_ref(p, name);

 }
 
 /* Attach an ACTION to the current rule.  */
 
 void
 }
 
 /* Attach an ACTION to the current rule.  */
 
 void

-grammar_current_rule_action_append (const char *action, location loc)
+grammar_current_rule_action_append (const char *action, location loc,
+                                   named_ref *name, bool is_predicate)

 {
 {

-  if (current_rule->action)
+  if (current_rule->action_props.code)

     grammar_midrule_action ();
   /* After all symbol declarations have been parsed, packgram invokes
     grammar_midrule_action ();
   /* After all symbol declarations have been parsed, packgram invokes

-     translate_rule_action.  */
-  current_rule->action = action;
-  current_rule->action_location = loc;
+     code_props_translate_code.  */
+  code_props_rule_action_init (&current_rule->action_props, action, loc,
+                               current_rule, name, is_predicate);

 }
 
 \f
 }
 
 \f


@@ -468,11 +503,11 @@ packgram (void)
     {
       int rule_length = 0;
       symbol *ruleprec = p->ruleprec;
     {
       int rule_length = 0;
       symbol *ruleprec = p->ruleprec;

-      record_merge_function_type (p->merger, p->sym->type_name,
+      record_merge_function_type (p->merger, p->content.sym->type_name,

                                  p->merger_declaration_location);
       rules[ruleno].user_number = ruleno;
       rules[ruleno].number = ruleno;
                                  p->merger_declaration_location);
       rules[ruleno].user_number = ruleno;
       rules[ruleno].number = ruleno;

-      rules[ruleno].lhs = p->sym;
+      rules[ruleno].lhs = p->content.sym;

       rules[ruleno].rhs = ritem + itemno;
       rules[ruleno].prec = NULL;
       rules[ruleno].dprec = p->dprec;
       rules[ruleno].rhs = ritem + itemno;
       rules[ruleno].prec = NULL;
       rules[ruleno].dprec = p->dprec;


@@ -480,17 +515,27 @@ packgram (void)
       rules[ruleno].precsym = NULL;
       rules[ruleno].location = p->location;
       rules[ruleno].useful = true;
       rules[ruleno].precsym = NULL;
       rules[ruleno].location = p->location;
       rules[ruleno].useful = true;

-      rules[ruleno].action = p->action ? translate_rule_action (p) : NULL;
-      rules[ruleno].action_location = p->action_location;
-
-      /* If this rule contains midrules, rest assured that
-        grammar_midrule_action inserted the midrules into grammar before this
-        rule.  Thus, the midrule actions have already been scanned in order to
-        set `used' flags for this rule's rhs, so grammar_rule_check will work
-        properly.  */
-      grammar_rule_check (p);
-
-      for (p = p->next; p && p->sym; p = p->next)
+      rules[ruleno].action = p->action_props.code;
+      rules[ruleno].action_location = p->action_props.location;
+      rules[ruleno].is_predicate = p->action_props.is_predicate;
+
+      /* If the midrule's $$ is set or its $n is used, remove the `$' from the
+        symbol name so that it's a user-defined symbol so that the default
+        %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))
+       p->content.sym->tag += 1;
+
+      /* Don't check the generated rule 0.  It has no action, so some rhs
+        symbols may appear unused, but the parsing algorithm ensures that
+        %destructor's are invoked appropriately.  */
+      if (p != grammar)
+       grammar_rule_check (p);
+
+      for (p = p->next; p && p->content.sym; p = p->next)

        {
          ++rule_length;
 
        {
          ++rule_length;
 


@@ -501,11 +546,12 @@ packgram (void)
 
          /* item_number = symbol_number.
             But the former needs to contain more: negative rule numbers. */
 
          /* item_number = symbol_number.
             But the former needs to contain more: negative rule numbers. */

-         ritem[itemno++] = symbol_number_as_item_number (p->sym->number);
+         ritem[itemno++] =
+            symbol_number_as_item_number (p->content.sym->number);

          /* A rule gets by default the precedence and associativity
             of its last token.  */
          /* A rule gets by default the precedence and associativity
             of its last token.  */

-         if (p->sym->class == token_sym && default_prec)
-           rules[ruleno].prec = p->sym;
+         if (p->content.sym->class == token_sym && default_prec)
+           rules[ruleno].prec = p->content.sym;

        }
 
       /* If this rule has a %prec,
        }
 
       /* If this rule has a %prec,


@@ -517,15 +563,15 @@ packgram (void)
        }
       /* An item ends by the rule number (negated).  */
       ritem[itemno++] = rule_number_as_item_number (ruleno);
        }
       /* An item ends by the rule number (negated).  */
       ritem[itemno++] = rule_number_as_item_number (ruleno);

-      assert (itemno < ITEM_NUMBER_MAX);
+      aver (itemno < ITEM_NUMBER_MAX);

       ++ruleno;
       ++ruleno;

-      assert (ruleno < RULE_NUMBER_MAX);
+      aver (ruleno < RULE_NUMBER_MAX);

 
       if (p)
        p = p->next;
     }
 
 
       if (p)
        p = p->next;
     }
 

-  assert (itemno == nritems);
+  aver (itemno == nritems);

 
   if (trace_flag & trace_sets)
     ritem_print (stderr);
 
   if (trace_flag & trace_sets)
     ritem_print (stderr);


@@ -560,16 +606,13 @@ reader (void)
   undeftoken->class = token_sym;
   undeftoken->number = ntokens++;
 
   undeftoken->class = token_sym;
   undeftoken->number = ntokens++;
 

-  /* Initialize the obstacks. */
-  obstack_init (&pre_prologue_obstack);
-  obstack_init (&post_prologue_obstack);
-

   gram_in = xfopen (grammar_file, "r");
 
   gram__flex_debug = trace_flag & trace_scan;
   gram_debug = trace_flag & trace_parse;
   gram_scanner_initialize ();
   gram_parse ();
   gram_in = xfopen (grammar_file, "r");
 
   gram__flex_debug = trace_flag & trace_scan;
   gram_debug = trace_flag & trace_parse;
   gram_scanner_initialize ();
   gram_parse ();

+  prepare_percent_define_front_end_variables ();

 
   if (! complaint_issued)
     check_and_convert_grammar ();
 
   if (! complaint_issued)
     check_and_convert_grammar ();


@@ -577,6 +620,35 @@ reader (void)
   xfclose (gram_in);
 }
 
   xfclose (gram_in);
 }
 

+static void
+prepare_percent_define_front_end_variables (void)
+{
+  /* Set %define front-end variable defaults.  */
+  muscle_percent_define_default ("lr.keep-unreachable-states", "false");
+  {
+    char *lr_type;
+    /* IELR would be a better default, but LALR is historically the
+       default.  */
+    muscle_percent_define_default ("lr.type", "lalr");
+    lr_type = muscle_percent_define_get ("lr.type");
+    if (0 != strcmp (lr_type, "canonical-lr"))
+      muscle_percent_define_default ("lr.default-reductions", "all");
+    else
+      muscle_percent_define_default ("lr.default-reductions", "accepting");
+    free (lr_type);
+  }
+
+  /* Check %define front-end variables.  */
+  {
+    static char const * const values[] = {
+      "lr.type", "lalr", "ielr", "canonical-lr", NULL,
+      "lr.default-reductions", "all", "consistent", "accepting", NULL,
+      NULL
+    };
+    muscle_percent_define_check_values (values);
+  }
+}
+

 
 /*-------------------------------------------------------------.
 | Check the grammar that has just been read, and convert it to |
 
 /*-------------------------------------------------------------.
 | Check the grammar that has just been read, and convert it to |


@@ -590,9 +662,6 @@ check_and_convert_grammar (void)
   if (nrules == 0)
     fatal (_("no rules in the input grammar"));
 
   if (nrules == 0)
     fatal (_("no rules in the input grammar"));
 

-  /* Report any undefined symbols and consider them nonterminals.  */
-  symbols_check_defined ();
-

   /* If the user did not define her ENDTOKEN, do it now. */
   if (!endtoken)
     {
   /* If the user did not define her ENDTOKEN, do it now. */
   if (!endtoken)
     {


@@ -603,31 +672,69 @@ check_and_convert_grammar (void)
       endtoken->user_token_number = 0;
     }
 
       endtoken->user_token_number = 0;
     }
 

+  /* Report any undefined symbols and consider them nonterminals.  */
+  symbols_check_defined ();
+
+  /* Find the start symbol if no %start.  */
+  if (!start_flag)
+    {
+      symbol_list *node;
+      for (node = grammar;
+           node != NULL && symbol_is_dummy (node->content.sym);
+           node = node->next)
+        {
+          for (node = node->next;
+               node != NULL && node->content.sym != NULL;
+               node = node->next)
+            ;
+        }
+      aver (node != NULL);
+      grammar_start_symbol_set (node->content.sym,
+                                node->content.sym->location);
+    }
+

   /* Insert the initial rule, whose line is that of the first rule
      (not that of the start symbol):
 
      accept: %start EOF.  */
   {
   /* Insert the initial rule, whose line is that of the first rule
      (not that of the start symbol):
 
      accept: %start EOF.  */
   {

-    symbol_list *p = symbol_list_new (accept, empty_location);
+    symbol_list *p = symbol_list_sym_new (accept, empty_location);

     p->location = grammar->location;
     p->location = grammar->location;

-    p->next = symbol_list_new (startsymbol, empty_location);
-    p->next->next = symbol_list_new (endtoken, empty_location);
-    p->next->next->next = symbol_list_new (NULL, empty_location);
+    p->next = symbol_list_sym_new (startsymbol, empty_location);
+    p->next->next = symbol_list_sym_new (endtoken, empty_location);
+    p->next->next->next = symbol_list_sym_new (NULL, empty_location);

     p->next->next->next->next = grammar;
     nrules += 1;
     nritems += 3;
     grammar = p;
   }
 
     p->next->next->next->next = grammar;
     nrules += 1;
     nritems += 3;
     grammar = p;
   }
 

-  assert (nsyms <= SYMBOL_NUMBER_MAXIMUM && nsyms == ntokens + nvars);
+  aver (nsyms <= SYMBOL_NUMBER_MAXIMUM && nsyms == ntokens + nvars);

 
   /* Assign the symbols their symbol numbers.  Write #defines for the
      token symbols into FDEFINES if requested.  */
   symbols_pack ();
 
 
   /* Assign the symbols their symbol numbers.  Write #defines for the
      token symbols into FDEFINES if requested.  */
   symbols_pack ();
 

+  /* Scan rule actions after invoking symbol_check_alias_consistency (in
+     symbols_pack above) so that token types are set correctly before the rule
+     action type checking.
+
+     Before invoking grammar_rule_check (in packgram below) on any rule, make
+     sure all actions have already been scanned in order to set `used' flags.
+     Otherwise, checking that a midrule's $$ should be set will not always work
+     properly because the check must forward-reference the midrule's parent
+     rule.  For the same reason, all the `used' flags must be set before
+     checking whether to remove `$' from any midrule symbol name (also in
+     packgram).  */
+  {
+    symbol_list *sym;
+    for (sym = grammar; sym; sym = sym->next)
+      code_props_translate_code (&sym->action_props);
+  }
+

   /* Convert the grammar into the format described in gram.h.  */
   packgram ();
 
   /* The grammar as a symbol_list is no longer needed. */
   /* Convert the grammar into the format described in gram.h.  */
   packgram ();
 
   /* The grammar as a symbol_list is no longer needed. */

-  LIST_FREE (symbol_list, grammar);
+  symbol_list_free (grammar);

 }
 }