doc: clean up references to `Tracking Locations'.

[bison.git] / src / reader.c

diff --git a/src/reader.c b/src/reader.c
index 0adee6fc8c5c301632364e0485ea05186f43e7f6..20f81d687fec8c4344bf70e70e293116845aada0 100644 (file)
--- a/src/reader.c
+++ b/src/reader.c
@@ -1,27 +1,27 @@
 /* Input parser for Bison
 
 /* Input parser for Bison
 

-   Copyright (C) 1984, 1986, 1989, 1992, 1998, 2000, 2001, 2002, 2003
-   Free Software Foundation, Inc.
+   Copyright (C) 1984, 1986, 1989, 1992, 1998, 2000-2003, 2005-2007,
+   2009-2011 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., 59 Temple Place - Suite 330,
-   Boston, MA 02111-1307, USA.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

 
 

+#include <config.h>

 #include "system.h"
 
 #include "system.h"
 

+#include <quote.h>

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


@@ -29,18 +29,28 @@
 #include "files.h"
 #include "getargs.h"
 #include "gram.h"
 #include "files.h"
 #include "getargs.h"
 #include "gram.h"

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

 #include "reader.h"
 #include "symlist.h"
 #include "symtab.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 bool start_flag = false;
 merger_list *merge_functions;
 
 
 static symbol_list *grammar = NULL;
 static bool start_flag = false;
 merger_list *merge_functions;
 

-/* Has %union been seen?  */
-bool typed = false;
+/* Was %union seen?  */
+bool union_seen = false;
+
+/* Was a tag seen?  */
+bool tag_seen = false;
+
+/* Should rules have a default precedence?  */
+bool default_prec = true;

 \f
 /*-----------------------.
 | Set the start symbol.  |
 \f
 /*-----------------------.
 | Set the start symbol.  |


@@ -59,35 +69,15 @@ grammar_start_symbol_set (symbol *sym, location loc)
     }
 }
 
     }
 }
 

-
-/*----------------------------------------------------------------.
-| There are two prologues: one before %union, one after.  Augment |
-| the current one.                                                |
-`----------------------------------------------------------------*/
-
-void
-prologue_augment (const char *prologue, location loc)
-{
-  struct obstack *oout =
-    !typed ? &pre_prologue_obstack : &post_prologue_obstack;
-
-  obstack_fgrow1 (oout, "]b4_syncline([[%d]], [[", loc.start.line);
-  MUSCLE_OBSTACK_SGROW (oout,
-                       quotearg_style (c_quoting_style, loc.start.file));
-  obstack_sgrow (oout, "]])[\n");
-  obstack_sgrow (oout, prologue);
-}
-

 \f
 
 \f
 

-/*-------------------------------------------------------------------.
-| Return the merger index for a merging function named NAME, whose   |
-| arguments have type TYPE.  Records the function, if new, in        |
-| MERGER_LIST.                                                      |
-`-------------------------------------------------------------------*/
+/*------------------------------------------------------------------------.
+| Return the merger index for a merging function named NAME.  Records the |
+| function, if new, in MERGER_LIST.                                       |
+`------------------------------------------------------------------------*/

 
 static int
 
 static int

-get_merge_function (uniqstr name, uniqstr type, location loc)
+get_merge_function (uniqstr name)

 {
   merger_list *syms;
   merger_list head;
 {
   merger_list *syms;
   merger_list head;


@@ -96,27 +86,59 @@ get_merge_function (uniqstr name, uniqstr type, location loc)
   if (! glr_parser)
     return 0;
 
   if (! glr_parser)
     return 0;
 

-  if (type == NULL)
-    type = uniqstr_new ("");
-

   head.next = merge_functions;
   head.next = merge_functions;

-  for (syms = &head, n = 1; syms->next != NULL; syms = syms->next, n += 1)
+  for (syms = &head, n = 1; syms->next; syms = syms->next, n += 1)

     if (UNIQSTR_EQ (name, syms->next->name))
       break;
   if (syms->next == NULL)
     {
     if (UNIQSTR_EQ (name, syms->next->name))
       break;
   if (syms->next == NULL)
     {

-      MALLOC (syms->next, 1);
+      syms->next = xmalloc (sizeof syms->next[0]);

       syms->next->name = uniqstr_new (name);
       syms->next->name = uniqstr_new (name);

-      syms->next->type = uniqstr_new (type);
+      /* After all symbol type declarations have been parsed, packgram invokes
+        record_merge_function_type to set the type.  */
+      syms->next->type = NULL;

       syms->next->next = NULL;
       merge_functions = head.next;
     }
       syms->next->next = NULL;
       merge_functions = head.next;
     }

-  else if (!UNIQSTR_EQ (type, syms->next->type))
-    warn_at (loc, _("result type clash on merge function %s: <%s> != <%s>"),
-            name, type, syms->next->type);

   return n;
 }
 
   return n;
 }
 

+/*-------------------------------------------------------------------------.
+| For the existing merging function with index MERGER, record the result   |
+| type as TYPE as required by the lhs of the rule whose %merge declaration |
+| is at DECLARATION_LOC.                                                   |
+`-------------------------------------------------------------------------*/
+
+static void
+record_merge_function_type (int merger, uniqstr type, location declaration_loc)
+{
+  int merger_find;
+  merger_list *merge_function;
+
+  if (merger <= 0)
+    return;
+
+  if (type == NULL)
+    type = uniqstr_new ("");
+
+  merger_find = 1;
+  for (merge_function = merge_functions;
+       merge_function != NULL && merger_find != merger;
+       merge_function = merge_function->next)
+    merger_find += 1;
+  aver (merge_function != NULL && merger_find == merger);
+  if (merge_function->type != NULL && !UNIQSTR_EQ (merge_function->type, type))
+    {
+      complain_at (declaration_loc,
+                  _("result type clash on merge function `%s': <%s> != <%s>"),
+                  merge_function->name, type, merge_function->type);
+      complain_at (merge_function->type_declaration_location,
+                  _("previous declaration"));
+    }
+  merge_function->type = uniqstr_new (type);
+  merge_function->type_declaration_location = declaration_loc;
+}
+

 /*--------------------------------------.
 | Free all merge-function definitions. |
 `--------------------------------------*/
 /*--------------------------------------.
 | Free all merge-function definitions. |
 `--------------------------------------*/


@@ -124,11 +146,8 @@ get_merge_function (uniqstr name, uniqstr type, location loc)
 void
 free_merger_functions (void)
 {
 void
 free_merger_functions (void)
 {

-  merger_list *L0;
-  if (! glr_parser)
-    return;
-  L0 = merge_functions;
-  while (L0 != NULL)
+  merger_list *L0 = merge_functions;
+  while (L0)

     {
       merger_list *L1 = L0->next;
       free (L0);
     {
       merger_list *L1 = L0->next;
       free (L0);


@@ -146,23 +165,16 @@ free_merger_functions (void)
 |                                                                    |
 | All actions are copied out, labelled by the rule number they apply |
 | to.                                                                |
 |                                                                    |
 | All actions are copied out, labelled by the rule number they apply |
 | to.                                                                |

-|                                                                    |
-| Bison used to allow some %directives in the rules sections, but    |
-| this is no longer consider appropriate: (i) the documented grammar |
-| doesn't claim it, (ii), it would promote bad style, (iii), error   |
-| recovery for %directives consists in skipping the junk until a `%' |
-| is seen and helrp synchronizing.  This scheme is definitely wrong  |
-| in the rules section.                                              |

 `-------------------------------------------------------------------*/
 
 /* The (currently) last symbol of GRAMMAR. */
 `-------------------------------------------------------------------*/
 
 /* The (currently) last symbol of GRAMMAR. */

-symbol_list *grammar_end = NULL;
+static symbol_list *grammar_end = NULL;

 
 /* Append SYM to the grammar.  */
 
 /* Append SYM to the grammar.  */

-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;


@@ -170,13 +182,37 @@ grammar_symbol_append (symbol *sym, location loc)
     grammar = p;
 
   grammar_end = p;
     grammar = p;
 
   grammar_end = p;

+
+  /* A null SYM stands for an end of rule; it is not an actual
+     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).  */

-symbol_list *current_rule = NULL;
-symbol_list *previous_rule_end = NULL;
+static symbol_list *current_rule = NULL;
+static symbol_list *previous_rule_end = NULL;

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


@@ -184,25 +220,22 @@ symbol_list *previous_rule_end = NULL;
 `----------------------------------------------*/
 
 void
 `----------------------------------------------*/
 
 void

-grammar_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;
 
   /* Start a new rule and record its lhs.  */
   ++nrules;

-  ++nritems;
-

   previous_rule_end = grammar_end;
   previous_rule_end = grammar_end;

-  grammar_symbol_append (lhs, loc);
+
+  p = grammar_symbol_append (lhs, loc);
+  if (lhs_name)
+    assign_named_ref (p, named_ref_copy (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.  */

-

   if (lhs->class == unknown_sym)
     {
       lhs->class = nterm_sym;
   if (lhs->class == unknown_sym)
     {
       lhs->class = nterm_sym;


@@ -213,39 +246,97 @@ grammar_rule_begin (symbol *lhs, location loc)
     complain_at (loc, _("rule given for %s, which is a token"), lhs->tag);
 }
 
     complain_at (loc, _("rule given for %s, which is a token"), lhs->tag);
 }
 

-/* Check that the last rule (CURRENT_RULE) is properly defined.  For
-   instance, there should be no type clash on the default action.  */
+
+/*----------------------------------------------------------------------.
+| A symbol should be used if either:                                    |
+|   1. It has a destructor.                                             |
+|   2. 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, bool *midrule_warning)
+{
+  if (symbol_destructor_get (s->content.sym)->code)
+    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))
+    {
+      *midrule_warning = true;
+      return true;
+    }
+  return false;
+}
+
+/*----------------------------------------------------------------.
+| Check that the rule R is properly defined.  For instance, there |
+| should be no type clash on the default action.                  |
+`----------------------------------------------------------------*/

 
 static void
 
 static void

-grammar_current_rule_check (void)
+grammar_rule_check (const symbol_list *r)

 {
 {

-  symbol *lhs = current_rule->sym;
-  char const *lhs_type = lhs->type_name;
-  symbol *first_rhs = current_rule->next->sym;
+  /* Type check.

 
 

-  /* If there is an action, then there is nothing we can do: the user
-     is allowed to shoot herself in the foot.  */
-  if (current_rule->action)
-    return;
+     If there is an action, then there is nothing we can do: the user
+     is allowed to shoot herself in the foot.

 
 

-  /* Don't worry about the default action if $$ is untyped, since $$'s
+     Don't worry about the default action if $$ is untyped, since $$'s

      value can't be used.  */
      value can't be used.  */

-  if (! lhs_type)
-    return;
-
-  /* If $$ is being set in default way, report if any type mismatch.  */
-  if (first_rhs)
+  if (!r->action_props.code && r->content.sym->type_name)

     {
     {

-      const char *rhs_type = first_rhs->type_name ? first_rhs->type_name : "";
-      if (!UNIQSTR_EQ (lhs_type, rhs_type))
-       warn_at (current_rule->location,
-                _("type clash on default action: <%s> != <%s>"),
-                lhs_type, rhs_type);
+      symbol *first_rhs = r->next->content.sym;
+      /* If $$ is being set in default way, report if any type mismatch.  */
+      if (first_rhs)
+       {
+         char const *lhs_type = r->content.sym->type_name;
+         const char *rhs_type =
+           first_rhs->type_name ? first_rhs->type_name : "";
+         if (!UNIQSTR_EQ (lhs_type, rhs_type))
+           warn_at (r->location,
+                    _("type clash on default action: <%s> != <%s>"),
+                    lhs_type, rhs_type);
+       }
+      /* Warn if there is no default for $$ but we need one.  */
+      else
+       warn_at (r->location,
+                _("empty rule for typed nonterminal, and no action"));

     }
     }

-  /* Warn if there is no default for $$ but we need one.  */
-  else
-    warn_at (current_rule->location,
-            _("empty rule for typed nonterminal, and no action"));
+
+  /* Check that symbol values that should be used are in fact used.  */
+  {
+    symbol_list const *l = r;
+    int n = 0;
+    for (; l && l->content.sym; l = l->next, ++n)
+      {
+        bool midrule_warning = false;
+        if (!l->action_props.is_value_used
+            && symbol_should_be_used (l, &midrule_warning)
+            /* The default action, $$ = $1, `uses' both.  */
+            && (r->action_props.code || (n != 0 && n != 1)))
+          {
+            void (*warn_at_ptr)(location, char const*, ...) =
+              midrule_warning ? midrule_value_at : warn_at;
+            if (n)
+              warn_at_ptr (r->location, _("unused value: $%d"), n);
+            else
+              warn_at_ptr (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);

 }
 
 
 }
 
 


@@ -254,12 +345,11 @@ grammar_current_rule_check (void)
 `-------------------------------------*/
 
 void
 `-------------------------------------*/
 
 void

-grammar_rule_end (location loc)
+grammar_current_rule_end (location loc)

 {
   /* Put an empty link in the list to mark the end of this rule  */
   grammar_symbol_append (NULL, grammar_end->location);
   current_rule->location = loc;
 {
   /* Put an empty link in the list to mark the end of this rule  */
   grammar_symbol_append (NULL, grammar_end->location);
   current_rule->location = loc;

-  grammar_current_rule_check ();

 }
 
 
 }
 
 


@@ -279,9 +369,12 @@ 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.  */


@@ -289,9 +382,12 @@ 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;
+  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;


@@ -299,14 +395,18 @@ grammar_midrule_action (void)
     grammar = midrule;
 
   /* End the dummy's rule.  */
     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_sym_new (NULL, dummy_location);
+  midrule->next->next = current_rule;

 
 

-  midrule->next = previous_rule_end;
+  previous_rule_end = midrule->next;

 
   /* Insert the dummy nonterminal replacing the midrule action into
 
   /* Insert the dummy nonterminal replacing the midrule action into

-     the current rule.  */
-  grammar_current_rule_symbol_append (dummy, dummy_location);
+     the current rule.  Bind it to its dedicated rule.  */
+  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);

 }
 
 /* Set the precedence symbol of the current rule to PRECSYM. */
 }
 
 /* Set the precedence symbol of the current rule to PRECSYM. */


@@ -314,6 +414,17 @@ 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;


@@ -343,32 +454,37 @@ grammar_current_rule_merge_set (uniqstr name, location loc)
     warn_at (loc, _("%s affects only GLR parsers"), "%merge");
   if (current_rule->merger != 0)
     complain_at (loc, _("only one %s allowed per rule"), "%merge");
     warn_at (loc, _("%s affects only GLR parsers"), "%merge");
   if (current_rule->merger != 0)
     complain_at (loc, _("only one %s allowed per rule"), "%merge");

-  current_rule->merger =
-    get_merge_function (name, current_rule->sym->type_name, loc);
+  current_rule->merger = get_merge_function (name);
+  current_rule->merger_declaration_location = loc;

 }
 
 /* Attach SYM to the current rule.  If needed, move the previous
    action as a mid-rule action.  */
 
 void
 }
 
 /* Attach SYM to the current rule.  If needed, move the previous
    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 ();

-  ++nritems;
-  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.  If needed, move the previous
-   action as a mid-rule action.  */
+/* Attach an ACTION to the current rule.  */

 
 void
 
 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 ();
     grammar_midrule_action ();

-  current_rule->action = action;
-  current_rule->action_location = loc;
+  /* After all symbol declarations have been parsed, packgram invokes
+     code_props_translate_code.  */
+  code_props_rule_action_init (&current_rule->action_props, action, loc,
+                               current_rule, name, is_predicate);

 }
 
 \f
 }
 
 \f


@@ -384,35 +500,66 @@ packgram (void)
   rule_number ruleno = 0;
   symbol_list *p = grammar;
 
   rule_number ruleno = 0;
   symbol_list *p = grammar;
 

-  CALLOC (ritem, nritems);
-  CALLOC (rules, nrules);
+  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)
     {
 
   while (p)
     {

+      int rule_length = 0;

       symbol *ruleprec = p->ruleprec;
       symbol *ruleprec = p->ruleprec;

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

       rules[ruleno].user_number = ruleno;
       rules[ruleno].number = ruleno;
       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].rhs = ritem + itemno;

-      rules[ruleno].location = p->location;
-      rules[ruleno].useful = true;
-      rules[ruleno].action = p->action;
-      rules[ruleno].action_location = p->action_location;
+      rules[ruleno].prec = NULL;

       rules[ruleno].dprec = p->dprec;
       rules[ruleno].merger = p->merger;
       rules[ruleno].dprec = p->dprec;
       rules[ruleno].merger = p->merger;

-
-      p = p->next;
-      while (p && p->sym)
+      rules[ruleno].precsym = NULL;
+      rules[ruleno].location = p->location;
+      rules[ruleno].useful = true;
+      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;
+
+         /* Don't allow rule_length == INT_MAX, since that might
+            cause confusion with strtol if INT_MAX == LONG_MAX.  */
+         if (rule_length == INT_MAX)
+             fatal_at (rules[ruleno].location, _("rule is too long"));
+

          /* 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
          /* A rule gets by default the precedence and associativity

-            of the last token in it.  */
-         if (p->sym->class == token_sym)
-           rules[ruleno].prec = p->sym;
-         if (p)
-           p = p->next;
+            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,
        }
 
       /* If this rule has a %prec,


@@ -422,15 +569,17 @@ packgram (void)
          rules[ruleno].precsym = ruleprec;
          rules[ruleno].prec = ruleprec;
        }
          rules[ruleno].precsym = ruleprec;
          rules[ruleno].prec = ruleprec;
        }

+      /* An item ends by the rule number (negated).  */

       ritem[itemno++] = rule_number_as_item_number (ruleno);
       ritem[itemno++] = rule_number_as_item_number (ruleno);

+      aver (itemno < ITEM_NUMBER_MAX);

       ++ruleno;
       ++ruleno;

+      aver (ruleno < RULE_NUMBER_MAX);

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

-  if (itemno != nritems)
-    abort ();
+  aver (itemno == nritems);

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


@@ -465,30 +614,62 @@ 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);
-
-  finput = xfopen (grammar_file, "r");
-  gram_in = finput;
+  gram_in = xfopen (grammar_file, "r");

 
   gram__flex_debug = trace_flag & trace_scan;
   gram_debug = trace_flag & trace_parse;
 
   gram__flex_debug = trace_flag & trace_scan;
   gram_debug = trace_flag & trace_parse;

-  scanner_initialize ();
+  gram_scanner_initialize ();

   gram_parse ();
   gram_parse ();

+  prepare_percent_define_front_end_variables ();

 
 

-  /* If something went wrong during the parsing, don't try to
-     continue.  */
-  if (complaint_issued)
-    return;
+  if (! complaint_issued)
+    check_and_convert_grammar ();

 
 

-  /* Grammar has been read.  Do some checking */
+  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", "most");
+    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", "most", "consistent", "accepting", NULL,
+      NULL
+    };
+    muscle_percent_define_check_values (values);
+  }
+}
+
+
+/*-------------------------------------------------------------.
+| 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"));
 
   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)
     {


@@ -499,34 +680,69 @@ reader (void)
       endtoken->user_token_number = 0;
     }
 
       endtoken->user_token_number = 0;
     }
 

-  /* Insert the initial rule, which line is that of the first rule
+  /* 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.  */
   {
      (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;
   }
 

-  if (! (nsyms <= SYMBOL_NUMBER_MAXIMUM && nsyms == ntokens + nvars))
-    abort ();
-
-  xfclose (finput);
+  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);

 }
 }