NEWS: update.

[bison.git] / src / output.c

diff --git a/src/output.c b/src/output.c
index ad9e5a97a9b30a9bdb2d8eab64801e691dbdb731..c481e14e9cac8960b168c80afa9e624efd334f9b 100644 (file)
--- a/src/output.c
+++ b/src/output.c
@@ -1,53 +1,50 @@
 /* Output the generated parsing program for Bison.
 
 /* Output the generated parsing program for Bison.
 

-   Copyright (C) 1984, 1986, 1989, 1992, 2000, 2001, 2002
-   Free Software Foundation, Inc.
+   Copyright (C) 1984, 1986, 1989, 1992, 2000-2012 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 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.
+   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
+   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, 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.
+   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
 
    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 <configmake.h>

 #include <error.h>
 #include <get-errno.h>
 #include <quotearg.h>
 #include <error.h>
 #include <get-errno.h>
 #include <quotearg.h>

-#include <subpipe.h>
+#include <spawn-pipe.h>

 #include <timevar.h>
 #include <timevar.h>

+#include <wait-process.h>

 
 #include "complain.h"
 #include "files.h"
 #include "getargs.h"
 #include "gram.h"
 
 #include "complain.h"
 #include "files.h"
 #include "getargs.h"
 #include "gram.h"

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

 #include "output.h"
 #include "reader.h"
 #include "output.h"
 #include "reader.h"

+#include "scan-code.h"    /* max_left_semantic_context */
+#include "scan-skel.h"

 #include "symtab.h"
 #include "tables.h"
 
 #include "symtab.h"
 #include "tables.h"
 

-/* From src/scan-skel.l. */
-void scan_skel (FILE *);
-
+# define ARRAY_CARDINALITY(Array) (sizeof (Array) / sizeof *(Array))

 
 static struct obstack format_obstack;
 
 
 static struct obstack format_obstack;
 

-int error_verbose = 0;
-
-

 
 /*-------------------------------------------------------------------.
 | Create a function NAME which associates to the muscle NAME the     |
 
 /*-------------------------------------------------------------------.
 | Create a function NAME which associates to the muscle NAME the     |


@@ -60,7 +57,7 @@ int error_verbose = 0;
 #define GENERATE_MUSCLE_INSERT_TABLE(Name, Type)                       \
                                                                        \
 static void                                                            \
 #define GENERATE_MUSCLE_INSERT_TABLE(Name, Type)                       \
                                                                        \
 static void                                                            \

-Name (const char *name,                                                        \
+Name (char const *name,                                                        \

       Type *table_data,                                                        \
       Type first,                                                      \
       int begin,                                                       \
       Type *table_data,                                                        \
       Type first,                                                      \
       int begin,                                                       \


@@ -106,7 +103,6 @@ Name (const char *name,                                                     \
 
 GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_unsigned_int_table, unsigned int)
 GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_int_table, int)
 
 GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_unsigned_int_table, unsigned int)
 GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_int_table, int)

-GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_short_table, short)

 GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_base_table, base_number)
 GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_rule_number_table, rule_number)
 GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_symbol_number_table, symbol_number)
 GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_base_table, base_number)
 GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_rule_number_table, rule_number)
 GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_symbol_number_table, symbol_number)


@@ -114,17 +110,17 @@ GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_item_number_table, item_number)
 GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_state_number_table, state_number)
 
 
 GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_state_number_table, state_number)
 
 

-/*----------------------------------------------------------------------.
-| Print to OUT a representation of FILENAME escaped both for C and M4.  |
-`----------------------------------------------------------------------*/
+/*--------------------------------------------------------------------.
+| Print to OUT a representation of STRING escaped both for C and M4.  |
+`--------------------------------------------------------------------*/

 
 static void
 
 static void

-escaped_file_name_output (FILE *out, char const *filename)
+escaped_output (FILE *out, char const *string)

 {
   char const *p;
   fprintf (out, "[[");
 
 {
   char const *p;
   fprintf (out, "[[");
 

-  for (p = quotearg_style (c_quoting_style, filename); *p; p++)
+  for (p = quotearg_style (c_quoting_style, string); *p; p++)

     switch (*p)
       {
       case '$': fputs ("$][", out); break;
     switch (*p)
       {
       case '$': fputs ("$][", out); break;


@@ -146,6 +142,7 @@ escaped_file_name_output (FILE *out, char const *filename)
 static void
 prepare_symbols (void)
 {
 static void
 prepare_symbols (void)
 {

+  MUSCLE_INSERT_BOOL ("token_table", token_table_flag);

   MUSCLE_INSERT_INT ("tokens_number", ntokens);
   MUSCLE_INSERT_INT ("nterms_number", nvars);
   MUSCLE_INSERT_INT ("undef_token_number", undeftoken->number);
   MUSCLE_INSERT_INT ("tokens_number", ntokens);
   MUSCLE_INSERT_INT ("nterms_number", nvars);
   MUSCLE_INSERT_INT ("undef_token_number", undeftoken->number);


@@ -159,31 +156,33 @@ prepare_symbols (void)
   /* tname -- token names.  */
   {
     int i;
   /* tname -- token names.  */
   {
     int i;

-    int j = 0;
+    /* We assume that the table will be output starting at column 2. */
+    int j = 2;
+    struct quoting_options *qo = clone_quoting_options (0);
+    set_quoting_style (qo, c_quoting_style);
+    set_quoting_flags (qo, QA_SPLIT_TRIGRAPHS);

     for (i = 0; i < nsyms; i++)
       {
     for (i = 0; i < nsyms; i++)
       {

-       /* Be sure not to use twice the same QUOTEARG slot:
-          SYMBOL_TAG_GET uses slot 0.  */
-       const char *cp =
-         quotearg_n_style (1, c_quoting_style,
-                           symbols[i]->tag);
-       /* Width of the next token, including the two quotes, the comma
-          and the space.  */
+       char *cp = quotearg_alloc (symbols[i]->tag, -1, qo);
+       /* Width of the next token, including the two quotes, the
+          comma and the space.  */

        int width = strlen (cp) + 2;
 
        if (j + width > 75)
          {
        int width = strlen (cp) + 2;
 
        if (j + width > 75)
          {

-           obstack_sgrow (&format_obstack, "\n  ");
-           j = 2;
+           obstack_sgrow (&format_obstack, "\n ");
+           j = 1;

          }
 
          }
 

+       if (i)
+         obstack_1grow (&format_obstack, ' ');

        MUSCLE_OBSTACK_SGROW (&format_obstack, cp);
        MUSCLE_OBSTACK_SGROW (&format_obstack, cp);

-       obstack_sgrow (&format_obstack, ", ");
+        free (cp);
+       obstack_1grow (&format_obstack, ',');

        j += width;
       }
        j += width;
       }

-    /* Add a NULL entry to list of tokens (well, 0, as NULL might not be
-       defined).  */
-    obstack_sgrow (&format_obstack, "0");
+    free (qo);
+    obstack_sgrow (&format_obstack, " ]b4_null[");

 
     /* Finish table and store. */
     obstack_1grow (&format_obstack, 0);
 
     /* Finish table and store. */
     obstack_1grow (&format_obstack, 0);


@@ -193,7 +192,7 @@ prepare_symbols (void)
   /* Output YYTOKNUM. */
   {
     int i;
   /* Output YYTOKNUM. */
   {
     int i;

-    int *values = MALLOC (values, ntokens);
+    int *values = xnmalloc (ntokens, sizeof *values);

     for (i = 0; i < ntokens; ++i)
       values[i] = symbols[i]->user_token_number;
     muscle_insert_int_table ("toknum", values,
     for (i = 0; i < ntokens; ++i)
       values[i] = symbols[i]->user_token_number;
     muscle_insert_int_table ("toknum", values,


@@ -213,13 +212,13 @@ prepare_rules (void)
 {
   rule_number r;
   unsigned int i = 0;
 {
   rule_number r;
   unsigned int i = 0;

-  item_number *rhs = MALLOC (rhs, nritems);
-  unsigned int *prhs = MALLOC (prhs, nrules);
-  unsigned int *rline = MALLOC (rline, nrules);
-  symbol_number *r1 = MALLOC (r1, nrules);
-  unsigned int *r2 = MALLOC (r2, nrules);
-  short *dprec = MALLOC (dprec, nrules);
-  short *merger = MALLOC (merger, nrules);
+  item_number *rhs = xnmalloc (nritems, sizeof *rhs);
+  unsigned int *prhs = xnmalloc (nrules, sizeof *prhs);
+  unsigned int *rline = xnmalloc (nrules, sizeof *rline);
+  symbol_number *r1 = xnmalloc (nrules, sizeof *r1);
+  unsigned int *r2 = xnmalloc (nrules, sizeof *r2);
+  int *dprec = xnmalloc (nrules, sizeof *dprec);
+  int *merger = xnmalloc (nrules, sizeof *merger);

 
   for (r = 0; r < nrules; ++r)
     {
 
   for (r = 0; r < nrules; ++r)
     {


@@ -242,18 +241,18 @@ prepare_rules (void)
       /* Merger-function index (GLR).  */
       merger[r] = rules[r].merger;
     }
       /* Merger-function index (GLR).  */
       merger[r] = rules[r].merger;
     }

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

 
   muscle_insert_item_number_table ("rhs", rhs, ritem[0], 1, nritems);
   muscle_insert_unsigned_int_table ("prhs", prhs, 0, 0, nrules);
   muscle_insert_unsigned_int_table ("rline", rline, 0, 0, nrules);
   muscle_insert_symbol_number_table ("r1", r1, 0, 0, nrules);
   muscle_insert_unsigned_int_table ("r2", r2, 0, 0, nrules);
 
   muscle_insert_item_number_table ("rhs", rhs, ritem[0], 1, nritems);
   muscle_insert_unsigned_int_table ("prhs", prhs, 0, 0, nrules);
   muscle_insert_unsigned_int_table ("rline", rline, 0, 0, nrules);
   muscle_insert_symbol_number_table ("r1", r1, 0, 0, nrules);
   muscle_insert_unsigned_int_table ("r2", r2, 0, 0, nrules);

-  muscle_insert_short_table ("dprec", dprec, 0, 0, nrules);
-  muscle_insert_short_table ("merger", merger, 0, 0, nrules);
+  muscle_insert_int_table ("dprec", dprec, 0, 0, nrules);
+  muscle_insert_int_table ("merger", merger, 0, 0, nrules);

 
   MUSCLE_INSERT_INT ("rules_number", nrules);
 
   MUSCLE_INSERT_INT ("rules_number", nrules);

+  MUSCLE_INSERT_INT ("max_left_semantic_context", max_left_semantic_context);

 
   free (rhs);
   free (prhs);
 
   free (rhs);
   free (prhs);


@@ -272,7 +271,7 @@ static void
 prepare_states (void)
 {
   state_number i;
 prepare_states (void)
 {
   state_number i;

-  symbol_number *values = MALLOC (values, nstates);
+  symbol_number *values = xnmalloc (nstates, sizeof *values);

   for (i = 0; i < nstates; ++i)
     values[i] = states[i]->accessing_symbol;
   muscle_insert_symbol_number_table ("stos", values,
   for (i = 0; i < nstates; ++i)
     values[i] = states[i]->accessing_symbol;
   muscle_insert_symbol_number_table ("stos", values,


@@ -295,20 +294,16 @@ user_actions_output (FILE *out)
 {
   rule_number r;
 
 {
   rule_number r;
 

-  fputs ("m4_define([b4_actions], \n[[", out);
+  fputs ("m4_define([b4_actions], \n[", out);

   for (r = 0; r < nrules; ++r)
     if (rules[r].action)
       {
   for (r = 0; r < nrules; ++r)
     if (rules[r].action)
       {

-       fprintf (out, "  case %d:\n", r + 1);
-
-       fprintf (out, "]b4_syncline([[%d]], ",
+       fprintf (out, "b4_case(%d, [b4_syncline(%d, ", r + 1,

                 rules[r].action_location.start.line);
                 rules[r].action_location.start.line);

-       escaped_file_name_output (out, rules[r].action_location.start.file);
-       fprintf (out, ")[\n");
-       fprintf (out, "    %s\n    break;\n\n",
-                rules[r].action);
+       escaped_output (out, rules[r].action_location.start.file);
+       fprintf (out, ")\n[    %s]])\n\n", rules[r].action);

       }
       }

-  fputs ("]])\n\n", out);
+  fputs ("])\n\n", out);

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


@@ -325,10 +320,10 @@ merger_output (FILE *out)
   for (n = 1, p = merge_functions; p != NULL; n += 1, p = p->next)
     {
       if (p->type[0] == '\0')
   for (n = 1, p = merge_functions; p != NULL; n += 1, p = p->next)
     {
       if (p->type[0] == '\0')

-       fprintf (out, "  case %d: yyval = %s (*yy0, *yy1); break;\n",
+       fprintf (out, "  case %d: *yy0 = %s (*yy0, *yy1); break;\n",

                 n, p->name);
       else
                 n, p->name);
       else

-       fprintf (out, "  case %d: yyval.%s = %s (*yy0, *yy1); break;\n",
+       fprintf (out, "  case %d: yy0->%s = %s (*yy0, *yy1); break;\n",

                 n, p->type, p->name);
     }
   fputs ("]])\n\n", out);
                 n, p->type, p->name);
     }
   fputs ("]])\n\n", out);


@@ -342,7 +337,7 @@ static void
 token_definitions_output (FILE *out)
 {
   int i;
 token_definitions_output (FILE *out)
 {
   int i;

-  int first = 1;
+  char const *sep = "";

 
   fputs ("m4_define([b4_tokens], \n[", out);
   for (i = 0; i < ntokens; ++i)
 
   fputs ("m4_define([b4_tokens], \n[", out);
   for (i = 0; i < ntokens; ++i)


@@ -350,11 +345,10 @@ token_definitions_output (FILE *out)
       symbol *sym = symbols[i];
       int number = sym->user_token_number;
 
       symbol *sym = symbols[i];
       int number = sym->user_token_number;
 

-      /* At this stage, if there are literal aliases, they are part of
-        SYMBOLS, so we should not find symbols which are the aliases
-        here.  */
-      if (number == USER_NUMBER_ALIAS)
-       abort ();
+      /* At this stage, if there are literal string aliases, they are
+         part of SYMBOLS, so we should not find their aliased symbols
+         here.  */
+      aver (number != USER_NUMBER_HAS_STRING_ALIAS);

 
       /* Skip error token.  */
       if (sym == errtoken)
 
       /* Skip error token.  */
       if (sym == errtoken)


@@ -371,86 +365,56 @@ token_definitions_output (FILE *out)
       if (sym->tag[0] == '\'' || sym->tag[0] == '\"')
        continue;
 
       if (sym->tag[0] == '\'' || sym->tag[0] == '\"')
        continue;
 

-      /* Don't #define nonliteral tokens whose names contain periods
-        or '$' (as does the default value of the EOF token).  */
-      if (strchr (sym->tag, '.') || strchr (sym->tag, '$'))
+      /* Don't #define nonliteral tokens whose names contain periods,
+         dashes or '$' (as does the default value of the EOF token).  */
+      if (mbschr (sym->tag, '.')
+          || mbschr (sym->tag, '-')
+          || mbschr (sym->tag, '$'))

        continue;
 
        continue;
 

-      fprintf (out, "%s[[[%s]], [%d]]",
-              first ? "" : ",\n", sym->tag, number);
-
-      first = 0;
+      fprintf (out, "%s[[[%s]], %d]",
+              sep, sym->tag, number);
+      sep = ",\n";

     }
   fputs ("])\n\n", out);
 }
 
 
     }
   fputs ("])\n\n", out);
 }
 
 

-/*---------------------------------------.
-| Output the symbol destructors to OUT.  |
-`---------------------------------------*/
-
-static void
-symbol_destructors_output (FILE *out)
-{
-  int i;
-  int first = 1;
-
-  fputs ("m4_define([b4_symbol_destructors], \n[", out);
-  for (i = 0; i < nsyms; ++i)
-    if (symbols[i]->destructor)
-      {
-       symbol *sym = symbols[i];
-
-       /* Filename, lineno,
-          Symbol-name, Symbol-number,
-          destructor, typename. */
-       fprintf (out, "%s[",
-                first ? "" : ",\n");
-       escaped_file_name_output (out, sym->destructor_location.start.file);
-       fprintf (out, ", [[%d]], [[%s]], [[%d]], [[%s]], [[%s]]]",
-                sym->destructor_location.start.line,
-                sym->tag,
-                sym->number,
-                sym->destructor,
-                sym->type_name);
-
-       first = 0;
-      }
-  fputs ("])\n\n", out);
-}
-
-
-/*------------------------------------.
-| Output the symbol printers to OUT.  |
-`------------------------------------*/
+/*---------------------------------------------------.
+| Output the symbol destructors or printers to OUT.  |
+`---------------------------------------------------*/

 
 static void
 
 static void

-symbol_printers_output (FILE *out)
+symbol_code_props_output (FILE *out, char const *what,
+                          code_props const *(*get)(symbol const *))

 {
   int i;
 {
   int i;

-  int first = 1;
+  char const *sep = "";

 
 

-  fputs ("m4_define([b4_symbol_printers], \n[", out);
+  fputs ("m4_define([b4_symbol_", out);
+  fputs (what, out);
+  fputs ("], \n[", out);

   for (i = 0; i < nsyms; ++i)
   for (i = 0; i < nsyms; ++i)

-    if (symbols[i]->printer)
-      {
-       symbol *sym = symbols[i];
-
-       /* Filename, lineno,
-          Symbol-name, Symbol-number,
-          printer, typename. */
-       fprintf (out, "%s[",
-                first ? "" : ",\n");
-       escaped_file_name_output (out, sym->printer_location.start.file);
-       fprintf (out, ", [[%d]], [[%s]], [[%d]], [[%s]], [[%s]]]",
-                sym->printer_location.start.line,
-                sym->tag,
-                sym->number,
-                sym->printer,
-                sym->type_name);
-
-       first = 0;
-      }
+    {
+      symbol *sym = symbols[i];
+      char const *code = (*get) (sym)->code;
+      if (code)
+        {
+          location loc = (*get) (sym)->location;
+          /* Filename, lineno,
+             Symbol-name, Symbol-number,
+             code, optional typename.  */
+          fprintf (out, "%s[", sep);
+          sep = ",\n";
+          escaped_output (out, loc.start.file);
+          fprintf (out, ", %d, ", loc.start.line);
+          escaped_output (out, sym->tag);
+          fprintf (out, ", %d, [[%s]]", sym->number, code);
+          if (sym->type_name)
+            fprintf (out, ", [[%s]]", sym->type_name);
+          fputc (']', out);
+        }
+    }

   fputs ("])\n\n", out);
 }
 
   fputs ("])\n\n", out);
 }
 


@@ -499,9 +463,26 @@ prepare_actions (void)
   muscle_insert_unsigned_int_table ("conflict_list_heads", conflict_table,
                                    conflict_table[0], 1, high + 1);
   muscle_insert_unsigned_int_table ("conflicting_rules", conflict_list,
   muscle_insert_unsigned_int_table ("conflict_list_heads", conflict_table,
                                    conflict_table[0], 1, high + 1);
   muscle_insert_unsigned_int_table ("conflicting_rules", conflict_list,

-                                   conflict_list[0], 1, conflict_list_cnt);
+                                   0, 1, conflict_list_cnt);

 }
 
 }
 

+/*--------------------------------------------.
+| Output the definitions of all the muscles.  |
+`--------------------------------------------*/
+
+static void
+muscles_output (FILE *out)
+{
+  fputs ("m4_init()\n", out);
+
+  user_actions_output (out);
+  merger_output (out);
+  token_definitions_output (out);
+  symbol_code_props_output (out, "destructors", &symbol_destructor_get);
+  symbol_code_props_output (out, "printers", &symbol_printer_get);
+
+  muscles_m4_output (out);
+}

 \f
 /*---------------------------.
 | Call the skeleton parser.  |
 \f
 /*---------------------------.
 | Call the skeleton parser.  |


@@ -511,118 +492,171 @@ static void
 output_skeleton (void)
 {
   FILE *in;
 output_skeleton (void)
 {
   FILE *in;

-  FILE *out;

   int filter_fd[2];
   int filter_fd[2];

-  char const *argv[6];
+  char const *argv[10];

   pid_t pid;
 
   pid_t pid;
 

-  /* Compute the names of the package data dir and skeleton file.
-     Test whether m4sugar.m4 is readable, to check for proper
-     installation.  A faulty installation can cause deadlock, so a
-     cheap sanity check is worthwhile.  */
+  /* Compute the names of the package data dir and skeleton files.  */

   char const m4sugar[] = "m4sugar/m4sugar.m4";
   char const m4sugar[] = "m4sugar/m4sugar.m4";

+  char const m4bison[] = "bison.m4";

   char *full_m4sugar;
   char *full_m4sugar;

-  char *full_cm4;
-  char *full_path;
+  char *full_m4bison;
+  char *full_skeleton;

   char const *p;
   char const *m4 = (p = getenv ("M4")) ? p : M4;
   char const *p;
   char const *m4 = (p = getenv ("M4")) ? p : M4;

-  char const *pkgdatadir = (p = getenv ("BISON_PKGDATADIR")) ? p : PKGDATADIR;
+  char const *pkgdatadir = compute_pkgdatadir ();

   size_t skeleton_size = strlen (skeleton) + 1;
   size_t pkgdatadirlen = strlen (pkgdatadir);
   while (pkgdatadirlen && pkgdatadir[pkgdatadirlen - 1] == '/')
     pkgdatadirlen--;
   size_t skeleton_size = strlen (skeleton) + 1;
   size_t pkgdatadirlen = strlen (pkgdatadir);
   while (pkgdatadirlen && pkgdatadir[pkgdatadirlen - 1] == '/')
     pkgdatadirlen--;

-  full_path = xmalloc (pkgdatadirlen + 1
-                      + (skeleton_size < sizeof m4sugar
-                         ? sizeof m4sugar : skeleton_size));
-  strcpy (full_path, pkgdatadir);
-  full_path[pkgdatadirlen] = '/';
-  strcpy (full_path + pkgdatadirlen + 1, m4sugar);
-  full_m4sugar = xstrdup (full_path);
-  strcpy (full_path + pkgdatadirlen + 1, "c.m4");
-  full_cm4 = xstrdup (full_path);
-  strcpy (full_path + pkgdatadirlen + 1, skeleton);
+  full_skeleton = xmalloc (pkgdatadirlen + 1
+                          + (skeleton_size < sizeof m4sugar
+                             ? sizeof m4sugar : skeleton_size));
+  strncpy (full_skeleton, pkgdatadir, pkgdatadirlen);
+  full_skeleton[pkgdatadirlen] = '/';
+  strcpy (full_skeleton + pkgdatadirlen + 1, m4sugar);
+  full_m4sugar = xstrdup (full_skeleton);
+  strcpy (full_skeleton + pkgdatadirlen + 1, m4bison);
+  full_m4bison = xstrdup (full_skeleton);
+  if (mbschr (skeleton, '/'))
+    strcpy (full_skeleton, skeleton);
+  else
+    strcpy (full_skeleton + pkgdatadirlen + 1, skeleton);
+
+  /* Test whether m4sugar.m4 is readable, to check for proper
+     installation.  A faulty installation can cause deadlock, so a
+     cheap sanity check is worthwhile.  */

   xfclose (xfopen (full_m4sugar, "r"));
 
   /* Create an m4 subprocess connected to us via two pipes.  */
 
   if (trace_flag & trace_tools)
     fprintf (stderr, "running: %s %s - %s %s\n",
   xfclose (xfopen (full_m4sugar, "r"));
 
   /* Create an m4 subprocess connected to us via two pipes.  */
 
   if (trace_flag & trace_tools)
     fprintf (stderr, "running: %s %s - %s %s\n",

-            m4, full_m4sugar, full_cm4, full_path);
+             m4, full_m4sugar, full_m4bison, full_skeleton);

 
 

-  argv[0] = m4;
-  argv[1] = full_m4sugar;
-  argv[2] = "-";
-  argv[3] = full_cm4;
-  argv[4] = full_path;
-  argv[5] = NULL;
+  /* Some future version of GNU M4 (most likely 1.6) may treat the -dV in a
+     position-dependent manner.  Keep it as the first argument so that all
+     files are traced.

 
 

-  init_subpipe ();
-  pid = create_subpipe (argv, filter_fd);
-  free (full_m4sugar);
-  free (full_cm4);
-  free (full_path);
-
-  out = fdopen (filter_fd[0], "w");
-  if (! out)
-    error (EXIT_FAILURE, get_errno (), "fdopen");
-
-  /* Output the definitions of all the muscles.  */
-  fputs ("m4_init()\n", out);
-
-  user_actions_output (out);
-  merger_output (out);
-  token_definitions_output (out);
-  symbol_destructors_output (out);
-  symbol_printers_output (out);
+     See the thread starting at
+     <http://lists.gnu.org/archive/html/bug-bison/2008-07/msg00000.html>
+     for details.  */
+  {
+    int i = 0;
+    argv[i++] = m4;
+
+    /* When POSIXLY_CORRECT is set, GNU M4 1.6 and later disable GNU
+       extensions, which Bison's skeletons depend on.  With older M4,
+       it has no effect.  M4 1.4.12 added a -g/--gnu command-line
+       option to make it explicit that a program wants GNU M4
+       extensions even when POSIXLY_CORRECT is set.
+
+       See the thread starting at
+       <http://lists.gnu.org/archive/html/bug-bison/2008-07/msg00000.html>
+       for details.  */
+    if (*M4_GNU_OPTION)
+      argv[i++] = M4_GNU_OPTION;
+
+    argv[i++] = "-I";
+    argv[i++] = pkgdatadir;
+    if (trace_flag & trace_m4)
+      argv[i++] = "-dV";
+    argv[i++] = full_m4sugar;
+    argv[i++] = "-";
+    argv[i++] = full_m4bison;
+    argv[i++] = full_skeleton;
+    argv[i++] = NULL;
+    aver (i <= ARRAY_CARDINALITY (argv));
+  }

 
 

-  muscles_m4_output (out);
+  /* The ugly cast is because gnulib gets the const-ness wrong.  */
+  pid = create_pipe_bidi ("m4", m4, (char **)(void*)argv, false, true,
+                          true, filter_fd);
+  free (full_m4sugar);
+  free (full_m4bison);
+  free (full_skeleton);

 
 

-  fputs ("m4_wrap([m4_divert_pop(0)])\n", out);
-  fputs ("m4_divert_push(0)dnl\n", out);
-  xfclose (out);
+  if (trace_flag & trace_muscles)
+    muscles_output (stderr);
+  {
+    FILE *out = fdopen (filter_fd[1], "w");
+    if (! out)
+      error (EXIT_FAILURE, get_errno (),
+             "fdopen");
+    muscles_output (out);
+    xfclose (out);
+  }

 
   /* Read and process m4's output.  */
   timevar_push (TV_M4);
 
   /* Read and process m4's output.  */
   timevar_push (TV_M4);

-  in = fdopen (filter_fd[1], "r");
+  in = fdopen (filter_fd[0], "r");

   if (! in)
   if (! in)

-    error (EXIT_FAILURE, get_errno (), "fdopen");
+    error (EXIT_FAILURE, get_errno (),
+          "fdopen");

   scan_skel (in);
   scan_skel (in);

+  /* scan_skel should have read all of M4's output.  Otherwise, when we
+     close the pipe, we risk letting M4 report a broken-pipe to the
+     Bison user.  */
+  aver (feof (in));

   xfclose (in);
   xfclose (in);

-  reap_subpipe (pid, m4);
+  wait_subprocess (pid, "m4", false, false, true, true, NULL);

   timevar_pop (TV_M4);
 }
 
 static void
 prepare (void)
 {
   timevar_pop (TV_M4);
 }
 
 static void
 prepare (void)
 {

+  /* BISON_USE_PUSH_FOR_PULL is for the test suite and should not be documented
+     for the user.  */
+  char const *use_push_for_pull_env = getenv ("BISON_USE_PUSH_FOR_PULL");
+  bool use_push_for_pull_flag = false;
+  if (use_push_for_pull_env != NULL
+      && use_push_for_pull_env[0] != '\0'
+      && 0 != strcmp (use_push_for_pull_env, "0"))
+    use_push_for_pull_flag = true;
+

   /* Flags. */
   /* Flags. */

-  MUSCLE_INSERT_INT ("debug", debug_flag);
-  MUSCLE_INSERT_INT ("defines_flag", defines_flag);
-  MUSCLE_INSERT_INT ("error_verbose", error_verbose);
-  MUSCLE_INSERT_INT ("locations_flag", locations_flag);
-  MUSCLE_INSERT_INT ("pure", pure_parser);
-  MUSCLE_INSERT_INT ("synclines_flag", !no_lines_flag);
+  MUSCLE_INSERT_BOOL ("debug_flag", debug_flag);
+  MUSCLE_INSERT_BOOL ("defines_flag", defines_flag);
+  MUSCLE_INSERT_BOOL ("error_verbose_flag", error_verbose);
+  MUSCLE_INSERT_BOOL ("glr_flag", glr_parser);
+  MUSCLE_INSERT_BOOL ("locations_flag", locations_flag);
+  MUSCLE_INSERT_BOOL ("nondeterministic_flag", nondeterministic_parser);
+  MUSCLE_INSERT_BOOL ("synclines_flag", !no_lines_flag);
+  MUSCLE_INSERT_BOOL ("tag_seen_flag", tag_seen);
+  MUSCLE_INSERT_BOOL ("use_push_for_pull_flag", use_push_for_pull_flag);
+  MUSCLE_INSERT_BOOL ("yacc_flag", yacc_flag);

 
   /* File names.  */
 
   /* File names.  */

-  MUSCLE_INSERT_STRING ("prefix", spec_name_prefix ? spec_name_prefix : "yy");
-
-  /* User Code.  */
-  obstack_1grow (&pre_prologue_obstack, 0);
-  obstack_1grow (&post_prologue_obstack, 0);
-  muscle_insert ("pre_prologue", obstack_finish (&pre_prologue_obstack));
-  muscle_insert ("post_prologue", obstack_finish (&post_prologue_obstack));
-
-  /* Find the right skeleton file.  */
-  if (!skeleton)
-    {
-      if (glr_parser)
-       skeleton = "glr.c";
-      else
-       skeleton = "yacc.c";
-    }
-
-  /* Parse the skeleton file and output the needed parsers.  */
-  MUSCLE_INSERT_C_STRING ("skeleton", skeleton);
+  if (spec_name_prefix)
+    MUSCLE_INSERT_STRING ("prefix", spec_name_prefix);
+
+  MUSCLE_INSERT_STRING ("file_name_all_but_ext", all_but_ext);
+
+#define DEFINE(Name) MUSCLE_INSERT_STRING (#Name, Name ? Name : "")
+  DEFINE (dir_prefix);
+  DEFINE (parser_file_name);
+  DEFINE (spec_defines_file);
+  DEFINE (spec_file_prefix);
+  DEFINE (spec_graph_file);
+  DEFINE (spec_name_prefix);
+  DEFINE (spec_outfile);
+  DEFINE (spec_verbose_file);
+#undef DEFINE
+
+  /* Find the right skeleton file, and add muscles about the skeletons.  */
+  if (skeleton)
+    MUSCLE_INSERT_C_STRING ("skeleton", skeleton);
+  else
+    skeleton = language->skeleton;
+
+  /* About the skeletons.  */
+  {
+    /* b4_pkgdatadir is used inside m4_include in the skeletons, so digraphs
+       would never be expanded.  Hopefully no one has M4-special characters in
+       his Bison installation path.  */
+    MUSCLE_INSERT_STRING_RAW ("pkgdatadir", compute_pkgdatadir ());
+  }

 }
 
 
 }
 
 


@@ -646,6 +680,11 @@ output (void)
   output_skeleton ();
 
   obstack_free (&format_obstack, NULL);
   output_skeleton ();
 
   obstack_free (&format_obstack, NULL);

-  obstack_free (&pre_prologue_obstack, NULL);
-  obstack_free (&post_prologue_obstack, NULL);
+}
+
+char const *
+compute_pkgdatadir (void)
+{
+  char const *pkgdatadir = getenv ("BISON_PKGDATADIR");
+  return pkgdatadir ? pkgdatadir : PKGDATADIR;

 }
 }