Merge remote-tracking branch 'origin/maint'

[bison.git] / src / output.c

diff --git a/src/output.c b/src/output.c
index 12204461d0c6bd8862ac0989ac99febf67fd9545..4fe11ccb79cc7bcbf3365aeda8758f69323ae5d2 100644 (file)
--- a/src/output.c
+++ b/src/output.c
@@ -1,7 +1,7 @@
 /* Output the generated parsing program for Bison.
 
 /* Output the generated parsing program for Bison.
 

-   Copyright (C) 1984, 1986, 1989, 1992, 2000, 2001, 2002, 2003, 2004,
-   2005, 2006, 2007, 2008, 2009 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.
 


@@ -21,12 +21,14 @@
 #include <config.h>
 #include "system.h"
 
 #include <config.h>
 #include "system.h"
 

+#include <concat-filename.h>

 #include <configmake.h>
 #include <configmake.h>

-#include <error.h>
+#include <filename.h>

 #include <get-errno.h>
 #include <quotearg.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 "complain.h"
 #include "files.h"


@@ -40,6 +42,7 @@
 #include "symtab.h"
 #include "tables.h"
 
 #include "symtab.h"
 #include "tables.h"
 

+# define ARRAY_CARDINALITY(Array) (sizeof (Array) / sizeof *(Array))

 
 static struct obstack format_obstack;
 
 
 static struct obstack format_obstack;
 


@@ -52,51 +55,51 @@ static struct obstack format_obstack;
 `-------------------------------------------------------------------*/
 
 
 `-------------------------------------------------------------------*/
 
 

-#define GENERATE_MUSCLE_INSERT_TABLE(Name, Type)                       \
-                                                                       \
-static void                                                            \
-Name (char const *name,                                                        \
-      Type *table_data,                                                        \
-      Type first,                                                      \
-      int begin,                                                       \
-      int end)                                                         \
-{                                                                      \
-  Type min = first;                                                    \
-  Type max = first;                                                    \
-  long int lmin;                                                       \
-  long int lmax;                                                       \
-  int i;                                                               \
-  int j = 1;                                                           \
-                                                                       \
-  obstack_fgrow1 (&format_obstack, "%6d", first);                      \
-  for (i = begin; i < end; ++i)                                                \
-    {                                                                  \
-      obstack_1grow (&format_obstack, ',');                            \
-      if (j >= 10)                                                     \
-       {                                                               \
-         obstack_sgrow (&format_obstack, "\n  ");                      \
-         j = 1;                                                        \
-       }                                                               \
-      else                                                             \
-       ++j;                                                            \
-      obstack_fgrow1 (&format_obstack, "%6d", table_data[i]);          \
-      if (table_data[i] < min)                                         \
-       min = table_data[i];                                            \
-      if (max < table_data[i])                                         \
-       max = table_data[i];                                            \
-    }                                                                  \
-  obstack_1grow (&format_obstack, 0);                                  \
-  muscle_insert (name, obstack_finish (&format_obstack));              \
-                                                                       \
-  lmin = min;                                                          \
-  lmax = max;                                                          \
-  /* Build `NAME_min' and `NAME_max' in the obstack. */                        \
-  obstack_fgrow1 (&format_obstack, "%s_min", name);                    \
-  obstack_1grow (&format_obstack, 0);                                  \
-  MUSCLE_INSERT_LONG_INT (obstack_finish (&format_obstack), lmin);     \
-  obstack_fgrow1 (&format_obstack, "%s_max", name);                    \
-  obstack_1grow (&format_obstack, 0);                                  \
-  MUSCLE_INSERT_LONG_INT (obstack_finish (&format_obstack), lmax);     \
+#define GENERATE_MUSCLE_INSERT_TABLE(Name, Type)                        \
+                                                                        \
+static void                                                             \
+Name (char const *name,                                                 \
+      Type *table_data,                                                 \
+      Type first,                                                       \
+      int begin,                                                        \
+      int end)                                                          \
+{                                                                       \
+  Type min = first;                                                     \
+  Type max = first;                                                     \
+  long int lmin;                                                        \
+  long int lmax;                                                        \
+  int i;                                                                \
+  int j = 1;                                                            \
+                                                                        \
+  obstack_fgrow1 (&format_obstack, "%6d", first);                       \
+  for (i = begin; i < end; ++i)                                         \
+    {                                                                   \
+      obstack_1grow (&format_obstack, ',');                             \
+      if (j >= 10)                                                      \
+        {                                                               \
+          obstack_sgrow (&format_obstack, "\n  ");                      \
+          j = 1;                                                        \
+        }                                                               \
+      else                                                              \
+        ++j;                                                            \
+      obstack_fgrow1 (&format_obstack, "%6d", table_data[i]);           \
+      if (table_data[i] < min)                                          \
+        min = table_data[i];                                            \
+      if (max < table_data[i])                                          \
+        max = table_data[i];                                            \
+    }                                                                   \
+  obstack_1grow (&format_obstack, 0);                                   \
+  muscle_insert (name, obstack_finish (&format_obstack));               \
+                                                                        \
+  lmin = min;                                                           \
+  lmax = max;                                                           \
+  /* Build `NAME_min' and `NAME_max' in the obstack. */                 \
+  obstack_fgrow1 (&format_obstack, "%s_min", name);                     \
+  obstack_1grow (&format_obstack, 0);                                   \
+  MUSCLE_INSERT_LONG_INT (obstack_finish (&format_obstack), lmin);      \
+  obstack_fgrow1 (&format_obstack, "%s_max", name);                     \
+  obstack_1grow (&format_obstack, 0);                                   \
+  MUSCLE_INSERT_LONG_INT (obstack_finish (&format_obstack), lmax);      \

 }
 
 GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_unsigned_int_table, unsigned int)
 }
 
 GENERATE_MUSCLE_INSERT_TABLE(muscle_insert_unsigned_int_table, unsigned int)


@@ -147,9 +150,9 @@ prepare_symbols (void)
   MUSCLE_INSERT_INT ("user_token_number_max", max_user_token_number);
 
   muscle_insert_symbol_number_table ("translate",
   MUSCLE_INSERT_INT ("user_token_number_max", max_user_token_number);
 
   muscle_insert_symbol_number_table ("translate",

-                                    token_translations,
-                                    token_translations[0],
-                                    1, max_user_token_number + 1);
+                                     token_translations,
+                                     token_translations[0],
+                                     1, max_user_token_number + 1);

 
   /* tname -- token names.  */
   {
 
   /* tname -- token names.  */
   {


@@ -161,23 +164,23 @@ prepare_symbols (void)
     set_quoting_flags (qo, QA_SPLIT_TRIGRAPHS);
     for (i = 0; i < nsyms; i++)
       {
     set_quoting_flags (qo, QA_SPLIT_TRIGRAPHS);
     for (i = 0; i < nsyms; i++)
       {

-       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)
-         {
-           obstack_sgrow (&format_obstack, "\n ");
-           j = 1;
-         }
-
-       if (i)
-         obstack_1grow (&format_obstack, ' ');
-       MUSCLE_OBSTACK_SGROW (&format_obstack, cp);
+        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)
+          {
+            obstack_sgrow (&format_obstack, "\n ");
+            j = 1;
+          }
+
+        if (i)
+          obstack_1grow (&format_obstack, ' ');
+        MUSCLE_OBSTACK_SGROW (&format_obstack, cp);

         free (cp);
         free (cp);

-       obstack_1grow (&format_obstack, ',');
-       j += width;
+        obstack_1grow (&format_obstack, ',');
+        j += width;

       }
     free (qo);
     obstack_sgrow (&format_obstack, " ]b4_null[");
       }
     free (qo);
     obstack_sgrow (&format_obstack, " ]b4_null[");


@@ -194,7 +197,7 @@ prepare_symbols (void)
     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,

-                            values[0], 1, ntokens);
+                             values[0], 1, ntokens);

     free (values);
   }
 }
     free (values);
   }
 }


@@ -202,7 +205,7 @@ prepare_symbols (void)
 
 /*----------------------------------------------------------------.
 | Prepare the muscles related to the rules: r1, r2, rline, dprec, |
 
 /*----------------------------------------------------------------.
 | Prepare the muscles related to the rules: r1, r2, rline, dprec, |

-| merger.                                                         |
+| merger, immediate.                                              |

 `----------------------------------------------------------------*/
 
 static void
 `----------------------------------------------------------------*/
 
 static void


@@ -213,6 +216,7 @@ prepare_rules (void)
   unsigned int *r2 = xnmalloc (nrules, sizeof *r2);
   int *dprec = xnmalloc (nrules, sizeof *dprec);
   int *merger = xnmalloc (nrules, sizeof *merger);
   unsigned int *r2 = xnmalloc (nrules, sizeof *r2);
   int *dprec = xnmalloc (nrules, sizeof *dprec);
   int *merger = xnmalloc (nrules, sizeof *merger);

+  int *immediate = xnmalloc (nrules, sizeof *immediate);

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


@@ -227,6 +231,8 @@ prepare_rules (void)
       dprec[r] = rules[r].dprec;
       /* Merger-function index (GLR).  */
       merger[r] = rules[r].merger;
       dprec[r] = rules[r].dprec;
       /* Merger-function index (GLR).  */
       merger[r] = rules[r].merger;

+      /* Immediate reduction flags (GLR).  */
+      immediate[r] = rules[r].is_predicate;

     }
 
   muscle_insert_unsigned_int_table ("rline", rline, 0, 0, nrules);
     }
 
   muscle_insert_unsigned_int_table ("rline", rline, 0, 0, nrules);


@@ -234,6 +240,7 @@ prepare_rules (void)
   muscle_insert_unsigned_int_table ("r2", r2, 0, 0, nrules);
   muscle_insert_int_table ("dprec", dprec, 0, 0, nrules);
   muscle_insert_int_table ("merger", merger, 0, 0, nrules);
   muscle_insert_unsigned_int_table ("r2", r2, 0, 0, nrules);
   muscle_insert_int_table ("dprec", dprec, 0, 0, nrules);
   muscle_insert_int_table ("merger", merger, 0, 0, nrules);

+  muscle_insert_int_table ("immediate", immediate, 0, 0, nrules);

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


@@ -243,6 +250,7 @@ prepare_rules (void)
   free (r2);
   free (dprec);
   free (merger);
   free (r2);
   free (dprec);
   free (merger);

+  free (immediate);

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


@@ -257,7 +265,7 @@ prepare_states (void)
   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,

-                                    0, 1, nstates);
+                                     0, 1, nstates);

   free (values);
 
   MUSCLE_INSERT_INT ("last", high);
   free (values);
 
   MUSCLE_INSERT_INT ("last", high);


@@ -347,10 +355,11 @@ user_actions_output (FILE *out)
   for (r = 0; r < nrules; ++r)
     if (rules[r].action)
       {
   for (r = 0; r < nrules; ++r)
     if (rules[r].action)
       {

-       fprintf (out, "b4_case(%d, [b4_syncline(%d, ", r + 1,
-                rules[r].action_location.start.line);
-       escaped_output (out, rules[r].action_location.start.file);
-       fprintf (out, ")\n[    %s]])\n\n", rules[r].action);
+        fprintf (out, "b4_%scase(%d, [b4_syncline(%d, ",
+                 rules[r].is_predicate ? "predicate_" : "",
+                 r + 1, rules[r].action_location.start.line);
+        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);
 }


@@ -369,11 +378,11 @@ 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: *yy0 = %s (*yy0, *yy1); break;\n",
-                n, p->name);
+        fprintf (out, "  case %d: *yy0 = %s (*yy0, *yy1); break;\n",
+                 n, p->name);

       else
       else

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

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


@@ -393,9 +402,16 @@ prepare_symbol_definitions (void)
       const char *key;
       const char *value;
 
       const char *key;
       const char *value;
 

-#define SET_KEY(Entry)                                                  \
-      obstack_fgrow2 (&format_obstack, "symbol(%d, %s)", i, Entry);     \
-      obstack_1grow (&format_obstack, 0);                               \
+#define SET_KEY(Entry)                                          \
+      obstack_fgrow2 (&format_obstack, "symbol(%d, %s)",        \
+                      i, Entry);                                \
+      obstack_1grow (&format_obstack, 0);                       \
+      key = obstack_finish (&format_obstack);
+
+#define SET_KEY2(Entry, Suffix)                                 \
+      obstack_fgrow3 (&format_obstack, "symbol(%d, %s_%s)",     \
+                      i, Entry, Suffix);                        \
+      obstack_1grow (&format_obstack, 0);                       \

       key = obstack_finish (&format_obstack);
 
       // Whether the symbol has an identifier.
       key = obstack_finish (&format_obstack);
 
       // Whether the symbol has an identifier.


@@ -427,28 +443,30 @@ prepare_symbol_definitions (void)
       SET_KEY("type");
       MUSCLE_INSERT_STRING (key, sym->type_name ? sym->type_name : "");
 
       SET_KEY("type");
       MUSCLE_INSERT_STRING (key, sym->type_name ? sym->type_name : "");
 

-#define CODE_PROP(PropName)                                             \
-      do {                                                              \
-        code_props const *p = symbol_ ## PropName ## _get (sym);        \
-        SET_KEY("has_" #PropName);                                      \
-        MUSCLE_INSERT_INT (key, !!p->code);                             \
-                                                                        \
-        if (p->code)                                                    \
-          {                                                             \
-            SET_KEY(#PropName "_file");                                 \
-            MUSCLE_INSERT_STRING (key, p->location.start.file);         \
-                                                                        \
-            SET_KEY(#PropName "_line");                                 \
-            MUSCLE_INSERT_INT (key, p->location.start.line);            \
-                                                                        \
-            SET_KEY(#PropName);                                         \
-            MUSCLE_INSERT_STRING_RAW (key, p->code);                    \
-          }                                                             \
-      } while (0)
-
-      CODE_PROP(destructor);
-      CODE_PROP(printer);
-#undef CODE_PROP
+      {
+        int j;
+        for (j = 0; j < CODE_PROPS_SIZE; ++j)
+          {
+            /* "printer", not "%printer".  */
+            char const *pname = code_props_type_string (j) + 1;
+            code_props const *p = symbol_code_props_get (sym, j);
+            SET_KEY2("has", pname);
+            MUSCLE_INSERT_INT (key, !!p->code);
+
+            if (p->code)
+              {
+                SET_KEY2(pname, "file");
+                MUSCLE_INSERT_STRING (key, p->location.start.file);
+
+                SET_KEY2(pname, "line");
+                MUSCLE_INSERT_INT (key, p->location.start.line);
+
+                SET_KEY(pname);
+                MUSCLE_INSERT_STRING_RAW (key, p->code);
+              }
+          }
+      }
+#undef SET_KEY2

 #undef SET_KEY
     }
 }
 #undef SET_KEY
     }
 }


@@ -469,35 +487,20 @@ 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.  */
-      aver (number != USER_NUMBER_ALIAS);
-
-      /* Skip error token.  */
-      if (sym == errtoken)
-       continue;
-
-      /* If this string has an alias, then it is necessarily the alias
-        which is to be output.  */
-      if (sym->alias)
-       sym = sym->alias;
-
-      /* Don't output literal chars or strings (when defined only as a
-        string).  Note that must be done after the alias resolution:
-        think about `%token 'f' "f"'.  */
-      if (sym->tag[0] == '\'' || sym->tag[0] == '\"')
-       continue;
-
-      /* Don't #define nonliteral tokens whose names contain periods
-        or '$' (as does the default value of the EOF token).  */
-      if (strchr (sym->tag, '.') || strchr (sym->tag, '$'))
-       continue;
-
-      fprintf (out, "%s[[[%s]], %d]",
-              sep, sym->tag, number);
-      sep = ",\n";
+      uniqstr id = symbol_id_get (sym);
+
+      /* 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 and tokens without identifier.  */
+      if (sym != errtoken && id)
+        {
+          fprintf (out, "%s[[[%s]], %d]",
+                   sep, id, number);
+          sep = ",\n";
+        }

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


@@ -510,30 +513,30 @@ prepare_actions (void)
      lookahead token type.  */
 
   muscle_insert_rule_number_table ("defact", yydefact,
      lookahead token type.  */
 
   muscle_insert_rule_number_table ("defact", yydefact,

-                                  yydefact[0], 1, nstates);
+                                   yydefact[0], 1, nstates);

 
   /* Figure out what to do after reducing with each rule, depending on
      the saved state from before the beginning of parsing the data
      that matched this rule.  */
   muscle_insert_state_number_table ("defgoto", yydefgoto,
 
   /* Figure out what to do after reducing with each rule, depending on
      the saved state from before the beginning of parsing the data
      that matched this rule.  */
   muscle_insert_state_number_table ("defgoto", yydefgoto,

-                                   yydefgoto[0], 1, nsyms - ntokens);
+                                    yydefgoto[0], 1, nsyms - ntokens);

 
 
   /* Output PACT. */
   muscle_insert_base_table ("pact", base,
 
 
   /* Output PACT. */
   muscle_insert_base_table ("pact", base,

-                            base[0], 1, nstates);
+                             base[0], 1, nstates);

   MUSCLE_INSERT_INT ("pact_ninf", base_ninf);
 
   /* Output PGOTO. */
   muscle_insert_base_table ("pgoto", base,
   MUSCLE_INSERT_INT ("pact_ninf", base_ninf);
 
   /* Output PGOTO. */
   muscle_insert_base_table ("pgoto", base,

-                            base[nstates], nstates + 1, nvectors);
+                             base[nstates], nstates + 1, nvectors);

 
   muscle_insert_base_table ("table", table,
 
   muscle_insert_base_table ("table", table,

-                           table[0], 1, high + 1);
+                            table[0], 1, high + 1);

   MUSCLE_INSERT_INT ("table_ninf", table_ninf);
 
   muscle_insert_base_table ("check", check,
   MUSCLE_INSERT_INT ("table_ninf", table_ninf);
 
   muscle_insert_base_table ("check", check,

-                           check[0], 1, high + 1);
+                            check[0], 1, high + 1);

 
   /* GLR parsing slightly modifies YYTABLE and YYCHECK (and thus
      YYPACT) so that in states with unresolved conflicts, the default
 
   /* GLR parsing slightly modifies YYTABLE and YYCHECK (and thus
      YYPACT) so that in states with unresolved conflicts, the default


@@ -545,9 +548,9 @@ prepare_actions (void)
      that case.  Nevertheless, it seems even better to be able to use
      the GLR skeletons even without the non-deterministic tables.  */
   muscle_insert_unsigned_int_table ("conflict_list_heads", conflict_table,
      that case.  Nevertheless, it seems even better to be able to use
      the GLR skeletons even without the non-deterministic tables.  */
   muscle_insert_unsigned_int_table ("conflict_list_heads", conflict_table,

-                                   conflict_table[0], 1, high + 1);
+                                    conflict_table[0], 1, high + 1);

   muscle_insert_unsigned_int_table ("conflicting_rules", conflict_list,
   muscle_insert_unsigned_int_table ("conflicting_rules", conflict_list,

-                                   0, 1, conflict_list_cnt);
+                                    0, 1, conflict_list_cnt);

 }
 
 
 }
 
 


@@ -575,48 +578,28 @@ muscles_output (FILE *out)
 static void
 output_skeleton (void)
 {
 static void
 output_skeleton (void)
 {

-  FILE *in;

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

-  char const *argv[9];

   pid_t pid;
 
   /* Compute the names of the package data dir and skeleton files.  */
   pid_t pid;
 
   /* Compute the names of the package data dir and skeleton files.  */

-  char const m4sugar[] = "m4sugar/m4sugar.m4";
-  char const m4bison[] = "bison.m4";
-  char *full_m4sugar;
-  char *full_m4bison;
-  char *full_skeleton;
-  char const *p;
-  char const *m4 = (p = getenv ("M4")) ? p : M4;
-  char const *pkgdatadir = compute_pkgdatadir ();
-  size_t skeleton_size = strlen (skeleton) + 1;
-  size_t pkgdatadirlen = strlen (pkgdatadir);
-  while (pkgdatadirlen && pkgdatadir[pkgdatadirlen - 1] == '/')
-    pkgdatadirlen--;
-  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 (strchr (skeleton, '/'))
-    strcpy (full_skeleton, skeleton);
-  else
-    strcpy (full_skeleton + pkgdatadirlen + 1, skeleton);
+  char const *m4 = (m4 = getenv ("M4")) ? m4 : M4;
+  char const *datadir = pkgdatadir ();
+  char *m4sugar = xconcatenated_filename (datadir, "m4sugar/m4sugar.m4", NULL);
+  char *m4bison = xconcatenated_filename (datadir, "bison.m4", NULL);
+  char *skel = (IS_PATH_WITH_DIR (skeleton)
+                ? xstrdup (skeleton)
+                : xconcatenated_filename (datadir, skeleton, NULL));

 
   /* Test whether m4sugar.m4 is readable, to check for proper
      installation.  A faulty installation can cause deadlock, so a
      cheap sanity check is worthwhile.  */
 
   /* 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"));
+  xfclose (xfopen (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",
 
   /* 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_m4bison, full_skeleton);
+             m4, m4sugar, m4bison, skel);

 
   /* 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
 
   /* 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


@@ -626,78 +609,72 @@ output_skeleton (void)
      <http://lists.gnu.org/archive/html/bug-bison/2008-07/msg00000.html>
      for details.  */
   {
      <http://lists.gnu.org/archive/html/bug-bison/2008-07/msg00000.html>
      for details.  */
   {

+    char const *argv[10];

     int i = 0;
     argv[i++] = m4;
     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++] = "-I";

-    argv[i++] = pkgdatadir;
+    argv[i++] = datadir;

     if (trace_flag & trace_m4)
       argv[i++] = "-dV";
     if (trace_flag & trace_m4)
       argv[i++] = "-dV";

-    argv[i++] = full_m4sugar;
+    argv[i++] = m4sugar;

     argv[i++] = "-";
     argv[i++] = "-";

-    argv[i++] = full_m4bison;
-    argv[i++] = full_skeleton;
+    argv[i++] = m4bison;
+    argv[i++] = skel;

     argv[i++] = NULL;
     argv[i++] = NULL;

+    aver (i <= ARRAY_CARDINALITY (argv));
+
+    /* 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);

   }
   }

-  /* When POSIXLY_CORRECT is set, some future versions of GNU M4 (most likely
-     2.0) may drop some of the GNU extensions that Bison's skeletons depend
-     upon.  So that the next release of Bison is forward compatible with those
-     future versions of GNU M4, we unset POSIXLY_CORRECT here.
-
-     FIXME: A user might set POSIXLY_CORRECT to affect processes run from
-     macros like m4_syscmd in a custom skeleton.  For now, Bison makes no
-     promises about the behavior of custom skeletons, so this scenario is not a
-     concern.  However, we eventually want to eliminate this shortcoming.  The
-     next release of GNU M4 (1.4.12 or 1.6) will accept the -g command-line
-     option as a no-op, and later releases will accept it to indicate that
-     POSIXLY_CORRECT should be ignored.  Once the GNU M4 versions that accept
-     -g are pervasive, Bison should use -g instead of unsetting
-     POSIXLY_CORRECT.

 
 

-     See the thread starting at
-     <http://lists.gnu.org/archive/html/bug-bison/2008-07/msg00000.html>
-     for details.  */
-  unsetenv ("POSIXLY_CORRECT");
-  init_subpipe ();
-  pid = create_subpipe (argv, filter_fd);
-  free (full_m4sugar);
-  free (full_m4bison);
-  free (full_skeleton);
+  free (m4sugar);
+  free (m4bison);
+  free (skel);

 
   if (trace_flag & trace_muscles)
     muscles_output (stderr);
   {
 
   if (trace_flag & trace_muscles)
     muscles_output (stderr);
   {

-    FILE *out = fdopen (filter_fd[0], "w");
-    if (! out)
-      error (EXIT_FAILURE, get_errno (),
-             "fdopen");
+    FILE *out = xfdopen (filter_fd[1], "w");

     muscles_output (out);
     xfclose (out);
   }
 
   /* Read and process m4's output.  */
   timevar_push (TV_M4);
     muscles_output (out);
     xfclose (out);
   }
 
   /* Read and process m4's output.  */
   timevar_push (TV_M4);

-  end_of_output_subpipe (pid, filter_fd);
-  in = fdopen (filter_fd[1], "r");
-  if (! in)
-    error (EXIT_FAILURE, get_errno (),
-          "fdopen");
-  scan_skel (in);
-  xfclose (in);
-  reap_subpipe (pid, m4);
+  {
+    FILE *in = xfdopen (filter_fd[0], "r");
+    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);
+  }
+  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;
+  /* BISON_USE_PUSH_FOR_PULL is for the test suite and should not be
+     documented for the user.  */
+  char const *cp = getenv ("BISON_USE_PUSH_FOR_PULL");
+  bool use_push_for_pull_flag = cp && *cp && strtol (cp, 0, 10);

 
   /* Flags. */
   MUSCLE_INSERT_BOOL ("defines_flag", defines_flag);
 
   /* Flags. */
   MUSCLE_INSERT_BOOL ("defines_flag", defines_flag);


@@ -736,7 +713,7 @@ prepare (void)
     /* 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.  */
     /* 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 ());
+    MUSCLE_INSERT_STRING_RAW ("pkgdatadir", pkgdatadir ());

   }
 }
 
   }
 }
 


@@ -765,8 +742,8 @@ output (void)
 }
 
 char const *
 }
 
 char const *

-compute_pkgdatadir (void)
+pkgdatadir (void)

 {
 {

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

 }
 }