From: Akim Demaille <akim@epita.fr>
Date: Tue, 12 Nov 2002 07:55:55 +0000 (+0000)
Subject: * src/symtab.c (symbol_free): Remove dead deactivated code:
X-Git-Tag: BISON-1_875~297
X-Git-Url: https://git.saurik.com/bison.git/commitdiff_plain/3e6656f9ab66ae7e629f8e5d5b41810bf070f09d?ds=sidebyside;hp=ccdb39e0a6f95cb4a3f19c08885a7c421cdebedb

* src/symtab.c (symbol_free): Remove dead deactivated code:
type_name are properly removed.
Don't use XFREE to free items that cannot be NULL.
* src/struniq.h, src/struniq.c: New.
* src/main.c (main): Initialize/free struniqs.
* src/parse-gram.y (%union): Add astruniq member.
(yyprint): Adjust.
* src/scan-gram.l (<{tag}>): Return a struniq.
Free the obstack bit that used to store it.
* src/symtab.h (symbol_t): The 'type_name' member is a struniq.
---

diff --git a/ChangeLog b/ChangeLog
index ffc64985..20d8cd18 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2002-11-12  Akim Demaille  <akim@epita.fr>
+
+	* src/symtab.c (symbol_free): Remove dead deactivated code:
+	type_name are properly removed.
+	Don't use XFREE to free items that cannot be NULL.
+	* src/struniq.h, src/struniq.c: New.
+	* src/main.c (main): Initialize/free struniqs.
+	* src/parse-gram.y (%union): Add astruniq member.
+	(yyprint): Adjust.
+	* src/scan-gram.l (<{tag}>): Return a struniq.
+	Free the obstack bit that used to store it.
+	* src/symtab.h (symbol_t): The 'type_name' member is a struniq.
+
 2002-11-11  Paul Eggert  <eggert@twinsun.com>
 
 	Revamp to fix many (but not all) of the C- and M4-related quoting
diff --git a/src/Makefile.am b/src/Makefile.am
index 7a388a06..58833818 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -55,6 +55,7 @@ bison_SOURCES = 				  \
 	scan-gram.l				  \
 	scan-skel.l				  \
 	state.c state.h				  \
+	struniq.c struniq.h			  \
 	symlist.c symlist.h			  \
 	symtab.c symtab.h			  \
 	system.h				  \
diff --git a/src/main.c b/src/main.c
index 04957a2b..f86bfda9 100644
--- a/src/main.c
+++ b/src/main.c
@@ -24,6 +24,7 @@
 #include "bitset_stats.h"
 #include "bitset.h"
 #include "getargs.h"
+#include "struniq.h"
 #include "symtab.h"
 #include "gram.h"
 #include "files.h"
@@ -63,6 +64,7 @@ main (int argc, char *argv[])
   if (trace_flag & trace_bitsets)
     bitset_stats_enable ();
 
+  struniqs_new ();
   muscle_init ();
 
   /* Read the input.  Copy some parts of it to FGUARD, FACTION, FTABLE
@@ -165,6 +167,7 @@ main (int argc, char *argv[])
      contains things such as user actions, prologue, epilogue etc.  */
   scanner_free ();
   muscle_free ();
+  struniqs_free ();
   /* If using alloca.c, flush the alloca'ed memory for the benefit of
      people running Bison as a library in IDEs.  */
 #if C_ALLOCA
diff --git a/src/parse-gram.c b/src/parse-gram.c
index 27596094..69ef7ebc 100644
--- a/src/parse-gram.c
+++ b/src/parse-gram.c
@@ -1,4 +1,4 @@
-/* A Bison parser, made by GNU Bison 1.75b.  */
+/* A Bison parser, made from parse-gram.y, by GNU bison 1.75b.  */
 
 /* Skeleton parser for Yacc-like parsing with Bison,
    Copyright (C) 1984, 1989, 1990, 2000, 2001, 2002 Free Software Foundation, Inc.
@@ -236,9 +236,10 @@ typedef union {
   int integer;
   char *string;
   assoc_t assoc;
+  struniq_t struniq;
 } yystype;
-/* Line 212 of /tmp/prefix/share/bison/yacc.c.  */
-#line 241 "parse-gram.c"
+/* Line 237 of /usr/local/share/bison/yacc.c.  */
+#line 243 "parse-gram.c"
 # define YYSTYPE yystype
 # define YYSTYPE_IS_TRIVIAL 1
 #endif
@@ -258,8 +259,8 @@ typedef struct yyltype
 /* Copy the second part of user declarations.  */
 
 
-/* Line 232 of /tmp/prefix/share/bison/yacc.c.  */
-#line 262 "parse-gram.c"
+/* Line 257 of /usr/local/share/bison/yacc.c.  */
+#line 264 "parse-gram.c"
 
 #if ! defined (yyoverflow) || YYERROR_VERBOSE
 
@@ -457,14 +458,14 @@ static const yysigned_char yyrhs[] =
 /* YYRLINE[YYN] -- source line where rule number YYN was defined.  */
 static const unsigned short yyrline[] =
 {
-       0,   167,   167,   180,   182,   185,   187,   188,   189,   190,
-     191,   192,   193,   194,   195,   197,   198,   199,   200,   201,
-     203,   204,   205,   206,   207,   210,   212,   213,   217,   224,
-     223,   234,   233,   246,   245,   251,   251,   256,   265,   280,
-     282,   283,   286,   288,   293,   295,   299,   304,   309,   315,
-     321,   331,   334,   343,   345,   351,   353,   358,   365,   364,
-     369,   371,   374,   377,   379,   381,   383,   385,   389,   391,
-     394,   400,   409,   417,   422,   428,   430
+       0,   168,   168,   181,   183,   186,   188,   189,   190,   191,
+     192,   193,   194,   195,   196,   198,   199,   200,   201,   202,
+     204,   205,   206,   207,   208,   211,   213,   214,   218,   225,
+     224,   235,   234,   247,   246,   252,   252,   257,   266,   281,
+     283,   284,   287,   289,   294,   296,   300,   305,   310,   316,
+     322,   332,   335,   344,   346,   352,   354,   359,   366,   365,
+     370,   372,   375,   378,   380,   382,   384,   386,   390,   392,
+     395,   401,   410,   418,   423,   429,   431
 };
 #endif
 
@@ -1215,7 +1216,7 @@ yyreduce:
   switch (yyn)
     {
         case 2:
-#line 169 "parse-gram.y"
+#line 170 "parse-gram.y"
     {
       yycontrol->errcode = 0;
       epilogue_set (yyvsp[0].string, yylsp[0]);
@@ -1223,109 +1224,109 @@ yyreduce:
     break;
 
   case 6:
-#line 187 "parse-gram.y"
+#line 188 "parse-gram.y"
     { prologue_augment (yyvsp[0].string, yylsp[0]); }
     break;
 
   case 7:
-#line 188 "parse-gram.y"
+#line 189 "parse-gram.y"
     { debug_flag = 1; }
     break;
 
   case 8:
-#line 189 "parse-gram.y"
+#line 190 "parse-gram.y"
     { muscle_insert (yyvsp[-1].string, yyvsp[0].string); }
     break;
 
   case 9:
-#line 190 "parse-gram.y"
+#line 191 "parse-gram.y"
     { defines_flag = 1; }
     break;
 
   case 10:
-#line 191 "parse-gram.y"
+#line 192 "parse-gram.y"
     { error_verbose = 1; }
     break;
 
   case 11:
-#line 192 "parse-gram.y"
+#line 193 "parse-gram.y"
     { expected_conflicts = yyvsp[0].integer; }
     break;
 
   case 12:
-#line 193 "parse-gram.y"
+#line 194 "parse-gram.y"
     { spec_file_prefix = yyvsp[0].string; }
     break;
 
   case 13:
-#line 194 "parse-gram.y"
+#line 195 "parse-gram.y"
     { glr_parser = 1; }
     break;
 
   case 14:
-#line 196 "parse-gram.y"
+#line 197 "parse-gram.y"
     { muscle_pair_list_grow ("lex_param", yyvsp[-2].string, yyvsp[0].string); }
     break;
 
   case 15:
-#line 197 "parse-gram.y"
+#line 198 "parse-gram.y"
     { locations_flag = 1; }
     break;
 
   case 16:
-#line 198 "parse-gram.y"
+#line 199 "parse-gram.y"
     { spec_name_prefix = yyvsp[0].string; }
     break;
 
   case 17:
-#line 199 "parse-gram.y"
+#line 200 "parse-gram.y"
     { no_lines_flag = 1; }
     break;
 
   case 18:
-#line 200 "parse-gram.y"
+#line 201 "parse-gram.y"
     { spec_outfile = yyvsp[0].string; }
     break;
 
   case 19:
-#line 202 "parse-gram.y"
+#line 203 "parse-gram.y"
     { muscle_pair_list_grow ("parse_param", yyvsp[-2].string, yyvsp[0].string); }
     break;
 
   case 20:
-#line 203 "parse-gram.y"
+#line 204 "parse-gram.y"
     { pure_parser = 1; }
     break;
 
   case 21:
-#line 204 "parse-gram.y"
+#line 205 "parse-gram.y"
     { skeleton = yyvsp[0].string; }
     break;
 
   case 22:
-#line 205 "parse-gram.y"
+#line 206 "parse-gram.y"
     { token_table_flag = 1; }
     break;
 
   case 23:
-#line 206 "parse-gram.y"
+#line 207 "parse-gram.y"
     { report_flag = 1; }
     break;
 
   case 24:
-#line 207 "parse-gram.y"
+#line 208 "parse-gram.y"
     { yacc_flag = 1; }
     break;
 
   case 27:
-#line 214 "parse-gram.y"
+#line 215 "parse-gram.y"
     {
       grammar_start_symbol_set (yyvsp[0].symbol, yylsp[0]);
     }
     break;
 
   case 28:
-#line 218 "parse-gram.y"
+#line 219 "parse-gram.y"
     {
       typed = 1;
       MUSCLE_INSERT_INT ("stype_line", yylsp[0].first_line);
@@ -1334,12 +1335,12 @@ yyreduce:
     break;
 
   case 29:
-#line 224 "parse-gram.y"
+#line 225 "parse-gram.y"
     { current_braced_code = destructor_braced_code; }
     break;
 
   case 30:
-#line 226 "parse-gram.y"
+#line 227 "parse-gram.y"
     {
       symbol_list_t *list;
       for (list = yyvsp[0].list; list; list = list->next)
@@ -1350,12 +1351,12 @@ yyreduce:
     break;
 
   case 31:
-#line 234 "parse-gram.y"
+#line 235 "parse-gram.y"
     { current_braced_code = printer_braced_code; }
     break;
 
   case 32:
-#line 236 "parse-gram.y"
+#line 237 "parse-gram.y"
     {
       symbol_list_t *list;
       for (list = yyvsp[0].list; list; list = list->next)
@@ -1366,12 +1367,12 @@ yyreduce:
     break;
 
   case 33:
-#line 246 "parse-gram.y"
+#line 247 "parse-gram.y"
     { current_class = nterm_sym; }
     break;
 
   case 34:
-#line 247 "parse-gram.y"
+#line 248 "parse-gram.y"
     {
       current_class = unknown_sym;
       current_type = NULL;
@@ -1379,12 +1380,12 @@ yyreduce:
     break;
 
   case 35:
-#line 251 "parse-gram.y"
+#line 252 "parse-gram.y"
     { current_class = token_sym; }
     break;
 
   case 36:
-#line 252 "parse-gram.y"
+#line 253 "parse-gram.y"
     {
       current_class = unknown_sym;
       current_type = NULL;
@@ -1392,7 +1393,7 @@ yyreduce:
     break;
 
   case 37:
-#line 257 "parse-gram.y"
+#line 258 "parse-gram.y"
     {
       symbol_list_t *list;
       for (list = yyvsp[0].list; list; list = list->next)
@@ -1402,7 +1403,7 @@ yyreduce:
     break;
 
   case 38:
-#line 267 "parse-gram.y"
+#line 268 "parse-gram.y"
     {
       symbol_list_t *list;
       ++current_prec;
@@ -1417,49 +1418,49 @@ yyreduce:
     break;
 
   case 39:
-#line 281 "parse-gram.y"
+#line 282 "parse-gram.y"
     { yyval.assoc = left_assoc; }
     break;
 
   case 40:
-#line 282 "parse-gram.y"
+#line 283 "parse-gram.y"
     { yyval.assoc = right_assoc; }
     break;
 
   case 41:
-#line 283 "parse-gram.y"
+#line 284 "parse-gram.y"
     { yyval.assoc = non_assoc; }
     break;
 
   case 42:
-#line 287 "parse-gram.y"
+#line 288 "parse-gram.y"
     { current_type = NULL; }
     break;
 
   case 43:
-#line 288 "parse-gram.y"
+#line 289 "parse-gram.y"
     { current_type = yyvsp[0].string; }
     break;
 
   case 44:
-#line 294 "parse-gram.y"
+#line 295 "parse-gram.y"
     { yyval.list = symbol_list_new (yyvsp[0].symbol, yylsp[0]); }
     break;
 
   case 45:
-#line 295 "parse-gram.y"
+#line 296 "parse-gram.y"
     { yyval.list = symbol_list_prepend (yyvsp[-1].list, yyvsp[0].symbol, yylsp[0]); }
     break;
 
   case 46:
-#line 301 "parse-gram.y"
+#line 302 "parse-gram.y"
     {
        current_type = yyvsp[0].string;
      }
     break;
 
   case 47:
-#line 305 "parse-gram.y"
+#line 306 "parse-gram.y"
     {
        symbol_class_set (yyvsp[0].symbol, current_class, yylsp[0]);
        symbol_type_set (yyvsp[0].symbol, current_type, yylsp[0]);
@@ -1467,7 +1468,7 @@ yyreduce:
     break;
 
   case 48:
-#line 310 "parse-gram.y"
+#line 311 "parse-gram.y"
     {
       symbol_class_set (yyvsp[-1].symbol, current_class, yylsp[-1]);
       symbol_type_set (yyvsp[-1].symbol, current_type, yylsp[-1]);
@@ -1476,7 +1477,7 @@ yyreduce:
     break;
 
   case 49:
-#line 316 "parse-gram.y"
+#line 317 "parse-gram.y"
     {
       symbol_class_set (yyvsp[-1].symbol, current_class, yylsp[-1]);
       symbol_type_set (yyvsp[-1].symbol, current_type, yylsp[-1]);
@@ -1485,7 +1486,7 @@ yyreduce:
     break;
 
   case 50:
-#line 322 "parse-gram.y"
+#line 323 "parse-gram.y"
     {
       symbol_class_set (yyvsp[-2].symbol, current_class, yylsp[-2]);
       symbol_type_set (yyvsp[-2].symbol, current_type, yylsp[-2]);
@@ -1495,17 +1496,17 @@ yyreduce:
     break;
 
   case 51:
-#line 333 "parse-gram.y"
+#line 334 "parse-gram.y"
     {;}
     break;
 
   case 52:
-#line 335 "parse-gram.y"
+#line 336 "parse-gram.y"
     {;}
     break;
 
   case 56:
-#line 354 "parse-gram.y"
+#line 355 "parse-gram.y"
     {
       if (yacc_flag)
 	complain_at (yyloc, _("POSIX forbids declarations in the grammar"));
@@ -1513,79 +1514,79 @@ yyreduce:
     break;
 
   case 57:
-#line 359 "parse-gram.y"
+#line 360 "parse-gram.y"
     {
       yyerrok;
     }
     break;
 
   case 58:
-#line 365 "parse-gram.y"
+#line 366 "parse-gram.y"
     { current_lhs = yyvsp[-1].symbol; current_lhs_location = yylsp[-1]; }
     break;
 
   case 59:
-#line 366 "parse-gram.y"
+#line 367 "parse-gram.y"
     {;}
     break;
 
   case 60:
-#line 370 "parse-gram.y"
+#line 371 "parse-gram.y"
     { grammar_rule_end (yylsp[0]); }
     break;
 
   case 61:
-#line 371 "parse-gram.y"
+#line 372 "parse-gram.y"
     { grammar_rule_end (yylsp[0]); }
     break;
 
   case 62:
-#line 376 "parse-gram.y"
+#line 377 "parse-gram.y"
     { grammar_rule_begin (current_lhs, current_lhs_location); }
     break;
 
   case 63:
-#line 378 "parse-gram.y"
+#line 379 "parse-gram.y"
     { grammar_current_rule_symbol_append (yyvsp[0].symbol, yylsp[0]); }
     break;
 
   case 64:
-#line 380 "parse-gram.y"
+#line 381 "parse-gram.y"
     { grammar_current_rule_action_append (yyvsp[0].string, yylsp[0]); }
     break;
 
   case 65:
-#line 382 "parse-gram.y"
+#line 383 "parse-gram.y"
     { grammar_current_rule_prec_set (yyvsp[0].symbol, yylsp[0]); }
     break;
 
   case 66:
-#line 384 "parse-gram.y"
+#line 385 "parse-gram.y"
     { grammar_current_rule_dprec_set (yyvsp[0].integer, yylsp[0]); }
     break;
 
   case 67:
-#line 386 "parse-gram.y"
+#line 387 "parse-gram.y"
     { grammar_current_rule_merge_set (yyvsp[0].string, yylsp[0]); }
     break;
 
   case 68:
-#line 390 "parse-gram.y"
+#line 391 "parse-gram.y"
     { yyval.symbol = yyvsp[0].symbol; }
     break;
 
   case 69:
-#line 391 "parse-gram.y"
+#line 392 "parse-gram.y"
     { yyval.symbol = yyvsp[0].symbol; }
     break;
 
   case 70:
-#line 396 "parse-gram.y"
+#line 397 "parse-gram.y"
     { yyval.string = yyvsp[0].string; }
     break;
 
   case 71:
-#line 402 "parse-gram.y"
+#line 403 "parse-gram.y"
     {
       yyval.symbol = symbol_get (yyvsp[0].string, yylsp[0]);
       symbol_class_set (yyval.symbol, token_sym, yylsp[0]);
@@ -1593,7 +1594,7 @@ yyreduce:
     break;
 
   case 72:
-#line 411 "parse-gram.y"
+#line 412 "parse-gram.y"
     {
       yyval.string = yyvsp[0].string + 1;
       yyval.string[strlen (yyval.string) - 1] = '\0';
@@ -1601,14 +1602,14 @@ yyreduce:
     break;
 
   case 73:
-#line 419 "parse-gram.y"
+#line 420 "parse-gram.y"
     {
       yyval.string = xstrdup ("");
     }
     break;
 
   case 74:
-#line 423 "parse-gram.y"
+#line 424 "parse-gram.y"
     {
       yyval.string = yyvsp[0].string;
     }
@@ -1617,8 +1618,8 @@ yyreduce:
 
     }
 
-/* Line 1031 of /tmp/prefix/share/bison/yacc.c.  */
-#line 1621 "parse-gram.c"
+/* Line 1056 of /usr/local/share/bison/yacc.c.  */
+#line 1623 "parse-gram.c"
 
   yyvsp -= yylen;
   yyssp -= yylen;
@@ -1837,7 +1838,7 @@ yyreturn:
 }
 
 
-#line 432 "parse-gram.y"
+#line 433 "parse-gram.y"
 
 /*------------------------------------------------------------------.
 | When debugging the parser, display tokens' locations and values.  |
@@ -1863,7 +1864,7 @@ yyprint (FILE *file,
       break;
 
     case TYPE:
-      fprintf (file, " = <%s>", value->string);
+      fprintf (file, " = <%s>", value->struniq);
       break;
 
     case BRACED_CODE:
diff --git a/src/parse-gram.h b/src/parse-gram.h
index ea92cb3a..96ee3d74 100644
--- a/src/parse-gram.h
+++ b/src/parse-gram.h
@@ -1,4 +1,4 @@
-/* A Bison parser, made by GNU Bison 1.75b.  */
+/* A Bison parser, made from parse-gram.y, by GNU bison 1.75b.  */
 
 /* Skeleton parser for Yacc-like parsing with Bison,
    Copyright (C) 1984, 1989, 1990, 2000, 2001, 2002 Free Software Foundation, Inc.
@@ -23,6 +23,9 @@
    This special exception was added by the Free Software Foundation
    in version 1.24 of Bison.  */
 
+#ifndef BISON_PARSE_GRAM_H
+# define BISON_PARSE_GRAM_H
+
 /* Tokens.  */
 #ifndef YYTOKENTYPE
 # define YYTOKENTYPE
@@ -133,11 +136,11 @@ typedef union {
   int integer;
   char *string;
   assoc_t assoc;
+  struniq_t struniq;
 } yystype;
-/* Line 1293 of /tmp/prefix/share/bison/yacc.c.  */
-#line 138 "y.tab.h"
+/* Line 1321 of /usr/local/share/bison/yacc.c.  */
+#line 143 "y.tab.h"
 # define YYSTYPE yystype
-# define YYSTYPE_IS_TRIVIAL 1
 #endif
 
 
@@ -155,4 +158,5 @@ typedef struct yyltype
 
 
 
+#endif /* not BISON_PARSE_GRAM_H */
 
diff --git a/src/parse-gram.y b/src/parse-gram.y
index aa307881..70356942 100644
--- a/src/parse-gram.y
+++ b/src/parse-gram.y
@@ -92,6 +92,7 @@ braced_code_t current_braced_code = action_braced_code;
   int integer;
   char *string;
   assoc_t assoc;
+  struniq_t struniq;
 };
 
 /* Define the tokens together with their human representation.  */
@@ -454,7 +455,7 @@ yyprint (FILE *file,
       break;
 
     case TYPE:
-      fprintf (file, " = <%s>", value->string);
+      fprintf (file, " = <%s>", value->struniq);
       break;
 
     case BRACED_CODE:
diff --git a/src/reader.c b/src/reader.c
index e6b74764..64601e34 100644
--- a/src/reader.c
+++ b/src/reader.c
@@ -99,7 +99,7 @@ epilogue_set (const char *epilogue, location_t location)
 
 
 
- /*-------------------------------------------------------------------.
+/*-------------------------------------------------------------------.
 | Return the merger index for a merging function named NAME, whose   |
 | arguments have type TYPE.  Records the function, if new, in        |
 | merger_list.							     |
diff --git a/src/scan-gram.l b/src/scan-gram.l
index 8f18c355..da92baaf 100644
--- a/src/scan-gram.l
+++ b/src/scan-gram.l
@@ -27,6 +27,7 @@
 #include "mbswidth.h"
 #include "complain.h"
 #include "quote.h"
+#include "struniq.h"
 #include "getargs.h"
 #include "gram.h"
 #include "reader.h"
@@ -301,7 +302,8 @@ splice	 (\\[ \f\t\v]*\n)*
   "<"{tag}">" {
     obstack_grow (&string_obstack, yytext + 1, yyleng - 2);
     YY_OBS_FINISH;
-    yylval->string = last_string;
+    yylval->struniq = struniq_new (last_string);
+    YY_OBS_FREE;
     return TYPE;
   }
 
diff --git a/src/struniq.c b/src/struniq.c
new file mode 100644
index 00000000..4260a70f
--- /dev/null
+++ b/src/struniq.c
@@ -0,0 +1,134 @@
+/* Keeping a unique copy of strings.
+   Copyright (C) 2002 Free Software Foundation, Inc.
+
+   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.
+
+   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.
+
+   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.  */
+
+#include "system.h"
+#include "quotearg.h"
+#include "hash.h"
+#include "struniq.h"
+
+/*-----------------------.
+| A struniq hash table.  |
+`-----------------------*/
+
+/* Initial capacity of struniq hash table.  */
+#define HT_INITIAL_CAPACITY 257
+
+static struct hash_table *struniqs_table = NULL;
+
+/*-------------------------------------.
+| Create the struniq for S if needed.  |
+`-------------------------------------*/
+
+const struniq_t
+struniq_new (const char *s)
+{
+  /* Keep the struniqs in a printable form.  */
+  struniq_t res = hash_lookup (struniqs_table, 
+			       quotearg_style (escape_quoting_style, s));
+
+  if (!res)
+    {
+      /* First insertion in the hash. */
+      res = xstrdup (quotearg_style (escape_quoting_style, s));
+      hash_insert (struniqs_table, res);
+    }
+  return res;
+}
+
+
+/*--------------------.
+| Print the struniq.  |
+`--------------------*/
+
+static bool
+struniq_print (const struniq_t s)
+{
+  fprintf (stderr, "%s\n", s);
+  return true;
+}
+
+
+/*-----------------------.
+| A struniq hash table.  |
+`-----------------------*/
+
+static bool
+hash_compare_struniq_t (const struniq_t m1, const struniq_t m2)
+{
+  return strcmp (m1, m2) == 0;
+}
+
+static unsigned int
+hash_struniq_t (const struniq_t m, unsigned int tablesize)
+{
+  return hash_string (m, tablesize);
+}
+
+/* A function to apply to each symbol. */
+typedef bool (*struniq_processor_t) (const struniq_t);
+
+/*----------------------------.
+| Create the struniqs table.  |
+`----------------------------*/
+
+void
+struniqs_new (void)
+{
+  struniqs_table = hash_initialize (HT_INITIAL_CAPACITY,
+				    NULL,
+				    (Hash_hasher) hash_struniq_t,
+				    (Hash_comparator) hash_compare_struniq_t,
+				    (Hash_data_freer) free);
+}
+
+
+/*-------------------------------------.
+| Perform a task on all the struniqs.  |
+`-------------------------------------*/
+
+static void
+struniqs_do (struniq_processor_t processor, void *processor_data)
+{
+  hash_do_for_each (struniqs_table,
+		    (Hash_processor) processor,
+		    processor_data);
+}
+
+
+/*-----------------.
+| Print them all.  |
+`-----------------*/
+
+void
+struniqs_print (void)
+{
+  struniqs_do (struniq_print, NULL);
+}
+
+
+/*--------------------.
+| Free the struniqs.  |
+`--------------------*/
+
+void
+struniqs_free (void)
+{
+  hash_free (struniqs_table);
+}
diff --git a/src/struniq.h b/src/struniq.h
new file mode 100644
index 00000000..e83a0834
--- /dev/null
+++ b/src/struniq.h
@@ -0,0 +1,46 @@
+/* Keeping a unique copy of strings.
+   Copyright (C) 2002 Free Software Foundation, Inc.
+
+   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.
+
+   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.
+
+   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.  */
+
+#ifndef STRUNIQ_H_
+# define STRUNIQ_H_
+
+/*------------------------------------------------------.
+| struniq_t -- pointers to unique copies of C strings.  |
+`------------------------------------------------------*/
+
+typedef char *struniq_t;
+
+/* Return the struniq for S.  */
+const struniq_t struniq_new (const char *s);
+
+/*--------------------------------------.
+| Initializing, destroying, debugging.  |
+`--------------------------------------*/
+
+/* Create the string table.  */
+void struniqs_new (void);
+
+/* Free all the memory allocated for symbols.  */
+void struniqs_free (void);
+
+/* Report them all.  */
+void struniqs_print (void);
+
+#endif /* !STRUNIQ_H_ */
diff --git a/src/symtab.c b/src/symtab.c
index 7a2ac14b..c293de2a 100644
--- a/src/symtab.c
+++ b/src/symtab.c
@@ -200,13 +200,8 @@ symbol_user_token_number_set (symbol_t *symbol,
 static void
 symbol_free (symbol_t *this)
 {
-#if 0
-  /* This causes crashes because one string can appear more
-     than once.  */
-  XFREE (this->type_name);
-#endif
-  XFREE (this->tag);
-  XFREE (this);
+  free (this->tag);
+  free (this);
 }
 
 
diff --git a/src/symtab.h b/src/symtab.h
index 61bd4017..ecf28cd0 100644
--- a/src/symtab.h
+++ b/src/symtab.h
@@ -22,6 +22,7 @@
 #ifndef SYMTAB_H_
 # define SYMTAB_H_
 
+# include "struniq.h"
 # include "location.h"
 # include "assoc.h"
 
@@ -52,7 +53,7 @@ struct symbol_s
   location_t location;
 
   /* Its %type and associated printer and destructor.  */
-  char *type_name;
+  struniq_t type_name;
   char *destructor;
   location_t destructor_location;
   char *printer;