Fix handling of yychar manipulation in user semantic actions.

The problem was that yacc.c didn't always update the yychar
translation afterwards.  However, other skeletons appear to be
fine.  glr.c appears to already translate yychar before every
use.  lalr1.cc does not define yychar and does not document its
replacement, yyla, for users.  It does provide yyclearin, but
that does not manipulate yyla and thus requires no translation
update.  In lalr1.java, yychar is out of scope during semantic
actions.
* NEWS (2.5): Document.
* data/yacc.c (YYBACKUP): Don't bother translating yychar into
yytoken here.
(yyparse, yypush_parse): Instead, translate before every use of
yytoken, and add comments explaining this approach.
* tests/actions.at (Destroying lookahead assigned by semantic
action): New test group checking that translation happens before
lookahead destructor calls at parser return.  Previously,
incorrect destructors were called.
* tests/conflicts.at (%error-verbose and consistent
errors): New test group checking that translation happens at
syntax error detection before the associated verbose error
message and the associated lookahead destructor calls.  While
the destructor call is fixed by this patch, the verbose error
message is currently incorrect due to another bug (see
comments in test group), so this is an expected failure for now.
(cherry picked from commit df222dfaf4da6becae8665d344669eefc705d7f7)

Conflicts:

	src/parse-gram.c
	src/parse-gram.h

diff --git a/ChangeLog b/ChangeLog
index 312796a4921439537b7c44e771283fbf5815167e..ec11063313f52c1646d2239b6ee99ff437335376 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,31 @@
+2009-12-20  Joel E. Denny  <jdenny@clemson.edu>
+
+       Fix handling of yychar manipulation in user semantic actions.
+       The problem was that yacc.c didn't always update the yychar
+       translation afterwards.  However, other skeletons appear to be
+       fine.  glr.c appears to already translate yychar before every
+       use.  lalr1.cc does not define yychar and does not document its
+       replacement, yyla, for users.  It does provide yyclearin, but
+       that does not manipulate yyla and thus requires no translation
+       update.  In lalr1.java, yychar is out of scope during semantic
+       actions.
+       * NEWS (2.5): Document.
+       * data/yacc.c (YYBACKUP): Don't bother translating yychar into
+       yytoken here.
+       (yyparse, yypush_parse): Instead, translate before every use of
+       yytoken, and add comments explaining this approach.
+       * tests/actions.at (Destroying lookahead assigned by semantic
+       action): New test group checking that translation happens before
+       lookahead destructor calls at parser return.  Previously,
+       incorrect destructors were called.
+       * tests/conflicts.at (%error-verbose and consistent
+       errors): New test group checking that translation happens at
+       syntax error detection before the associated verbose error
+       message and the associated lookahead destructor calls.  While
+       the destructor call is fixed by this patch, the verbose error
+       message is currently incorrect due to another bug (see
+       comments in test group), so this is an expected failure for now.
+
 2009-12-21  Joel E. Denny  <jdenny@clemson.edu>
 
        YYFAIL: warn about uses and remove from lalr1.java.

diff --git a/NEWS b/NEWS
index d6eed9123bb0e27eaac991e6ab5d642d54a4e494..7553a8614ca416b21955d37434d8377cad2fce87 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -173,6 +173,13 @@ Bison News
   were resolved with %nonassoc.  Such tokens are now properly omitted
   from the list.
 
+** Destructor calls fixed for lookaheads altered in semantic actions.
+
+  Previously for deterministic parsers in C, if a user semantic action
+  altered yychar, the parser in some cases used the old yychar value to
+  determine which destructor to call for the lookahead upon a syntax
+  error or upon parser return.  This bug has been fixed.
+
 * Changes in version 2.4.2 (????-??-??):
 
 ** Detection of GNU M4 1.4.6 or newer during configure is improved.

diff --git a/data/yacc.c b/data/yacc.c
index 357539e4c333f7d936c9b7ed107f43cecca09707..fc74e58a14a390242960fc08437a16436e9ff10c 100644 (file)
--- a/data/yacc.c
+++ b/data/yacc.c
@@ -698,7 +698,6 @@ do                                                          \
     {                                                          \
       yychar = (Token);                                                \
       yylval = (Value);                                                \
-      yytoken = YYTRANSLATE (yychar);                          \
       YYPOPSTACK (1);                                          \
       goto yybackup;                                           \
     }                                                          \
@@ -1495,6 +1494,17 @@ yyreduce:
       ]b4_user_actions[
       default: break;
     }
+  /* User semantic actions sometimes alter yychar, and that requires
+     that yytoken be updated with the new translation.  We take the
+     approach of translating immediately before every use of yytoken.
+     One alternative is translating here after every semantic action,
+     but that translation would be missed if the semantic action invokes
+     YYABORT, YYACCEPT, or YYERROR immediately after altering yychar or
+     if it invokes YYBACKUP.  In the case of YYABORT or YYACCEPT, an
+     incorrect destructor might then be invoked immediately.  In the
+     case of YYERROR or YYBACKUP, subsequent parser actions might lead
+     to an incorrect destructor call or verbose syntax error message
+     before the lookahead is translated.  */
   YY_SYMBOL_PRINT ("-> $$ =", yyr1[yyn], &yyval, &yyloc);
 
   YYPOPSTACK (yylen);
@@ -1523,6 +1533,10 @@ yyreduce:
 | yyerrlab -- here on detecting error |
 `------------------------------------*/
 yyerrlab:
+  /* Make sure we have latest lookahead translation.  See comments at
+     user semantic actions for why this is necessary.  */
+  yytoken = YYTRANSLATE (yychar);
+
   /* If not already recovering from an error, report this error.  */
   if (!yyerrstatus)
     {
@@ -1675,8 +1689,13 @@ yyexhaustedlab:
 
 yyreturn:
   if (yychar != YYEMPTY)
-     yydestruct ("Cleanup: discarding lookahead",
-                yytoken, &yylval]b4_locations_if([, &yylloc])[]b4_user_args[);
+    {
+      /* Make sure we have latest lookahead translation.  See comments at
+         user semantic actions for why this is necessary.  */
+      yytoken = YYTRANSLATE (yychar);
+      yydestruct ("Cleanup: discarding lookahead",
+                  yytoken, &yylval]b4_locations_if([, &yylloc])[]b4_user_args[);
+    }
   /* Do not reclaim the symbols of the rule which action triggered
      this YYABORT or YYACCEPT.  */
   YYPOPSTACK (yylen);

diff --git a/src/parse-gram.c b/src/parse-gram.c
index 2fe9c9ace3361f723c16c75c0132834b6338c31c..19038b32fab6a4486a32494f5a69c432072d271c 100644 (file)
--- a/src/parse-gram.c
+++ b/src/parse-gram.c
@@ -1,4 +1,4 @@
-/* A Bison parser, made by GNU Bison 2.4.1.171-692d.  */
+/* A Bison parser, made by GNU Bison 2.4.1.173-62efdd.  */
 
 /* Skeleton implementation for Bison's Yacc-like parsers in C
    
@@ -45,7 +45,7 @@
 #define YYBISON 1
 
 /* Bison version.  */
-#define YYBISON_VERSION "2.4.1.171-692d"
+#define YYBISON_VERSION "2.4.1.173-62efdd"
 
 /* Skeleton name.  */
 #define YYSKELETON_NAME "yacc.c"
@@ -927,7 +927,6 @@ do                                                          \
     {                                                          \
       yychar = (Token);                                                \
       yylval = (Value);                                                \
-      yytoken = YYTRANSLATE (yychar);                          \
       YYPOPSTACK (1);                                          \
       goto yybackup;                                           \
     }                                                          \
@@ -1050,165 +1049,165 @@ yy_symbol_value_print (yyoutput, yytype, yyvaluep, yylocationp)
     {
       case 3: /* "\"string\"" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 184 "parse-gram.y"
        { fputs (quotearg_style (c_quoting_style, (yyvaluep->chars)), stderr); };
 
-/* Line 799 of yacc.c  */
-#line 1059 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1058 "parse-gram.c"
        break;
       case 4: /* "\"integer\"" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 196 "parse-gram.y"
        { fprintf (stderr, "%d", (yyvaluep->integer)); };
 
-/* Line 799 of yacc.c  */
-#line 1068 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1067 "parse-gram.c"
        break;
       case 43: /* "\"{...}\"" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 186 "parse-gram.y"
        { fprintf (stderr, "{\n%s\n}", (yyvaluep->code)); };
 
-/* Line 799 of yacc.c  */
-#line 1077 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1076 "parse-gram.c"
        break;
       case 44: /* "\"[identifier]\"" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 191 "parse-gram.y"
        { fprintf (stderr, "[%s]", (yyvaluep->uniqstr)); };
 
-/* Line 799 of yacc.c  */
-#line 1086 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1085 "parse-gram.c"
        break;
       case 45: /* "\"char\"" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 178 "parse-gram.y"
        { fputs (char_name ((yyvaluep->character)), stderr); };
 
-/* Line 799 of yacc.c  */
-#line 1095 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1094 "parse-gram.c"
        break;
       case 46: /* "\"epilogue\"" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 186 "parse-gram.y"
        { fprintf (stderr, "{\n%s\n}", (yyvaluep->chars)); };
 
-/* Line 799 of yacc.c  */
-#line 1104 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1103 "parse-gram.c"
        break;
       case 48: /* "\"identifier\"" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 190 "parse-gram.y"
        { fputs ((yyvaluep->uniqstr), stderr); };
 
-/* Line 799 of yacc.c  */
-#line 1113 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1112 "parse-gram.c"
        break;
       case 49: /* "\"identifier:\"" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 192 "parse-gram.y"
        { fprintf (stderr, "%s:", (yyvaluep->uniqstr)); };
 
-/* Line 799 of yacc.c  */
-#line 1122 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1121 "parse-gram.c"
        break;
       case 52: /* "\"%{...%}\"" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 186 "parse-gram.y"
        { fprintf (stderr, "{\n%s\n}", (yyvaluep->chars)); };
 
-/* Line 799 of yacc.c  */
-#line 1131 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1130 "parse-gram.c"
        break;
       case 54: /* "\"type\"" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 193 "parse-gram.y"
        { fprintf (stderr, "<%s>", (yyvaluep->uniqstr)); };
 
-/* Line 799 of yacc.c  */
-#line 1140 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1139 "parse-gram.c"
        break;
       case 71: /* "symbol.prec" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 199 "parse-gram.y"
        { fprintf (stderr, "%s", (yyvaluep->symbol)->tag); };
 
-/* Line 799 of yacc.c  */
-#line 1149 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1148 "parse-gram.c"
        break;
       case 84: /* "variable" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 190 "parse-gram.y"
        { fputs ((yyvaluep->uniqstr), stderr); };
 
-/* Line 799 of yacc.c  */
-#line 1158 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1157 "parse-gram.c"
        break;
       case 85: /* "content.opt" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 186 "parse-gram.y"
        { fprintf (stderr, "{\n%s\n}", (yyvaluep->chars)); };
 
-/* Line 799 of yacc.c  */
-#line 1167 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1166 "parse-gram.c"
        break;
       case 86: /* "braceless" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 186 "parse-gram.y"
        { fprintf (stderr, "{\n%s\n}", (yyvaluep->chars)); };
 
-/* Line 799 of yacc.c  */
-#line 1176 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1175 "parse-gram.c"
        break;
       case 87: /* "id" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 199 "parse-gram.y"
        { fprintf (stderr, "%s", (yyvaluep->symbol)->tag); };
 
-/* Line 799 of yacc.c  */
-#line 1185 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1184 "parse-gram.c"
        break;
       case 88: /* "id_colon" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 200 "parse-gram.y"
        { fprintf (stderr, "%s:", (yyvaluep->symbol)->tag); };
 
-/* Line 799 of yacc.c  */
-#line 1194 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1193 "parse-gram.c"
        break;
       case 89: /* "symbol" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 199 "parse-gram.y"
        { fprintf (stderr, "%s", (yyvaluep->symbol)->tag); };
 
-/* Line 799 of yacc.c  */
-#line 1203 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1202 "parse-gram.c"
        break;
       case 90: /* "string_as_id" */
 
-/* Line 799 of yacc.c  */
+/* Line 798 of yacc.c  */
 #line 199 "parse-gram.y"
        { fprintf (stderr, "%s", (yyvaluep->symbol)->tag); };
 
-/* Line 799 of yacc.c  */
-#line 1212 "parse-gram.c"
+/* Line 798 of yacc.c  */
+#line 1211 "parse-gram.c"
        break;
       default:
        break;
@@ -1735,7 +1734,7 @@ YYLTYPE yylloc;
 
 /* User initialization code.  */
 
-/* Line 1282 of yacc.c  */
+/* Line 1281 of yacc.c  */
 #line 86 "parse-gram.y"
 {
   /* Bison's grammar can initial empty locations, hence a default
@@ -1744,8 +1743,8 @@ YYLTYPE yylloc;
   boundary_set (&yylloc.end, current_file, 1, 1);
 }
 
-/* Line 1282 of yacc.c  */
-#line 1749 "parse-gram.c"
+/* Line 1281 of yacc.c  */
+#line 1748 "parse-gram.c"
   yylsp[0] = yylloc;
 
   goto yysetstate;
@@ -1932,7 +1931,7 @@ yyreduce:
     {
         case 6:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 225 "parse-gram.y"
     {
       code_props plain_code;
@@ -1947,14 +1946,14 @@ yyreduce:
 
   case 7:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 234 "parse-gram.y"
     { debug_flag = true; }
     break;
 
   case 8:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 236 "parse-gram.y"
     {
       muscle_percent_define_insert ((yyvsp[(2) - (3)].uniqstr), (yylsp[(2) - (3)]), (yyvsp[(3) - (3)].chars),
@@ -1964,14 +1963,14 @@ yyreduce:
 
   case 9:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 240 "parse-gram.y"
     { defines_flag = true; }
     break;
 
   case 10:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 242 "parse-gram.y"
     {
       defines_flag = true;
@@ -1981,42 +1980,42 @@ yyreduce:
 
   case 11:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 246 "parse-gram.y"
     { error_verbose = true; }
     break;
 
   case 12:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 247 "parse-gram.y"
     { expected_sr_conflicts = (yyvsp[(2) - (2)].integer); }
     break;
 
   case 13:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 248 "parse-gram.y"
     { expected_rr_conflicts = (yyvsp[(2) - (2)].integer); }
     break;
 
   case 14:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 249 "parse-gram.y"
     { spec_file_prefix = (yyvsp[(2) - (2)].chars); }
     break;
 
   case 15:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 250 "parse-gram.y"
     { spec_file_prefix = (yyvsp[(3) - (3)].chars); }
     break;
 
   case 16:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 252 "parse-gram.y"
     {
       nondeterministic_parser = true;
@@ -2026,7 +2025,7 @@ yyreduce:
 
   case 17:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 257 "parse-gram.y"
     {
       code_props action;
@@ -2040,77 +2039,77 @@ yyreduce:
 
   case 18:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 265 "parse-gram.y"
     { language_argmatch ((yyvsp[(2) - (2)].chars), grammar_prio, (yylsp[(1) - (2)])); }
     break;
 
   case 19:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 266 "parse-gram.y"
     { add_param ("lex_param", (yyvsp[(2) - (2)].code), (yylsp[(2) - (2)])); }
     break;
 
   case 20:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 267 "parse-gram.y"
     { locations_flag = true; }
     break;
 
   case 21:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 268 "parse-gram.y"
     { spec_name_prefix = (yyvsp[(2) - (2)].chars); }
     break;
 
   case 22:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 269 "parse-gram.y"
     { spec_name_prefix = (yyvsp[(3) - (3)].chars); }
     break;
 
   case 23:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 270 "parse-gram.y"
     { no_lines_flag = true; }
     break;
 
   case 24:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 271 "parse-gram.y"
     { nondeterministic_parser = true; }
     break;
 
   case 25:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 272 "parse-gram.y"
     { spec_outfile = (yyvsp[(2) - (2)].chars); }
     break;
 
   case 26:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 273 "parse-gram.y"
     { spec_outfile = (yyvsp[(3) - (3)].chars); }
     break;
 
   case 27:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 274 "parse-gram.y"
     { add_param ("parse_param", (yyvsp[(2) - (2)].code), (yylsp[(2) - (2)])); }
     break;
 
   case 28:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 276 "parse-gram.y"
     {
       /* %pure-parser is deprecated in favor of `%define api.pure', so use
@@ -2130,14 +2129,14 @@ yyreduce:
 
   case 29:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 290 "parse-gram.y"
     { version_check (&(yylsp[(2) - (2)]), (yyvsp[(2) - (2)].chars)); }
     break;
 
   case 30:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 292 "parse-gram.y"
     {
       char const *skeleton_user = (yyvsp[(2) - (2)].chars);
@@ -2166,28 +2165,28 @@ yyreduce:
 
   case 31:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 315 "parse-gram.y"
     { token_table_flag = true; }
     break;
 
   case 32:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 316 "parse-gram.y"
     { report_flag |= report_states; }
     break;
 
   case 33:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 317 "parse-gram.y"
     { yacc_flag = true; }
     break;
 
   case 37:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 325 "parse-gram.y"
     {
       grammar_start_symbol_set ((yyvsp[(2) - (2)].symbol), (yylsp[(2) - (2)]));
@@ -2196,7 +2195,7 @@ yyreduce:
 
   case 38:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 329 "parse-gram.y"
     {
       symbol_list *list;
@@ -2208,7 +2207,7 @@ yyreduce:
 
   case 39:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 336 "parse-gram.y"
     {
       symbol_list *list;
@@ -2220,7 +2219,7 @@ yyreduce:
 
   case 40:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 343 "parse-gram.y"
     {
       default_prec = true;
@@ -2229,7 +2228,7 @@ yyreduce:
 
   case 41:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 347 "parse-gram.y"
     {
       default_prec = false;
@@ -2238,7 +2237,7 @@ yyreduce:
 
   case 42:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 351 "parse-gram.y"
     {
       /* Do not invoke muscle_percent_code_grow here since it invokes
@@ -2250,7 +2249,7 @@ yyreduce:
 
   case 43:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 358 "parse-gram.y"
     {
       muscle_percent_code_grow ((yyvsp[(2) - (3)].uniqstr), (yylsp[(2) - (3)]), (yyvsp[(3) - (3)].chars), (yylsp[(3) - (3)]));
@@ -2260,21 +2259,21 @@ yyreduce:
 
   case 44:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 372 "parse-gram.y"
     {}
     break;
 
   case 45:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 373 "parse-gram.y"
     { muscle_code_grow ("union_name", (yyvsp[(1) - (1)].uniqstr), (yylsp[(1) - (1)])); }
     break;
 
   case 46:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 378 "parse-gram.y"
     {
       union_seen = true;
@@ -2285,14 +2284,14 @@ yyreduce:
 
   case 47:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 389 "parse-gram.y"
     { current_class = nterm_sym; }
     break;
 
   case 48:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 390 "parse-gram.y"
     {
       current_class = unknown_sym;
@@ -2302,14 +2301,14 @@ yyreduce:
 
   case 49:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 394 "parse-gram.y"
     { current_class = token_sym; }
     break;
 
   case 50:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 395 "parse-gram.y"
     {
       current_class = unknown_sym;
@@ -2319,7 +2318,7 @@ yyreduce:
 
   case 51:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 400 "parse-gram.y"
     {
       symbol_list *list;
@@ -2332,7 +2331,7 @@ yyreduce:
 
   case 52:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 411 "parse-gram.y"
     {
       symbol_list *list;
@@ -2349,126 +2348,126 @@ yyreduce:
 
   case 53:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 425 "parse-gram.y"
     { (yyval.assoc) = left_assoc; }
     break;
 
   case 54:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 426 "parse-gram.y"
     { (yyval.assoc) = right_assoc; }
     break;
 
   case 55:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 427 "parse-gram.y"
     { (yyval.assoc) = non_assoc; }
     break;
 
   case 56:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 431 "parse-gram.y"
     { current_type = NULL; }
     break;
 
   case 57:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 432 "parse-gram.y"
     { current_type = (yyvsp[(1) - (1)].uniqstr); tag_seen = true; }
     break;
 
   case 58:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 438 "parse-gram.y"
     { (yyval.list) = symbol_list_sym_new ((yyvsp[(1) - (1)].symbol), (yylsp[(1) - (1)])); }
     break;
 
   case 59:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 440 "parse-gram.y"
     { (yyval.list) = symbol_list_prepend ((yyvsp[(1) - (2)].list), symbol_list_sym_new ((yyvsp[(2) - (2)].symbol), (yylsp[(2) - (2)]))); }
     break;
 
   case 60:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 444 "parse-gram.y"
     { (yyval.symbol) = (yyvsp[(1) - (1)].symbol); }
     break;
 
   case 61:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 445 "parse-gram.y"
     { (yyval.symbol) = (yyvsp[(1) - (2)].symbol); symbol_user_token_number_set ((yyvsp[(1) - (2)].symbol), (yyvsp[(2) - (2)].integer), (yylsp[(2) - (2)])); }
     break;
 
   case 62:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 451 "parse-gram.y"
     { (yyval.list) = symbol_list_sym_new ((yyvsp[(1) - (1)].symbol), (yylsp[(1) - (1)])); }
     break;
 
   case 63:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 453 "parse-gram.y"
     { (yyval.list) = symbol_list_prepend ((yyvsp[(1) - (2)].list), symbol_list_sym_new ((yyvsp[(2) - (2)].symbol), (yylsp[(2) - (2)]))); }
     break;
 
   case 64:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 457 "parse-gram.y"
     { (yyval.list) = (yyvsp[(1) - (1)].list); }
     break;
 
   case 65:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 458 "parse-gram.y"
     { (yyval.list) = symbol_list_prepend ((yyvsp[(1) - (2)].list), (yyvsp[(2) - (2)].list)); }
     break;
 
   case 66:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 462 "parse-gram.y"
     { (yyval.list) = symbol_list_sym_new ((yyvsp[(1) - (1)].symbol), (yylsp[(1) - (1)])); }
     break;
 
   case 67:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 463 "parse-gram.y"
     { (yyval.list) = symbol_list_type_new ((yyvsp[(1) - (1)].uniqstr), (yylsp[(1) - (1)])); }
     break;
 
   case 68:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 464 "parse-gram.y"
     { (yyval.list) = symbol_list_default_tagged_new ((yylsp[(1) - (1)])); }
     break;
 
   case 69:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 465 "parse-gram.y"
     { (yyval.list) = symbol_list_default_tagless_new ((yylsp[(1) - (1)])); }
     break;
 
   case 70:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 471 "parse-gram.y"
     {
        current_type = (yyvsp[(1) - (1)].uniqstr);
@@ -2478,7 +2477,7 @@ yyreduce:
 
   case 71:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 476 "parse-gram.y"
     {
        symbol_class_set ((yyvsp[(1) - (1)].symbol), current_class, (yylsp[(1) - (1)]), true);
@@ -2488,7 +2487,7 @@ yyreduce:
 
   case 72:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 481 "parse-gram.y"
     {
       symbol_class_set ((yyvsp[(1) - (2)].symbol), current_class, (yylsp[(1) - (2)]), true);
@@ -2499,7 +2498,7 @@ yyreduce:
 
   case 73:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 487 "parse-gram.y"
     {
       symbol_class_set ((yyvsp[(1) - (2)].symbol), current_class, (yylsp[(1) - (2)]), true);
@@ -2510,7 +2509,7 @@ yyreduce:
 
   case 74:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 493 "parse-gram.y"
     {
       symbol_class_set ((yyvsp[(1) - (3)].symbol), current_class, (yylsp[(1) - (3)]), true);
@@ -2522,7 +2521,7 @@ yyreduce:
 
   case 81:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 523 "parse-gram.y"
     {
       yyerrok;
@@ -2531,7 +2530,7 @@ yyreduce:
 
   case 82:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 529 "parse-gram.y"
     { current_lhs = (yyvsp[(1) - (2)].symbol); current_lhs_location = (yylsp[(1) - (2)]);
     current_lhs_named_ref = (yyvsp[(2) - (2)].named_ref); }
@@ -2539,21 +2538,21 @@ yyreduce:
 
   case 84:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 534 "parse-gram.y"
     { grammar_current_rule_end ((yylsp[(1) - (1)])); }
     break;
 
   case 85:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 535 "parse-gram.y"
     { grammar_current_rule_end ((yylsp[(3) - (3)])); }
     break;
 
   case 87:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 541 "parse-gram.y"
     { grammar_current_rule_begin (current_lhs, current_lhs_location,
                                  current_lhs_named_ref); }
@@ -2561,77 +2560,77 @@ yyreduce:
 
   case 88:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 544 "parse-gram.y"
     { grammar_current_rule_symbol_append ((yyvsp[(2) - (3)].symbol), (yylsp[(2) - (3)]), (yyvsp[(3) - (3)].named_ref)); }
     break;
 
   case 89:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 546 "parse-gram.y"
     { grammar_current_rule_action_append ((yyvsp[(2) - (3)].code), (yylsp[(2) - (3)]), (yyvsp[(3) - (3)].named_ref)); }
     break;
 
   case 90:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 548 "parse-gram.y"
     { grammar_current_rule_prec_set ((yyvsp[(3) - (3)].symbol), (yylsp[(3) - (3)])); }
     break;
 
   case 91:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 550 "parse-gram.y"
     { grammar_current_rule_dprec_set ((yyvsp[(3) - (3)].integer), (yylsp[(3) - (3)])); }
     break;
 
   case 92:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 552 "parse-gram.y"
     { grammar_current_rule_merge_set ((yyvsp[(3) - (3)].uniqstr), (yylsp[(3) - (3)])); }
     break;
 
   case 93:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 556 "parse-gram.y"
     { (yyval.named_ref) = 0; }
     break;
 
   case 94:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 558 "parse-gram.y"
     { (yyval.named_ref) = named_ref_new((yyvsp[(1) - (1)].uniqstr), (yylsp[(1) - (1)])); }
     break;
 
   case 96:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 570 "parse-gram.y"
     { (yyval.uniqstr) = uniqstr_new ((yyvsp[(1) - (1)].chars)); }
     break;
 
   case 97:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 575 "parse-gram.y"
     { (yyval.chars) = ""; }
     break;
 
   case 98:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 576 "parse-gram.y"
     { (yyval.chars) = (yyvsp[(1) - (1)].uniqstr); }
     break;
 
   case 100:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 587 "parse-gram.y"
     {
       code_props plain_code;
@@ -2645,14 +2644,14 @@ yyreduce:
 
   case 101:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 607 "parse-gram.y"
     { (yyval.symbol) = symbol_from_uniqstr ((yyvsp[(1) - (1)].uniqstr), (yylsp[(1) - (1)])); }
     break;
 
   case 102:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 609 "parse-gram.y"
     {
       (yyval.symbol) = symbol_get (char_name ((yyvsp[(1) - (1)].character)), (yylsp[(1) - (1)]));
@@ -2663,14 +2662,14 @@ yyreduce:
 
   case 103:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 617 "parse-gram.y"
     { (yyval.symbol) = symbol_from_uniqstr ((yyvsp[(1) - (1)].uniqstr), (yylsp[(1) - (1)])); }
     break;
 
   case 106:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 629 "parse-gram.y"
     {
       (yyval.symbol) = symbol_get (quotearg_style (c_quoting_style, (yyvsp[(1) - (1)].chars)), (yylsp[(1) - (1)]));
@@ -2680,7 +2679,7 @@ yyreduce:
 
   case 108:
 
-/* Line 1495 of yacc.c  */
+/* Line 1494 of yacc.c  */
 #line 638 "parse-gram.y"
     {
       code_props plain_code;
@@ -2694,10 +2693,21 @@ yyreduce:
 
 
 
-/* Line 1495 of yacc.c  */
-#line 2699 "parse-gram.c"
+/* Line 1494 of yacc.c  */
+#line 2698 "parse-gram.c"
       default: break;
     }
+  /* User semantic actions sometimes alter yychar, and that requires
+     that yytoken be updated with the new translation.  We take the
+     approach of translating immediately before every use of yytoken.
+     One alternative is translating here after every semantic action,
+     but that translation would be missed if the semantic action invokes
+     YYABORT, YYACCEPT, or YYERROR immediately after altering yychar or
+     if it invokes YYBACKUP.  In the case of YYABORT or YYACCEPT, an
+     incorrect destructor might then be invoked immediately.  In the
+     case of YYERROR or YYBACKUP, subsequent parser actions might lead
+     to an incorrect destructor call or verbose syntax error message
+     before the lookahead is translated.  */
   YY_SYMBOL_PRINT ("-> $$ =", yyr1[yyn], &yyval, &yyloc);
 
   YYPOPSTACK (yylen);
@@ -2726,6 +2736,10 @@ yyreduce:
 | yyerrlab -- here on detecting error |
 `------------------------------------*/
 yyerrlab:
+  /* Make sure we have latest lookahead translation.  See comments at
+     user semantic actions for why this is necessary.  */
+  yytoken = YYTRANSLATE (yychar);
+
   /* If not already recovering from an error, report this error.  */
   if (!yyerrstatus)
     {
@@ -2878,8 +2892,13 @@ yyexhaustedlab:
 
 yyreturn:
   if (yychar != YYEMPTY)
-     yydestruct ("Cleanup: discarding lookahead",
-                yytoken, &yylval, &yylloc);
+    {
+      /* Make sure we have latest lookahead translation.  See comments at
+         user semantic actions for why this is necessary.  */
+      yytoken = YYTRANSLATE (yychar);
+      yydestruct ("Cleanup: discarding lookahead",
+                  yytoken, &yylval, &yylloc);
+    }
   /* Do not reclaim the symbols of the rule which action triggered
      this YYABORT or YYACCEPT.  */
   YYPOPSTACK (yylen);
@@ -2904,7 +2923,7 @@ yyreturn:
 
 
 
-/* Line 1706 of yacc.c  */
+/* Line 1725 of yacc.c  */
 #line 648 "parse-gram.y"
 
 

diff --git a/src/parse-gram.h b/src/parse-gram.h
index 8bd4bc3dc60da081ebb993aa4aa5a6a8379c6112..d307aa082671e41157987bf9a15d3f574e31b8ca 100644 (file)
--- a/src/parse-gram.h
+++ b/src/parse-gram.h
@@ -1,4 +1,4 @@
-/* A Bison parser, made by GNU Bison 2.4.1.171-692d.  */
+/* A Bison parser, made by GNU Bison 2.4.1.173-62efdd.  */
 
 /* Skeleton interface for Bison's Yacc-like parsers in C
    
@@ -161,7 +161,7 @@
 typedef union YYSTYPE
 {
 
-/* Line 1707 of yacc.c  */
+/* Line 1726 of yacc.c  */
 #line 94 "parse-gram.y"
 
   symbol *symbol;
@@ -176,7 +176,7 @@ typedef union YYSTYPE
 
 
 
-/* Line 1707 of yacc.c  */
+/* Line 1726 of yacc.c  */
 #line 181 "parse-gram.h"
 } YYSTYPE;
 # define YYSTYPE_IS_TRIVIAL 1

diff --git a/tests/actions.at b/tests/actions.at
index dd57b0809057a26bbfc0e615853814ed11678991..4833a4fb673bb6b02b3258e5d67a689ade299127 100644 (file)
--- a/tests/actions.at
+++ b/tests/actions.at
@@ -1408,3 +1408,74 @@ AT_MATCHES_CHECK([input.c], [[// TEST:Y:1 [;{}]*\n;\}$]],  [[12]])
 AT_MATCHES_CHECK([input.c], [[#define TEST_MACRO_N \\\n\[\]"broken\\" \$ \@ \$\$ \@\$ \[\];\\\nstring;"\}]], [[2]])
 
 AT_CLEANUP
+
+
+## -------------------------------------------------- ##
+## Destroying lookahead assigned by semantic action.  ##
+## -------------------------------------------------- ##
+
+AT_SETUP([[Destroying lookahead assigned by semantic action]])
+
+AT_DATA_GRAMMAR([input.y],
+[[
+%code {
+  #include <assert.h>
+  #include <stdio.h>
+  static void yyerror (char const *);
+  static int yylex (void);
+  #define USE(Var)
+}
+
+%destructor { fprintf (stderr, "'a' destructor\n"); } 'a'
+%destructor { fprintf (stderr, "'b' destructor\n"); } 'b'
+
+%%
+
+// In a previous version of Bison, yychar assigned by the semantic
+// action below was not translated into yytoken before the lookahead was
+// discarded and thus before its destructor (selected according to
+// yytoken) was called in order to return from yyparse.  This would
+// happen even if YYACCEPT was performed in a later semantic action as
+// long as only consistent states with default reductions were visited
+// in between.  However, we leave YYACCEPT in the same semantic action
+// for this test in order to show that skeletons cannot simply translate
+// immediately after every semantic action because a semantic action
+// that has set yychar might not always return normally.  Instead,
+// skeletons must translate before every use of yytoken.
+start: 'a' accept { USE($1); } ;
+accept: /*empty*/ {
+  assert (yychar == YYEMPTY);
+  yychar = 'b';
+  YYACCEPT;
+} ;
+
+%%
+
+static void
+yyerror (char const *msg)
+{
+  fprintf (stderr, "%s\n", msg);
+}
+
+static int
+yylex (void)
+{
+  static char const *input = "a";
+  return *input++;
+}
+
+int
+main (void)
+{
+  return yyparse ();
+}
+]])
+
+AT_BISON_CHECK([[-o input.c input.y]])
+AT_COMPILE([[input]])
+AT_PARSER_CHECK([[./input]], [[0]], [],
+[['b' destructor
+'a' destructor
+]])
+
+AT_CLEANUP

diff --git a/tests/conflicts.at b/tests/conflicts.at
index 6fefea05a4721655cd2226ec19b0ded3a3e68625..18877296c8c3ea0f35a0132fcea3855f4b9368fb 100644 (file)
--- a/tests/conflicts.at
+++ b/tests/conflicts.at
@@ -139,6 +139,130 @@ AT_CLEANUP
 
 
 
+## -------------------------------------- ##
+## %error-verbose and consistent errors.  ##
+## -------------------------------------- ##
+
+AT_SETUP([[%error-verbose and consistent errors]])
+
+m4_pushdef([AT_CONSISTENT_ERRORS_CHECK], [
+
+AT_BISON_CHECK([$1[ -o input.c input.y]])
+AT_COMPILE([[input]])
+
+m4_pushdef([AT_EXPECTING], [m4_if($3, [ab], [[, expecting 'a' or 'b']],
+                                  $3, [a],  [[, expecting 'a']],
+                                  $3, [b],  [[, expecting 'b']])])
+
+AT_PARSER_CHECK([[./input]], [[1]], [],
+[[syntax error, unexpected ]$2[]AT_EXPECTING[
+]])
+
+m4_popdef([AT_EXPECTING])
+
+])
+
+AT_DATA_GRAMMAR([input.y],
+[[%code {
+  #include <assert.h>
+  #include <stdio.h>
+  int yylex (void);
+  void yyerror (char const *);
+  #define USE(Var)
+}
+
+%error-verbose
+
+// The point isn't to test IELR here, but state merging happens to
+// complicate the example.
+%define lr.type ielr
+
+%nonassoc 'a'
+
+// If yylval=0 here, then we know that the 'a' destructor is being
+// invoked incorrectly for the 'b' set in the semantic action below.
+// All 'a' tokens are returned by yylex, which sets yylval=1.
+%destructor {
+  if (!$$)
+    fprintf (stderr, "Wrong destructor.\n");
+} 'a'
+
+%%
+
+// The lookahead assigned by the semantic action isn't needed before
+// either error action is encountered.  In a previous version of Bison,
+// this was a problem as it meant yychar was not translated into yytoken
+// before either error action.  The second error action thus invoked a
+// destructor that it selected according to the incorrect yytoken.  The
+// first error action would have reported an incorrect unexpected token
+// except that, due to another bug, the unexpected token is not reported
+// at all because the error action is the default action in a consistent
+// state.  That bug still needs to be fixed.
+start: error-reduce consistent-error 'a' { USE ($3); } ;
+
+error-reduce:
+  'a' 'a' consistent-reduction consistent-error 'a'
+  { USE (($1, $2, $5)); }
+| 'a' error
+  { USE ($1); }
+;
+
+consistent-reduction: /*empty*/ {
+  assert (yychar == YYEMPTY);
+  yylval = 0;
+  yychar = 'b';
+} ;
+
+consistent-error:
+  'a' { USE ($1); }
+| /*empty*/ %prec 'a'
+;
+
+// Provide another context in which all rules are useful so that this
+// test case looks a little more realistic.
+start: 'b' consistent-error 'b' ;
+
+%%
+
+int
+yylex (void)
+{
+  static char const *input = "aa";
+  yylval = 1;
+  return *input++;
+}
+
+void
+yyerror (char const *msg)
+{
+  fprintf (stderr, "%s\n", msg);
+}
+
+int
+main (void)
+{
+  return yyparse ();
+}
+]])
+
+# See comments in grammar for why this test doesn't succeed.
+AT_XFAIL_IF([[:]])
+
+AT_CONSISTENT_ERRORS_CHECK([], [['b']], [[none]])
+AT_CONSISTENT_ERRORS_CHECK([[-Dlr.default-reductions=consistent]],
+                           [['b']], [[none]])
+
+# Canonical LR doesn't foresee the error for 'a'!
+AT_CONSISTENT_ERRORS_CHECK([[-Dlr.default-reductions=accepting]],
+                           [[$end]], [[a]])
+AT_CONSISTENT_ERRORS_CHECK([[-Flr.type=canonical-lr]], [[$end]], [[a]])
+
+m4_popdef([AT_CONSISTENT_ERRORS_CHECK])
+
+AT_CLEANUP
+
+
+
 ## ------------------------- ##
 ## Unresolved SR Conflicts.  ##
 ## ------------------------- ##