From d2060f0634f4adfb5db74cce540a9d27806091fe Mon Sep 17 00:00:00 2001
From: "Joel E. Denny" <joeldenny@joeldenny.org>
Date: Sun, 7 Nov 2010 16:01:56 -0500
Subject: [PATCH] yysyntax_error: fix for consistent error with lookahead.

* NEWS (2.5): Document.
* data/yacc.c (yysyntax_error): In a verbose syntax error
message while in a consistent state with a default action (which
must be an error action given that yysyntax_error is being
invoked), continue to drop the expected token list, but don't
drop the unexpected token unless there actually is no lookahead.
Moreover, handle that internally instead of returning 1 to tell
the caller to do it.  With that meaning of 1 gone, renumber
return codes more usefully.
(yyparse, yypush_parse): Update yysyntax_error usage.  Most
importantly, set yytoken to YYEMPTY when there's no lookahead.
* data/glr.c (yyreportSyntaxError): As in yacc.c, don't drop the
unexpected token unless there actually is no lookahead.
* data/lalr1.cc (yy::parser::parse): If there's no lookahead,
pass yyempty_ not yyla.type to yysyntax_error_.
(yy::parser::yysyntax_error_): Again, don't drop the unexpected
token unless there actually is no lookahead.
* data/lalr1.java (YYParser::parse): If there's no lookahead,
set yytoken to yyempty_ before invoking yysyntax_error.
(YYParser::yysyntax_error): Again, don't drop the unexpected
token unless there actually is no lookahead.
* tests/conflicts.at (parse.error=verbose and consistent
errors): Extend test group to further reveal how the previous
use of the simple "syntax error" message was too general.  Test
yacc.c, glr.c, lalr1.cc, and lalr1.java.  No longer an expected
failure.
* tests/java.at (AT_JAVA_COMPILE, AT_JAVA_PARSER_CHECK): Move
to...
* tests/local.at: ... here.
(_AT_BISON_OPTION_PUSHDEFS): Push AT_SKEL_JAVA_IF definition.
(AT_BISON_OPTION_POPDEFS): Pop it.
(AT_FULL_COMPILE): Extend to handle Java.
---
 ChangeLog          |  36 +++
 NEWS               |  43 +++-
 data/glr.c         |  52 ++--
 data/lalr1.cc      |  60 +++--
 data/lalr1.java    |  53 +++-
 data/yacc.c        |  84 +++---
 src/parse-gram.c   | 630 +++++++++++++++++++++++----------------------
 src/parse-gram.h   |  10 +-
 tests/conflicts.at | 200 ++++++++++++--
 tests/java.at      |  19 --
 tests/local.at     |  47 +++-
 11 files changed, 785 insertions(+), 449 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 019c2384..41ba7e5e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,39 @@
+2010-11-07  Joel E. Denny  <jdenny@clemson.edu>
+
+	yysyntax_error: fix for consistent error with lookahead.
+	* NEWS (2.5): Document.
+	* data/yacc.c (yysyntax_error): In a verbose syntax error
+	message while in a consistent state with a default action (which
+	must be an error action given that yysyntax_error is being
+	invoked), continue to drop the expected token list, but don't
+	drop the unexpected token unless there actually is no lookahead.
+	Moreover, handle that internally instead of returning 1 to tell
+	the caller to do it.  With that meaning of 1 gone, renumber
+	return codes more usefully.
+	(yyparse, yypush_parse): Update yysyntax_error usage.  Most
+	importantly, set yytoken to YYEMPTY when there's no lookahead.
+	* data/glr.c (yyreportSyntaxError): As in yacc.c, don't drop the
+	unexpected token unless there actually is no lookahead.
+	* data/lalr1.cc (yy::parser::parse): If there's no lookahead,
+	pass yyempty_ not yyla.type to yysyntax_error_.
+	(yy::parser::yysyntax_error_): Again, don't drop the unexpected
+	token unless there actually is no lookahead.
+	* data/lalr1.java (YYParser::parse): If there's no lookahead,
+	set yytoken to yyempty_ before invoking yysyntax_error.
+	(YYParser::yysyntax_error): Again, don't drop the unexpected
+	token unless there actually is no lookahead.
+	* tests/conflicts.at (parse.error=verbose and consistent
+	errors): Extend test group to further reveal how the previous
+	use of the simple "syntax error" message was too general.  Test
+	yacc.c, glr.c, lalr1.cc, and lalr1.java.  No longer an expected
+	failure.
+	* tests/java.at (AT_JAVA_COMPILE, AT_JAVA_PARSER_CHECK): Move
+	to...
+	* tests/local.at: ... here.
+	(_AT_BISON_OPTION_PUSHDEFS): Push AT_SKEL_JAVA_IF definition.
+	(AT_BISON_OPTION_POPDEFS): Pop it.
+	(AT_FULL_COMPILE): Extend to handle Java.
+
 2010-11-07  Joel E. Denny  <jdenny@clemson.edu>
 
 	yysyntax_error: more preparation for readability of next patch.
diff --git a/NEWS b/NEWS
index 177fbbb6..c8188395 100644
--- a/NEWS
+++ b/NEWS
@@ -223,14 +223,41 @@ Bison News
   Bison now warns when a character literal is not of length one.  In
   some future release, Bison will report an error instead.
 
-** Verbose error messages fixed for nonassociative tokens.
-
-  When %error-verbose is specified, syntax error messages produced by
-  the generated parser include the unexpected token as well as a list of
-  expected tokens.  Previously, this list erroneously included tokens
-  that would actually induce a syntax error because conflicts for them
-  were resolved with %nonassoc.  Such tokens are now properly omitted
-  from the list.
+** Verbose syntax error message fixes:
+
+  When %error-verbose or `#define YYERROR_VERBOSE' is specified, syntax
+  error messages produced by the generated parser include the unexpected
+  token as well as a list of expected tokens.  The effect of %nonassoc
+  on these verbose messages has been corrected in two ways, but
+  additional fixes are still being implemented:
+
+*** When %nonassoc is used, there can exist parser states that accept no
+    tokens, and so the parser does not always require a lookahead token
+    in order to detect a syntax error.  Because no unexpected token or
+    expected tokens can then be reported, the verbose syntax error
+    message described above is suppressed, and the parser instead
+    reports the simpler message, "syntax error".  Previously, this
+    suppression was sometimes erroneously triggered by %nonassoc when a
+    lookahead was actually required.  Now verbose messages are
+    suppressed only when all previous lookaheads have already been
+    shifted or discarded.
+
+*** Previously, the list of expected tokens erroneously included tokens
+    that would actually induce a syntax error because conflicts for them
+    were resolved with %nonassoc in the current parser state.  Such
+    tokens are now properly omitted from the list.
+
+*** Expected token lists are still often wrong due to state merging
+    (from LALR or IELR) and default reductions, which can both add and
+    subtract valid tokens.  Canonical LR almost completely fixes this
+    problem by eliminating state merging and default reductions.
+    However, there is one minor problem left even when using canonical
+    LR and even after the fixes above.  That is, if the resolution of a
+    conflict with %nonassoc appears in a later parser state than the one
+    at which some syntax error is discovered, the conflicted token is
+    still erroneously included in the expected token list.  We are
+    currently working on a fix to eliminate this problem and to
+    eliminate the need for canonical LR.
 
 ** Destructor calls fixed for lookaheads altered in semantic actions.
 
diff --git a/data/glr.c b/data/glr.c
index 93ed5128..d8b96047 100644
--- a/data/glr.c
+++ b/data/glr.c
@@ -2081,11 +2081,7 @@ yyreportSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
 #if ! YYERROR_VERBOSE
   yyerror (]b4_lyyerror_args[YY_("syntax error"));
 #else
-      int yyn;
-      yyn = yypact[yystackp->yytops.yystates[0]->yylrState];
-if (YYPACT_NINF < yyn && yyn <= YYLAST)
-  {
-  yySymbol yytoken = YYTRANSLATE (yychar);
+  yySymbol yytoken = yychar == YYEMPTY ? YYEMPTY : YYTRANSLATE (yychar);
   size_t yysize0 = yytnamerr (NULL, yytokenName (yytoken));
   size_t yysize = yysize0;
   size_t yysize1;
@@ -2096,23 +2092,47 @@ if (YYPACT_NINF < yyn && yyn <= YYLAST)
   const char *yyformat = 0;
   /* Arguments of yyformat. */
   char const *yyarg[YYERROR_VERBOSE_ARGS_MAXIMUM];
+  /* Number of reported tokens (one for the "unexpected", one per
+     "expected").  */
+  int yycount = 0;
 
+  /* There are many possibilities here to consider:
+     - If this state is a consistent state with a default action, then
+       the only way this function was invoked is if the default action
+       is an error action.  In that case, don't check for expected
+       tokens because there are none.
+     - The only way there can be no lookahead present (in yychar) is if
+       this state is a consistent state with a default action.  Thus,
+       detecting the absence of a lookahead is sufficient to determine
+       that there is no unexpected or expected token to report.  In that
+       case, just report a simple "syntax error".
+     - Don't assume there isn't a lookahead just because this state is a
+       consistent state with a default action.  There might have been a
+       previous inconsistent state, consistent state with a non-default
+       action, or user semantic action that manipulated yychar.
+     - Of course, the expected token list depends on states to have
+       correct lookahead information, and it depends on the parser not
+       to perform extra reductions after fetching a lookahead from the
+       scanner and before detecting a syntax error.  Thus, state merging
+       (from LALR or IELR) and default reductions corrupt the expected
+       token list.  However, the list is correct for canonical LR with
+       one exception: it will still contain any token that will not be
+       accepted due to an error action in a later state.
+  */
+  if (yytoken != YYEMPTY)
+    {
+      int yyn = yypact[yystackp->yytops.yystates[0]->yylrState];
+      yyarg[yycount++] = yytokenName (yytoken);
+      if (!yypact_value_is_default (yyn))
+        {
           /* Start YYX at -YYN if negative to avoid negative indexes in
              YYCHECK.  In other words, skip the first -YYN actions for this
              state because they are default actions.  */
           int yyxbegin = yyn < 0 ? -yyn : 0;
-
           /* Stay within bounds of both yycheck and yytname.  */
           int yychecklim = YYLAST - yyn + 1;
           int yyxend = yychecklim < YYNTOKENS ? yychecklim : YYNTOKENS;
-
-  /* Number of reported tokens (one for the "unexpected", one per
-     "expected").  */
-  int yycount = 0;
           int yyx;
-
-    yyarg[yycount++] = yytokenName (yytoken);
-
           for (yyx = yyxbegin; yyx < yyxend; ++yyx)
             if (yycheck[yyx + yyn] == yyx && yyx != YYTERROR
                 && !yytable_value_is_error (yytable[yyx + yyn]))
@@ -2128,6 +2148,8 @@ if (YYPACT_NINF < yyn && yyn <= YYLAST)
                 yysize_overflow |= yysize1 < yysize;
                 yysize = yysize1;
               }
+        }
+    }
 
   switch (yycount)
     {
@@ -2135,6 +2157,7 @@ if (YYPACT_NINF < yyn && yyn <= YYLAST)
       case N:                           \
         yyformat = S;                   \
       break
+      YYCASE_(0, YY_("syntax error"));
       YYCASE_(1, YY_("syntax error, unexpected %s"));
       YYCASE_(2, YY_("syntax error, unexpected %s, expecting %s"));
       YYCASE_(3, YY_("syntax error, unexpected %s, expecting %s or %s"));
@@ -2175,9 +2198,6 @@ if (YYPACT_NINF < yyn && yyn <= YYLAST)
       yyerror (]b4_lyyerror_args[YY_("syntax error"));
       yyMemoryExhausted (yystackp);
     }
-  }
-else
-  yyerror (]b4_lyyerror_args[YY_("syntax error"));
 #endif /* YYERROR_VERBOSE */
   yynerrs += 1;
 }
diff --git a/data/lalr1.cc b/data/lalr1.cc
index a3b22320..a18721e2 100644
--- a/data/lalr1.cc
+++ b/data/lalr1.cc
@@ -862,7 +862,8 @@ m4_ifdef([b4_lex_param], [, ]b4_lex_param)));])[
       {
 	++yynerrs_;
 	error (]b4_args(b4_locations_if([yyla.location]),
-                        [[yysyntax_error_ (yystack_[0].state, yyla.type)]])[);
+                        [[yysyntax_error_ (yystack_[0].state,
+                                           yyempty ? yyempty_ : yyla.type)]])[);
       }
 
 ]b4_locations_if([[
@@ -979,26 +980,52 @@ b4_error_verbose_if([state_type yystate, int yytoken],
                     [int, int])[)
   {]b4_error_verbose_if([[
     std::string yyres;
-    int yyn = yypact_[yystate];
-    if (yypact_ninf_ < yyn && yyn <= yylast_)
+    // Number of reported tokens (one for the "unexpected", one per
+    // "expected").
+    size_t yycount = 0;
+    // Its maximum.
+    enum { YYERROR_VERBOSE_ARGS_MAXIMUM = 5 };
+    // Arguments of yyformat.
+    char const *yyarg[YYERROR_VERBOSE_ARGS_MAXIMUM];
+
+    /* There are many possibilities here to consider:
+       - If this state is a consistent state with a default action, then
+         the only way this function was invoked is if the default action
+         is an error action.  In that case, don't check for expected
+         tokens because there are none.
+       - The only way there can be no lookahead present (in yytoken) is
+         if this state is a consistent state with a default action.
+         Thus, detecting the absence of a lookahead is sufficient to
+         determine that there is no unexpected or expected token to
+         report.  In that case, just report a simple "syntax error".
+       - Don't assume there isn't a lookahead just because this state is
+         a consistent state with a default action.  There might have
+         been a previous inconsistent state, consistent state with a
+         non-default action, or user semantic action that manipulated
+         yyla.  (However, yyla is currently not documented for users.)
+       - Of course, the expected token list depends on states to have
+         correct lookahead information, and it depends on the parser not
+         to perform extra reductions after fetching a lookahead from the
+         scanner and before detecting a syntax error.  Thus, state
+         merging (from LALR or IELR) and default reductions corrupt the
+         expected token list.  However, the list is correct for
+         canonical LR with one exception: it will still contain any
+         token that will not be accepted due to an error action in a
+         later state.
+    */
+    if (yytoken != yyempty_)
       {
+        yyarg[yycount++] = yytname_[yytoken];
+        int yyn = yypact_[yystate];
+        if (!yy_pact_value_is_default_ (yyn))
+          {
             /* Start YYX at -YYN if negative to avoid negative indexes in
                YYCHECK.  In other words, skip the first -YYN actions for
                this state because they are default actions.  */
             int yyxbegin = yyn < 0 ? -yyn : 0;
-
             /* Stay within bounds of both yycheck and yytname.  */
             int yychecklim = yylast_ - yyn + 1;
             int yyxend = yychecklim < yyntokens_ ? yychecklim : yyntokens_;
-
-        // Number of reported tokens (one for the "unexpected", one per
-        // "expected").
-        size_t yycount = 0;
-        // Its maximum.
-        enum { YYERROR_VERBOSE_ARGS_MAXIMUM = 5 };
-        // Arguments of yyformat.
-        char const *yyarg[YYERROR_VERBOSE_ARGS_MAXIMUM];
-        yyarg[yycount++] = yytname_[yytoken];
             for (int yyx = yyxbegin; yyx < yyxend; ++yyx)
               if (yycheck_[yyx + yyn] == yyx && yyx != yyterror_
                   && !yy_table_value_is_error_ (yytable_[yyx + yyn]))
@@ -1011,6 +1038,8 @@ b4_error_verbose_if([state_type yystate, int yytoken],
                   else
                     yyarg[yycount++] = yytname_[yyx];
                 }
+          }
+      }
 
     char const* yyformat = 0;
     switch (yycount)
@@ -1019,6 +1048,7 @@ b4_error_verbose_if([state_type yystate, int yytoken],
         case N:                               \
           yyformat = S;                       \
         break
+        YYCASE_(0, YY_("syntax error"));
         YYCASE_(1, YY_("syntax error, unexpected %s"));
         YYCASE_(2, YY_("syntax error, unexpected %s, expecting %s"));
         YYCASE_(3, YY_("syntax error, unexpected %s, expecting %s or %s"));
@@ -1026,6 +1056,7 @@ b4_error_verbose_if([state_type yystate, int yytoken],
         YYCASE_(5, YY_("syntax error, unexpected %s, expecting %s or %s or %s or %s"));
 #undef YYCASE_
       }
+
     // Argument number.
     size_t yyi = 0;
     for (char const* yyp = yyformat; *yyp; ++yyp)
@@ -1036,9 +1067,6 @@ b4_error_verbose_if([state_type yystate, int yytoken],
         }
       else
         yyres += *yyp;
-    }
-  else
-    yyres = YY_("syntax error");
     return yyres;]], [[
     return YY_("syntax error");]])[
   }
diff --git a/data/lalr1.java b/data/lalr1.java
index 27256e1d..a2772ff7 100644
--- a/data/lalr1.java
+++ b/data/lalr1.java
@@ -627,6 +627,8 @@ m4_popdef([b4_at_dollar])])dnl
         if (yyerrstatus_ == 0)
           {
             ++yynerrs_;
+            if (yychar == yyempty_)
+              yytoken = yyempty_;
             yyerror (]b4_locations_if([yylloc, ])[yysyntax_error (yystate, yytoken));
           }
 
@@ -727,17 +729,52 @@ m4_popdef([b4_at_dollar])])dnl
   {]b4_error_verbose_if([[
     if (yyErrorVerbose)
       {
-        int yyn = yypact_[yystate];
-        if (yypact_ninf_ < yyn && yyn <= yylast_)
+        /* There are many possibilities here to consider:
+           - Assume YYFAIL is not used.  It's too flawed to consider.
+             See
+             <http://lists.gnu.org/archive/html/bison-patches/2009-12/msg00024.html>
+             for details.  YYERROR is fine as it does not invoke this
+             function.
+           - If this state is a consistent state with a default action,
+             then the only way this function was invoked is if the
+             default action is an error action.  In that case, don't
+             check for expected tokens because there are none.
+           - The only way there can be no lookahead present (in tok) is
+             if this state is a consistent state with a default action.
+             Thus, detecting the absence of a lookahead is sufficient to
+             determine that there is no unexpected or expected token to
+             report.  In that case, just report a simple "syntax error".
+           - Don't assume there isn't a lookahead just because this
+             state is a consistent state with a default action.  There
+             might have been a previous inconsistent state, consistent
+             state with a non-default action, or user semantic action
+             that manipulated yychar.  (However, yychar is currently out
+             of scope during semantic actions.)
+           - Of course, the expected token list depends on states to
+             have correct lookahead information, and it depends on the
+             parser not to perform extra reductions after fetching a
+             lookahead from the scanner and before detecting a syntax
+             error.  Thus, state merging (from LALR or IELR) and default
+             reductions corrupt the expected token list.  However, the
+             list is correct for canonical LR with one exception: it
+             will still contain any token that will not be accepted due
+             to an error action in a later state.
+        */
+        if (tok != yyempty_)
           {
-            StringBuffer res;
-
+            // FIXME: This method of building the message is not compatible
+            // with internationalization.
+            StringBuffer res =
+              new StringBuffer ("syntax error, unexpected ");
+            res.append (yytnamerr_ (yytname_[tok]));
+            int yyn = yypact_[yystate];
+            if (!yy_pact_value_is_default_ (yyn))
+              {
                 /* Start YYX at -YYN if negative to avoid negative
                    indexes in YYCHECK.  In other words, skip the first
                    -YYN actions for this state because they are default
                    actions.  */
                 int yyxbegin = yyn < 0 ? -yyn : 0;
-
                 /* Stay within bounds of both yycheck and yytname.  */
                 int yychecklim = yylast_ - yyn + 1;
                 int yyxend = yychecklim < yyntokens_ ? yychecklim : yyntokens_;
@@ -746,11 +783,6 @@ m4_popdef([b4_at_dollar])])dnl
                   if (yycheck_[x + yyn] == x && x != yyterror_
                       && !yy_table_value_is_error_ (yytable_[x + yyn]))
                     ++count;
-
-            // FIXME: This method of building the message is not compatible
-            // with internationalization.
-            res = new StringBuffer ("syntax error, unexpected ");
-            res.append (yytnamerr_ (yytname_[tok]));
                 if (count < 5)
                   {
                     count = 0;
@@ -762,6 +794,7 @@ m4_popdef([b4_at_dollar])])dnl
                           res.append (yytnamerr_ (yytname_[x]));
                         }
                   }
+              }
             return res.toString ();
           }
       }
diff --git a/data/yacc.c b/data/yacc.c
index d1715367..5cf15eed 100644
--- a/data/yacc.c
+++ b/data/yacc.c
@@ -906,20 +906,13 @@ yytnamerr (char *yyres, const char *yystr)
 /* Copy into *YYMSG, which is of size *YYMSG_ALLOC, an error message
    about the unexpected token YYTOKEN while in state YYSTATE.
 
-   Return 0 if *YYMSG was successfully written.  Return 1 if an ordinary
-   "syntax error" message will suffice instead.  Return 2 if *YYMSG is
-   not large enough to hold the message.  In the last case, also set
-   *YYMSG_ALLOC to either (a) the required number of bytes or (b) zero
-   if the required number of bytes is too large to store.  */
+   Return 0 if *YYMSG was successfully written.  Return 1 if *YYMSG is
+   not large enough to hold the message.  In that case, also set
+   *YYMSG_ALLOC to the required number of bytes.  Return 2 if the
+   required number of bytes is too large to store.  */
 static int
 yysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,
                 int yystate, int yytoken)
-{
-  int yyn = yypact[yystate];
-
-  if (! (YYPACT_NINF < yyn && yyn <= YYLAST))
-    return 1;
-  else
 {
   YYSIZE_T yysize0 = yytnamerr (0, yytname[yytoken]);
   YYSIZE_T yysize = yysize0;
@@ -929,22 +922,51 @@ yysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,
   const char *yyformat = 0;
   /* Arguments of yyformat. */
   char const *yyarg[YYERROR_VERBOSE_ARGS_MAXIMUM];
+  /* Number of reported tokens (one for the "unexpected", one per
+     "expected"). */
+  int yycount = 0;
 
+  /* There are many possibilities here to consider:
+     - Assume YYFAIL is not used.  It's too flawed to consider.  See
+       <http://lists.gnu.org/archive/html/bison-patches/2009-12/msg00024.html>
+       for details.  YYERROR is fine as it does not invoke this
+       function.
+     - If this state is a consistent state with a default action, then
+       the only way this function was invoked is if the default action
+       is an error action.  In that case, don't check for expected
+       tokens because there are none.
+     - The only way there can be no lookahead present (in yychar) is if
+       this state is a consistent state with a default action.  Thus,
+       detecting the absence of a lookahead is sufficient to determine
+       that there is no unexpected or expected token to report.  In that
+       case, just report a simple "syntax error".
+     - Don't assume there isn't a lookahead just because this state is a
+       consistent state with a default action.  There might have been a
+       previous inconsistent state, consistent state with a non-default
+       action, or user semantic action that manipulated yychar.
+     - Of course, the expected token list depends on states to have
+       correct lookahead information, and it depends on the parser not
+       to perform extra reductions after fetching a lookahead from the
+       scanner and before detecting a syntax error.  Thus, state merging
+       (from LALR or IELR) and default reductions corrupt the expected
+       token list.  However, the list is correct for canonical LR with
+       one exception: it will still contain any token that will not be
+       accepted due to an error action in a later state.
+  */
+  if (yytoken != YYEMPTY)
+    {
+      int yyn = yypact[yystate];
+      yyarg[yycount++] = yytname[yytoken];
+      if (!yypact_value_is_default (yyn))
+        {
           /* Start YYX at -YYN if negative to avoid negative indexes in
              YYCHECK.  In other words, skip the first -YYN actions for
              this state because they are default actions.  */
           int yyxbegin = yyn < 0 ? -yyn : 0;
-
           /* Stay within bounds of both yycheck and yytname.  */
           int yychecklim = YYLAST - yyn + 1;
           int yyxend = yychecklim < YYNTOKENS ? yychecklim : YYNTOKENS;
-  /* Number of reported tokens (one for the "unexpected", one per
-     "expected"). */
-  int yycount = 0;
           int yyx;
-
-  yyarg[yycount++] = yytname[yytoken];
-
           for (yyx = yyxbegin; yyx < yyxend; ++yyx)
             if (yycheck[yyx + yyn] == yyx && yyx != YYTERROR
                 && !yytable_value_is_error (yytable[yyx + yyn]))
@@ -957,14 +979,13 @@ yysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,
                   }
                 yyarg[yycount++] = yytname[yyx];
                 yysize1 = yysize + yytnamerr (0, yytname[yyx]);
-                if (! (yysize <= yysize1 && yysize1 <= YYSTACK_ALLOC_MAXIMUM))
-                  {
-                    /* Overflow.  */
-                    *yymsg_alloc = 0;
-                    return 2;
-                  }
+                if (! (yysize <= yysize1
+                       && yysize1 <= YYSTACK_ALLOC_MAXIMUM))
+                  return 2;
                 yysize = yysize1;
               }
+        }
+    }
 
   switch (yycount)
     {
@@ -972,6 +993,7 @@ yysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,
       case N:                               \
         yyformat = S;                       \
       break
+      YYCASE_(0, YY_("syntax error"));
       YYCASE_(1, YY_("syntax error, unexpected %s"));
       YYCASE_(2, YY_("syntax error, unexpected %s, expecting %s"));
       YYCASE_(3, YY_("syntax error, unexpected %s, expecting %s or %s"));
@@ -982,11 +1004,7 @@ yysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,
 
   yysize1 = yysize + yystrlen (yyformat);
   if (! (yysize <= yysize1 && yysize1 <= YYSTACK_ALLOC_MAXIMUM))
-    {
-      /* Overflow.  */
-      *yymsg_alloc = 0;
-      return 2;
-    }
+    return 2;
   yysize = yysize1;
 
   if (*yymsg_alloc < yysize)
@@ -995,7 +1013,7 @@ yysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,
       if (! (yysize <= *yymsg_alloc
              && *yymsg_alloc <= YYSTACK_ALLOC_MAXIMUM))
         *yymsg_alloc = YYSTACK_ALLOC_MAXIMUM;
-      return 2;
+      return 1;
     }
 
   /* Avoid sprintf, as that infringes on the user's name space.
@@ -1018,7 +1036,6 @@ yysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,
   }
   return 0;
 }
-}
 #endif /* YYERROR_VERBOSE */
 
 
@@ -1467,7 +1484,7 @@ yyreduce:
 yyerrlab:
   /* Make sure we have latest lookahead translation.  See comments at
      user semantic actions for why this is necessary.  */
-  yytoken = YYTRANSLATE (yychar);
+  yytoken = yychar == YYEMPTY ? YYEMPTY : YYTRANSLATE (yychar);
 
   /* If not already recovering from an error, report this error.  */
   if (!yyerrstatus)
@@ -1483,7 +1500,7 @@ yyerrlab:
         int yysyntax_error_status = YYSYNTAX_ERROR;
         if (yysyntax_error_status == 0)
           yymsgp = yymsg;
-        else if (yysyntax_error_status == 2 && 0 < yymsg_alloc)
+        else if (yysyntax_error_status == 1)
           {
             if (yymsg != yymsgbuf)
               YYSTACK_FREE (yymsg);
@@ -1492,6 +1509,7 @@ yyerrlab:
               {
                 yymsg = yymsgbuf;
                 yymsg_alloc = sizeof yymsgbuf;
+                yysyntax_error_status = 2;
               }
             else
               {
diff --git a/src/parse-gram.c b/src/parse-gram.c
index 5072a8eb..f55a15b6 100644
--- a/src/parse-gram.c
+++ b/src/parse-gram.c
@@ -1461,20 +1461,13 @@ yytnamerr (char *yyres, const char *yystr)
 /* Copy into *YYMSG, which is of size *YYMSG_ALLOC, an error message
    about the unexpected token YYTOKEN while in state YYSTATE.
 
-   Return 0 if *YYMSG was successfully written.  Return 1 if an ordinary
-   "syntax error" message will suffice instead.  Return 2 if *YYMSG is
-   not large enough to hold the message.  In the last case, also set
-   *YYMSG_ALLOC to either (a) the required number of bytes or (b) zero
-   if the required number of bytes is too large to store.  */
+   Return 0 if *YYMSG was successfully written.  Return 1 if *YYMSG is
+   not large enough to hold the message.  In that case, also set
+   *YYMSG_ALLOC to the required number of bytes.  Return 2 if the
+   required number of bytes is too large to store.  */
 static int
 yysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,
                 int yystate, int yytoken)
-{
-  int yyn = yypact[yystate];
-
-  if (! (YYPACT_NINF < yyn && yyn <= YYLAST))
-    return 1;
-  else
 {
   YYSIZE_T yysize0 = yytnamerr (0, yytname[yytoken]);
   YYSIZE_T yysize = yysize0;
@@ -1484,22 +1477,51 @@ yysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,
   const char *yyformat = 0;
   /* Arguments of yyformat. */
   char const *yyarg[YYERROR_VERBOSE_ARGS_MAXIMUM];
+  /* Number of reported tokens (one for the "unexpected", one per
+     "expected"). */
+  int yycount = 0;
 
+  /* There are many possibilities here to consider:
+     - Assume YYFAIL is not used.  It's too flawed to consider.  See
+       <http://lists.gnu.org/archive/html/bison-patches/2009-12/msg00024.html>
+       for details.  YYERROR is fine as it does not invoke this
+       function.
+     - If this state is a consistent state with a default action, then
+       the only way this function was invoked is if the default action
+       is an error action.  In that case, don't check for expected
+       tokens because there are none.
+     - The only way there can be no lookahead present (in yychar) is if
+       this state is a consistent state with a default action.  Thus,
+       detecting the absence of a lookahead is sufficient to determine
+       that there is no unexpected or expected token to report.  In that
+       case, just report a simple "syntax error".
+     - Don't assume there isn't a lookahead just because this state is a
+       consistent state with a default action.  There might have been a
+       previous inconsistent state, consistent state with a non-default
+       action, or user semantic action that manipulated yychar.
+     - Of course, the expected token list depends on states to have
+       correct lookahead information, and it depends on the parser not
+       to perform extra reductions after fetching a lookahead from the
+       scanner and before detecting a syntax error.  Thus, state merging
+       (from LALR or IELR) and default reductions corrupt the expected
+       token list.  However, the list is correct for canonical LR with
+       one exception: it will still contain any token that will not be
+       accepted due to an error action in a later state.
+  */
+  if (yytoken != YYEMPTY)
+    {
+      int yyn = yypact[yystate];
+      yyarg[yycount++] = yytname[yytoken];
+      if (!yypact_value_is_default (yyn))
+        {
           /* Start YYX at -YYN if negative to avoid negative indexes in
              YYCHECK.  In other words, skip the first -YYN actions for
              this state because they are default actions.  */
           int yyxbegin = yyn < 0 ? -yyn : 0;
-
           /* Stay within bounds of both yycheck and yytname.  */
           int yychecklim = YYLAST - yyn + 1;
           int yyxend = yychecklim < YYNTOKENS ? yychecklim : YYNTOKENS;
-  /* Number of reported tokens (one for the "unexpected", one per
-     "expected"). */
-  int yycount = 0;
           int yyx;
-
-  yyarg[yycount++] = yytname[yytoken];
-
           for (yyx = yyxbegin; yyx < yyxend; ++yyx)
             if (yycheck[yyx + yyn] == yyx && yyx != YYTERROR
                 && !yytable_value_is_error (yytable[yyx + yyn]))
@@ -1512,14 +1534,13 @@ yysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,
                   }
                 yyarg[yycount++] = yytname[yyx];
                 yysize1 = yysize + yytnamerr (0, yytname[yyx]);
-                if (! (yysize <= yysize1 && yysize1 <= YYSTACK_ALLOC_MAXIMUM))
-                  {
-                    /* Overflow.  */
-                    *yymsg_alloc = 0;
-                    return 2;
-                  }
+                if (! (yysize <= yysize1
+                       && yysize1 <= YYSTACK_ALLOC_MAXIMUM))
+                  return 2;
                 yysize = yysize1;
               }
+        }
+    }
 
   switch (yycount)
     {
@@ -1527,6 +1548,7 @@ yysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,
       case N:                               \
         yyformat = S;                       \
       break
+      YYCASE_(0, YY_("syntax error"));
       YYCASE_(1, YY_("syntax error, unexpected %s"));
       YYCASE_(2, YY_("syntax error, unexpected %s, expecting %s"));
       YYCASE_(3, YY_("syntax error, unexpected %s, expecting %s or %s"));
@@ -1537,11 +1559,7 @@ yysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,
 
   yysize1 = yysize + yystrlen (yyformat);
   if (! (yysize <= yysize1 && yysize1 <= YYSTACK_ALLOC_MAXIMUM))
-    {
-      /* Overflow.  */
-      *yymsg_alloc = 0;
-      return 2;
-    }
+    return 2;
   yysize = yysize1;
 
   if (*yymsg_alloc < yysize)
@@ -1550,7 +1568,7 @@ yysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,
       if (! (yysize <= *yymsg_alloc
              && *yymsg_alloc <= YYSTACK_ALLOC_MAXIMUM))
         *yymsg_alloc = YYSTACK_ALLOC_MAXIMUM;
-      return 2;
+      return 1;
     }
 
   /* Avoid sprintf, as that infringes on the user's name space.
@@ -1573,7 +1591,6 @@ yysyntax_error (YYSIZE_T *yymsg_alloc, char **yymsg,
   }
   return 0;
 }
-}
 #endif /* YYERROR_VERBOSE */
 
 
@@ -1748,7 +1765,7 @@ YYLTYPE yylloc;
 #endif
 
 /* User initialization code.  */
-/* Line 1213 of yacc.c  */
+/* Line 1230 of yacc.c  */
 #line 80 "src/parse-gram.y"
 {
   /* Bison's grammar can initial empty locations, hence a default
@@ -1756,8 +1773,8 @@ YYLTYPE yylloc;
   boundary_set (&yylloc.start, current_file, 1, 1);
   boundary_set (&yylloc.end, current_file, 1, 1);
 }
-/* Line 1213 of yacc.c  */
-#line 1761 "src/parse-gram.c"
+/* Line 1230 of yacc.c  */
+#line 1778 "src/parse-gram.c"
   yylsp[0] = yylloc;
 
   goto yysetstate;
@@ -1943,7 +1960,7 @@ yyreduce:
   switch (yyn)
     {
         case 6:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 267 "src/parse-gram.y"
     {
       code_props plain_code;
@@ -1954,106 +1971,106 @@ yyreduce:
                         plain_code.code, (yylsp[0]));
       code_scanner_last_string_free ();
     }
-/* Line 1426 of yacc.c  */
-#line 1959 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 1976 "src/parse-gram.c"
     break;
 
   case 7:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 277 "src/parse-gram.y"
     {
       muscle_percent_define_ensure ((yyvsp[0].uniqstr), (yylsp[0]), true);
     }
-/* Line 1426 of yacc.c  */
-#line 1969 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 1986 "src/parse-gram.c"
     break;
 
   case 8:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 281 "src/parse-gram.y"
     {
       muscle_percent_define_insert ((yyvsp[-1].uniqstr), (yylsp[-1]), (yyvsp[0].chars),
                                     MUSCLE_PERCENT_DEFINE_GRAMMAR_FILE);
     }
-/* Line 1426 of yacc.c  */
-#line 1980 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 1997 "src/parse-gram.c"
     break;
 
   case 9:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 285 "src/parse-gram.y"
     { defines_flag = true; }
-/* Line 1426 of yacc.c  */
-#line 1988 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2005 "src/parse-gram.c"
     break;
 
   case 10:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 287 "src/parse-gram.y"
     {
       defines_flag = true;
       spec_defines_file = xstrdup ((yyvsp[0].chars));
     }
-/* Line 1426 of yacc.c  */
-#line 1999 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2016 "src/parse-gram.c"
     break;
 
   case 11:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 292 "src/parse-gram.y"
     {
       muscle_percent_define_insert ("parse.error", (yylsp[0]), "verbose",
                                     MUSCLE_PERCENT_DEFINE_GRAMMAR_FILE);
     }
-/* Line 1426 of yacc.c  */
-#line 2010 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2027 "src/parse-gram.c"
     break;
 
   case 12:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 296 "src/parse-gram.y"
     { expected_sr_conflicts = (yyvsp[0].integer); }
-/* Line 1426 of yacc.c  */
-#line 2018 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2035 "src/parse-gram.c"
     break;
 
   case 13:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 297 "src/parse-gram.y"
     { expected_rr_conflicts = (yyvsp[0].integer); }
-/* Line 1426 of yacc.c  */
-#line 2026 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2043 "src/parse-gram.c"
     break;
 
   case 14:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 298 "src/parse-gram.y"
     { spec_file_prefix = (yyvsp[0].chars); }
-/* Line 1426 of yacc.c  */
-#line 2034 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2051 "src/parse-gram.c"
     break;
 
   case 15:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 299 "src/parse-gram.y"
     { spec_file_prefix = (yyvsp[0].chars); }
-/* Line 1426 of yacc.c  */
-#line 2042 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2059 "src/parse-gram.c"
     break;
 
   case 16:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 301 "src/parse-gram.y"
     {
       nondeterministic_parser = true;
       glr_parser = true;
     }
-/* Line 1426 of yacc.c  */
-#line 2053 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2070 "src/parse-gram.c"
     break;
 
   case 17:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 306 "src/parse-gram.y"
     {
       code_props action;
@@ -2063,92 +2080,92 @@ yyreduce:
       muscle_code_grow ("initial_action", action.code, (yylsp[0]));
       code_scanner_last_string_free ();
     }
-/* Line 1426 of yacc.c  */
-#line 2068 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2085 "src/parse-gram.c"
     break;
 
   case 18:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 314 "src/parse-gram.y"
     { language_argmatch ((yyvsp[0].chars), grammar_prio, (yylsp[-1])); }
-/* Line 1426 of yacc.c  */
-#line 2076 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2093 "src/parse-gram.c"
     break;
 
   case 19:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 315 "src/parse-gram.y"
     { spec_name_prefix = (yyvsp[0].chars); }
-/* Line 1426 of yacc.c  */
-#line 2084 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2101 "src/parse-gram.c"
     break;
 
   case 20:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 316 "src/parse-gram.y"
     { spec_name_prefix = (yyvsp[0].chars); }
-/* Line 1426 of yacc.c  */
-#line 2092 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2109 "src/parse-gram.c"
     break;
 
   case 21:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 317 "src/parse-gram.y"
     { no_lines_flag = true; }
-/* Line 1426 of yacc.c  */
-#line 2100 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2117 "src/parse-gram.c"
     break;
 
   case 22:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 318 "src/parse-gram.y"
     { nondeterministic_parser = true; }
-/* Line 1426 of yacc.c  */
-#line 2108 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2125 "src/parse-gram.c"
     break;
 
   case 23:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 319 "src/parse-gram.y"
     { spec_outfile = (yyvsp[0].chars); }
-/* Line 1426 of yacc.c  */
-#line 2116 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2133 "src/parse-gram.c"
     break;
 
   case 24:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 320 "src/parse-gram.y"
     { spec_outfile = (yyvsp[0].chars); }
-/* Line 1426 of yacc.c  */
-#line 2124 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2141 "src/parse-gram.c"
     break;
 
   case 25:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 321 "src/parse-gram.y"
     { current_param = (yyvsp[0].param); }
-/* Line 1426 of yacc.c  */
-#line 2132 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2149 "src/parse-gram.c"
     break;
 
   case 26:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 321 "src/parse-gram.y"
     { current_param = param_none; }
-/* Line 1426 of yacc.c  */
-#line 2140 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2157 "src/parse-gram.c"
     break;
 
   case 27:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 322 "src/parse-gram.y"
     { version_check (&(yylsp[0]), (yyvsp[0].chars)); }
-/* Line 1426 of yacc.c  */
-#line 2148 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2165 "src/parse-gram.c"
     break;
 
   case 28:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 324 "src/parse-gram.y"
     {
       char const *skeleton_user = (yyvsp[0].chars);
@@ -2173,62 +2190,62 @@ yyreduce:
         }
       skeleton_arg (skeleton_user, grammar_prio, (yylsp[-1]));
     }
-/* Line 1426 of yacc.c  */
-#line 2178 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2195 "src/parse-gram.c"
     break;
 
   case 29:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 347 "src/parse-gram.y"
     { token_table_flag = true; }
-/* Line 1426 of yacc.c  */
-#line 2186 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2203 "src/parse-gram.c"
     break;
 
   case 30:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 348 "src/parse-gram.y"
     { report_flag |= report_states; }
-/* Line 1426 of yacc.c  */
-#line 2194 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2211 "src/parse-gram.c"
     break;
 
   case 31:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 349 "src/parse-gram.y"
     { yacc_flag = true; }
-/* Line 1426 of yacc.c  */
-#line 2202 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2219 "src/parse-gram.c"
     break;
 
   case 33:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 354 "src/parse-gram.y"
     { add_param (current_param, (yyvsp[0].code), (yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2210 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2227 "src/parse-gram.c"
     break;
 
   case 34:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 355 "src/parse-gram.y"
     { add_param (current_param, (yyvsp[0].code), (yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2218 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2235 "src/parse-gram.c"
     break;
 
   case 37:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 367 "src/parse-gram.y"
     {
       grammar_start_symbol_set ((yyvsp[0].symbol), (yylsp[0]));
     }
-/* Line 1426 of yacc.c  */
-#line 2228 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2245 "src/parse-gram.c"
     break;
 
   case 38:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 371 "src/parse-gram.y"
     {
       symbol_list *list;
@@ -2236,12 +2253,12 @@ yyreduce:
 	symbol_list_destructor_set (list, (yyvsp[-1].code), (yylsp[-1]));
       symbol_list_free ((yyvsp[0].list));
     }
-/* Line 1426 of yacc.c  */
-#line 2241 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2258 "src/parse-gram.c"
     break;
 
   case 39:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 378 "src/parse-gram.y"
     {
       symbol_list *list;
@@ -2249,32 +2266,32 @@ yyreduce:
 	symbol_list_printer_set (list, (yyvsp[-1].code), (yylsp[-1]));
       symbol_list_free ((yyvsp[0].list));
     }
-/* Line 1426 of yacc.c  */
-#line 2254 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2271 "src/parse-gram.c"
     break;
 
   case 40:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 385 "src/parse-gram.y"
     {
       default_prec = true;
     }
-/* Line 1426 of yacc.c  */
-#line 2264 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2281 "src/parse-gram.c"
     break;
 
   case 41:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 389 "src/parse-gram.y"
     {
       default_prec = false;
     }
-/* Line 1426 of yacc.c  */
-#line 2274 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2291 "src/parse-gram.c"
     break;
 
   case 42:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 393 "src/parse-gram.y"
     {
       /* Do not invoke muscle_percent_code_grow here since it invokes
@@ -2282,89 +2299,89 @@ yyreduce:
       muscle_code_grow ("percent_code()", (yyvsp[0].chars), (yylsp[0]));
       code_scanner_last_string_free ();
     }
-/* Line 1426 of yacc.c  */
-#line 2287 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2304 "src/parse-gram.c"
     break;
 
   case 43:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 400 "src/parse-gram.y"
     {
       muscle_percent_code_grow ((yyvsp[-1].uniqstr), (yylsp[-1]), (yyvsp[0].chars), (yylsp[0]));
       code_scanner_last_string_free ();
     }
-/* Line 1426 of yacc.c  */
-#line 2298 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2315 "src/parse-gram.c"
     break;
 
   case 44:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 414 "src/parse-gram.y"
     {}
-/* Line 1426 of yacc.c  */
-#line 2306 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2323 "src/parse-gram.c"
     break;
 
   case 45:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 415 "src/parse-gram.y"
     { muscle_code_grow ("union_name", (yyvsp[0].uniqstr), (yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2314 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2331 "src/parse-gram.c"
     break;
 
   case 46:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 420 "src/parse-gram.y"
     {
       union_seen = true;
       muscle_code_grow ("stype", (yyvsp[0].chars), (yylsp[0]));
       code_scanner_last_string_free ();
     }
-/* Line 1426 of yacc.c  */
-#line 2326 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2343 "src/parse-gram.c"
     break;
 
   case 47:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 431 "src/parse-gram.y"
     { current_class = nterm_sym; }
-/* Line 1426 of yacc.c  */
-#line 2334 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2351 "src/parse-gram.c"
     break;
 
   case 48:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 432 "src/parse-gram.y"
     {
       current_class = unknown_sym;
       current_type = NULL;
     }
-/* Line 1426 of yacc.c  */
-#line 2345 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2362 "src/parse-gram.c"
     break;
 
   case 49:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 436 "src/parse-gram.y"
     { current_class = token_sym; }
-/* Line 1426 of yacc.c  */
-#line 2353 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2370 "src/parse-gram.c"
     break;
 
   case 50:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 437 "src/parse-gram.y"
     {
       current_class = unknown_sym;
       current_type = NULL;
     }
-/* Line 1426 of yacc.c  */
-#line 2364 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2381 "src/parse-gram.c"
     break;
 
   case 51:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 442 "src/parse-gram.y"
     {
       symbol_list *list;
@@ -2373,12 +2390,12 @@ yyreduce:
 	symbol_type_set (list->content.sym, (yyvsp[-1].uniqstr), (yylsp[-1]));
       symbol_list_free ((yyvsp[0].list));
     }
-/* Line 1426 of yacc.c  */
-#line 2378 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2395 "src/parse-gram.c"
     break;
 
   case 52:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 453 "src/parse-gram.y"
     {
       symbol_list *list;
@@ -2391,202 +2408,202 @@ yyreduce:
       symbol_list_free ((yyvsp[0].list));
       current_type = NULL;
     }
-/* Line 1426 of yacc.c  */
-#line 2396 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2413 "src/parse-gram.c"
     break;
 
   case 53:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 467 "src/parse-gram.y"
     { (yyval.assoc) = left_assoc; }
-/* Line 1426 of yacc.c  */
-#line 2404 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2421 "src/parse-gram.c"
     break;
 
   case 54:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 468 "src/parse-gram.y"
     { (yyval.assoc) = right_assoc; }
-/* Line 1426 of yacc.c  */
-#line 2412 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2429 "src/parse-gram.c"
     break;
 
   case 55:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 469 "src/parse-gram.y"
     { (yyval.assoc) = non_assoc; }
-/* Line 1426 of yacc.c  */
-#line 2420 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2437 "src/parse-gram.c"
     break;
 
   case 56:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 470 "src/parse-gram.y"
     { (yyval.assoc) = precedence_assoc; }
-/* Line 1426 of yacc.c  */
-#line 2428 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2445 "src/parse-gram.c"
     break;
 
   case 57:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 474 "src/parse-gram.y"
     { current_type = NULL; }
-/* Line 1426 of yacc.c  */
-#line 2436 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2453 "src/parse-gram.c"
     break;
 
   case 58:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 475 "src/parse-gram.y"
     { current_type = (yyvsp[0].uniqstr); tag_seen = true; }
-/* Line 1426 of yacc.c  */
-#line 2444 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2461 "src/parse-gram.c"
     break;
 
   case 59:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 481 "src/parse-gram.y"
     { (yyval.list) = symbol_list_sym_new ((yyvsp[0].symbol), (yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2452 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2469 "src/parse-gram.c"
     break;
 
   case 60:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 483 "src/parse-gram.y"
     { (yyval.list) = symbol_list_prepend ((yyvsp[-1].list), symbol_list_sym_new ((yyvsp[0].symbol), (yylsp[0]))); }
-/* Line 1426 of yacc.c  */
-#line 2460 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2477 "src/parse-gram.c"
     break;
 
   case 61:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 487 "src/parse-gram.y"
     { (yyval.symbol) = (yyvsp[0].symbol); }
-/* Line 1426 of yacc.c  */
-#line 2468 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2485 "src/parse-gram.c"
     break;
 
   case 62:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 488 "src/parse-gram.y"
     { (yyval.symbol) = (yyvsp[-1].symbol); symbol_user_token_number_set ((yyvsp[-1].symbol), (yyvsp[0].integer), (yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2476 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2493 "src/parse-gram.c"
     break;
 
   case 63:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 494 "src/parse-gram.y"
     { (yyval.list) = symbol_list_sym_new ((yyvsp[0].symbol), (yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2484 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2501 "src/parse-gram.c"
     break;
 
   case 64:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 496 "src/parse-gram.y"
     { (yyval.list) = symbol_list_prepend ((yyvsp[-1].list), symbol_list_sym_new ((yyvsp[0].symbol), (yylsp[0]))); }
-/* Line 1426 of yacc.c  */
-#line 2492 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2509 "src/parse-gram.c"
     break;
 
   case 65:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 500 "src/parse-gram.y"
     { (yyval.list) = (yyvsp[0].list); }
-/* Line 1426 of yacc.c  */
-#line 2500 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2517 "src/parse-gram.c"
     break;
 
   case 66:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 501 "src/parse-gram.y"
     { (yyval.list) = symbol_list_prepend ((yyvsp[-1].list), (yyvsp[0].list)); }
-/* Line 1426 of yacc.c  */
-#line 2508 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2525 "src/parse-gram.c"
     break;
 
   case 67:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 505 "src/parse-gram.y"
     { (yyval.list) = symbol_list_sym_new ((yyvsp[0].symbol), (yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2516 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2533 "src/parse-gram.c"
     break;
 
   case 68:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 506 "src/parse-gram.y"
     { (yyval.list) = symbol_list_type_new ((yyvsp[0].uniqstr), (yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2524 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2541 "src/parse-gram.c"
     break;
 
   case 69:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 507 "src/parse-gram.y"
     { (yyval.list) = symbol_list_default_tagged_new ((yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2532 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2549 "src/parse-gram.c"
     break;
 
   case 70:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 508 "src/parse-gram.y"
     { (yyval.list) = symbol_list_default_tagless_new ((yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2540 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2557 "src/parse-gram.c"
     break;
 
   case 71:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 514 "src/parse-gram.y"
     {
        current_type = (yyvsp[0].uniqstr);
        tag_seen = true;
      }
-/* Line 1426 of yacc.c  */
-#line 2551 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2568 "src/parse-gram.c"
     break;
 
   case 72:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 519 "src/parse-gram.y"
     {
        symbol_class_set ((yyvsp[0].symbol), current_class, (yylsp[0]), true);
        symbol_type_set ((yyvsp[0].symbol), current_type, (yylsp[0]));
      }
-/* Line 1426 of yacc.c  */
-#line 2562 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2579 "src/parse-gram.c"
     break;
 
   case 73:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 524 "src/parse-gram.y"
     {
       symbol_class_set ((yyvsp[-1].symbol), current_class, (yylsp[-1]), true);
       symbol_type_set ((yyvsp[-1].symbol), current_type, (yylsp[-1]));
       symbol_user_token_number_set ((yyvsp[-1].symbol), (yyvsp[0].integer), (yylsp[0]));
     }
-/* Line 1426 of yacc.c  */
-#line 2574 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2591 "src/parse-gram.c"
     break;
 
   case 74:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 530 "src/parse-gram.y"
     {
       symbol_class_set ((yyvsp[-1].symbol), current_class, (yylsp[-1]), true);
       symbol_type_set ((yyvsp[-1].symbol), current_type, (yylsp[-1]));
       symbol_make_alias ((yyvsp[-1].symbol), (yyvsp[0].symbol), (yyloc));
     }
-/* Line 1426 of yacc.c  */
-#line 2586 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2603 "src/parse-gram.c"
     break;
 
   case 75:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 536 "src/parse-gram.y"
     {
       symbol_class_set ((yyvsp[-2].symbol), current_class, (yylsp[-2]), true);
@@ -2594,144 +2611,144 @@ yyreduce:
       symbol_user_token_number_set ((yyvsp[-2].symbol), (yyvsp[-1].integer), (yylsp[-1]));
       symbol_make_alias ((yyvsp[-2].symbol), (yyvsp[0].symbol), (yyloc));
     }
-/* Line 1426 of yacc.c  */
-#line 2599 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2616 "src/parse-gram.c"
     break;
 
   case 82:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 566 "src/parse-gram.y"
     {
       yyerrok;
     }
-/* Line 1426 of yacc.c  */
-#line 2609 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2626 "src/parse-gram.c"
     break;
 
   case 83:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 572 "src/parse-gram.y"
     { current_lhs = (yyvsp[-1].symbol); current_lhs_location = (yylsp[-1]);
     current_lhs_named_ref = (yyvsp[0].named_ref); }
-/* Line 1426 of yacc.c  */
-#line 2618 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2635 "src/parse-gram.c"
     break;
 
   case 85:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 577 "src/parse-gram.y"
     { grammar_current_rule_end ((yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2626 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2643 "src/parse-gram.c"
     break;
 
   case 86:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 578 "src/parse-gram.y"
     { grammar_current_rule_end ((yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2634 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2651 "src/parse-gram.c"
     break;
 
   case 88:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 584 "src/parse-gram.y"
     { grammar_current_rule_begin (current_lhs, current_lhs_location,
 				  current_lhs_named_ref); }
-/* Line 1426 of yacc.c  */
-#line 2643 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2660 "src/parse-gram.c"
     break;
 
   case 89:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 587 "src/parse-gram.y"
     { grammar_current_rule_symbol_append ((yyvsp[-1].symbol), (yylsp[-1]), (yyvsp[0].named_ref)); }
-/* Line 1426 of yacc.c  */
-#line 2651 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2668 "src/parse-gram.c"
     break;
 
   case 90:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 589 "src/parse-gram.y"
     { grammar_current_rule_action_append ((yyvsp[-1].code), (yylsp[-1]), (yyvsp[0].named_ref), false); }
-/* Line 1426 of yacc.c  */
-#line 2659 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2676 "src/parse-gram.c"
     break;
 
   case 91:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 591 "src/parse-gram.y"
     { grammar_current_rule_action_append ((yyvsp[0].code), (yylsp[0]), NULL, true); }
-/* Line 1426 of yacc.c  */
-#line 2667 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2684 "src/parse-gram.c"
     break;
 
   case 92:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 593 "src/parse-gram.y"
     { grammar_current_rule_prec_set ((yyvsp[0].symbol), (yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2675 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2692 "src/parse-gram.c"
     break;
 
   case 93:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 595 "src/parse-gram.y"
     { grammar_current_rule_dprec_set ((yyvsp[0].integer), (yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2683 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2700 "src/parse-gram.c"
     break;
 
   case 94:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 597 "src/parse-gram.y"
     { grammar_current_rule_merge_set ((yyvsp[0].uniqstr), (yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2691 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2708 "src/parse-gram.c"
     break;
 
   case 95:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 601 "src/parse-gram.y"
     { (yyval.named_ref) = 0; }
-/* Line 1426 of yacc.c  */
-#line 2699 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2716 "src/parse-gram.c"
     break;
 
   case 96:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 603 "src/parse-gram.y"
     { (yyval.named_ref) = named_ref_new((yyvsp[0].uniqstr), (yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2707 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2724 "src/parse-gram.c"
     break;
 
   case 98:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 614 "src/parse-gram.y"
     { (yyval.uniqstr) = uniqstr_new ((yyvsp[0].chars)); }
-/* Line 1426 of yacc.c  */
-#line 2715 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2732 "src/parse-gram.c"
     break;
 
   case 99:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 619 "src/parse-gram.y"
     { (yyval.chars) = ""; }
-/* Line 1426 of yacc.c  */
-#line 2723 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2740 "src/parse-gram.c"
     break;
 
   case 100:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 620 "src/parse-gram.y"
     { (yyval.chars) = (yyvsp[0].uniqstr); }
-/* Line 1426 of yacc.c  */
-#line 2731 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2748 "src/parse-gram.c"
     break;
 
   case 102:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 631 "src/parse-gram.y"
     {
       code_props plain_code;
@@ -2741,51 +2758,51 @@ yyreduce:
       gram_scanner_last_string_free ();
       (yyval.chars) = plain_code.code;
     }
-/* Line 1426 of yacc.c  */
-#line 2746 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2763 "src/parse-gram.c"
     break;
 
   case 103:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 651 "src/parse-gram.y"
     { (yyval.symbol) = symbol_from_uniqstr ((yyvsp[0].uniqstr), (yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2754 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2771 "src/parse-gram.c"
     break;
 
   case 104:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 653 "src/parse-gram.y"
     {
       (yyval.symbol) = symbol_get (char_name ((yyvsp[0].character)), (yylsp[0]));
       symbol_class_set ((yyval.symbol), token_sym, (yylsp[0]), false);
       symbol_user_token_number_set ((yyval.symbol), (yyvsp[0].character), (yylsp[0]));
     }
-/* Line 1426 of yacc.c  */
-#line 2766 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2783 "src/parse-gram.c"
     break;
 
   case 105:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 661 "src/parse-gram.y"
     { (yyval.symbol) = symbol_from_uniqstr ((yyvsp[0].uniqstr), (yylsp[0])); }
-/* Line 1426 of yacc.c  */
-#line 2774 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2791 "src/parse-gram.c"
     break;
 
   case 108:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 673 "src/parse-gram.y"
     {
       (yyval.symbol) = symbol_get (quotearg_style (c_quoting_style, (yyvsp[0].chars)), (yylsp[0]));
       symbol_class_set ((yyval.symbol), token_sym, (yylsp[0]), false);
     }
-/* Line 1426 of yacc.c  */
-#line 2785 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2802 "src/parse-gram.c"
     break;
 
   case 110:
-/* Line 1426 of yacc.c  */
+/* Line 1443 of yacc.c  */
 #line 682 "src/parse-gram.y"
     {
       code_props plain_code;
@@ -2795,13 +2812,13 @@ yyreduce:
       muscle_code_grow ("epilogue", plain_code.code, (yylsp[0]));
       code_scanner_last_string_free ();
     }
-/* Line 1426 of yacc.c  */
-#line 2800 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2817 "src/parse-gram.c"
     break;
 
 
-/* Line 1426 of yacc.c  */
-#line 2805 "src/parse-gram.c"
+/* Line 1443 of yacc.c  */
+#line 2822 "src/parse-gram.c"
       default: break;
     }
   /* User semantic actions sometimes alter yychar, and that requires
@@ -2845,7 +2862,7 @@ yyreduce:
 yyerrlab:
   /* Make sure we have latest lookahead translation.  See comments at
      user semantic actions for why this is necessary.  */
-  yytoken = YYTRANSLATE (yychar);
+  yytoken = yychar == YYEMPTY ? YYEMPTY : YYTRANSLATE (yychar);
 
   /* If not already recovering from an error, report this error.  */
   if (!yyerrstatus)
@@ -2861,7 +2878,7 @@ yyerrlab:
         int yysyntax_error_status = YYSYNTAX_ERROR;
         if (yysyntax_error_status == 0)
           yymsgp = yymsg;
-        else if (yysyntax_error_status == 2 && 0 < yymsg_alloc)
+        else if (yysyntax_error_status == 1)
           {
             if (yymsg != yymsgbuf)
               YYSTACK_FREE (yymsg);
@@ -2870,6 +2887,7 @@ yyerrlab:
               {
                 yymsg = yymsgbuf;
                 yymsg_alloc = sizeof yymsgbuf;
+                yysyntax_error_status = 2;
               }
             else
               {
@@ -3034,7 +3052,7 @@ yyreturn:
   return YYID (yyresult);
 }
 
-/* Line 1662 of yacc.c  */
+/* Line 1680 of yacc.c  */
 #line 692 "src/parse-gram.y"
 
 
diff --git a/src/parse-gram.h b/src/parse-gram.h
index 01a3e296..fd1c8571 100644
--- a/src/parse-gram.h
+++ b/src/parse-gram.h
@@ -31,7 +31,7 @@
    This special exception was added by the Free Software Foundation in
    version 2.2 of Bison.  */
 /* "%code requires" blocks.  */
-/* Line 1663 of yacc.c  */
+/* Line 1681 of yacc.c  */
 #line 202 "src/parse-gram.y"
 
 # ifndef PARAM_TYPE
@@ -46,7 +46,7 @@
 # endif
 
 
-/* Line 1663 of yacc.c  */
+/* Line 1681 of yacc.c  */
 #line 51 "src/parse-gram.h"
 
 /* Tokens.  */
@@ -175,7 +175,7 @@
 #if ! defined YYSTYPE && ! defined YYSTYPE_IS_DECLARED
 typedef union YYSTYPE
 {
-/* Line 1663 of yacc.c  */
+/* Line 1681 of yacc.c  */
 #line 88 "src/parse-gram.y"
 
   assoc assoc;
@@ -188,13 +188,13 @@ typedef union YYSTYPE
   uniqstr uniqstr;
   unsigned char character;
 
-/* Line 1663 of yacc.c  */
+/* Line 1681 of yacc.c  */
 #line 226 "src/parse-gram.y"
 
   param_type param;
 
 
-/* Line 1663 of yacc.c  */
+/* Line 1681 of yacc.c  */
 #line 199 "src/parse-gram.h"
 } YYSTYPE;
 # define YYSTYPE_IS_TRIVIAL 1
diff --git a/tests/conflicts.at b/tests/conflicts.at
index 72f56963..655a666c 100644
--- a/tests/conflicts.at
+++ b/tests/conflicts.at
@@ -147,15 +147,30 @@ AT_SETUP([[parse.error=verbose and consistent errors]])
 
 m4_pushdef([AT_CONSISTENT_ERRORS_CHECK], [
 
-AT_DATA_GRAMMAR([input.y],
-[[%code {
+AT_BISON_OPTION_PUSHDEFS([$1])
+
+m4_pushdef([AT_YYLEX_PROTOTYPE],
+[AT_SKEL_CC_IF([[int yylex (yy::parser::semantic_type *lvalp)]],
+               [[int yylex (YYSTYPE *lvalp)]])])
+
+AT_SKEL_JAVA_IF([AT_DATA], [AT_DATA_GRAMMAR])([input.y],
+[AT_SKEL_JAVA_IF([[
+
+%code imports {
+  import java.io.IOException;
+}]], [[
+
+%code {]AT_SKEL_CC_IF([[
+  #include <string>]], [[
   #include <assert.h>
   #include <stdio.h>
-  int yylex (void);
-  void yyerror (char const *);
+  void yyerror (char const *msg);]])[
+  ]AT_YYLEX_PROTOTYPE[;
   #define USE(Var)
 }
 
+]AT_SKEL_CC_IF([[%defines]], [[%define api.pure]])])[
+
 ]$1[
 
 %define parse.error verbose
@@ -164,63 +179,193 @@ AT_DATA_GRAMMAR([input.y],
 
 ]$2[
 
-%%
+]AT_SKEL_JAVA_IF([[%code lexer {]], [[%%]])[
 
-int
-yylex (void)
+/*--------.
+| yylex.  |
+`--------*/]AT_SKEL_JAVA_IF([[
+
+public String input = "]$3[";
+public int index = 0;
+public int yylex ()
+{
+  if (index < input.length ())
+    return input.charAt (index++);
+  else
+    return 0;
+}
+public Object getLVal ()
+{
+  return new Integer(1);
+}]], [[
+
+]AT_YYLEX_PROTOTYPE[
 {
   static char const *input = "]$3[";
-  yylval = 1;
+  *lvalp = 1;
   return *input++;
+}]])[
+
+/*----------.
+| yyerror.  |
+`----------*/]AT_SKEL_JAVA_IF([[
+
+public void yyerror (String msg)
+{
+  System.err.println (msg);
 }
 
+};
+
+%%]], [AT_SKEL_CC_IF([[
+
+void
+yy::parser::error (std::string const &msg)
+{
+  std::cerr << msg << std::endl;
+}]], [[
+
 void
 yyerror (char const *msg)
 {
   fprintf (stderr, "%s\n", msg);
-}
+}]])])[
+
+/*-------.
+| main.  |
+`-------*/]AT_SKEL_JAVA_IF([[
+
+class input
+{
+  public static void main (String args[]) throws IOException
+  {
+    YYParser p = new YYParser ();
+    p.parse ();
+  }
+}]], [AT_SKEL_CC_IF([[
+
+int
+main (void)
+{
+  yy::parser parser;
+  return parser.parse ();
+}]], [[
 
 int
 main (void)
 {
   return yyparse ();
-}
+}]])])[
 ]])
-AT_BISON_CHECK([[-o input.c input.y]])
-AT_COMPILE([[input]])
+
+AT_FULL_COMPILE([[input]])
 
 m4_pushdef([AT_EXPECTING], [m4_if($5, [ab], [[, expecting 'a' or 'b']],
                                   $5, [a],  [[, expecting 'a']],
                                   $5, [b],  [[, expecting 'b']])])
 
-AT_PARSER_CHECK([[./input]], [[1]], [[]],
+AT_SKEL_JAVA_IF([AT_JAVA_PARSER_CHECK([[input]], [[0]]],
+                [AT_PARSER_CHECK([[./input]], [[1]]]),
+[[]],
 [[syntax error, unexpected ]$4[]AT_EXPECTING[
 ]])
 
 m4_popdef([AT_EXPECTING])
+m4_popdef([AT_YYLEX_PROTOTYPE])
+AT_BISON_OPTION_POPDEFS
 
 ])
 
+m4_pushdef([AT_PREVIOUS_STATE_GRAMMAR],
+[[%nonassoc 'a';
+
+start: consistent-error-on-a-a 'a' ;
+
+consistent-error-on-a-a:
+    'a' default-reduction
+  | 'a' default-reduction 'a'
+  | 'a' shift
+  ;
+
+default-reduction: /*empty*/ ;
+shift: 'b' ;
+
+// Provide another context in which all rules are useful so that this
+// test case looks a little more realistic.
+start: 'b' consistent-error-on-a-a 'c' ;
+]])
+
+m4_pushdef([AT_PREVIOUS_STATE_INPUT], [[a]])
+
+# Unfortunately, no expected tokens are reported even though 'b' can be
+# accepted.  Nevertheless, the main point of this test is to make sure
+# that at least the unexpected token is reported.  In a previous version
+# of Bison, it wasn't reported because the error is detected in a
+# consistent state with an error action, and that case always triggered
+# the simple "syntax error" message.
+#
+# The point isn't to test IELR here, but state merging happens to
+# complicate this example.
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type ielr]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[$end]], [[none]])
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type ielr
+                             %glr-parser]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[$end]], [[none]])
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type ielr
+                             %language "c++"]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[$end]], [[none]])
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type ielr
+                             %language "java"]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[end of input]], [[none]])
+
+# Even canonical LR doesn't foresee the error for 'a'!
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type ielr
+                             %define lr.default-reductions consistent]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[$end]], [[ab]])
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type ielr
+                             %define lr.default-reductions accepting]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[$end]], [[ab]])
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type canonical-lr]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[$end]], [[ab]])
+
+m4_popdef([AT_PREVIOUS_STATE_GRAMMAR])
+m4_popdef([AT_PREVIOUS_STATE_INPUT])
+
 m4_pushdef([AT_USER_ACTION_GRAMMAR],
 [[%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.
+// If $$ = 0 here, then we know that the 'a' destructor is being invoked
+// incorrectly for the 'b' set in the semantic action below.  All 'a'
+// tokens are returned by yylex, which sets $$ = 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
+// Rather than depend on an inconsistent state to induce reading a
+// lookahead as in the previous grammar, just assign the lookahead in a
+// semantic action.  That lookahead 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.
+// except that, due to the bug described in the previous grammar, the
+// unexpected token was not reported at all.
 start: error-reduce consistent-error 'a' { USE ($][3); } ;
 
 error-reduce:
@@ -247,13 +392,16 @@ start: 'b' consistent-error 'b' ;
 ]])
 m4_pushdef([AT_USER_ACTION_INPUT], [[aa]])
 
-# See comments in grammar for why this test doesn't succeed.
-AT_XFAIL_IF([[:]])
-
 AT_CONSISTENT_ERRORS_CHECK([[]],
                            [AT_USER_ACTION_GRAMMAR],
                            [AT_USER_ACTION_INPUT],
                            [['b']], [[none]])
+AT_CONSISTENT_ERRORS_CHECK([[%glr-parser]],
+                           [AT_USER_ACTION_GRAMMAR],
+                           [AT_USER_ACTION_INPUT],
+                           [['b']], [[none]])
+# No C++ or Java test because yychar cannot be manipulated by users.
+
 AT_CONSISTENT_ERRORS_CHECK([[%define lr.default-reductions consistent]],
                            [AT_USER_ACTION_GRAMMAR],
                            [AT_USER_ACTION_INPUT],
diff --git a/tests/java.at b/tests/java.at
index 9ea703fe..dfd42523 100644
--- a/tests/java.at
+++ b/tests/java.at
@@ -219,25 +219,6 @@ m4_define([AT_DATA_JAVA_CALC_Y],
 ])
 
 
-
-# AT_JAVA_COMPILE(SOURCE)
-# -----------------------
-# Compile SOURCES into Java class files.  Skip the test if java or javac is
-# not installed.
-m4_define([AT_JAVA_COMPILE],
-[AT_KEYWORDS(java)
-AT_CHECK([test -n "$CONF_JAVA" || exit 77
-test -n "$CONF_JAVAC" || exit 77])
-AT_CHECK([$SHELL ../../../javacomp.sh $1],
-         0, [ignore], [ignore])])
-
-
-# AT_JAVA_PARSER_CHECK(COMMAND, EXIT-STATUS, EXPOUT, EXPERR, [PRE])
-# -----------------------------------------------------------------
-m4_define([AT_JAVA_PARSER_CHECK],
-[AT_CHECK([$5 $SHELL ../../../javaexec.sh $1], [$2], [$3], [$4])])
-
-
 # _AT_CHECK_JAVA_CALC_ERROR(BISON-OPTIONS, INPUT,
 #                           [VERBOSE-AND-LOCATED-ERROR-MESSAGE])
 # ---------------------------------------------------------
diff --git a/tests/local.at b/tests/local.at
index d3b245c2..bdcbfc49 100644
--- a/tests/local.at
+++ b/tests/local.at
@@ -80,6 +80,8 @@ m4_pushdef([AT_DEFINES_IF],
 [m4_bmatch([$3], [%defines], [$1], [$2])])
 m4_pushdef([AT_SKEL_CC_IF],
 [m4_bmatch([$3], [%language "[Cc]\+\+"\|%skeleton "[a-z0-9]+\.cc"], [$1], [$2])])
+m4_pushdef([AT_SKEL_JAVA_IF],
+[m4_bmatch([$3], [%language "[Jj][Aa][Vv][Aa]"\|%skeleton "[a-z0-9]+\.java"], [$1], [$2])])
 m4_pushdef([AT_GLR_IF],
 [m4_bmatch([$3], [%glr-parser\|%skeleton "glr\.], [$1], [$2])])
 m4_pushdef([AT_LALR1_CC_IF],
@@ -189,6 +191,7 @@ m4_popdef([AT_LEXPARAM_IF])
 m4_popdef([AT_YACC_IF])
 m4_popdef([AT_GLR_IF])
 m4_popdef([AT_SKEL_CC_IF])
+m4_popdef([AT_SKEL_JAVA_IF])
 m4_popdef([AT_GLR_CC_IF])
 m4_popdef([AT_LALR1_CC_IF])
 m4_popdef([AT_DEFINES_IF])
@@ -404,19 +407,38 @@ AT_CHECK([$BISON_CXX_WORKS], 0, ignore, ignore)
 AT_CHECK([$CXX $CXXFLAGS $CPPFLAGS m4_bmatch([$1], [[.]], [], [$LDFLAGS ])-o $1 m4_default([$2], [$1.cc])[]m4_bmatch([$1], [[.]], [], [ $LIBS])],
 	 0, [ignore], [ignore])])
 
+# AT_JAVA_COMPILE(SOURCES)
+# ------------------------
+# Compile SOURCES into Java class files.  Skip the test if java or javac
+# is not installed.
+m4_define([AT_JAVA_COMPILE],
+[AT_KEYWORDS(java)
+AT_CHECK([[test -n "$CONF_JAVA" || exit 77
+           test -n "$CONF_JAVAC" || exit 77]])
+AT_CHECK([[$SHELL ../../../javacomp.sh ]$1],
+         [[0]], [ignore], [ignore])])
 
 # AT_FULL_COMPILE(OUTPUT, [OTHER])
 # --------------------------------
-# Compile OUTPUT.y to OUTPUT.c or OUTPUT.cc, and compile it to OUTPUT.
-# If OTHER is specified, compile OUTPUT-OTHER.c or OUTPUT-OTHER.cc to OUTPUT
-# along with it.
-# Relies on AT_SKEL_CC_IF.
-m4_define([AT_FULL_COMPILE],
-[AT_SKEL_CC_IF(
-  [AT_BISON_CHECK([-o $1.cc $1.y])
-   AT_COMPILE_CXX([$1]m4_ifval($2, [, [$1.cc $1-$2.cc]]))],
-  [AT_BISON_CHECK([-o $1.c $1.y])
-   AT_COMPILE([$1]m4_ifval($2, [, [$1.c $1-$2.c]]))])
+# Compile OUTPUT.y to OUTPUT.c, OUTPUT.cc, or OUTPUT.java, and then
+# compile it to OUTPUT or OUTPUT.class.  If OTHER is specified, compile
+# OUTPUT-OTHER.c, OUTPUT-OTHER.cc, or OUTPUT-OTHER.java to OUTPUT or
+# OUTPUT.java along with it.  Relies on AT_SKEL_CC_IF and
+# AT_SKEL_JAVA_IF.
+m4_define([AT_FULL_COMPILE], [
+  AT_SKEL_JAVA_IF([
+    AT_BISON_CHECK([[-o ]$1[.java ]$1[.y]])
+    AT_JAVA_COMPILE([$1[.java]]m4_ifval($2,
+                                        [[$1[.java ]$1[-]$2[.java]]]))
+  ], [
+    AT_SKEL_CC_IF([
+      AT_BISON_CHECK([[-o ]$1[.cc ]$1[.y]])
+      AT_COMPILE_CXX([$1]m4_ifval($2, [, [$1[.cc ]$1[-]$2[.cc]]]))
+    ], [
+      AT_BISON_CHECK([[-o ]$1[.c ]$1[.y]])
+      AT_COMPILE([$1]m4_ifval($2, [, [$1[.c ]$1[-]$2[.c]]]))
+    ])
+  ])
 ])
 
 
@@ -430,6 +452,11 @@ m4_define([AT_FULL_COMPILE],
 m4_define([AT_PARSER_CHECK],
 [AT_CHECK([$5 $PREPARSER $1], [$2], [$3], [$4])])
 
+# AT_JAVA_PARSER_CHECK(COMMAND, EXIT-STATUS, EXPOUT, EXPERR, [PRE])
+# -----------------------------------------------------------------
+m4_define([AT_JAVA_PARSER_CHECK],
+[AT_CHECK([$5[ $SHELL ../../../javaexec.sh ]$1], [$2], [$3], [$4])])
+
 # AT_TEST_TABLES_AND_PARSE(TITLE, COND-VALUE, TEST-SPEC,
 #                          DECLS, GRAMMAR, INPUT,
 #                          BISON-STDERR, TABLES-OR-LAST-STATE,
-- 
2.45.2