From 827bc59ca118956fe84309e2ea3db6bfaabf374c Mon Sep 17 00:00:00 2001
From: Akim Demaille <akim@lrde.epita.fr>
Date: Sun, 4 Jan 2015 14:16:23 +0100
Subject: [PATCH] %union: fix the support for named %union

Bison supports a union tag, for obscure reasons.  But it does a poor
job at it, especially since Bison 3.0.
Reported by Stephen Cameron and Tobias Frost.

It did not ensure that the name was not given several times.  An easy
way to do this is to make the %union tag be handled as a %define
variable, as they cannot be defined several times.

Since Bison 3.0, the synclines were wrongly placed, resulting in
invalid code.  Addressing this issue, because of the way the union tag
was stored (as a code muscle), would have been tedious.  Unless we
rather define the %union tag as a %percent variable, whose synclines
are easier to manipulate.

So replace the b4_union_name muscle by the api.value.union.name
%define variable, document, and check.

* data/bison.m4: Make sure that api.value.union.name has a keyword value.
* data/c++.m4: Make sure that api.value.union.name is not defined.
* data/c.m4 (b4_union_name): No longer use it, use api.value.union.name.
* doc/bison.texi (%define Summary): Document it.
* src/parse-gram.y (union_name): No longer define b4_uion_name, but
api.value.union.name.
* tests/input.at (Redefined %union name): New.
* tests/synclines.at (%union name syncline): New.
* tests/types.at: Check named %unions.
---
 NEWS               |   9 ++
 THANKS             |   2 +
 data/bison.m4      |   3 +
 data/c++.m4        |   5 +
 data/c.m4          |  16 +-
 doc/bison.texi     |  32 +++-
 src/parse-gram.c   | 374 +++++++++++++++++++++++----------------------
 src/parse-gram.h   |   8 +-
 src/parse-gram.y   |   4 +-
 tests/input.at     |  45 ++++++
 tests/synclines.at |  29 ++++
 tests/types.at     |  48 ++++--
 12 files changed, 363 insertions(+), 212 deletions(-)

diff --git a/NEWS b/NEWS
index 0b022cf8..490e89ed 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,15 @@ GNU Bison NEWS
 
 ** Bug fixes
 
+*** Named %union support
+
+  Bison 3.0 introduced a regression on named %union such as
+
+    %union foo { int ival; };
+
+  The possibility to use a name was introduced ``for Yacc compatibility''.
+  It is however not required by POSIX Yacc, and its usefulness is not clear.
+
 *** %define api.value.type union with %defines
 
   The yacc.c and glr.c parsers were broken when %defines was used
diff --git a/THANKS b/THANKS
index b38affc6..095d3683 100644
--- a/THANKS
+++ b/THANKS
@@ -126,6 +126,7 @@ Sebastien Fricker         sebastien.fricker@gmail.com
 Sergei Steshenko          sergstesh@yahoo.com
 Shura                     debil_urod@ngs.ru
 Stefano Lattarini         stefano.lattarini@gmail.com
+Stephen Cameron           stephenmcameron@gmail.com
 Steve Murphy              murf@parsetree.com
 Sum Wu                    sum@geekhouse.org
 Théophile Ranquet         theophile.ranquet@gmail.com
@@ -133,6 +134,7 @@ Thiru Ramakrishnan        thiru.ramakrishnan@gmail.com
 Tim Josling               tej@melbpc.org.au
 Tim Landscheidt           tim@tim-landscheidt.de
 Tim Van Holder            tim.van.holder@pandora.be
+Tobias Frost              tobi@debian.org
 Tom Lane                  tgl@sss.pgh.pa.us
 Tom Tromey                tromey@cygnus.com
 Tommy Nordgren            tommy.nordgren@chello.se
diff --git a/data/bison.m4 b/data/bison.m4
index c416c6c2..da59baf5 100644
--- a/data/bison.m4
+++ b/data/bison.m4
@@ -1061,3 +1061,6 @@ b4_percent_define_ifdef([api.value.type],
                 [['%s' and '%s' cannot be used together]],
                 [%yacc],
                 [%define api.value.type "union"])])])])
+
+# api.value.union.name.
+b4_percent_define_check_kind([api.value.union.name], [keyword])
diff --git a/data/c++.m4 b/data/c++.m4
index ffbde266..7c0fd78e 100644
--- a/data/c++.m4
+++ b/data/c++.m4
@@ -17,6 +17,11 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+# Sanity checks, before defaults installed by c.m4.
+b4_percent_define_ifdef([[api.value.union.name]],
+  [b4_complain_at(b4_percent_define_get_loc([[api.value.union.name]]),
+                  [named %union is invalid in C++])])
+
 m4_include(b4_pkgdatadir/[c.m4])
 
 # b4_comment(TEXT, [PREFIX])
diff --git a/data/c.m4 b/data/c.m4
index d56f8d76..738244d4 100644
--- a/data/c.m4
+++ b/data/c.m4
@@ -97,7 +97,8 @@ m4_define([b4_api_PREFIX],
 m4_define_default([b4_prefix], [b4_api_prefix])
 
 # If the %union is not named, its name is YYSTYPE.
-m4_define_default([b4_union_name], [b4_api_PREFIX[]STYPE])
+b4_percent_define_default([[api.value.union.name]],
+                          [b4_api_PREFIX[][STYPE]])
 
 
 ## ------------------------ ##
@@ -608,10 +609,9 @@ m4_copy_force([b4_symbol_value_union], [b4_symbol_value])
 ])
 
 
-# ---------------- #
-# api.value.type.  #
-# ---------------- #
-
+# -------------------------- #
+# api.value.type = variant.  #
+# -------------------------- #
 
 # b4_value_type_setup_variant
 # ---------------------------
@@ -686,11 +686,13 @@ typedef ]b4_percent_define_get([[api.value.type]])[ ]b4_api_PREFIX[STYPE;
 [m4_bmatch(b4_percent_define_get([[api.value.type]]),
 [union\|union-directive],
 [[#if ! defined ]b4_api_PREFIX[STYPE && ! defined ]b4_api_PREFIX[STYPE_IS_DECLARED
-typedef union ]b4_union_name[ ]b4_api_PREFIX[STYPE;
-union ]b4_union_name[
+]b4_percent_define_get_syncline([[api.value.union.name]])[
+union ]b4_percent_define_get([[api.value.union.name]])[
 {
 ]b4_user_union_members[
 };
+]b4_percent_define_get_syncline([[api.value.union.name]])[
+typedef union ]b4_percent_define_get([[api.value.union.name]])[ ]b4_api_PREFIX[STYPE;
 # define ]b4_api_PREFIX[STYPE_IS_TRIVIAL 1
 # define ]b4_api_PREFIX[STYPE_IS_DECLARED 1
 #endif
diff --git a/doc/bison.texi b/doc/bison.texi
index c3c9746f..11bd2d86 100644
--- a/doc/bison.texi
+++ b/doc/bison.texi
@@ -3851,7 +3851,7 @@ example:
 @noindent
 specifies the union tag @code{value}, so the corresponding C type is
 @code{union value}.  If you do not specify a tag, it defaults to
-@code{YYSTYPE}.
+@code{YYSTYPE} (@pxref{%define Summary,,api.value.union.name}).
 
 As another extension to POSIX, you may specify multiple @code{%union}
 declarations; their contents are concatenated.  However, only the first
@@ -6014,12 +6014,12 @@ Use this @var{type} as semantic value.
 @item Default Value:
 @itemize @minus
 @item
-@code{%union} if @code{%union} is used, otherwise @dots{}
+@code{union-directive} if @code{%union} is used, otherwise @dots{}
 @item
 @code{int} if type tags are used (i.e., @samp{%token <@var{type}>@dots{}} or
-@samp{%token <@var{type}>@dots{}} is used), otherwise @dots{}
+@samp{%type <@var{type}>@dots{}} is used), otherwise @dots{}
 @item
-@code{""}
+undefined.
 @end itemize
 
 @item History:
@@ -6030,6 +6030,30 @@ introduced in Bison 3.0.  Was introduced for Java only in 2.3b as
 @c api.value.type
 
 
+@c ================================================== api.value.union.name
+@deffn Directive {%define api.value.union.name} @var{name}
+@itemize @bullet
+@item Language(s):
+C
+
+@item Purpose:
+The tag of the generated @code{union} (@emph{not} the name of the
+@code{typedef}).  This variable is set to @code{@var{id}} when @samp{%union
+@var{id}} is used.  There is no clear reason to give this union a name.
+
+@item Accepted Values:
+Any valid identifier.
+
+@item Default Value:
+@code{YYSTYPE}.
+
+@item History:
+Introduced in Bison 3.0.3.
+@end itemize
+@end deffn
+@c api.value.type
+
+
 @c ================================================== location_type
 @deffn Directive {%define location_type}
 Obsoleted by @code{api.location.type} since Bison 2.7.
diff --git a/src/parse-gram.c b/src/parse-gram.c
index 9251b149..825e2b09 100644
--- a/src/parse-gram.c
+++ b/src/parse-gram.c
@@ -129,7 +129,7 @@ extern int gram_debug;
     param_parse  = 1 << 1,
     param_both   = param_lex | param_parse
   } param_type;
-#line 645 "src/parse-gram.y" /* yacc.c:355  */
+#line 647 "src/parse-gram.y" /* yacc.c:355  */
 #include "muscle-tab.h"
 
 #line 136 "src/parse-gram.c" /* yacc.c:355  */
@@ -200,7 +200,7 @@ extern int gram_debug;
 
 /* Value type.  */
 #if ! defined GRAM_STYPE && ! defined GRAM_STYPE_IS_DECLARED
-typedef union GRAM_STYPE GRAM_STYPE;
+
 union GRAM_STYPE
 {
 #line 182 "src/parse-gram.y" /* yacc.c:355  */
@@ -223,7 +223,7 @@ named_ref *named_ref;
 param_type param;
 #line 409 "src/parse-gram.y" /* yacc.c:355  */
 code_props_type code_type;
-#line 647 "src/parse-gram.y" /* yacc.c:355  */
+#line 649 "src/parse-gram.y" /* yacc.c:355  */
 
   struct
   {
@@ -233,6 +233,8 @@ code_props_type code_type;
 
 #line 235 "src/parse-gram.c" /* yacc.c:355  */
 };
+
+typedef union GRAM_STYPE GRAM_STYPE;
 # define GRAM_STYPE_IS_TRIVIAL 1
 # define GRAM_STYPE_IS_DECLARED 1
 #endif
@@ -259,7 +261,7 @@ int gram_parse (void);
 
 /* Copy the second part of user declarations.  */
 
-#line 263 "src/parse-gram.c" /* yacc.c:358  */
+#line 265 "src/parse-gram.c" /* yacc.c:358  */
 /* Unqualified %code blocks.  */
 #line 33 "src/parse-gram.y" /* yacc.c:359  */
 
@@ -335,7 +337,7 @@ int gram_parse (void);
   static void add_param (param_type type, char *decl, location loc);
   static param_type current_param = param_none;
 
-#line 339 "src/parse-gram.c" /* yacc.c:359  */
+#line 341 "src/parse-gram.c" /* yacc.c:359  */
 
 #ifdef short
 # undef short
@@ -621,14 +623,14 @@ static const yytype_uint16 yyrline[] =
      295,   300,   306,   307,   308,   309,   314,   319,   320,   321,
      322,   323,   324,   324,   325,   326,   350,   351,   352,   353,
      357,   358,   367,   368,   369,   373,   385,   389,   393,   401,
-     412,   413,   423,   424,   428,   440,   440,   445,   445,   450,
-     461,   476,   477,   478,   479,   483,   484,   489,   491,   496,
-     501,   511,   513,   518,   519,   523,   524,   528,   529,   530,
-     535,   540,   545,   551,   557,   568,   569,   578,   579,   585,
-     586,   587,   594,   594,   602,   603,   604,   609,   612,   614,
-     616,   618,   620,   622,   624,   629,   630,   640,   641,   666,
-     667,   668,   669,   681,   683,   692,   697,   698,   703,   711,
-     712
+     412,   413,   423,   424,   430,   442,   442,   447,   447,   452,
+     463,   478,   479,   480,   481,   485,   486,   491,   493,   498,
+     503,   513,   515,   520,   521,   525,   526,   530,   531,   532,
+     537,   542,   547,   553,   559,   570,   571,   580,   581,   587,
+     588,   589,   596,   596,   604,   605,   606,   611,   614,   616,
+     618,   620,   622,   624,   626,   631,   632,   642,   643,   668,
+     669,   670,   671,   683,   685,   694,   699,   700,   705,   713,
+     714
 };
 #endif
 
@@ -1002,73 +1004,73 @@ yy_symbol_value_print (FILE *yyoutput, int yytype, YYSTYPE const * const yyvalue
           case 3: /* "string"  */
 #line 188 "src/parse-gram.y" /* yacc.c:684  */
       { fputs (quotearg_style (c_quoting_style, ((*yyvaluep).code)), yyo); }
-#line 1006 "src/parse-gram.c" /* yacc.c:684  */
+#line 1008 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 23: /* "%<flag>"  */
 #line 196 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "%%%s", ((*yyvaluep).uniqstr)); }
-#line 1012 "src/parse-gram.c" /* yacc.c:684  */
+#line 1014 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 39: /* "{...}"  */
 #line 189 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "{\n%s\n}", ((*yyvaluep).code)); }
-#line 1018 "src/parse-gram.c" /* yacc.c:684  */
+#line 1020 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 40: /* "%?{...}"  */
 #line 189 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "{\n%s\n}", ((*yyvaluep).code)); }
-#line 1024 "src/parse-gram.c" /* yacc.c:684  */
+#line 1026 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 41: /* "[identifier]"  */
 #line 194 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "[%s]", ((*yyvaluep).uniqstr)); }
-#line 1030 "src/parse-gram.c" /* yacc.c:684  */
+#line 1032 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 42: /* "char"  */
 #line 184 "src/parse-gram.y" /* yacc.c:684  */
       { fputs (char_name (((*yyvaluep).character)), yyo); }
-#line 1036 "src/parse-gram.c" /* yacc.c:684  */
+#line 1038 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 43: /* "epilogue"  */
 #line 189 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "{\n%s\n}", ((*yyvaluep).code)); }
-#line 1042 "src/parse-gram.c" /* yacc.c:684  */
+#line 1044 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 45: /* "identifier"  */
 #line 193 "src/parse-gram.y" /* yacc.c:684  */
       { fputs (((*yyvaluep).uniqstr), yyo); }
-#line 1048 "src/parse-gram.c" /* yacc.c:684  */
+#line 1050 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 46: /* "identifier:"  */
 #line 195 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "%s:", ((*yyvaluep).uniqstr)); }
-#line 1054 "src/parse-gram.c" /* yacc.c:684  */
+#line 1056 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 49: /* "%{...%}"  */
 #line 189 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "{\n%s\n}", ((*yyvaluep).code)); }
-#line 1060 "src/parse-gram.c" /* yacc.c:684  */
+#line 1062 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 51: /* "<tag>"  */
 #line 197 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "<%s>", ((*yyvaluep).uniqstr)); }
-#line 1066 "src/parse-gram.c" /* yacc.c:684  */
+#line 1068 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 54: /* "integer"  */
 #line 201 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "%d", ((*yyvaluep).integer)); }
-#line 1072 "src/parse-gram.c" /* yacc.c:684  */
+#line 1074 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 55: /* "%param"  */
@@ -1085,35 +1087,35 @@ yy_symbol_value_print (FILE *yyoutput, int yytype, YYSTYPE const * const yyvalue
       case param_none: aver (false); break;
     }
 }
-#line 1089 "src/parse-gram.c" /* yacc.c:684  */
+#line 1091 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 65: /* code_props_type  */
 #line 410 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "%s", code_props_type_string (((*yyvaluep).code_type))); }
-#line 1095 "src/parse-gram.c" /* yacc.c:684  */
+#line 1097 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 74: /* symbol.prec  */
 #line 205 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "%s", ((*yyvaluep).symbol)->tag); }
-#line 1101 "src/parse-gram.c" /* yacc.c:684  */
+#line 1103 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 78: /* tag  */
 #line 197 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "<%s>", ((*yyvaluep).uniqstr)); }
-#line 1107 "src/parse-gram.c" /* yacc.c:684  */
+#line 1109 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 88: /* variable  */
 #line 193 "src/parse-gram.y" /* yacc.c:684  */
       { fputs (((*yyvaluep).uniqstr), yyo); }
-#line 1113 "src/parse-gram.c" /* yacc.c:684  */
+#line 1115 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 89: /* value  */
-#line 656 "src/parse-gram.y" /* yacc.c:684  */
+#line 658 "src/parse-gram.y" /* yacc.c:684  */
       {
   switch (((*yyvaluep).value).kind)
     {
@@ -1122,31 +1124,31 @@ yy_symbol_value_print (FILE *yyoutput, int yytype, YYSTYPE const * const yyvalue
     case muscle_string:  fprintf (yyo, "\"%s\"", ((*yyvaluep).value).chars); break;
     }
 }
-#line 1126 "src/parse-gram.c" /* yacc.c:684  */
+#line 1128 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 90: /* id  */
 #line 205 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "%s", ((*yyvaluep).symbol)->tag); }
-#line 1132 "src/parse-gram.c" /* yacc.c:684  */
+#line 1134 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 91: /* id_colon  */
 #line 206 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "%s:", ((*yyvaluep).symbol)->tag); }
-#line 1138 "src/parse-gram.c" /* yacc.c:684  */
+#line 1140 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 92: /* symbol  */
 #line 205 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "%s", ((*yyvaluep).symbol)->tag); }
-#line 1144 "src/parse-gram.c" /* yacc.c:684  */
+#line 1146 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
     case 93: /* string_as_id  */
 #line 205 "src/parse-gram.y" /* yacc.c:684  */
       { fprintf (yyo, "%s", ((*yyvaluep).symbol)->tag); }
-#line 1150 "src/parse-gram.c" /* yacc.c:684  */
+#line 1152 "src/parse-gram.c" /* yacc.c:684  */
         break;
 
 
@@ -1848,7 +1850,7 @@ YYLTYPE yylloc = yyloc_default;
   boundary_set (&yylloc.end, current_file, 1, 1);
 }
 
-#line 1852 "src/parse-gram.c" /* yacc.c:1429  */
+#line 1854 "src/parse-gram.c" /* yacc.c:1429  */
   yylsp[0] = yylloc;
   goto yysetstate;
 
@@ -2048,7 +2050,7 @@ yyreduce:
                         translate_code ((yyvsp[0].code), (yylsp[0]), true), (yylsp[0]));
       code_scanner_last_string_free ();
     }
-#line 2052 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2054 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 7:
@@ -2056,7 +2058,7 @@ yyreduce:
     {
       muscle_percent_define_ensure ((yyvsp[0].uniqstr), (yylsp[0]), true);
     }
-#line 2060 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2062 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 8:
@@ -2065,13 +2067,13 @@ yyreduce:
       muscle_percent_define_insert ((yyvsp[-1].uniqstr), (yylsp[-1]), (yyvsp[0].value).kind, (yyvsp[0].value).chars,
                                     MUSCLE_PERCENT_DEFINE_GRAMMAR_FILE);
     }
-#line 2069 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2071 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 9:
 #line 294 "src/parse-gram.y" /* yacc.c:1646  */
     { defines_flag = true; }
-#line 2075 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2077 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 10:
@@ -2080,7 +2082,7 @@ yyreduce:
       defines_flag = true;
       spec_defines_file = xstrdup ((yyvsp[0].code));
     }
-#line 2084 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2086 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 11:
@@ -2090,25 +2092,25 @@ yyreduce:
                                     "verbose",
                                     MUSCLE_PERCENT_DEFINE_GRAMMAR_FILE);
     }
-#line 2094 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2096 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 12:
 #line 306 "src/parse-gram.y" /* yacc.c:1646  */
     { expected_sr_conflicts = (yyvsp[0].integer); }
-#line 2100 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2102 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 13:
 #line 307 "src/parse-gram.y" /* yacc.c:1646  */
     { expected_rr_conflicts = (yyvsp[0].integer); }
-#line 2106 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2108 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 14:
 #line 308 "src/parse-gram.y" /* yacc.c:1646  */
     { spec_file_prefix = (yyvsp[0].code); }
-#line 2112 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2114 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 15:
@@ -2117,7 +2119,7 @@ yyreduce:
       nondeterministic_parser = true;
       glr_parser = true;
     }
-#line 2121 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2123 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 16:
@@ -2126,55 +2128,55 @@ yyreduce:
       muscle_code_grow ("initial_action", translate_code ((yyvsp[0].code), (yylsp[0]), false), (yylsp[0]));
       code_scanner_last_string_free ();
     }
-#line 2130 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2132 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 17:
 #line 319 "src/parse-gram.y" /* yacc.c:1646  */
     { language_argmatch ((yyvsp[0].code), grammar_prio, (yylsp[-1])); }
-#line 2136 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2138 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 18:
 #line 320 "src/parse-gram.y" /* yacc.c:1646  */
     { spec_name_prefix = (yyvsp[0].code); }
-#line 2142 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2144 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 19:
 #line 321 "src/parse-gram.y" /* yacc.c:1646  */
     { no_lines_flag = true; }
-#line 2148 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2150 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 20:
 #line 322 "src/parse-gram.y" /* yacc.c:1646  */
     { nondeterministic_parser = true; }
-#line 2154 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2156 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 21:
 #line 323 "src/parse-gram.y" /* yacc.c:1646  */
     { spec_outfile = (yyvsp[0].code); }
-#line 2160 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2162 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 22:
 #line 324 "src/parse-gram.y" /* yacc.c:1646  */
     { current_param = (yyvsp[0].param); }
-#line 2166 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2168 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 23:
 #line 324 "src/parse-gram.y" /* yacc.c:1646  */
     { current_param = param_none; }
-#line 2172 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2174 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 24:
 #line 325 "src/parse-gram.y" /* yacc.c:1646  */
     { version_check (&(yylsp[0]), (yyvsp[0].code)); }
-#line 2178 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2180 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 25:
@@ -2202,37 +2204,37 @@ yyreduce:
         }
       skeleton_arg (skeleton_user, grammar_prio, (yylsp[-1]));
     }
-#line 2206 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2208 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 26:
 #line 350 "src/parse-gram.y" /* yacc.c:1646  */
     { token_table_flag = true; }
-#line 2212 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2214 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 27:
 #line 351 "src/parse-gram.y" /* yacc.c:1646  */
     { report_flag |= report_states; }
-#line 2218 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2220 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 28:
 #line 352 "src/parse-gram.y" /* yacc.c:1646  */
     { yacc_flag = true; }
-#line 2224 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2226 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 30:
 #line 357 "src/parse-gram.y" /* yacc.c:1646  */
     { add_param (current_param, (yyvsp[0].code), (yylsp[0])); }
-#line 2230 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2232 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 31:
 #line 358 "src/parse-gram.y" /* yacc.c:1646  */
     { add_param (current_param, (yyvsp[0].code), (yylsp[0])); }
-#line 2236 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2238 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 34:
@@ -2240,7 +2242,7 @@ yyreduce:
     {
       grammar_start_symbol_set ((yyvsp[0].symbol), (yylsp[0]));
     }
-#line 2244 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2246 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 35:
@@ -2256,7 +2258,7 @@ yyreduce:
         symbol_list_free ((yyvsp[0].list));
       }
     }
-#line 2260 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2262 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 36:
@@ -2264,7 +2266,7 @@ yyreduce:
     {
       default_prec = true;
     }
-#line 2268 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2270 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 37:
@@ -2272,7 +2274,7 @@ yyreduce:
     {
       default_prec = false;
     }
-#line 2276 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2278 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 38:
@@ -2284,7 +2286,7 @@ yyreduce:
                         translate_code_braceless ((yyvsp[0].code), (yylsp[0])), (yylsp[0]));
       code_scanner_last_string_free ();
     }
-#line 2288 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2290 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 39:
@@ -2293,75 +2295,77 @@ yyreduce:
       muscle_percent_code_grow ((yyvsp[-1].uniqstr), (yylsp[-1]), translate_code_braceless ((yyvsp[0].code), (yylsp[0])), (yylsp[0]));
       code_scanner_last_string_free ();
     }
-#line 2297 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2299 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 40:
 #line 412 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.code_type) = destructor; }
-#line 2303 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2305 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 41:
 #line 413 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.code_type) = printer; }
-#line 2309 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2311 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 42:
 #line 423 "src/parse-gram.y" /* yacc.c:1646  */
     {}
-#line 2315 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2317 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 43:
 #line 424 "src/parse-gram.y" /* yacc.c:1646  */
-    { muscle_code_grow ("union_name", (yyvsp[0].uniqstr), (yylsp[0])); }
-#line 2321 "src/parse-gram.c" /* yacc.c:1646  */
+    { muscle_percent_define_insert ("api.value.union.name",
+                                         (yylsp[0]), muscle_keyword, (yyvsp[0].uniqstr),
+                                         MUSCLE_PERCENT_DEFINE_GRAMMAR_FILE); }
+#line 2325 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 44:
-#line 429 "src/parse-gram.y" /* yacc.c:1646  */
+#line 431 "src/parse-gram.y" /* yacc.c:1646  */
     {
       union_seen = true;
       muscle_code_grow ("union_members", translate_code_braceless ((yyvsp[0].code), (yylsp[0])), (yylsp[0]));
       code_scanner_last_string_free ();
     }
-#line 2331 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2335 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 45:
-#line 440 "src/parse-gram.y" /* yacc.c:1646  */
+#line 442 "src/parse-gram.y" /* yacc.c:1646  */
     { current_class = nterm_sym; }
-#line 2337 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2341 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 46:
-#line 441 "src/parse-gram.y" /* yacc.c:1646  */
+#line 443 "src/parse-gram.y" /* yacc.c:1646  */
     {
       current_class = unknown_sym;
       current_type = NULL;
     }
-#line 2346 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2350 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 47:
-#line 445 "src/parse-gram.y" /* yacc.c:1646  */
+#line 447 "src/parse-gram.y" /* yacc.c:1646  */
     { current_class = token_sym; }
-#line 2352 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2356 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 48:
-#line 446 "src/parse-gram.y" /* yacc.c:1646  */
+#line 448 "src/parse-gram.y" /* yacc.c:1646  */
     {
       current_class = unknown_sym;
       current_type = NULL;
     }
-#line 2361 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2365 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 49:
-#line 451 "src/parse-gram.y" /* yacc.c:1646  */
+#line 453 "src/parse-gram.y" /* yacc.c:1646  */
     {
       symbol_list *list;
       tag_seen = true;
@@ -2369,11 +2373,11 @@ yyreduce:
         symbol_type_set (list->content.sym, (yyvsp[-1].uniqstr), (yylsp[-1]));
       symbol_list_free ((yyvsp[0].list));
     }
-#line 2373 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2377 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 50:
-#line 462 "src/parse-gram.y" /* yacc.c:1646  */
+#line 464 "src/parse-gram.y" /* yacc.c:1646  */
     {
       symbol_list *list;
       ++current_prec;
@@ -2385,341 +2389,341 @@ yyreduce:
       symbol_list_free ((yyvsp[0].list));
       current_type = NULL;
     }
-#line 2389 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2393 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 51:
-#line 476 "src/parse-gram.y" /* yacc.c:1646  */
+#line 478 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.assoc) = left_assoc; }
-#line 2395 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2399 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 52:
-#line 477 "src/parse-gram.y" /* yacc.c:1646  */
+#line 479 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.assoc) = right_assoc; }
-#line 2401 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2405 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 53:
-#line 478 "src/parse-gram.y" /* yacc.c:1646  */
+#line 480 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.assoc) = non_assoc; }
-#line 2407 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2411 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 54:
-#line 479 "src/parse-gram.y" /* yacc.c:1646  */
+#line 481 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.assoc) = precedence_assoc; }
-#line 2413 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2417 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 55:
-#line 483 "src/parse-gram.y" /* yacc.c:1646  */
+#line 485 "src/parse-gram.y" /* yacc.c:1646  */
     { current_type = NULL; }
-#line 2419 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2423 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 56:
-#line 484 "src/parse-gram.y" /* yacc.c:1646  */
+#line 486 "src/parse-gram.y" /* yacc.c:1646  */
     { current_type = (yyvsp[0].uniqstr); tag_seen = true; }
-#line 2425 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2429 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 57:
-#line 490 "src/parse-gram.y" /* yacc.c:1646  */
+#line 492 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.list) = symbol_list_sym_new ((yyvsp[0].symbol), (yylsp[0])); }
-#line 2431 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2435 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 58:
-#line 492 "src/parse-gram.y" /* yacc.c:1646  */
+#line 494 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.list) = symbol_list_append ((yyvsp[-1].list), symbol_list_sym_new ((yyvsp[0].symbol), (yylsp[0]))); }
-#line 2437 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2441 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 59:
-#line 497 "src/parse-gram.y" /* yacc.c:1646  */
+#line 499 "src/parse-gram.y" /* yacc.c:1646  */
     {
       (yyval.symbol) = (yyvsp[0].symbol);
       symbol_class_set ((yyvsp[0].symbol), token_sym, (yylsp[0]), false);
     }
-#line 2446 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2450 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 60:
-#line 502 "src/parse-gram.y" /* yacc.c:1646  */
+#line 504 "src/parse-gram.y" /* yacc.c:1646  */
     {
       (yyval.symbol) = (yyvsp[-1].symbol);
       symbol_user_token_number_set ((yyvsp[-1].symbol), (yyvsp[0].integer), (yylsp[0]));
       symbol_class_set ((yyvsp[-1].symbol), token_sym, (yylsp[-1]), false);
     }
-#line 2456 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2460 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 61:
-#line 512 "src/parse-gram.y" /* yacc.c:1646  */
+#line 514 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.list) = symbol_list_sym_new ((yyvsp[0].symbol), (yylsp[0])); }
-#line 2462 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2466 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 62:
-#line 514 "src/parse-gram.y" /* yacc.c:1646  */
+#line 516 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.list) = symbol_list_append ((yyvsp[-1].list), symbol_list_sym_new ((yyvsp[0].symbol), (yylsp[0]))); }
-#line 2468 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2472 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 63:
-#line 518 "src/parse-gram.y" /* yacc.c:1646  */
+#line 520 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.list) = (yyvsp[0].list); }
-#line 2474 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2478 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 64:
-#line 519 "src/parse-gram.y" /* yacc.c:1646  */
+#line 521 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.list) = symbol_list_append ((yyvsp[-1].list), (yyvsp[0].list)); }
-#line 2480 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2484 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 65:
-#line 523 "src/parse-gram.y" /* yacc.c:1646  */
+#line 525 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.list) = symbol_list_sym_new ((yyvsp[0].symbol), (yylsp[0])); }
-#line 2486 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2490 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 66:
-#line 524 "src/parse-gram.y" /* yacc.c:1646  */
+#line 526 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.list) = symbol_list_type_new ((yyvsp[0].uniqstr), (yylsp[0])); }
-#line 2492 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2496 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 68:
-#line 529 "src/parse-gram.y" /* yacc.c:1646  */
+#line 531 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.uniqstr) = uniqstr_new ("*"); }
-#line 2498 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2502 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 69:
-#line 530 "src/parse-gram.y" /* yacc.c:1646  */
+#line 532 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.uniqstr) = uniqstr_new (""); }
-#line 2504 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2508 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 70:
-#line 536 "src/parse-gram.y" /* yacc.c:1646  */
+#line 538 "src/parse-gram.y" /* yacc.c:1646  */
     {
       current_type = (yyvsp[0].uniqstr);
       tag_seen = true;
     }
-#line 2513 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2517 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 71:
-#line 541 "src/parse-gram.y" /* yacc.c:1646  */
+#line 543 "src/parse-gram.y" /* yacc.c:1646  */
     {
       symbol_class_set ((yyvsp[0].symbol), current_class, (yylsp[0]), true);
       symbol_type_set ((yyvsp[0].symbol), current_type, (yylsp[0]));
     }
-#line 2522 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2526 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 72:
-#line 546 "src/parse-gram.y" /* yacc.c:1646  */
+#line 548 "src/parse-gram.y" /* yacc.c:1646  */
     {
       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 2532 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2536 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 73:
-#line 552 "src/parse-gram.y" /* yacc.c:1646  */
+#line 554 "src/parse-gram.y" /* yacc.c:1646  */
     {
       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 2542 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2546 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 74:
-#line 558 "src/parse-gram.y" /* yacc.c:1646  */
+#line 560 "src/parse-gram.y" /* yacc.c:1646  */
     {
       symbol_class_set ((yyvsp[-2].symbol), current_class, (yylsp[-2]), true);
       symbol_type_set ((yyvsp[-2].symbol), current_type, (yylsp[-2]));
       symbol_user_token_number_set ((yyvsp[-2].symbol), (yyvsp[-1].integer), (yylsp[-1]));
       symbol_make_alias ((yyvsp[-2].symbol), (yyvsp[0].symbol), (yyloc));
     }
-#line 2553 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2557 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 81:
-#line 588 "src/parse-gram.y" /* yacc.c:1646  */
+#line 590 "src/parse-gram.y" /* yacc.c:1646  */
     {
       yyerrok;
     }
-#line 2561 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2565 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 82:
-#line 594 "src/parse-gram.y" /* yacc.c:1646  */
+#line 596 "src/parse-gram.y" /* yacc.c:1646  */
     { current_lhs ((yyvsp[-1].symbol), (yylsp[-1]), (yyvsp[0].named_ref)); }
-#line 2567 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2571 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 83:
-#line 595 "src/parse-gram.y" /* yacc.c:1646  */
+#line 597 "src/parse-gram.y" /* yacc.c:1646  */
     {
     /* Free the current lhs. */
     current_lhs (0, (yylsp[-3]), 0);
   }
-#line 2576 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2580 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 84:
-#line 602 "src/parse-gram.y" /* yacc.c:1646  */
+#line 604 "src/parse-gram.y" /* yacc.c:1646  */
     { grammar_current_rule_end ((yylsp[0])); }
-#line 2582 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2586 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 85:
-#line 603 "src/parse-gram.y" /* yacc.c:1646  */
+#line 605 "src/parse-gram.y" /* yacc.c:1646  */
     { grammar_current_rule_end ((yylsp[0])); }
-#line 2588 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2592 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 87:
-#line 610 "src/parse-gram.y" /* yacc.c:1646  */
+#line 612 "src/parse-gram.y" /* yacc.c:1646  */
     { grammar_current_rule_begin (current_lhs_symbol, current_lhs_location,
                                   current_lhs_named_ref); }
-#line 2595 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2599 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 88:
-#line 613 "src/parse-gram.y" /* yacc.c:1646  */
+#line 615 "src/parse-gram.y" /* yacc.c:1646  */
     { grammar_current_rule_symbol_append ((yyvsp[-1].symbol), (yylsp[-1]), (yyvsp[0].named_ref)); }
-#line 2601 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2605 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 89:
-#line 615 "src/parse-gram.y" /* yacc.c:1646  */
+#line 617 "src/parse-gram.y" /* yacc.c:1646  */
     { grammar_current_rule_action_append ((yyvsp[-1].code), (yylsp[-1]), (yyvsp[0].named_ref), false); }
-#line 2607 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2611 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 90:
-#line 617 "src/parse-gram.y" /* yacc.c:1646  */
+#line 619 "src/parse-gram.y" /* yacc.c:1646  */
     { grammar_current_rule_action_append ((yyvsp[0].code), (yylsp[0]), NULL, true); }
-#line 2613 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2617 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 91:
-#line 619 "src/parse-gram.y" /* yacc.c:1646  */
+#line 621 "src/parse-gram.y" /* yacc.c:1646  */
     { grammar_current_rule_empty_set ((yylsp[0])); }
-#line 2619 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2623 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 92:
-#line 621 "src/parse-gram.y" /* yacc.c:1646  */
+#line 623 "src/parse-gram.y" /* yacc.c:1646  */
     { grammar_current_rule_prec_set ((yyvsp[0].symbol), (yylsp[0])); }
-#line 2625 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2629 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 93:
-#line 623 "src/parse-gram.y" /* yacc.c:1646  */
+#line 625 "src/parse-gram.y" /* yacc.c:1646  */
     { grammar_current_rule_dprec_set ((yyvsp[0].integer), (yylsp[0])); }
-#line 2631 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2635 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 94:
-#line 625 "src/parse-gram.y" /* yacc.c:1646  */
+#line 627 "src/parse-gram.y" /* yacc.c:1646  */
     { grammar_current_rule_merge_set ((yyvsp[0].uniqstr), (yylsp[0])); }
-#line 2637 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2641 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 95:
-#line 629 "src/parse-gram.y" /* yacc.c:1646  */
+#line 631 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.named_ref) = 0; }
-#line 2643 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2647 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 96:
-#line 630 "src/parse-gram.y" /* yacc.c:1646  */
+#line 632 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.named_ref) = named_ref_new ((yyvsp[0].uniqstr), (yylsp[0])); }
-#line 2649 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2653 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 98:
-#line 641 "src/parse-gram.y" /* yacc.c:1646  */
+#line 643 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.uniqstr) = uniqstr_new ((yyvsp[0].code)); }
-#line 2655 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2659 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 99:
-#line 666 "src/parse-gram.y" /* yacc.c:1646  */
+#line 668 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.value).kind = muscle_keyword; (yyval.value).chars = ""; }
-#line 2661 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2665 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 100:
-#line 667 "src/parse-gram.y" /* yacc.c:1646  */
+#line 669 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.value).kind = muscle_keyword; (yyval.value).chars = (yyvsp[0].uniqstr); }
-#line 2667 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2671 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 101:
-#line 668 "src/parse-gram.y" /* yacc.c:1646  */
+#line 670 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.value).kind = muscle_string;  (yyval.value).chars = (yyvsp[0].code); }
-#line 2673 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2677 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 102:
-#line 669 "src/parse-gram.y" /* yacc.c:1646  */
+#line 671 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.value).kind = muscle_code;    (yyval.value).chars = strip_braces ((yyvsp[0].code)); }
-#line 2679 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2683 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 103:
-#line 682 "src/parse-gram.y" /* yacc.c:1646  */
+#line 684 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.symbol) = symbol_from_uniqstr ((yyvsp[0].uniqstr), (yylsp[0])); }
-#line 2685 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2689 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 104:
-#line 684 "src/parse-gram.y" /* yacc.c:1646  */
+#line 686 "src/parse-gram.y" /* yacc.c:1646  */
     {
       (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 2695 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2699 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 105:
-#line 692 "src/parse-gram.y" /* yacc.c:1646  */
+#line 694 "src/parse-gram.y" /* yacc.c:1646  */
     { (yyval.symbol) = symbol_from_uniqstr ((yyvsp[0].uniqstr), (yylsp[0])); }
-#line 2701 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2705 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 108:
-#line 704 "src/parse-gram.y" /* yacc.c:1646  */
+#line 706 "src/parse-gram.y" /* yacc.c:1646  */
     {
       (yyval.symbol) = symbol_get (quotearg_style (c_quoting_style, (yyvsp[0].code)), (yylsp[0]));
       symbol_class_set ((yyval.symbol), token_sym, (yylsp[0]), false);
     }
-#line 2710 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2714 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
   case 110:
-#line 713 "src/parse-gram.y" /* yacc.c:1646  */
+#line 715 "src/parse-gram.y" /* yacc.c:1646  */
     {
       muscle_code_grow ("epilogue", translate_code ((yyvsp[0].code), (yylsp[0]), true), (yylsp[0]));
       code_scanner_last_string_free ();
     }
-#line 2719 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2723 "src/parse-gram.c" /* yacc.c:1646  */
     break;
 
 
-#line 2723 "src/parse-gram.c" /* yacc.c:1646  */
+#line 2727 "src/parse-gram.c" /* yacc.c:1646  */
         default: break;
       }
     if (yychar_backup != yychar)
@@ -2966,7 +2970,7 @@ yyreturn:
 #endif
   return yyresult;
 }
-#line 719 "src/parse-gram.y" /* yacc.c:1906  */
+#line 721 "src/parse-gram.y" /* yacc.c:1906  */
 
 
 /* Return the location of the left-hand side of a rule whose
diff --git a/src/parse-gram.h b/src/parse-gram.h
index b2c6e59b..c40151da 100644
--- a/src/parse-gram.h
+++ b/src/parse-gram.h
@@ -61,7 +61,7 @@ extern int gram_debug;
     param_parse  = 1 << 1,
     param_both   = param_lex | param_parse
   } param_type;
-#line 645 "src/parse-gram.y" /* yacc.c:1909  */
+#line 647 "src/parse-gram.y" /* yacc.c:1909  */
 #include "muscle-tab.h"
 
 #line 68 "src/parse-gram.h" /* yacc.c:1909  */
@@ -132,7 +132,7 @@ extern int gram_debug;
 
 /* Value type.  */
 #if ! defined GRAM_STYPE && ! defined GRAM_STYPE_IS_DECLARED
-typedef union GRAM_STYPE GRAM_STYPE;
+
 union GRAM_STYPE
 {
 #line 182 "src/parse-gram.y" /* yacc.c:1909  */
@@ -155,7 +155,7 @@ named_ref *named_ref;
 param_type param;
 #line 409 "src/parse-gram.y" /* yacc.c:1909  */
 code_props_type code_type;
-#line 647 "src/parse-gram.y" /* yacc.c:1909  */
+#line 649 "src/parse-gram.y" /* yacc.c:1909  */
 
   struct
   {
@@ -165,6 +165,8 @@ code_props_type code_type;
 
 #line 167 "src/parse-gram.h" /* yacc.c:1909  */
 };
+
+typedef union GRAM_STYPE GRAM_STYPE;
 # define GRAM_STYPE_IS_TRIVIAL 1
 # define GRAM_STYPE_IS_DECLARED 1
 #endif
diff --git a/src/parse-gram.y b/src/parse-gram.y
index 39431ef7..9184d5f8 100644
--- a/src/parse-gram.y
+++ b/src/parse-gram.y
@@ -421,7 +421,9 @@ code_props_type:
 
 union_name:
   %empty {}
-| ID     { muscle_code_grow ("union_name", $1, @1); }
+| ID     { muscle_percent_define_insert ("api.value.union.name",
+                                         @1, muscle_keyword, $1,
+                                         MUSCLE_PERCENT_DEFINE_GRAMMAR_FILE); }
 ;
 
 grammar_declaration:
diff --git a/tests/input.at b/tests/input.at
index 9e9296aa..895ec202 100644
--- a/tests/input.at
+++ b/tests/input.at
@@ -1904,6 +1904,51 @@ m4_popdef([AT_TEST])
 AT_CLEANUP
 
 
+## ----------------------- ##
+## Redefined %union name.  ##
+## ----------------------- ##
+
+AT_SETUP([[Redefined %union name]])
+
+# AT_TEST(DIRECTIVES, ERROR)
+# --------------------------
+m4_pushdef([AT_TEST],
+[AT_DATA([[input.y]],
+[$1
+%%
+exp: %empty;
+])
+
+AT_BISON_CHECK([[input.y]], [[1]], [[]],
+[$2])
+])
+
+AT_TEST([[%union foo {};
+%union {};
+%union foo {};
+%define api.value.union.name foo]],
+[[input.y:3.8-10: error: %define variable 'api.value.union.name' redefined
+input.y:1.8-10:     previous definition
+input.y:4.9-28: error: %define variable 'api.value.union.name' redefined
+input.y:3.8-10:     previous definition
+]])
+
+AT_TEST([[%define api.value.union.name {foo}]],
+[[input.y:1.9-28: error: %define variable 'api.value.union.name' requires keyword values
+input.y:1.9-28: error: %define variable 'api.value.union.name' is not used
+]])
+
+AT_TEST([[%define api.value.union.name "foo"]],
+[[input.y:1.9-28: error: %define variable 'api.value.union.name' requires keyword values
+input.y:1.9-28: error: %define variable 'api.value.union.name' is not used
+]])
+
+m4_popdef([AT_TEST])
+AT_CLEANUP
+
+
+
+
 ## -------------- ##
 ## Stray $ or @.  ##
 ## -------------- ##
diff --git a/tests/synclines.at b/tests/synclines.at
index de132f43..260e2f9e 100644
--- a/tests/synclines.at
+++ b/tests/synclines.at
@@ -182,6 +182,35 @@ exp: '0';
 ])
 
 
+## ---------------------- ##
+## %union name syncline.  ##
+## ---------------------- ##
+
+# Check that invalid union names are properly reported in the
+# source file.
+AT_SETUP([%union name syncline])
+AT_BISON_OPTION_PUSHDEFS
+AT_DATA([[input.y]],
+[[%union break
+{
+  char dummy;
+}
+%{
+]AT_YYERROR_DECLARE_EXTERN[
+]AT_YYLEX_DECLARE_EXTERN[
+%}
+%%
+exp: '0';
+%%
+]])
+
+AT_BISON_CHECK([-o input.c input.y])
+AT_SYNCLINES_COMPILE([input.c])
+AT_CHECK([[grep '^input.y:1' stdout]], 0, [ignore])
+AT_BISON_OPTION_POPDEFS
+AT_CLEANUP
+
+
 ## ----------------------- ##
 ## Postprologue syncline.  ##
 ## ----------------------- ##
diff --git a/tests/types.at b/tests/types.at
index d735d83f..0c108d9d 100644
--- a/tests/types.at
+++ b/tests/types.at
@@ -197,18 +197,23 @@ m4_foreach([b4_skel], [[yacc.c], [glr.c], [lalr1.cc], [glr.cc]],
              AT_VAL.fval = .2f],
           [10 0.2])
 
-  # A %union.
-  AT_TEST([%skeleton "]b4_skel["
-           %union { float fval; int ival; };],
-          [%token <ival> '1';
-           %token <fval> '2';],
-          ['1' '2' { printf ("%d %2.1f\n", $1, $2); }],
-          ["12"],
-          [if (res == '1')
-             AT_VAL.ival = 10;
-           else
-             AT_VAL.fval = 0.2f],
-          [10 0.2])
+  # A %union and a named %union.  In C++ named %union is an error.
+  m4_foreach([b4_union],
+             [m4_bmatch(b4_skel, [\.cc$],
+                       [[%union]],
+                        [[%union], [%union foo],
+                         [%define api.value.union.name foo; %union]])],
+   [AT_TEST([%skeleton "]b4_skel["
+             ]b4_union[ { float fval; int ival; };],
+            [%token <ival> '1';
+             %token <fval> '2';],
+            ['1' '2' { printf ("%d %2.1f\n", $1, $2); }],
+            ["12"],
+            [if (res == '1')
+               AT_VAL.ival = 10;
+             else
+               AT_VAL.fval = 0.2f],
+            [10 0.2])])
 
   # A Bison-defined union.
   # The tokens names are not available directly in C++, we use their
@@ -249,3 +254,22 @@ m4_foreach([b4_skel], [[yacc.c], [glr.c], [lalr1.cc], [glr.cc]],
 
 m4_popdef([AT_TEST])
 m4_popdef([_AT_TEST])
+
+
+## ------------------- ##
+## C++: Named %union.  ##
+## ------------------- ##
+
+m4_foreach([b4_skel], [[lalr1.cc], [glr.cc]],
+[AT_SETUP([b4_skel: Named %union])
+AT_DATA([input.y],
+[%skeleton "]b4_skel["
+%union foo { float fval; int ival; };
+%%
+exp: %empty;
+])
+AT_BISON_CHECK([input.y], 1, [],
+[[input.y:2.8-10: error: named %union is invalid in C++
+]])
+AT_CLEANUP
+])
-- 
2.45.2