X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/d6a44ffd0021ab0ca23e5e6243ecacb4e4b17ef1..ae7cd18c98d9bad7e95d4f4070d2d09e8db675f8:/data/c.m4

diff --git a/data/c.m4 b/data/c.m4
index 12794e06..b1b43948 100644
--- a/data/c.m4
+++ b/data/c.m4
@@ -2,7 +2,7 @@
 
 # C M4 Macros for Bison.
 
-# Copyright (C) 2002, 2004-2012 Free Software Foundation, Inc.
+# Copyright (C) 2002, 2004-2013 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -17,6 +17,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+m4_include(b4_pkgdatadir/[c-like.m4])
 
 # b4_tocpp(STRING)
 # ----------------
@@ -29,31 +30,27 @@ m4_define([b4_tocpp],
 # ------------------
 # A valid C macro name to use as a CPP header guard for FILE.
 m4_define([b4_cpp_guard],
-[b4_tocpp(m4_defn([b4_prefix])/[$1])])
+[[YY_]b4_tocpp(m4_defn([b4_prefix])/[$1])[_INCLUDED]])
 
 
 # b4_cpp_guard_open(FILE)
 # b4_cpp_guard_close(FILE)
 # ------------------------
-# Open/close CPP inclusion guards for FILE.
+# If FILE does not expand to nothing, open/close CPP inclusion guards for FILE.
 m4_define([b4_cpp_guard_open],
+[m4_ifval(m4_quote($1),
 [#ifndef b4_cpp_guard([$1])
-# define b4_cpp_guard([$1])])
+# define b4_cpp_guard([$1])])])
 
 m4_define([b4_cpp_guard_close],
-[#endif b4_comment([!b4_cpp_guard([$1])])])
+[m4_ifval(m4_quote($1),
+[#endif b4_comment([!b4_cpp_guard([$1])])])])
 
 
 ## ---------------- ##
 ## Identification.  ##
 ## ---------------- ##
 
-# b4_comment(TEXT)
-# ----------------
-m4_define([b4_comment], [/* m4_bpatsubst([$1], [
-], [
-   ])  */])
-
 # b4_identification
 # -----------------
 # Depends on individual skeletons to define b4_pure_flag, b4_push_flag, or
@@ -107,10 +104,27 @@ m4_define_default([b4_union_name], [b4_api_PREFIX[]STYPE])
 ## Pure/impure interfaces.  ##
 ## ------------------------ ##
 
+# b4_lex_formals
+# --------------
+# All the yylex formal arguments.
+# b4_lex_param arrives quoted twice, but we want to keep only one level.
+m4_define([b4_lex_formals],
+[b4_pure_if([[[[YYSTYPE *yylvalp]], [[&yylval]]][]dnl
+b4_locations_if([, [[YYLTYPE *yyllocp], [&yylloc]]])])dnl
+m4_ifdef([b4_lex_param], [, ]b4_lex_param)])
+
+
+# b4_lex
+# ------
+# Call yylex.
+m4_define([b4_lex],
+[b4_function_call([yylex], [int], b4_lex_formals)])
+
+
 # b4_user_args
 # ------------
 m4_define([b4_user_args],
-[m4_ifset([b4_parse_param], [, b4_c_args(b4_parse_param)])])
+[m4_ifset([b4_parse_param], [, b4_args(b4_parse_param)])])
 
 
 # b4_parse_param
@@ -134,11 +148,13 @@ m4_popdef([$2])dnl
 m4_popdef([$1])dnl
 ])])
 
-# b4_parse_param_use
-# ------------------
-# `YYUSE' all the parse-params.
+# b4_parse_param_use([VAL], [LOC])
+# --------------------------------
+# 'YYUSE' VAL, LOC if locations are enabled, and all the parse-params.
 m4_define([b4_parse_param_use],
-[b4_parse_param_for([Decl], [Formal], [  YYUSE (Formal);
+[m4_ifvaln([$1], [  YYUSE ([$1]);])dnl
+b4_locations_if([m4_ifvaln([$2], [  YYUSE ([$2]);])])dnl
+b4_parse_param_for([Decl], [Formal], [  YYUSE (Formal);
 ])dnl
 ])
 
@@ -160,13 +176,13 @@ m4_define([b4_int_type],
 
        m4_eval([0 <= $1]),                [1], [unsigned int],
 
-					       [int])])
+                                               [int])])
 
 
 # b4_int_type_for(NAME)
 # ---------------------
 # Return the smallest int type able to handle numbers ranging from
-# `NAME_min' to `NAME_max' (included).
+# 'NAME_min' to 'NAME_max' (included).
 m4_define([b4_int_type_for],
 [b4_int_type($1_min, $1_max)])
 
@@ -175,13 +191,56 @@ m4_define([b4_int_type_for],
 # --------------------------------------------
 # Without inducing a comparison warning from the compiler, check if the
 # literal value LITERAL equals VALUE from table TABLE, which must have
-# TABLE_min and TABLE_max defined.  YYID must be defined as an identity
-# function that suppresses warnings about constant conditions.
+# TABLE_min and TABLE_max defined.
 m4_define([b4_table_value_equals],
 [m4_if(m4_eval($3 < m4_indir([b4_]$1[_min])
                || m4_indir([b4_]$1[_max]) < $3), [1],
-       [[YYID (0)]],
-       [[((]$2[) == (]$3[))]])])
+       [[0]],
+       [(!!(($2) == ($3)))])])
+
+
+## ----------------- ##
+## Compiler issues.  ##
+## ----------------- ##
+
+# b4_attribute_define
+# -------------------
+# Provide portability for __attribute__.
+m4_define([b4_attribute_define],
+[#ifndef __attribute__
+/* This feature is available in gcc versions 2.5 and later.  */
+# if (! defined __GNUC__ || __GNUC__ < 2 \
+      || (__GNUC__ == 2 && __GNUC_MINOR__ < 5))
+#  define __attribute__(Spec) /* empty */
+# endif
+#endif
+
+/* Suppress unused-variable warnings by "using" E.  */
+#if ! defined lint || defined __GNUC__
+# define YYUSE(E) ((void) (E))
+#else
+# define YYUSE(E) /* empty */
+#endif
+
+#if defined __GNUC__ && 407 <= __GNUC__ * 100 + __GNUC_MINOR__
+/* Suppress an incorrect diagnostic about yylval being uninitialized.  */
+# define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN \
+    _Pragma ("GCC diagnostic push") \
+    _Pragma ("GCC diagnostic ignored \"-Wuninitialized\"")\
+    _Pragma ("GCC diagnostic ignored \"-Wmaybe-uninitialized\"")
+# define YY_IGNORE_MAYBE_UNINITIALIZED_END \
+    _Pragma ("GCC diagnostic pop")
+#else
+# define YY_INITIAL_VALUE(Value) Value
+#endif
+#ifndef YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+# define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+# define YY_IGNORE_MAYBE_UNINITIALIZED_END
+#endif
+#ifndef YY_INITIAL_VALUE
+# define YY_INITIAL_VALUE(Value) /* Nothing. */
+#endif
+])
 
 
 ## ---------##
@@ -209,166 +268,123 @@ m4_define([b4_null_define],
 # Return a null pointer constant.
 m4_define([b4_null], [YY_NULL])
 
+# b4_integral_parser_table_define(TABLE-NAME, CONTENT, COMMENT)
+# -------------------------------------------------------------
+# Define "yy<TABLE-NAME>" whose contents is CONTENT.
+m4_define([b4_integral_parser_table_define],
+[m4_ifvaln([$3], [b4_comment([$3], [  ])])dnl
+static const b4_int_type_for([$2]) yy$1[[]] =
+{
+  $2
+};dnl
+])
 
 
 ## ------------------------- ##
 ## Assigning token numbers.  ##
 ## ------------------------- ##
 
-# b4_token_define(TOKEN-NAME, TOKEN-NUMBER)
-# -----------------------------------------
+# b4_token_define(TOKEN-NUM)
+# --------------------------
 # Output the definition of this token as #define.
 m4_define([b4_token_define],
-[#define $1 $2
-])
-
+[b4_token_format([#define %s %s], [$1])])
 
-# b4_token_defines(LIST-OF-PAIRS-TOKEN-NAME-TOKEN-NUMBER)
-# -------------------------------------------------------
-# Output the definition of the tokens (if there are) as #defines.
+# b4_token_defines
+# ----------------
+# Output the definition of the tokens.
 m4_define([b4_token_defines],
-[m4_if([$#$1], [1], [],
-[/* Tokens.  */
-m4_map([b4_token_define], [$@])])
-])
+[b4_any_token_visible_if([/* Tokens.  */
+m4_join([
+], b4_symbol_map([b4_token_define]))
+])])
 
 
-# b4_token_enum(TOKEN-NAME, TOKEN-NUMBER)
-# ---------------------------------------
+# b4_token_enum(TOKEN-NUM)
+# ------------------------
 # Output the definition of this token as an enum.
 m4_define([b4_token_enum],
-[$1 = $2])
+[b4_token_format([%s = %s], [$1])])
 
 
-# b4_token_enums(LIST-OF-PAIRS-TOKEN-NAME-TOKEN-NUMBER)
-# -----------------------------------------------------
+# b4_token_enums
+# --------------
 # Output the definition of the tokens (if there are) as enums.
 m4_define([b4_token_enums],
-[m4_if([$#$1], [1], [],
-[[/* Tokens.  */
+[b4_any_token_visible_if([[/* Token type.  */
 #ifndef ]b4_api_PREFIX[TOKENTYPE
 # define ]b4_api_PREFIX[TOKENTYPE
-   /* Put the tokens into the symbol table, so that GDB and other debuggers
-      know about them.  */
-   enum ]b4_api_prefix[tokentype {
-]m4_map_sep([     b4_token_enum], [,
-],
-	   [$@])[
-   };
+  enum ]b4_api_prefix[tokentype
+  {
+    ]m4_join([,
+    ],
+             b4_symbol_map([b4_token_enum]))[
+  };
 #endif
 ]])])
 
 
-# b4_token_enums_defines(LIST-OF-PAIRS-TOKEN-NAME-TOKEN-NUMBER)
-# -------------------------------------------------------------
-# Output the definition of the tokens (if there are any) as enums and, if POSIX
-# Yacc is enabled, as #defines.
+# b4_token_enums_defines
+# ----------------------
+# Output the definition of the tokens (if there are any) as enums and,
+# if POSIX Yacc is enabled, as #defines.
 m4_define([b4_token_enums_defines],
-[b4_token_enums($@)b4_yacc_if([b4_token_defines($@)], [])
-])
+[b4_token_enums[]b4_yacc_if([b4_token_defines])])
 
 
+## ----------------- ##
+## Semantic Values.  ##
+## ----------------- ##
 
-## --------------------------------------------- ##
-## Defining C functions in both K&R and ANSI-C.  ##
-## --------------------------------------------- ##
 
+# b4_symbol_value(VAL, [TYPE])
+# ----------------------------
+# Given a semantic value VAL ($$, $1 etc.), extract its value of type
+# TYPE if TYPE is given, otherwise just return VAL.  The result can be
+# used safetly, it is put in parens to avoid nasty precedence issues.
+# TYPE is *not* put in braces, provide some if needed.
+m4_define([b4_symbol_value],
+[($1[]m4_ifval([$2], [.$2]))])
 
-# b4_modern_c
-# -----------
-# A predicate useful in #if to determine whether C is ancient or modern.
-#
-# If __STDC__ is defined, the compiler is modern.  IBM xlc 7.0 when run
-# as 'cc' doesn't define __STDC__ (or __STDC_VERSION__) for pedantic
-# reasons, but it defines __C99__FUNC__ so check that as well.
-# Microsoft C normally doesn't define these macros, but it defines _MSC_VER.
-# Consider a C++ compiler to be modern if it defines __cplusplus.
-#
-m4_define([b4_c_modern],
-  [[(defined __STDC__ || defined __C99__FUNC__ \
-     || defined __cplusplus || defined _MSC_VER)]])
 
-# b4_c_function_def(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
-# ----------------------------------------------------------
-# Declare the function NAME.
-m4_define([b4_c_function_def],
-[#if b4_c_modern
-b4_c_ansi_function_def($@)
-#else
-$2
-$1 (b4_c_knr_formal_names(m4_shift2($@)))
-b4_c_knr_formal_decls(m4_shift2($@))
-#endif[]dnl
-])
+
+## ---------------------- ##
+## Defining C functions.  ##
+## ---------------------- ##
 
 
-# b4_c_ansi_function_def(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
-# ---------------------------------------------------------------
-# Declare the function NAME in ANSI.
-m4_define([b4_c_ansi_function_def],
+# b4_function_define(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
+# -----------------------------------------------------------
+# Declare the function NAME in C.
+m4_define([b4_function_define],
 [$2
-$1 (b4_c_ansi_formals(m4_shift2($@)))[]dnl
+$1 (b4_formals(m4_shift2($@)))[]dnl
 ])
 
 
-# b4_c_ansi_formals([DECL1, NAME1], ...)
-# --------------------------------------
-# Output the arguments ANSI-C definition.
-m4_define([b4_c_ansi_formals],
+# b4_formals([DECL1, NAME1], ...)
+# -------------------------------
+# The formal arguments of a C function definition.
+m4_define([b4_formals],
 [m4_if([$#], [0], [void],
        [$#$1], [1], [void],
-	       [m4_map_sep([b4_c_ansi_formal], [, ], [$@])])])
+               [m4_map_sep([b4_formal], [, ], [$@])])])
 
-m4_define([b4_c_ansi_formal],
+m4_define([b4_formal],
 [$1])
 
 
-# b4_c_knr_formal_names([DECL1, NAME1], ...)
-# ------------------------------------------
-# Output the argument names.
-m4_define([b4_c_knr_formal_names],
-[m4_map_sep([b4_c_knr_formal_name], [, ], [$@])])
-
-m4_define([b4_c_knr_formal_name],
-[$2])
 
+## ----------------------- ##
+## Declaring C functions.  ##
+## ----------------------- ##
 
-# b4_c_knr_formal_decls([DECL1, NAME1], ...)
-# ------------------------------------------
-# Output the K&R argument declarations.
-m4_define([b4_c_knr_formal_decls],
-[m4_map_sep([b4_c_knr_formal_decl],
-	    [
-],
-	    [$@])])
 
-m4_define([b4_c_knr_formal_decl],
-[    $1;])
-
-
-
-## ------------------------------------------------------------ ##
-## Declaring (prototyping) C functions in both K&R and ANSI-C.  ##
-## ------------------------------------------------------------ ##
-
-
-# b4_c_function_decl(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
-# -----------------------------------------------------------
+# b4_function_declare(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
+# ------------------------------------------------------------
 # Declare the function NAME.
-m4_define([b4_c_function_decl],
-[#if defined __STDC__ || defined __cplusplus
-b4_c_ansi_function_decl($@)
-#else
-$2 $1 ();
-#endif[]dnl
-])
-
-
-# b4_c_ansi_function_decl(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
-# ----------------------------------------------------------------
-# Declare the function NAME.
-m4_define([b4_c_ansi_function_decl],
-[$2 $1 (b4_c_ansi_formals(m4_shift2($@)));[]dnl
+m4_define([b4_function_declare],
+[$2 $1 (b4_formals(m4_shift2($@)));[]dnl
 ])
 
 
@@ -379,21 +395,21 @@ m4_define([b4_c_ansi_function_decl],
 ## --------------------- ##
 
 
-# b4_c_function_call(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
+# b4_function_call(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
 # -----------------------------------------------------------
 # Call the function NAME with arguments NAME1, NAME2 etc.
-m4_define([b4_c_function_call],
-[$1 (b4_c_args(m4_shift2($@)))[]dnl
+m4_define([b4_function_call],
+[$1 (b4_args(m4_shift2($@)))[]dnl
 ])
 
 
-# b4_c_args([DECL1, NAME1], ...)
-# ------------------------------
+# b4_args([DECL1, NAME1], ...)
+# ----------------------------
 # Output the arguments NAME1, NAME2...
-m4_define([b4_c_args],
-[m4_map_sep([b4_c_arg], [, ], [$@])])
+m4_define([b4_args],
+[m4_map_sep([b4_arg], [, ], [$@])])
 
-m4_define([b4_c_arg],
+m4_define([b4_arg],
 [$2])
 
 
@@ -402,7 +418,7 @@ m4_define([b4_c_arg],
 ## ----------- ##
 
 # b4_sync_start(LINE, FILE)
-# -----------------------
+# -------------------------
 m4_define([b4_sync_start], [[#]line $1 $2])
 
 
@@ -415,65 +431,28 @@ m4_define([b4_sync_start], [[#]line $1 $2])
 m4_define([b4_case],
 [  case $1:
 $2
+b4_syncline([@oline@], [@ofile@])
     break;])
 
-# b4_dollar_dollar_(NAME, FIELD, DEFAULT-FIELD)
-# ---------------------------------------------
-# If FIELD (or DEFAULT-FIELD) is non-null, read it in pointer NAME,
-# otherwise just dereference.
-m4_define([b4_dollar_dollar_],
-[m4_if([$2], [[]],
-       [m4_ifval([$3], [($1->$3)],
-                 [(*$1)])],
-       [($1->$2)])])
-
-# b4_dollar_pushdef(VALUE, DEFAULT-FIELD, LOCATION)
-# b4_dollar_popdef
-# -------------------------------------------------
-# Define b4_dollar_dollar for VALUE and DEFAULT-FIELD,
-# and b4_at_dollar for LOCATION.
-m4_define([b4_dollar_pushdef],
-[m4_pushdef([b4_dollar_dollar],
-   [b4_dollar_dollar_([$1], m4_dquote($][1), [$2])])dnl
-m4_pushdef([b4_at_dollar], [(*yylocationp)])dnl
-])
-m4_define([b4_dollar_popdef],
-[m4_popdef([b4_at_dollar])dnl
-m4_popdef([b4_dollar_dollar])dnl
-])
 
-
-# b4_symbol_actions(FILENAME, LINENO,
-#                   SYMBOL-TAG, SYMBOL-NUM,
-#                   SYMBOL-ACTION, SYMBOL-TYPENAME)
-# -------------------------------------------------
-# Issue the code for a symbol action (e.g., %printer).
-#
-# Define b4_dollar_dollar([TYPE-NAME]), and b4_at_dollar, which are
-# invoked where $<TYPE-NAME>$ and @$ were specified by the user.
-m4_define([b4_symbol_actions],
-[b4_dollar_pushdef([yyvaluep], [$6], [(*yylocationp)])dnl
-      case $4: /* $3 */
-b4_syncline([$2], [$1])
-	$5;
+# b4_predicate_case(LABEL, CONDITIONS)
+# ------------------------------------
+m4_define([b4_predicate_case],
+[  case $1:
+    if (! ($2)) YYERROR;
 b4_syncline([@oline@], [@ofile@])
-	break;
-b4_dollar_popdef[]dnl
-])
+    break;])
 
 
-# b4_yydestruct_generate(FUNCTION-DECLARATOR)
-# -------------------------------------------
-# Generate the "yydestruct" function, which declaration is issued using
-# FUNCTION-DECLARATOR, which may be "b4_c_ansi_function_def" for ISO C
-# or "b4_c_function_def" for K&R.
-m4_define_default([b4_yydestruct_generate],
+# b4_yydestruct_define
+# --------------------
+# Define the "yydestruct" function.
+m4_define_default([b4_yydestruct_define],
 [[/*-----------------------------------------------.
 | Release the memory associated to this symbol.  |
 `-----------------------------------------------*/
 
-/*ARGSUSED*/
-]$1([yydestruct],
+]b4_function_define([yydestruct],
     [static void],
     [[const char *yymsg],    [yymsg]],
     [[int yytype],           [yytype]],
@@ -481,64 +460,47 @@ m4_define_default([b4_yydestruct_generate],
 b4_locations_if(            [, [[YYLTYPE *yylocationp], [yylocationp]]])[]dnl
 m4_ifset([b4_parse_param], [, b4_parse_param]))[
 {
-  YYUSE (yyvaluep);
-]b4_locations_if([  YYUSE (yylocationp);
-])dnl
-b4_parse_param_use[]dnl
-[
-  if (!yymsg)
+]b4_parse_param_use([yyvaluep], [yylocationp])dnl
+[  if (!yymsg)
     yymsg = "Deleting";
   YY_SYMBOL_PRINT (yymsg, yytype, yyvaluep, yylocationp);
 
-  switch (yytype)
-    {
-]m4_map([b4_symbol_actions], m4_defn([b4_symbol_destructors]))[
-      default:
-	break;
-    }
+  YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+  ]b4_symbol_actions([destructor])[
+  YY_IGNORE_MAYBE_UNINITIALIZED_END
 }]dnl
 ])
 
 
-# b4_yy_symbol_print_generate(FUNCTION-DECLARATOR)
-# ------------------------------------------------
-# Generate the "yy_symbol_print" function, which declaration is issued using
-# FUNCTION-DECLARATOR, which may be "b4_c_ansi_function_def" for ISO C
-# or "b4_c_function_def" for K&R.
-m4_define_default([b4_yy_symbol_print_generate],
+# b4_yy_symbol_print_define
+# -------------------------
+# Define the "yy_symbol_print" function.
+m4_define_default([b4_yy_symbol_print_define],
 [[
-/*--------------------------------.
-| Print this symbol on YYOUTPUT.  |
-`--------------------------------*/
+/*----------------------------------------.
+| Print this symbol's value on YYOUTPUT.  |
+`----------------------------------------*/
 
-/*ARGSUSED*/
-]$1([yy_symbol_value_print],
+]b4_function_define([yy_symbol_value_print],
     [static void],
-	       [[FILE *yyoutput],                       [yyoutput]],
-	       [[int yytype],                           [yytype]],
-	       [[YYSTYPE const * const yyvaluep],       [yyvaluep]][]dnl
+               [[FILE *yyoutput],                       [yyoutput]],
+               [[int yytype],                           [yytype]],
+               [[YYSTYPE const * const yyvaluep],       [yyvaluep]][]dnl
 b4_locations_if([, [[YYLTYPE const * const yylocationp], [yylocationp]]])[]dnl
 m4_ifset([b4_parse_param], [, b4_parse_param]))[
 {
   FILE *yyo = yyoutput;
-  YYUSE (yyo);
-  if (!yyvaluep)
-    return;
-]b4_locations_if([  YYUSE (yylocationp);
-])dnl
-b4_parse_param_use[]dnl
-[# ifdef YYPRINT
+]b4_parse_param_use([yyo], [yylocationp])dnl
+[  if (!yyvaluep)
+    return;]
+dnl glr.c does not feature yytoknum.
+m4_if(b4_skeleton, ["yacc.c"],
+[[# ifdef YYPRINT
   if (yytype < YYNTOKENS)
     YYPRINT (yyoutput, yytoknum[yytype], *yyvaluep);
-# else
-  YYUSE (yyoutput);
 # endif
-  switch (yytype)
-    {
-]m4_map([b4_symbol_actions], m4_defn([b4_symbol_printers]))dnl
-[      default:
-	break;
-    }
+]])dnl
+  b4_symbol_actions([printer])[
 }
 
 
@@ -546,18 +508,16 @@ b4_parse_param_use[]dnl
 | Print this symbol on YYOUTPUT.  |
 `--------------------------------*/
 
-]$1([yy_symbol_print],
+]b4_function_define([yy_symbol_print],
     [static void],
-	       [[FILE *yyoutput],                       [yyoutput]],
-	       [[int yytype],                           [yytype]],
-	       [[YYSTYPE const * const yyvaluep],       [yyvaluep]][]dnl
+               [[FILE *yyoutput],                       [yyoutput]],
+               [[int yytype],                           [yytype]],
+               [[YYSTYPE const * const yyvaluep],       [yyvaluep]][]dnl
 b4_locations_if([, [[YYLTYPE const * const yylocationp], [yylocationp]]])[]dnl
 m4_ifset([b4_parse_param], [, b4_parse_param]))[
 {
-  if (yytype < YYNTOKENS)
-    YYFPRINTF (yyoutput, "token %s (", yytname[yytype]);
-  else
-    YYFPRINTF (yyoutput, "nterm %s (", yytname[yytype]);
+  YYFPRINTF (yyoutput, "%s %s (",
+             yytype < YYNTOKENS ? "token" : "nterm", yytname[yytype]);
 
 ]b4_locations_if([  YY_LOCATION_PRINT (yyoutput, *yylocationp);
   YYFPRINTF (yyoutput, ": ");
@@ -568,64 +528,206 @@ b4_locations_if([, yylocationp])[]b4_user_args[);
 }]dnl
 ])
 
+
+## ---------------- ##
+## api.value.type.  ##
+## ---------------- ##
+
+
+# ---------------------- #
+# api.value.type=union.  #
+# ---------------------- #
+
+# b4_symbol_type_register(SYMBOL-NUM)
+# -----------------------------------
+# Symbol SYMBOL-NUM has a type (for variant) instead of a type-tag.
+# Extend the definition of %union's body with a field of that type,
+# and extend the symbol's "type" field to point to the field name,
+# instead of the type name.
+m4_define([b4_symbol_type_register],
+[m4_define([b4_symbol($1, type_tag)],
+           [b4_symbol_if([$1], [has_id],
+                         [b4_symbol([$1], [id])],
+                         [yytype_[]b4_symbol([$1], [number])])])dnl
+m4_append([b4_user_union_members],
+m4_expand([
+  b4_symbol_tag_comment([$1])dnl
+  b4_symbol([$1], [type]) b4_symbol([$1], [type_tag]);]))
+])
+
+
+# b4_type_define_tag(SYMBOL1-NUM, ...)
+# ------------------------------------
+# For the batch of symbols SYMBOL1-NUM... (which all have the same
+# type), enhance the %union definition for each of them, and set
+# there "type" field to the field tag name, instead of the type name.
+m4_define([b4_type_define_tag],
+[b4_symbol_if([$1], [has_type],
+              [m4_map([b4_symbol_type_register], [$@])])
+])
+
+
+# b4_symbol_value_union(VAL, [TYPE])
+# ----------------------------------
+# Same of b4_symbol_value, but when api.value.type=union.
+m4_define([b4_symbol_value_union],
+[m4_ifval([$2],
+          [(*($2*)(&$1))],
+          [$1])])
+])
+
+
+# b4_value_type_setup_union
+# -------------------------
+# Setup support for api.value.type=union.  Symbols are defined with a
+# type instead of a union member name: build the corresponding union,
+# and give the symbols their tag.
+m4_define([b4_value_type_setup_union],
+[m4_define([b4_union_members])
+b4_type_foreach([b4_type_define_tag])
+m4_copy_force([b4_symbol_value_union], [b4_symbol_value])
+])
+
+
+# ---------------- #
+# api.value.type.  #
+# ---------------- #
+
+
+# b4_value_type_setup_variant
+# ---------------------------
+# Setup support for api.value.type=variant.  By default, fail, specialized
+# by other skeletons.
+m4_define([b4_value_type_setup_variant],
+[b4_complain_at(b4_percent_define_get_loc([[api.value.type]]),
+                [['%s' does not support '%s']],
+                [b4_skeleton],
+                [%define api.value.type variant])])
+
+
+# _b4_value_type_setup_keyword
+# ----------------------------
+# api.value.type is defined with a keyword/string syntax.  Check if
+# that is properly defined, and prepare its use.
+m4_define([_b4_value_type_setup_keyword],
+[b4_percent_define_check_values([[[[api.value.type]],
+                                  [[none]],
+                                  [[union]],
+                                  [[union-directive]],
+                                  [[variant]],
+                                  [[yystype]]]])dnl
+m4_case(b4_percent_define_get([[api.value.type]]),
+        [union],   [b4_value_type_setup_union],
+        [variant], [b4_value_type_setup_variant])])
+
+
+# b4_value_type_setup
+# -------------------
+# Check if api.value.type is properly defined, and possibly prepare
+# its use.
+b4_define_silent([b4_value_type_setup],
+[# Define default value.
+b4_percent_define_ifdef([[api.value.type]], [],
+[# %union => api.value.type=union-directive
+m4_ifdef([b4_union_members],
+[m4_define([b4_percent_define_kind(api.value.type)], [keyword])
+m4_define([b4_percent_define(api.value.type)], [union-directive])],
+[# no tag seen => api.value.type={int}
+m4_if(b4_tag_seen_flag, 0,
+[m4_define([b4_percent_define_kind(api.value.type)], [code])
+m4_define([b4_percent_define(api.value.type)], [int])],
+[# otherwise api.value.type=yystype
+m4_define([b4_percent_define_kind(api.value.type)], [keyword])
+m4_define([b4_percent_define(api.value.type)], [yystype])])])])
+
+# Set up.
+m4_bmatch(b4_percent_define_get_kind([[api.value.type]]),
+   [keyword\|string], [_b4_value_type_setup_keyword])
+])
+
+
 ## -------------- ##
 ## Declarations.  ##
 ## -------------- ##
 
-# b4_declare_yylstype
-# -------------------
-# Declarations that might either go into the header (if --defines) or
-# in the parser body.  Declare YYSTYPE/YYLTYPE, and yylval/yylloc.
-m4_define([b4_declare_yylstype],
+
+# b4_value_type_define
+# --------------------
+m4_define([b4_value_type_define],
+[b4_value_type_setup[]dnl
+/* Value type.  */
+m4_bmatch(b4_percent_define_get_kind([[api.value.type]]),
+[code],
 [[#if ! defined ]b4_api_PREFIX[STYPE && ! defined ]b4_api_PREFIX[STYPE_IS_DECLARED
-]m4_ifdef([b4_stype],
-[[typedef union ]b4_union_name[
+typedef ]b4_percent_define_get([[api.value.type]])[ ]b4_api_PREFIX[STYPE;
+# define ]b4_api_PREFIX[STYPE_IS_TRIVIAL 1
+# define ]b4_api_PREFIX[STYPE_IS_DECLARED 1
+#endif
+]],
+[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_user_stype[
-} ]b4_api_PREFIX[STYPE;
-# define ]b4_api_PREFIX[STYPE_IS_TRIVIAL 1]],
-[m4_if(b4_tag_seen_flag, 0,
-[[typedef int ]b4_api_PREFIX[STYPE;
-# define ]b4_api_PREFIX[STYPE_IS_TRIVIAL 1]])])[
-# define ]b4_api_prefix[stype ]b4_api_PREFIX[STYPE /* obsolescent; will be withdrawn */
+]b4_user_union_members[
+};
+# define ]b4_api_PREFIX[STYPE_IS_TRIVIAL 1
 # define ]b4_api_PREFIX[STYPE_IS_DECLARED 1
-#endif]b4_locations_if([[
+#endif
+]])])])
+
 
+# b4_location_type_define
+# -----------------------
+m4_define([b4_location_type_define],
+[[/* Location type.  */
 #if ! defined ]b4_api_PREFIX[LTYPE && ! defined ]b4_api_PREFIX[LTYPE_IS_DECLARED
-typedef struct ]b4_api_PREFIX[LTYPE
+typedef struct ]b4_api_PREFIX[LTYPE ]b4_api_PREFIX[LTYPE;
+struct ]b4_api_PREFIX[LTYPE
 {
   int first_line;
   int first_column;
   int last_line;
   int last_column;
-} ]b4_api_PREFIX[LTYPE;
-# define ]b4_api_prefix[ltype ]b4_api_PREFIX[LTYPE /* obsolescent; will be withdrawn */
+};
 # define ]b4_api_PREFIX[LTYPE_IS_DECLARED 1
 # define ]b4_api_PREFIX[LTYPE_IS_TRIVIAL 1
-#endif]])
+#endif
+]])
+
+
+# b4_declare_yylstype
+# -------------------
+# Declarations that might either go into the header (if --defines) or
+# in the parser body.  Declare YYSTYPE/YYLTYPE, and yylval/yylloc.
+m4_define([b4_declare_yylstype],
+[b4_value_type_define[]b4_locations_if([
+b4_location_type_define])
 
 b4_pure_if([], [[extern ]b4_api_PREFIX[STYPE ]b4_prefix[lval;
 ]b4_locations_if([[extern ]b4_api_PREFIX[LTYPE ]b4_prefix[lloc;]])])[]dnl
 ])
 
+
 # b4_YYDEBUG_define
-# ------------------
+# -----------------
 m4_define([b4_YYDEBUG_define],
-[[/* Enabling traces.  */
+[[/* Debug traces.  */
 ]m4_if(b4_api_prefix, [yy],
 [[#ifndef YYDEBUG
-# define YYDEBUG ]b4_debug_flag[
+# define YYDEBUG ]b4_parse_trace_if([1], [0])[
 #endif]],
 [[#ifndef ]b4_api_PREFIX[DEBUG
 # if defined YYDEBUG
-#  if YYDEBUG
+#if YYDEBUG
 #   define ]b4_api_PREFIX[DEBUG 1
 #  else
 #   define ]b4_api_PREFIX[DEBUG 0
 #  endif
 # else /* ! defined YYDEBUG */
-#  define ]b4_api_PREFIX[DEBUG ]b4_debug_flag[
-# endif /* ! defined ]b4_api_PREFIX[DEBUG */
+#  define ]b4_api_PREFIX[DEBUG ]b4_parse_trace_if([1], [0])[
+# endif /* ! defined YYDEBUG */
 #endif  /* ! defined ]b4_api_PREFIX[DEBUG */]])[]dnl
 ])
 
@@ -649,7 +751,7 @@ m4_define([b4_yylloc_default_define],
 #ifndef YYLLOC_DEFAULT
 # define YYLLOC_DEFAULT(Current, Rhs, N)                                \
     do                                                                  \
-      if (YYID (N))                                                     \
+      if (N)                                                            \
         {                                                               \
           (Current).first_line   = YYRHSLOC (Rhs, 1).first_line;        \
           (Current).first_column = YYRHSLOC (Rhs, 1).first_column;      \
@@ -663,6 +765,75 @@ m4_define([b4_yylloc_default_define],
           (Current).first_column = (Current).last_column =              \
             YYRHSLOC (Rhs, 0).last_column;                              \
         }                                                               \
-    while (YYID (0))
+    while (0)
 #endif
 ]])
+
+# b4_yy_location_print_define
+# ---------------------------
+# Define YY_LOCATION_PRINT.
+m4_define([b4_yy_location_print_define],
+[b4_locations_if([[
+/* YY_LOCATION_PRINT -- Print the location on the stream.
+   This macro was not mandated originally: define only if we know
+   we won't break user code: when these are the locations we know.  */
+
+#ifndef YY_LOCATION_PRINT
+# if defined ]b4_api_PREFIX[LTYPE_IS_TRIVIAL && ]b4_api_PREFIX[LTYPE_IS_TRIVIAL
+
+/* Print *YYLOCP on YYO.  Private, do not rely on its existence. */
+
+__attribute__((__unused__))
+]b4_function_define([yy_location_print_],
+    [static unsigned],
+               [[FILE *yyo],                    [yyo]],
+               [[YYLTYPE const * const yylocp], [yylocp]])[
+{
+  unsigned res = 0;
+  int end_col = 0 != yylocp->last_column ? yylocp->last_column - 1 : 0;
+  if (0 <= yylocp->first_line)
+    {
+      res += YYFPRINTF (yyo, "%d", yylocp->first_line);
+      if (0 <= yylocp->first_column)
+        res += YYFPRINTF (yyo, ".%d", yylocp->first_column);
+    }
+  if (0 <= yylocp->last_line)
+    {
+      if (yylocp->first_line < yylocp->last_line)
+        {
+          res += YYFPRINTF (yyo, "-%d", yylocp->last_line);
+          if (0 <= end_col)
+            res += YYFPRINTF (yyo, ".%d", end_col);
+        }
+      else if (0 <= end_col && yylocp->first_column < end_col)
+        res += YYFPRINTF (yyo, "-%d", end_col);
+    }
+  return res;
+ }
+
+#  define YY_LOCATION_PRINT(File, Loc)          \
+  yy_location_print_ (File, &(Loc))
+
+# else
+#  define YY_LOCATION_PRINT(File, Loc) ((void) 0)
+# endif
+#endif]],
+[[/* This macro is provided for backward compatibility. */
+#ifndef YY_LOCATION_PRINT
+# define YY_LOCATION_PRINT(File, Loc) ((void) 0)
+#endif]])
+])
+
+# b4_yyloc_default
+# ----------------
+# Expand to a possible default value for yylloc.
+m4_define([b4_yyloc_default],
+[[
+# if defined ]b4_api_PREFIX[LTYPE_IS_TRIVIAL && ]b4_api_PREFIX[LTYPE_IS_TRIVIAL
+  = { ]m4_join([, ],
+               m4_defn([b4_location_initial_line]),
+               m4_defn([b4_location_initial_column]),
+               m4_defn([b4_location_initial_line]),
+               m4_defn([b4_location_initial_column]))[ }
+# endif
+]])