build: restore C90 compatibility

[bison.git] / data / bison.m4

diff --git a/data/bison.m4 b/data/bison.m4
index 6ac4d9b070104ed2d0297de5b638c79ff3c8476c..d01124bb486f936a88e126016ab4616d70fd3300 100644 (file)
--- a/data/bison.m4
+++ b/data/bison.m4
@@ -1,41 +1,43 @@
                                                             -*- Autoconf -*-
 
 # Language-independent M4 Macros for Bison.
                                                             -*- Autoconf -*-
 
 # Language-independent M4 Macros for Bison.

-# Copyright (C) 2002, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.

 
 

-# This program is free software; you can redistribute it and/or modify
+# 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
 # it under the terms of the GNU General Public License as published by

-# the Free Software Foundation; either version 2 of the License, or
+# the Free Software Foundation, either version 3 of the License, or

 # (at your option) any later version.
 # (at your option) any later version.

-
+#

 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.

-
+#

 # You should have received a copy of the GNU General Public License
 # You should have received a copy of the GNU General Public License

-# along with this program; if not, write to the Free Software
-# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
-# 02110-1301  USA
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.

 
 
 ## ---------------- ##
 ## Identification.  ##
 ## ---------------- ##
 
 
 
 ## ---------------- ##
 ## Identification.  ##
 ## ---------------- ##
 

-# b4_copyright(TITLE, YEARS)
-# --------------------------
+# b4_copyright(TITLE, [YEARS])
+# ----------------------------
+# If YEARS are not defined, use b4_copyright_years.

 m4_define([b4_copyright],
 [b4_comment([A Bison parser, made by GNU Bison b4_version.])
 
 b4_comment([$1
 
 m4_define([b4_copyright],
 [b4_comment([A Bison parser, made by GNU Bison b4_version.])
 
 b4_comment([$1
 

-m4_text_wrap([Copyright (C) $2 Free Software Foundation, Inc.], [   ])
+]m4_dquote(m4_text_wrap([Copyright (C)
+]m4_ifval([$2], [[$2]], [m4_defn([b4_copyright_years])])[
+Free Software Foundation, Inc.]))[

 
 

-This program is free software; you can redistribute it and/or modify
+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
 it under the terms of the GNU General Public License as published by

-the Free Software Foundation; either version 2, or (at your option)
-any later version.
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.

 
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of


@@ -43,9 +45,7 @@ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License

-along with this program; if not, write to the Free Software
-Foundation, Inc., 51 Franklin Street, Fifth Floor,
-Boston, MA 02110-1301, USA.])
+along with this program.  If not, see <http://www.gnu.org/licenses/>.])

 
 b4_comment([As a special exception, you may create a larger work that contains
 part or all of the Bison parser skeleton and distribute that work
 
 b4_comment([As a special exception, you may create a larger work that contains
 part or all of the Bison parser skeleton and distribute that work


@@ -61,108 +61,139 @@ This special exception was added by the Free Software Foundation in
 version 2.2 of Bison.])])
 
 
 version 2.2 of Bison.])])
 
 

+## -------- ##
+## Output.  ##
+## -------- ##
+
+# b4_output_begin(FILE)
+# ---------------------
+# Enable output, i.e., send to diversion 0, expand after "#", and
+# generate the tag to output into FILE.  Must be followed by EOL.
+m4_define([b4_output_begin],
+[m4_changecom()
+m4_divert_push(0)dnl
+@output(m4_unquote([$1])@)@dnl
+])
+
+
+# b4_output_end()
+# ---------------
+# Output nothing, restore # as comment character (no expansions after #).
+m4_define([b4_output_end],
+[m4_divert_pop(0)
+m4_changecom([#])
+])
+
+

 ## ---------------- ##
 ## Error handling.  ##
 ## ---------------- ##
 
 ## ---------------- ##
 ## Error handling.  ##
 ## ---------------- ##
 

-# b4_error(KIND, FORMAT, [ARG1], [ARG2], ...)
-# -------------------------------------------
-# Write @KIND(FORMAT@,ARG1@,ARG2@,...@) to diversion 0.
+# The following error handling macros print error directives that should not
+# become arguments of other macro invocations since they would likely then be
+# mangled.  Thus, they print to stdout directly.
+
+# b4_cat(TEXT)
+# ------------
+# Write TEXT to stdout.  Precede the final newline with an @ so that it's
+# escaped.  For example:
+#
+#   b4_cat([[@complain(invalid input@)]])
+m4_define([b4_cat],
+[m4_syscmd([cat <<'_m4eof'
+]m4_bpatsubst(m4_dquote($1), [_m4eof], [_m4@`eof])[@
+_m4eof
+])dnl
+m4_if(m4_sysval, [0], [], [m4_fatal([$0: cannot write to stdout])])])
+
+# b4_error(KIND, START, END, FORMAT, [ARG1], [ARG2], ...)
+# -------------------------------------------------------
+# Write @KIND(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to stdout.
+#
+# For example:
+#
+#   b4_error([[complain]], [[input.y:2.3]], [[input.y:5.4]],
+#            [[invalid %s]], [[foo]])

 m4_define([b4_error],
 m4_define([b4_error],

-[m4_divert_push(0)[@]$1[(]$2[]m4_if([$#], [2], [],
-[m4_foreach([b4_arg],
-            m4_dquote(m4_shift(m4_shift($@))),
-            [[@,]b4_arg])])[@)]m4_divert_pop(0)])
-
-# b4_error_at(KIND, START, END, FORMAT, [ARG1], [ARG2], ...)
-# ----------------------------------------------------------
-# Write @KIND(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to diversion 0.
-m4_define([b4_error_at],
-[m4_divert_push(0)[@]$1[_at(]$2[@,]$3[@,]$4[]m4_if([$#], [4], [],
-[m4_foreach([b4_arg],
-            m4_dquote(m4_shift(m4_shift(m4_shift(m4_shift($@))))),
-            [[@,]b4_arg])])[@)]m4_divert_pop(0)])
+[b4_cat([[@complain][(]$1[@,]$2[@,]$3[@,]$4[]]dnl
+[m4_if([$#], [4], [],
+       [m4_foreach([b4_arg],
+                   m4_dquote(m4_shift(m4_shift(m4_shift(m4_shift($@))))),
+                   [[@,]b4_arg])])[@)]])])

 
 # b4_warn(FORMAT, [ARG1], [ARG2], ...)
 # ------------------------------------
 
 # b4_warn(FORMAT, [ARG1], [ARG2], ...)
 # ------------------------------------

-# Write @warn(FORMAT@,ARG1@,ARG2@,...@) to diversion 0.
+# Write @warn(FORMAT@,ARG1@,ARG2@,...@) to stdout.
+#
+# For example:
+#
+#   b4_warn([[invalid value for '%s': %s]], [[foo]], [[3]])

 #
 # As a simple test suite, this:
 #
 #
 # As a simple test suite, this:
 #

+#   m4_divert(-1)

 #   m4_define([asdf], [ASDF])
 #   m4_define([fsa], [FSA])
 #   m4_define([fdsa], [FDSA])
 #   m4_define([asdf], [ASDF])
 #   m4_define([fsa], [FSA])
 #   m4_define([fdsa], [FDSA])

-#   b4_warn([[[asdf), asdf]]], [[[fsa), fsa]]], [[[fdsa), fdsa]]])
-#   m4_divert(0)
-#   b4_warn([[asdf), asdf]], [[fsa), fsa]], [[fdsa), fdsa]])
-#   m4_divert(0)
-#   b4_warn([asdf), asdf], [fsa), fsa], [fdsa), fdsa])
-#   m4_divert(0)
-#   b4_warn()
-#   m4_divert(0)
-#   b4_warn(1)
-#   m4_divert(0)
-#   b4_warn(1, 2)
-#
-# Should produce this:
-#
-#   @warn([asdf), asdf]@,[fsa), fsa]@,[fdsa), fdsa]@)
-#   @warn(asdf), asdf@,fsa), fsa@,fdsa), fdsa@)
-#   @warn(ASDF), ASDF@,FSA), FSA@,FDSA), FDSA@)
+#   b4_warn_at([[[asdf), asdf]]], [[[fsa), fsa]]], [[[fdsa), fdsa]]])
+#   b4_warn_at([[asdf), asdf]], [[fsa), fsa]], [[fdsa), fdsa]])
+#   b4_warn_at()
+#   b4_warn_at(1)
+#   b4_warn_at(1, 2)
+#
+# Should produce this without newlines:
+#
+#   @warn_at([asdf), asdf]@,@,@,[fsa), fsa]@,[fdsa), fdsa]@)
+#   @warn(asdf), asdf@,@,@,fsa), fsa@,fdsa), fdsa@)

 #   @warn(@)
 #   @warn(1@)
 #   @warn(1@,2@)
 m4_define([b4_warn],
 #   @warn(@)
 #   @warn(1@)
 #   @warn(1@,2@)
 m4_define([b4_warn],

-[b4_error([[warn]], $@)])
+[b4_error([[warn]], [], [], $@)])

 
 # b4_warn_at(START, END, FORMAT, [ARG1], [ARG2], ...)
 # ---------------------------------------------------
 
 # b4_warn_at(START, END, FORMAT, [ARG1], [ARG2], ...)
 # ---------------------------------------------------

-# Write @warn(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to diversion 0.
+# Write @warn(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to stdout.
+#
+# For example:
+#
+#   b4_warn_at([[input.y:2.3]], [[input.y:5.4]], [[invalid %s]], [[foo]])

 m4_define([b4_warn_at],
 m4_define([b4_warn_at],

-[b4_error_at([[warn]], $@)])
+[b4_error([[warn]], $@)])

 
 # b4_complain(FORMAT, [ARG1], [ARG2], ...)
 # ----------------------------------------
 
 # b4_complain(FORMAT, [ARG1], [ARG2], ...)
 # ----------------------------------------

-# Write @complain(FORMAT@,ARG1@,ARG2@,...@) to diversion 0.
+# Bounce to b4_complain_at.

 #
 #

-# See the test suite for b4_warn above.
+# See b4_warn example.

 m4_define([b4_complain],
 m4_define([b4_complain],

-[b4_error([[complain]], $@)])
+[b4_error([[complain]], [], [], $@)])

 
 # b4_complain_at(START, END, FORMAT, [ARG1], [ARG2], ...)
 # -------------------------------------------------------
 
 # b4_complain_at(START, END, FORMAT, [ARG1], [ARG2], ...)
 # -------------------------------------------------------

-# Write @complain(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to diversion 0.
+# Write @complain(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to stdout.
+#
+# See b4_warn_at example.

 m4_define([b4_complain_at],
 m4_define([b4_complain_at],

-[b4_error_at([[complain]], $@)])
+[b4_error([[complain]], $@)])

 
 # b4_fatal(FORMAT, [ARG1], [ARG2], ...)
 # -------------------------------------
 
 # b4_fatal(FORMAT, [ARG1], [ARG2], ...)
 # -------------------------------------

-# Write @fatal(FORMAT@,ARG1@,ARG2@,...@) to diversion 0.
+# Bounce to b4_fatal_at.

 #
 #

-# See the test suite for b4_warn above.
+# See b4_warn example.

 m4_define([b4_fatal],
 m4_define([b4_fatal],

-[b4_error([[fatal]], $@)])
+[b4_error([[fatal]], [], [], $@)dnl
+m4_exit(1)])

 
 # b4_fatal_at(START, END, FORMAT, [ARG1], [ARG2], ...)
 # ----------------------------------------------------
 
 # b4_fatal_at(START, END, FORMAT, [ARG1], [ARG2], ...)
 # ----------------------------------------------------

-# Write @fatal(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to diversion 0.
+# Write @fatal(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to stdout and exit.
+#
+# See b4_warn_at example.

 m4_define([b4_fatal_at],
 m4_define([b4_fatal_at],

-[b4_error_at([[fatal]], $@)])
-
-
-## ---------------- ##
-## Default values.  ##
-## ---------------- ##
-
-# m4_define_default([b4_lex_param], [])   dnl breaks other skeletons
-m4_define_default([b4_pre_prologue], [])
-m4_define_default([b4_post_prologue], [])
-m4_define_default([b4_epilogue], [])
-m4_define_default([b4_parse_param], [])
-
-# The initial column and line.
-m4_define_default([b4_location_initial_column], [1])
-m4_define_default([b4_location_initial_line],   [1])
+[b4_error([[fatal]], $@)dnl
+m4_exit(1)])

 
 
 ## ------------ ##
 
 
 ## ------------ ##


@@ -176,6 +207,87 @@ m4_define([b4_ints_in],
 [m4_eval([$3 <= $1 && $1 <= $4 && $3 <= $2 && $2 <= $4])])
 
 
 [m4_eval([$3 <= $1 && $1 <= $4 && $3 <= $2 && $2 <= $4])])
 
 

+# b4_subtract(LHS, RHS)
+# ---------------------
+# Evaluate LHS - RHS if they are integer literals, otherwise expand
+# to (LHS) - (RHS).
+m4_define([b4_subtract],
+[m4_bmatch([$1$2], [^[0123456789]*$],
+           [m4_eval([$1 - $2])],
+           [($1) - ($2)])])
+
+# b4_join(ARG1, ...)
+# _b4_join(ARG1, ...)
+# -------------------
+# Join with comma, skipping empty arguments.
+# b4_join calls itself recursively until it sees the first non-empty
+# argument, then calls _b4_join which prepends each non-empty argument
+# with a comma.
+m4_define([b4_join],
+[m4_if([$#$1],
+       [1], [],
+       [m4_ifval([$1],
+                 [$1[]_$0(m4_shift($@))],
+                 [$0(m4_shift($@))])])])
+
+# _b4_join(ARGS1, ...)
+# --------------------
+m4_define([_b4_join],
+[m4_if([$#$1],
+       [1], [],
+       [m4_ifval([$1], [, $1])[]$0(m4_shift($@))])])
+
+
+
+
+# b4_integral_parser_tables_map(MACRO)
+# -------------------------------------
+# Map MACRO on all the integral tables.  MACRO is expected to have
+# the signature MACRO(TABLE-NAME, CONTENT, COMMENT).
+m4_define([b4_integral_parser_tables_map],
+[$1([pact], [b4_pact],
+    [[YYPACT[STATE-NUM] -- Index in YYTABLE of the portion describing
+STATE-NUM.]])
+
+$1([defact], [b4_defact],
+   [[YYDEFACT[STATE-NUM] -- Default reduction number in state STATE-NUM.
+Performed when YYTABLE does not specify something else to do.  Zero
+means the default is an error.]])
+
+$1([pgoto], [b4_pgoto], [[YYPGOTO[NTERM-NUM].]])
+
+$1([defgoto], [b4_defgoto], [[YYDEFGOTO[NTERM-NUM].]])
+
+$1([table], [b4_table],
+   [[YYTABLE[YYPACT[STATE-NUM]] -- What to do in state STATE-NUM.  If
+positive, shift that token.  If negative, reduce the rule whose
+number is the opposite.  If YYTABLE_NINF, syntax error.]])
+
+$1([check], [b4_check])
+
+$1([stos], [b4_stos],
+   [[YYSTOS[STATE-NUM] -- The (internal number of the) accessing
+symbol of state STATE-NUM.]])
+
+$1([r1], [b4_r1],
+   [[YYR1[YYN] -- Symbol number of symbol that rule YYN derives.]])
+
+$1([r2], [b4_r2],
+   [[YYR2[YYN] -- Number of symbols on the right hand side of rule YYN.]])
+])
+
+
+# b4_parser_tables_declare
+# b4_parser_tables_define
+# ------------------------
+# Define/declare the (deterministic) parser tables.
+m4_define([b4_parser_tables_declare],
+[b4_integral_parser_tables_map([b4_integral_parser_table_declare])])
+
+m4_define([b4_parser_tables_define],
+[b4_integral_parser_tables_map([b4_integral_parser_table_define])])
+
+

 
 ## ------------------ ##
 ## Decoding options.  ##
 
 ## ------------------ ##
 ## Decoding options.  ##


@@ -187,8 +299,8 @@ m4_define([b4_ints_in],
 m4_define([b4_flag_if],
 [m4_case(b4_$1_flag,
          [0], [$3],
 m4_define([b4_flag_if],
 [m4_case(b4_$1_flag,
          [0], [$3],

-        [1], [$2],
-        [m4_fatal([invalid $1 value: ]$1)])])
+         [1], [$2],
+         [m4_fatal([invalid $1 value: ]b4_$1_flag)])])

 
 
 # b4_define_flag_if(FLAG)
 
 
 # b4_define_flag_if(FLAG)


@@ -200,9 +312,9 @@ m4_define([b4_define_flag_if],
 
 # _b4_define_flag_if($1, $2, FLAG)
 # --------------------------------
 
 # _b4_define_flag_if($1, $2, FLAG)
 # --------------------------------

-# This macro works around the impossibility to define macros
-# inside macros, because issuing `[$1]' is not possible in M4 :(.
-# This sucks hard, GNU M4 should really provide M5 like $$1.
+# Work around the impossibility to define macros inside macros,
+# because issuing `[$1]' is not possible in M4.  GNU M4 should provide
+# $$1 a la M5/TeX.

 m4_define([_b4_define_flag_if],
 [m4_if([$1$2], $[1]$[2], [],
        [m4_fatal([$0: Invalid arguments: $@])])dnl
 m4_define([_b4_define_flag_if],
 [m4_if([$1$2], $[1]$[2], [],
        [m4_fatal([$0: Invalid arguments: $@])])dnl


@@ -213,24 +325,204 @@ m4_define([b4_$3_if],
 # b4_FLAG_if(IF-TRUE, IF-FALSE)
 # -----------------------------
 # Expand IF-TRUE, if FLAG is true, IF-FALSE otherwise.
 # b4_FLAG_if(IF-TRUE, IF-FALSE)
 # -----------------------------
 # Expand IF-TRUE, if FLAG is true, IF-FALSE otherwise.

-b4_define_flag_if([defines])           # Whether headers are requested.
-b4_define_flag_if([error_verbose])     # Whether error are verbose.
-b4_define_flag_if([glr])               # Whether a GLR parser is requested.
-b4_define_flag_if([locations])         # Whether locations are tracked.
-b4_define_flag_if([nondeterministic])  # Whether conflicts should be handled.
-b4_define_flag_if([pull])              # Whether pull parsing is requested.
-b4_define_flag_if([pure])              # Whether the interface is pure.
-b4_define_flag_if([push])              # Whether push parsing is requested.
-b4_define_flag_if([use_push_for_pull])  # Whether push parsing should be used
-                                        # in place of pull parsing (where
-                                        # available) for the sake of the test
-                                        # suite.
-b4_define_flag_if([yacc])              # Whether POSIX Yacc is emulated.
-
-
-## ------------------------- ##
-## Assigning token numbers.  ##
-## ------------------------- ##
+b4_define_flag_if([defines])            # Whether headers are requested.
+b4_define_flag_if([glr])                # Whether a GLR parser is requested.
+b4_define_flag_if([nondeterministic])   # Whether conflicts should be handled.
+b4_define_flag_if([token_table])        # Whether yytoken_table is demanded.
+b4_define_flag_if([yacc])               # Whether POSIX Yacc is emulated.
+
+
+## --------- ##
+## Symbols.  ##
+## --------- ##
+
+# In order to unify the handling of the various aspects of symbols
+# (tag, type_name, whether terminal, etc.), bison.exe defines one
+# macro per (token, field), where field can has_id, id, etc.: see
+# src/output.c:prepare_symbols_definitions().
+#
+# The various FIELDS are:
+#
+# - has_id: 0 or 1.
+#   Whether the symbol has an id.
+# - id: string
+#   If has_id, the id.  Guaranteed to be usable as a C identifier.
+# - tag: string.
+#   A representat of the symbol.  Can be 'foo', 'foo.id', '"foo"' etc.
+# - user_number: integer
+#   The assigned (external) number as used by yylex.
+# - is_token: 0 or 1
+#   Whether this is a terminal symbol.
+# - number: integer
+#   The internalized number (used after yytranslate).
+# - has_type: 0, 1
+#   Whether has a semantic value.
+# - type
+#   If it has a semantic value, its type tag, or, if variant are used,
+#   its type.
+# - has_printer: 0, 1
+# - printer: string
+# - printer_file: string
+# - printer_line: integer
+#   If the symbol has a printer, everything about it.
+# - has_destructor, destructor, destructor_file, destructor_line
+#   Likewise.
+#
+# The following macros provide access to these values.
+
+# b4_symbol_(NUM, FIELD)
+# ----------------------
+# Recover a FIELD about symbol #NUM.  Thanks to m4_indir, fails if
+# undefined.
+m4_define([b4_symbol_],
+[m4_indir([b4_symbol($1, $2)])])
+
+
+# b4_symbol(NUM, FIELD)
+# ---------------------
+# Recover a FIELD about symbol #NUM.  Thanks to m4_indir, fails if
+# undefined.  If FIELD = id, prepend the token prefix.
+m4_define([b4_symbol],
+[m4_case([$2],
+         [id],    [m4_do([b4_percent_define_get([api.token.prefix])],
+                         [b4_symbol_([$1], [id])])],
+         [b4_symbol_($@)])])
+
+
+# b4_symbol_if(NUM, FIELD, IF-TRUE, IF-FALSE)
+# -------------------------------------------
+# If FIELD about symbol #NUM is 1 expand IF-TRUE, if is 0, expand IF-FALSE.
+# Otherwise an error.
+m4_define([b4_symbol_if],
+[m4_case(b4_symbol([$1], [$2]),
+         [1], [$3],
+         [0], [$4],
+         [m4_fatal([$0: field $2 of $1 is not a Boolean:] b4_symbol([$1], [$2]))])])
+
+
+# b4_symbol_tag_comment(SYMBOL-NUM)
+# ---------------------------------
+# Issue a comment giving the tag of symbol NUM.
+m4_define([b4_symbol_tag_comment],
+[b4_comment([b4_symbol([$1], [tag])])
+])
+
+
+# b4_symbol_action_location(SYMBOL-NUM, KIND)
+# -------------------------------------------
+# Report the location of the KIND action as FILE:LINE.
+m4_define([b4_symbol_action_location],
+[b4_symbol([$1], [$2_file]):b4_syncline([b4_symbol([$1], [$2_line])])])
+
+
+# b4_symbol_action(SYMBOL-NUM, KIND)
+# ----------------------------------
+# Run the action KIND (destructor or printer) for SYMBOL-NUM.
+# Same as in C, but using references instead of pointers.
+m4_define([b4_symbol_action],
+[b4_symbol_if([$1], [has_$2],
+[b4_dollar_pushdef([(*yyvaluep)],
+                   b4_symbol_if([$1], [has_type],
+                                [m4_dquote(b4_symbol([$1], [type]))]),
+                   [(*yylocationp)])dnl
+    b4_symbol_case_([$1])[]dnl
+b4_syncline([b4_symbol([$1], [$2_line])], ["b4_symbol([$1], [$2_file])"])
+      b4_symbol([$1], [$2])
+b4_syncline([@oline@], [@ofile@])
+        break;
+
+b4_dollar_popdef[]dnl
+])])
+
+
+# b4_symbol_destructor(SYMBOL-NUM)
+# b4_symbol_printer(SYMBOL-NUM)
+# --------------------------------
+m4_define([b4_symbol_destructor], [b4_symbol_action([$1], [destructor])])
+m4_define([b4_symbol_printer],    [b4_symbol_action([$1], [printer])])
+
+
+# b4_symbol_case_(SYMBOL-NUM)
+# ---------------------------
+# Issue a "case NUM" for SYMBOL-NUM.
+m4_define([b4_symbol_case_],
+[case b4_symbol([$1], [number]): b4_symbol_tag_comment([$1])])
+])
+
+
+# b4_symbol_foreach(MACRO)
+# ------------------------
+# Invoke MACRO(SYMBOL-NUM) for each SYMBOL-NUM.
+m4_define([b4_symbol_foreach],
+          [m4_map([$1], m4_defn([b4_symbol_numbers]))])
+
+# b4_symbol_map(MACRO)
+# --------------------
+# Return a list (possibly empty elements) of MACRO invoked for each
+# SYMBOL-NUM.
+m4_define([b4_symbol_map],
+[m4_map_args_sep([$1(], [)], [,], b4_symbol_numbers)])
+
+
+# b4_token_visible_if(NUM, IF-TRUE, IF-FALSE)
+# -------------------------------------------
+# Whether NUM denotes a token that has an exported definition (i.e.,
+# shows in enum yytokentype).
+m4_define([b4_token_visible_if],
+[b4_symbol_if([$1], [is_token],
+              [b4_symbol_if([$1], [has_id], [$2], [$3])],
+              [$3])])
+
+# b4_token_has_definition(NUM)
+# ----------------------------
+# 1 if NUM is visible, nothing otherwise.
+m4_define([b4_token_has_definition],
+[b4_token_visible_if([$1], [1])])
+
+# b4_any_token_visible_if([IF-TRUE], [IF-FALSE])
+# ----------------------------------------------
+# Whether there is a token that needs to be defined.
+m4_define([b4_any_token_visible_if],
+[m4_ifval(b4_symbol_foreach([b4_token_has_definition]),
+          [$1], [$2])])
+
+
+# b4_token_format(FORMAT, NUM)
+# ----------------------------
+m4_define([b4_token_format],
+[b4_token_visible_if([$2],
+[m4_quote(m4_format([$1],
+                     [b4_symbol([$2], [id])],
+                     [b4_symbol([$2], [user_number])]))])])
+
+
+## ------- ##
+## Types.  ##
+## ------- ##
+
+# b4_type_action_(NUMS)
+# ---------------------
+# Run actions for the symbol NUMS that all have the same type-name.
+# Skip NUMS that have no type-name.
+#
+# To specify the action to run, define b4_dollar_dollar(NUMBER,
+# TAG, TYPE).
+m4_define([b4_type_action_],
+[b4_symbol_if([$1], [has_type],
+[m4_map([      b4_symbol_case_], [$@])[]dnl
+        b4_dollar_dollar([b4_symbol([$1], [number])],
+                         [b4_symbol([$1], [tag])],
+                         [b4_symbol([$1], [type])]);
+        break;
+
+])])
+
+# b4_type_foreach(MACRO)
+# ----------------------
+# Invoke MACRO(SYMBOL-NUMS) for each set of SYMBOL-NUMS for each type set.
+m4_define([b4_type_foreach],
+          [m4_map([$1], m4_defn([b4_type_names]))])
+

 
 
 ## ----------- ##
 
 
 ## ----------- ##


@@ -248,12 +540,22 @@ m4_define([b4_basename],
 # b4_syncline(LINE, FILE)
 # -----------------------
 m4_define([b4_syncline],
 # b4_syncline(LINE, FILE)
 # -----------------------
 m4_define([b4_syncline],

-[b4_flag_if([synclines], [
-b4_sync_end([__line__], [b4_basename(m4_quote(__file__))])
-b4_sync_start([$1], [$2])])])
+[b4_flag_if([synclines],
+[b4_sync_start([$1], [$2]) b4_sync_end([__line__],
+                                       [b4_basename(m4_quote(__file__))])[]dnl
+])])
+
+# b4_sync_start(LINE, FILE)
+# -----------------------
+# Syncline for the new place.  Typically a directive for the compiler.
+m4_define([b4_sync_start], [b4_comment([$2:$1])])
+
+# b4_sync_end(LINE, FILE)
+# -----------------------
+# Syncline for the current place, which ends.  Typically a comment
+# left for the reader.
+m4_define([b4_sync_end],   [b4_comment([$2:$1])])

 
 

-m4_define([b4_sync_end], [b4_comment([Line $1 of $2])])
-m4_define([b4_sync_start], [b4_comment([Line $1 of $2])])

 
 # b4_user_code(USER-CODE)
 # -----------------------
 
 # b4_user_code(USER-CODE)
 # -----------------------


@@ -275,117 +577,374 @@ m4_define([b4_define_user_code],
 # b4_user_initial_action
 # b4_user_post_prologue
 # b4_user_pre_prologue
 # b4_user_initial_action
 # b4_user_post_prologue
 # b4_user_pre_prologue

-# b4_user_stype
+# b4_user_union_members

 # ----------------------
 # Macros that issue user code, ending with synclines.
 b4_define_user_code([actions])
 b4_define_user_code([initial_action])
 b4_define_user_code([post_prologue])
 b4_define_user_code([pre_prologue])
 # ----------------------
 # Macros that issue user code, ending with synclines.
 b4_define_user_code([actions])
 b4_define_user_code([initial_action])
 b4_define_user_code([post_prologue])
 b4_define_user_code([pre_prologue])

-b4_define_user_code([stype])
+b4_define_user_code([union_members])

 
 
 
 

-# b4_check_user_names(WHAT, USER-LIST, SKELETON-LIST)
-# ---------------------------------------------------
-# Warn if any name of type WHAT is used by the user (as recorded in USER-LIST)
-# but is not used by the skeleton (as recorded in SKELETON-LIST).
+# b4_check_user_names(WHAT, USER-LIST, BISON-NAMESPACE)
+# -----------------------------------------------------
+# Complain if any name of type WHAT is used by the user (as recorded in
+# USER-LIST) but is not used by Bison (as recorded by macros in the
+# namespace BISON-NAMESPACE).

 #
 #

-# USER-LIST must expand to a list specifying all grammar occurrences of all
-# names of type WHAT.   Each item in the list is a triplet specifying one
+# USER-LIST must expand to a list specifying all user occurrences of all names
+# of type WHAT.   Each item in the list must be a triplet specifying one

 # occurrence: name, start boundary, and end boundary.  Empty string names are
 # fine.  An empty list is fine.
 #
 # occurrence: name, start boundary, and end boundary.  Empty string names are
 # fine.  An empty list is fine.
 #

-# For example, to define b4_user_foo_names to be used for USER-LIST with three
+# For example, to define b4_foo_user_names to be used for USER-LIST with three

 # name occurrences and with correct quoting:
 #
 # name occurrences and with correct quoting:
 #

-#   m4_define([b4_user_foo_names],
+#   m4_define([b4_foo_user_names],

 #             [[[[[[bar]], [[parser.y:1.7]], [[parser.y:1.16]]]],
 #               [[[[bar]], [[parser.y:5.7]], [[parser.y:5.16]]]],
 #               [[[[baz]], [[parser.y:8.7]], [[parser.y:8.16]]]]]])
 #
 #             [[[[[[bar]], [[parser.y:1.7]], [[parser.y:1.16]]]],
 #               [[[[bar]], [[parser.y:5.7]], [[parser.y:5.16]]]],
 #               [[[[baz]], [[parser.y:8.7]], [[parser.y:8.16]]]]]])
 #

-# SKELETON-LIST must expand to a list specifying all names of type WHAT that
-# are used by the skeleton.  Multiple occurrences of the same name are fine.
-# Empty string names are fine, but it would be ugly for a Bison skeleton to
-# actually use one.  An empty list is fine.
+# The macro BISON-NAMESPACE(bar) must be defined iff the name bar of type WHAT
+# is used by Bison (in the front-end or in the skeleton).  Empty string names
+# are fine, but it would be ugly for Bison to actually use one.

 #
 #

-# For example, to define b4_skeleton_foo_names to be used for SKELETON-LIST
-# with two names and with correct quoting:
+# For example, to use b4_foo_bison_names for BISON-NAMESPACE and define that
+# the names bar and baz are used by Bison:

 #
 #

-#   m4_define([b4_skeleton_foo_names],
-#             [[[[bar]], [[baz]]]])
+#   m4_define([b4_foo_bison_names(bar)])
+#   m4_define([b4_foo_bison_names(baz)])

 #
 # To invoke b4_check_user_names with TYPE foo, with USER-LIST
 #
 # To invoke b4_check_user_names with TYPE foo, with USER-LIST

-# b4_user_foo_names, with SKELETON-LIST b4_skeleton_foo_names, and with correct
+# b4_foo_user_names, with BISON-NAMESPACE b4_foo_bison_names, and with correct

 # quoting:
 #
 # quoting:
 #

-#   b4_check_user_names([[foo]], [b4_user_foo_names], [b4_skeleton_foo_names])
+#   b4_check_user_names([[foo]], [b4_foo_user_names],
+#                       [[b4_foo_bison_names]])

 m4_define([b4_check_user_names],
 [m4_foreach([b4_occurrence], $2,
 [m4_pushdef([b4_occurrence], b4_occurrence)dnl
 m4_pushdef([b4_user_name], m4_car(b4_occurrence))dnl
 m4_pushdef([b4_start], m4_car(m4_shift(b4_occurrence)))dnl
 m4_pushdef([b4_end], m4_shift(m4_shift(b4_occurrence)))dnl
 m4_define([b4_check_user_names],
 [m4_foreach([b4_occurrence], $2,
 [m4_pushdef([b4_occurrence], b4_occurrence)dnl
 m4_pushdef([b4_user_name], m4_car(b4_occurrence))dnl
 m4_pushdef([b4_start], m4_car(m4_shift(b4_occurrence)))dnl
 m4_pushdef([b4_end], m4_shift(m4_shift(b4_occurrence)))dnl

-m4_pushdef([b4_found], [[0]])dnl
-m4_foreach([b4_skeleton_name], $3,
-           [m4_if(m4_quote(b4_user_name),
-                  m4_quote(b4_skeleton_name),
-                  [m4_define([b4_found], [[1]])])])dnl
-m4_if(b4_found, [0], [b4_warn_at([b4_start], [b4_end],
-                                 [[%s `%s' is not used]],
-                                 [$1], [b4_user_name])])[]dnl
-m4_popdef([b4_found])dnl
+m4_ifndef($3[(]m4_quote(b4_user_name)[)],
+          [b4_complain_at([b4_start], [b4_end],
+                          [[%s '%s' is not used]],
+                          [$1], [b4_user_name])])[]dnl

 m4_popdef([b4_occurrence])dnl
 m4_popdef([b4_user_name])dnl
 m4_popdef([b4_start])dnl
 m4_popdef([b4_end])dnl
 ])])
 
 m4_popdef([b4_occurrence])dnl
 m4_popdef([b4_user_name])dnl
 m4_popdef([b4_start])dnl
 m4_popdef([b4_end])dnl
 ])])
 

-# b4_get_percent_define(VARIABLE)
-# --------------------------------
-# If the %define variable VARIABLE is defined, emit it.  Also, record VARIABLE
-# in b4_skeleton_percent_define_variables.
-m4_define([b4_get_percent_define],
-[m4_append([b4_skeleton_percent_define_variables], [[$1]], [[, ]])dnl
-m4_ifdef([b4_percent_define_]$1, [b4_percent_define_]$1)])

 
 

-# b4_get_percent_code([QUALIFIER])
+
+## --------------------- ##
+## b4_percent_define_*.  ##
+## --------------------- ##
+
+
+# b4_percent_define_use(VARIABLE)
+# -------------------------------
+# Declare that VARIABLE was used.
+m4_define([b4_percent_define_use],
+[m4_define([b4_percent_define_bison_variables(]$1[)])dnl
+])
+
+# b4_percent_define_get(VARIABLE, [DEFAULT])
+# ------------------------------------------
+# Mimic muscle_percent_define_get in ../src/muscle-tab.h.  That is, if
+# the %define variable VARIABLE is defined, emit its value.  Contrary
+# to its C counterpart, return DEFAULT otherwise.  Also, record
+# Bison's usage of VARIABLE by defining
+# b4_percent_define_bison_variables(VARIABLE).
+#
+# For example:
+#
+#   b4_percent_define_get([[foo]])
+m4_define([b4_percent_define_get],
+[b4_percent_define_use([$1])dnl
+m4_ifdef([b4_percent_define(]$1[)],
+         [m4_indir([b4_percent_define(]$1[)])],
+         [$2])])
+
+# b4_percent_define_get_loc(VARIABLE)
+# -----------------------------------
+# Mimic muscle_percent_define_get_loc in ../src/muscle-tab.h exactly.  That is,
+# if the %define variable VARIABLE is undefined, complain fatally since that's
+# a Bison or skeleton error.  Otherwise, return its definition location in a
+# form approriate for the first two arguments of b4_warn_at, b4_complain_at, or
+# b4_fatal_at.  Don't record this as a Bison usage of VARIABLE as there's no
+# reason to suspect that the user-supplied value has yet influenced the output.
+#
+# For example:
+#
+#   b4_complain_at(b4_percent_define_get_loc([[foo]]), [[invalid foo]])
+m4_define([b4_percent_define_get_loc],
+[m4_ifdef([b4_percent_define_loc(]$1[)],
+          [m4_pushdef([b4_loc], m4_indir([b4_percent_define_loc(]$1[)]))dnl
+b4_loc[]dnl
+m4_popdef([b4_loc])],
+          [b4_fatal([[b4_percent_define_get_loc: undefined %%define variable '%s']], [$1])])])
+
+# b4_percent_define_get_syncline(VARIABLE)
+# ----------------------------------------
+# Mimic muscle_percent_define_get_syncline in ../src/muscle-tab.h exactly.
+# That is, if the %define variable VARIABLE is undefined, complain fatally
+# since that's a Bison or skeleton error.  Otherwise, return its definition
+# location as a b4_syncline invocation.  Don't record this as a Bison usage of
+# VARIABLE as there's no reason to suspect that the user-supplied value has yet
+# influenced the output.
+#
+# For example:
+#
+#   b4_percent_define_get_syncline([[foo]])
+m4_define([b4_percent_define_get_syncline],
+[m4_ifdef([b4_percent_define_syncline(]$1[)],
+          [m4_indir([b4_percent_define_syncline(]$1[)])],
+          [b4_fatal([[b4_percent_define_get_syncline: undefined %%define variable '%s']], [$1])])])
+
+# b4_percent_define_ifdef(VARIABLE, IF-TRUE, [IF-FALSE])
+# ------------------------------------------------------
+# Mimic muscle_percent_define_ifdef in ../src/muscle-tab.h exactly.  That is,
+# if the %define variable VARIABLE is defined, expand IF-TRUE, else expand
+# IF-FALSE.  Also, record Bison's usage of VARIABLE by defining
+# b4_percent_define_bison_variables(VARIABLE).
+#
+# For example:
+#
+#   b4_percent_define_ifdef([[foo]], [[it's defined]], [[it's undefined]])
+m4_define([b4_percent_define_ifdef],
+[m4_ifdef([b4_percent_define(]$1[)],
+          [b4_percent_define_use([$1])$2],
+          [$3])])
+
+
+## --------- ##
+## Options.  ##
+## --------- ##
+
+
+# b4_percent_define_flag_if(VARIABLE, IF-TRUE, [IF-FALSE])
+# --------------------------------------------------------
+# Mimic muscle_percent_define_flag_if in ../src/muscle-tab.h exactly.  That is,
+# if the %define variable VARIABLE is defined to "" or "true", expand IF-TRUE.
+# If it is defined to "false", expand IF-FALSE.  Complain if it is undefined
+# (a Bison or skeleton error since the default value should have been set
+# already) or defined to any other value (possibly a user error).  Also, record
+# Bison's usage of VARIABLE by defining
+# b4_percent_define_bison_variables(VARIABLE).
+#
+# For example:
+#
+#   b4_percent_define_flag_if([[foo]], [[it's true]], [[it's false]])
+m4_define([b4_percent_define_flag_if],
+[b4_percent_define_ifdef([$1],
+  [m4_case(b4_percent_define_get([$1]),
+           [], [$2], [true], [$2], [false], [$3],
+           [m4_expand_once([b4_complain_at(b4_percent_define_get_loc([$1]),
+                                           [[invalid value for %%define Boolean variable '%s']],
+                                           [$1])],
+                           [[b4_percent_define_flag_if($1)]])])],
+  [b4_fatal([[b4_percent_define_flag_if: undefined %%define variable '%s']], [$1])])])
+
+
+# b4_percent_define_default(VARIABLE, DEFAULT)
+# --------------------------------------------
+# Mimic muscle_percent_define_default in ../src/muscle-tab.h exactly.  That is,
+# if the %define variable VARIABLE is undefined, set its value to DEFAULT.
+# Don't record this as a Bison usage of VARIABLE as there's no reason to
+# suspect that the value has yet influenced the output.
+#
+# For example:
+#
+#   b4_percent_define_default([[foo]], [[default value]])
+m4_define([b4_percent_define_default],
+[m4_ifndef([b4_percent_define(]$1[)],
+           [m4_define([b4_percent_define(]$1[)], [$2])dnl
+            m4_define([b4_percent_define_loc(]$1[)],
+                      [[[[<skeleton default value>:-1.-1]],
+                        [[<skeleton default value>:-1.-1]]]])dnl
+            m4_define([b4_percent_define_syncline(]$1[)], [[]])])])
+
+
+# b4_percent_define_if_define(NAME, [VARIABLE = NAME])
+# ----------------------------------------------------
+# Define b4_NAME_if that executes its $1 or $2 depending whether
+# VARIABLE was %defined.  The characters `.' and `-' in VARIABLE are mapped
+# to `_'.
+m4_define([b4_percent_define_if_define_],
+[m4_define(m4_bpatsubst([b4_$1_if], [[-.]], [_]),
+           [b4_percent_define_flag_if(m4_default([$2], [$1]),
+                                      [$3], [$4])])])
+m4_define([b4_percent_define_if_define],
+[b4_percent_define_default([m4_default([$2], [$1])], [[false]])
+b4_percent_define_if_define_([$1], [$2], $[1], $[2])])
+
+
+# b4_percent_define_check_values(VALUES)
+# --------------------------------------
+# Mimic muscle_percent_define_check_values in ../src/muscle-tab.h exactly
+# except that the VALUES structure is more appropriate for M4.  That is, VALUES
+# is a list of sublists of strings.  For each sublist, the first string is the
+# name of a %define variable, and all remaining strings in that sublist are the
+# valid values for that variable.  Complain if such a variable is undefined (a
+# Bison error since the default value should have been set already) or defined
+# to any other value (possibly a user error).  Don't record this as a Bison
+# usage of the variable as there's no reason to suspect that the value has yet
+# influenced the output.
+#
+# For example:
+#
+#   b4_percent_define_check_values([[[[foo]], [[foo-value1]], [[foo-value2]]]],
+#                                  [[[[bar]], [[bar-value1]]]])
+m4_define([b4_percent_define_check_values],
+[m4_foreach([b4_sublist], m4_quote($@),
+            [_b4_percent_define_check_values(b4_sublist)])])
+
+m4_define([_b4_percent_define_check_values],
+[m4_ifdef([b4_percent_define(]$1[)],
+  [m4_pushdef([b4_good_value], [0])dnl
+   m4_if($#, 1, [],
+         [m4_foreach([b4_value], m4_dquote(m4_shift($@)),
+                     [m4_if(m4_indir([b4_percent_define(]$1[)]), b4_value,
+                            [m4_define([b4_good_value], [1])])])])dnl
+   m4_if(b4_good_value, [0],
+         [b4_complain_at(b4_percent_define_get_loc([$1]),
+                         [[invalid value for %%define variable '%s': '%s']],
+                         [$1],
+                         m4_dquote(m4_indir([b4_percent_define(]$1[)])))
+          m4_foreach([b4_value], m4_dquote(m4_shift($@)),
+                     [b4_error([[note]], b4_percent_define_get_loc([$1]), []
+                                     [[accepted value: '%s']],
+                                     m4_dquote(b4_value))])])dnl
+   m4_popdef([b4_good_value])],
+  [b4_fatal([[b4_percent_define_check_values: undefined %%define variable '%s']], [$1])])])
+
+# b4_percent_code_get([QUALIFIER])

 # --------------------------------
 # If any %code blocks for QUALIFIER are defined, emit them beginning with a
 # comment and ending with synclines and a newline.  If QUALIFIER is not
 # --------------------------------
 # If any %code blocks for QUALIFIER are defined, emit them beginning with a
 # comment and ending with synclines and a newline.  If QUALIFIER is not

-# specified (thus, b4_get_percent_code is invoked without parens), do this for
-# the unqualified %code blocks.  Also, record QUALIFIER (if specified) in
-# b4_skeleton_percent_code_qualifiers.
-m4_define([b4_get_percent_code],
-[m4_pushdef([b4_macro_name], [[b4_percent_code]]m4_if([$#], [1], [[[_]$1]]))dnl
-m4_if([$#], [1],
-      [m4_append([b4_skeleton_percent_code_qualifiers], [[$1]], [[, ]])])dnl
+# specified or empty, do this for the unqualified %code blocks.  Also, record
+# Bison's usage of QUALIFIER (if specified) by defining
+# b4_percent_code_bison_qualifiers(QUALIFIER).
+#
+# For example, to emit any unqualified %code blocks followed by any %code
+# blocks for the qualifier foo:
+#
+#   b4_percent_code_get
+#   b4_percent_code_get([[foo]])
+m4_define([b4_percent_code_get],
+[m4_pushdef([b4_macro_name], [[b4_percent_code(]$1[)]])dnl
+m4_ifval([$1], [m4_define([b4_percent_code_bison_qualifiers(]$1[)])])dnl

 m4_ifdef(b4_macro_name,
 [b4_comment([m4_if([$#], [0], [[Unqualified %code]],
 m4_ifdef(b4_macro_name,
 [b4_comment([m4_if([$#], [0], [[Unqualified %code]],

-                   [[%code "]$1["]])[ blocks.]])
-b4_user_code(b4_macro_name)])dnl
+                   [["%code ]$1["]])[ blocks.]])
+b4_user_code([m4_indir(b4_macro_name)])
+])dnl

 m4_popdef([b4_macro_name])])
 
 m4_popdef([b4_macro_name])])
 

+# b4_percent_code_ifdef(QUALIFIER, IF-TRUE, [IF-FALSE])
+# -----------------------------------------------------
+# If any %code blocks for QUALIFIER (or unqualified %code blocks if
+# QUALIFIER is empty) are defined, expand IF-TRUE, else expand IF-FALSE.
+# Also, record Bison's usage of QUALIFIER (if specified) by defining
+# b4_percent_code_bison_qualifiers(QUALIFIER).
+m4_define([b4_percent_code_ifdef],
+[m4_ifdef([b4_percent_code(]$1[)],
+          [m4_ifval([$1], [m4_define([b4_percent_code_bison_qualifiers(]$1[)])])$2],
+          [$3])])
+
+
+## ------------------ ##
+## Common variables.  ##
+## ------------------ ##
+
+# Default values for %define.
+# ---------------------------
+# If the api.token.prefix, it is empty.
+m4_percent_define_default([[api.token.prefix]], [[]])

 
 

-## --------------------------------------------------------- ##
-## After processing the skeletons, check that all the user's ##
-## %define variables and %code qualifiers were used.         ##
-## --------------------------------------------------------- ##
+# b4_parse_assert_if([IF-ASSERTIONS-ARE-USED], [IF-NOT])
+# b4_parse_trace_if([IF-DEBUG-TRACES-ARE-ENABLED], [IF-NOT])
+# b4_token_ctor_if([IF-YYLEX-RETURNS-A-TOKEN], [IF-NOT])
+# ----------------------------------------------
+b4_percent_define_if_define([token_ctor], [api.token.constructor])
+b4_percent_define_if_define([locations])     # Whether locations are tracked.
+b4_percent_define_if_define([parse.assert])
+b4_percent_define_if_define([parse.trace])

 
 

-m4_wrap([
-m4_pushdef([b4_check_user_names_wrap],
-[m4_ifdef([b4_skeleton_percent_$1],
-          [m4_define([b4_skeleton_percent_$1],
-                     m4_dquote(m4_dquote(b4_skeleton_percent_$1)))],
-          [m4_define([b4_skeleton_percent_$1], [[]])])

 
 

-m4_ifdef([b4_user_percent_$1],
-         [b4_check_user_names([$2],
-                              [b4_user_percent_$1],
-                              [b4_skeleton_percent_$1])])
+# b4_bison_locations_if([IF-TRUE])
+# --------------------------------
+# Expand IF-TRUE if using locations, and using the default location
+# type.
+m4_define([b4_bison_locations_if],
+[b4_locations_if([b4_percent_define_ifdef([[api.location.type]], [], [$1])])])
+
+
+# b4_error_verbose_if([IF-ERRORS-ARE-VERBOSE], [IF-NOT])
+# ------------------------------------------------------
+# Map %define parse.error "(simple|verbose)" to b4_error_verbose_if and
+# b4_error_verbose_flag.
+b4_percent_define_default([[parse.error]], [[simple]])
+b4_percent_define_check_values([[[[parse.error]],
+                                 [[simple]], [[verbose]]]])
+m4_define([b4_error_verbose_flag],
+          [m4_case(b4_percent_define_get([[parse.error]]),
+                   [simple],  [[0]],
+                   [verbose], [[1]])])
+b4_define_flag_if([error_verbose])
+
+# yytoken_table is needed to support verbose errors.
+b4_error_verbose_if([m4_define([b4_token_table_flag], [1])])
+
+
+# b4_variant_if([IF-VARIANT-ARE-USED], [IF-NOT])
+# ----------------------------------------------
+b4_percent_define_if_define([variant])
+m4_case(b4_percent_define_get([[api.value.type]]),
+        [variant], [m4_define([b4_variant_flag], [[1]])],
+                   [m4_define([b4_variant_flag], [[0]])])
+b4_define_flag_if([variant])
+
+
+## ----------------------------------------------------------- ##
+## After processing the skeletons, check that all the user's   ##
+## %define variables and %code qualifiers were used by Bison.  ##
+## ----------------------------------------------------------- ##
+
+m4_define([b4_check_user_names_wrap],
+[m4_ifdef([b4_percent_]$1[_user_]$2[s],
+          [b4_check_user_names([[%]$1 $2],
+                               [b4_percent_]$1[_user_]$2[s],
+                               [[b4_percent_]$1[_bison_]$2[s]])])])
+
+m4_wrap_lifo([
+b4_check_user_names_wrap([[define]], [[variable]])
+b4_check_user_names_wrap([[code]], [[qualifier]])

 ])
 
 ])
 

-b4_check_user_names_wrap([define_variables], [[%define variable]])
-b4_check_user_names_wrap([code_qualifiers], [[%code qualifier]])

 
 

-m4_popdef([b4_check_user_names_wrap])
-])
+## ---------------- ##
+## Default values.  ##
+## ---------------- ##
+
+# m4_define_default([b4_lex_param], [])   dnl breaks other skeletons
+m4_define_default([b4_pre_prologue], [])
+m4_define_default([b4_post_prologue], [])
+m4_define_default([b4_epilogue], [])
+m4_define_default([b4_parse_param], [])
+
+# The initial column and line.
+m4_define_default([b4_location_initial_column], [1])
+m4_define_default([b4_location_initial_line],   [1])
+
+# Sanity checks.
+b4_percent_define_ifdef([api.prefix],
+[m4_ifdef([b4_prefix],
+[b4_complain_at(b4_percent_define_get_loc([api.prefix]),
+                [['%s' and '%s' cannot be used together]],
+                [%name-prefix],
+                [%define api.prefix])])])