7 files changed, 5840 insertions, 0 deletions
diff --git a/tools/mhmake/src/bisondata/bison.m4 b/tools/mhmake/src/bisondata/bison.m4
new file mode 100644
index 000000000..af7c8f7a7
--- /dev/null
+++ b/tools/mhmake/src/bisondata/bison.m4
@@ -0,0 +1,556 @@
+                                                            -*- Autoconf -*-
+
+# Language-independent M4 Macros for Bison.
+# Copyright (C) 2002, 2004, 2005, 2006, 2007, 2008 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
+# 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
+# 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
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+## ---------------- ##
+## Identification.  ##
+## ---------------- ##
+
+# b4_copyright(TITLE, YEARS)
+# --------------------------
+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.], [   ])
+
+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
+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
+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
+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
+under terms of your choice, so long as that work isn't itself a
+parser generator using the skeleton or a modified version thereof
+as a parser skeleton.  Alternatively, if you modify or redistribute
+the parser skeleton itself, you may (at your option) remove this
+special exception, which will cause the skeleton and the resulting
+Bison output files to be licensed under the GNU General Public
+License without this special exception.
+
+This special exception was added by the Free Software Foundation in
+version 2.2 of Bison.])])
+
+
+## ---------------- ##
+## Error handling.  ##
+## ---------------- ##
+
+# 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, FORMAT, [ARG1], [ARG2], ...)
+# -------------------------------------------
+# Write @KIND(FORMAT@,ARG1@,ARG2@,...@) to stdout.
+#
+# For example:
+#
+#   b4_error([[warn]], [[invalid value for `%s': %s]], [[foo]], [[3]])
+m4_define([b4_error],
+[b4_cat([[@]$1[(]$2[]]dnl
+[m4_if([$#], [2], [],
+       [m4_foreach([b4_arg],
+                   m4_dquote(m4_shift(m4_shift($@))),
+                   [[@,]b4_arg])])[@)]])])
+
+# b4_error_at(KIND, START, END, FORMAT, [ARG1], [ARG2], ...)
+# ----------------------------------------------------------
+# Write @KIND_at(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to stdout.
+#
+# For example:
+#
+#   b4_error_at([[complain]], [[input.y:2.3]], [[input.y:5.4]],
+#               [[invalid %s]], [[foo]])
+m4_define([b4_error_at],
+[b4_cat([[@]$1[_at(]$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], ...)
+# ------------------------------------
+# Write @warn(FORMAT@,ARG1@,ARG2@,...@) to stdout.
+#
+# For example:
+#
+#   b4_warn([[invalid value for `%s': %s]], [[foo]], [[3]])
+#
+# As a simple test suite, this:
+#
+#   m4_divert(-1)
+#   m4_define([asdf], [ASDF])
+#   m4_define([fsa], [FSA])
+#   m4_define([fdsa], [FDSA])
+#   b4_warn([[[asdf), asdf]]], [[[fsa), fsa]]], [[[fdsa), fdsa]]])
+#   b4_warn([[asdf), asdf]], [[fsa), fsa]], [[fdsa), fdsa]])
+#   b4_warn()
+#   b4_warn(1)
+#   b4_warn(1, 2)
+#
+# Should produce this without newlines:
+#
+#   @warn([asdf), asdf]@,[fsa), fsa]@,[fdsa), fdsa]@)
+#   @warn(asdf), asdf@,fsa), fsa@,fdsa), fdsa@)
+#   @warn(@)
+#   @warn(1@)
+#   @warn(1@,2@)
+m4_define([b4_warn],
+[b4_error([[warn]], $@)])
+
+# b4_warn_at(START, END, FORMAT, [ARG1], [ARG2], ...)
+# ---------------------------------------------------
+# 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],
+[b4_error_at([[warn]], $@)])
+
+# b4_complain(FORMAT, [ARG1], [ARG2], ...)
+# ----------------------------------------
+# Write @complain(FORMAT@,ARG1@,ARG2@,...@) to stdout.
+#
+# See b4_warn example.
+m4_define([b4_complain],
+[b4_error([[complain]], $@)])
+
+# b4_complain_at(START, END, FORMAT, [ARG1], [ARG2], ...)
+# -------------------------------------------------------
+# Write @complain(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to stdout.
+#
+# See b4_warn_at example.
+m4_define([b4_complain_at],
+[b4_error_at([[complain]], $@)])
+
+# b4_fatal(FORMAT, [ARG1], [ARG2], ...)
+# -------------------------------------
+# Write @fatal(FORMAT@,ARG1@,ARG2@,...@) to stdout and exit.
+#
+# See b4_warn example.
+m4_define([b4_fatal],
+[b4_error([[fatal]], $@)dnl
+m4_exit(1)])
+
+# b4_fatal_at(START, END, FORMAT, [ARG1], [ARG2], ...)
+# ----------------------------------------------------
+# Write @fatal(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to stdout and exit.
+#
+# See b4_warn_at example.
+m4_define([b4_fatal_at],
+[b4_error_at([[fatal]], $@)dnl
+m4_exit(1)])
+
+
+## ---------------- ##
+## 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])
+
+
+## ------------ ##
+## Data Types.  ##
+## ------------ ##
+
+# b4_ints_in(INT1, INT2, LOW, HIGH)
+# ---------------------------------
+# Return 1 iff both INT1 and INT2 are in [LOW, HIGH], 0 otherwise.
+m4_define([b4_ints_in],
+[m4_eval([$3 <= $1 && $1 <= $4 && $3 <= $2 && $2 <= $4])])
+
+
+
+## ------------------ ##
+## Decoding options.  ##
+## ------------------ ##
+
+# b4_flag_if(FLAG, IF-TRUE, IF-FALSE)
+# -----------------------------------
+# Run IF-TRUE if b4_FLAG_flag is 1, IF-FALSE if FLAG is 0, otherwise fail.
+m4_define([b4_flag_if],
+[m4_case(b4_$1_flag,
+         [0], [$3],
+         [1], [$2],
+         [m4_fatal([invalid $1 value: ]$1)])])
+
+
+# b4_define_flag_if(FLAG)
+# -----------------------
+# Define "b4_FLAG_if(IF-TRUE, IF-FALSE)" that depends on the
+# value of the Boolean FLAG.
+m4_define([b4_define_flag_if],
+[_b4_define_flag_if($[1], $[2], [$1])])
+
+# _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.
+m4_define([_b4_define_flag_if],
+[m4_if([$1$2], $[1]$[2], [],
+       [m4_fatal([$0: Invalid arguments: $@])])dnl
+m4_define([b4_$3_if],
+          [b4_flag_if([$3], [$1], [$2])])])
+
+
+# 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([yacc])               # Whether POSIX Yacc is emulated.
+
+
+## ------------------------- ##
+## Assigning token numbers.  ##
+## ------------------------- ##
+
+
+## ----------- ##
+## Synclines.  ##
+## ----------- ##
+
+# b4_basename(NAME)
+# -----------------
+# Similar to POSIX basename; the differences don't matter here.
+# Beware that NAME is not evaluated.
+m4_define([b4_basename],
+[m4_bpatsubst([$1], [^.*/\([^/]+\)/*$], [\1])])
+
+
+# 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])])])
+
+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)
+# -----------------------
+# Emit code from the user, ending it with synclines.
+m4_define([b4_user_code],
+[$1
+b4_syncline([@oline@], [@ofile@])])
+
+
+# b4_define_user_code(MACRO)
+# --------------------------
+# From b4_MACRO, build b4_user_MACRO that includes the synclines.
+m4_define([b4_define_user_code],
+[m4_define([b4_user_$1],
+[b4_user_code([b4_$1])])])
+
+
+# b4_user_actions
+# b4_user_initial_action
+# b4_user_post_prologue
+# b4_user_pre_prologue
+# b4_user_stype
+# ----------------------
+# 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_check_user_names(WHAT, USER-LIST, BISON-NAMESPACE)
+# --------------------------------------------------------
+# Warn 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 must be a triplet specifying one
+# occurrence: name, start boundary, and end boundary.  Empty string names are
+# fine.  An empty list is fine.
+#
+# For example, to define b4_foo_user_names to be used for USER-LIST with three
+# name occurrences and with correct quoting:
+#
+#   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]]]]]])
+#
+# 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 use b4_foo_bison_names for BISON-NAMESPACE and define that
+# the names bar and baz are used by Bison:
+#
+#   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
+# b4_foo_user_names, with BISON-NAMESPACE b4_foo_bison_names, and with correct
+# quoting:
+#
+#   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_ifndef($3[(]m4_quote(b4_user_name)[)],
+          [b4_warn_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
+])])
+
+# b4_percent_define_get(VARIABLE)
+# -------------------------------
+# Mimic muscle_percent_define_get in ../src/muscle_tab.h exactly.  That is, if
+# the %define variable VARIABLE is defined, emit its value.  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],
+[m4_define([b4_percent_define_bison_variables(]$1[)])dnl
+m4_ifdef([b4_percent_define(]$1[)], [m4_indir([b4_percent_define(]$1[)])])])
+
+# 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([[undefined %%define variable `%s' passed to b4_percent_define_get_loc]], [$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([[undefined %%define variable `%s' passed to b4_percent_define_get_syncline]], [$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[)],
+          [m4_define([b4_percent_define_bison_variables(]$1[)])$2],
+          [$3])])
+
+# 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([[undefined %%define variable `%s' passed to b4_percent_define_flag_if]], [$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[)],
+                      [[[[[Bison:b4_percent_define_default]:1.0]], [[[Bison:b4_percent_define_default]:1.0]]]])dnl
+            m4_define([b4_percent_define_syncline(]$1[)],
+                      [[]b4_syncline(1, [["[Bison:b4_percent_define_default]"]])[
+]])])])
+
+# b4_percent_define_check_values(VALUES)
+# --------------------------------------
+# Mimic muscle_percent_define_check_values in ../src/muscle_tab.h exactly
+# except that the VALUES structure is more appropriate for M4.  That is, VALUES
+# is a list of sublists of strings.  For each sublist, the first string is the
+# name of a %define variable, and all remaining strings in that sublist are the
+# valid values for that variable.  Complain if such a variable is undefined (a
+# Bison error since the default value should have been set already) or defined
+# to any other value (possibly a user error).  Don't record this as a Bison
+# usage of the variable as there's no reason to suspect that the value has yet
+# influenced the output.
+#
+# For example:
+#
+#   b4_percent_define_check_values([[[[foo]], [[foo-value1]], [[foo-value2]]]],
+#                                  [[[[bar]], [[bar-value1]]]])
+m4_define([b4_percent_define_check_values],
+[m4_foreach([b4_sublist], m4_quote($@),
+            [_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[)])))])dnl
+   m4_popdef([b4_good_value])],
+  [b4_fatal([[undefined %%define variable `%s' passed to b4_percent_define_check_values]], [$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
+# 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]],
+                   [["%code ]$1["]])[ blocks.]])
+b4_user_code([m4_indir(b4_macro_name)])
+])dnl
+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])])
+
+
+## ----------------------------------------------------------- ##
+## 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]])
+])
diff --git a/tools/mhmake/src/bisondata/c++.m4 b/tools/mhmake/src/bisondata/c++.m4
new file mode 100644
index 000000000..a27064d7b
--- /dev/null
+++ b/tools/mhmake/src/bisondata/c++.m4
@@ -0,0 +1,170 @@
+                                                            -*- Autoconf -*-
+
+# C++ skeleton for Bison
+
+# Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008 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
+# 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
+# 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
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+m4_include(b4_pkgdatadir/[c.m4])
+
+## ---------------- ##
+## Default values.  ##
+## ---------------- ##
+
+# Default parser class name.
+b4_percent_define_default([[parser_class_name]], [[parser]])
+b4_percent_define_default([[location_type]], [[location]])
+b4_percent_define_default([[filename_type]], [[std::string]])
+b4_percent_define_default([[namespace]], m4_defn([b4_prefix]))
+b4_percent_define_default([[global_tokens_and_yystype]], [[false]])
+b4_percent_define_default([[define_location_comparison]],
+                          [m4_if(b4_percent_define_get([[filename_type]]),
+                                 [std::string], [[true]], [[false]])])
+
+
+## ----------- ##
+## Namespace.  ##
+## ----------- ##
+
+m4_define([b4_namespace_ref], [b4_percent_define_get([[namespace]])])
+
+# Don't permit an empty b4_namespace_ref.  Any `::parser::foo' appended to it
+# would compile as an absolute reference with `parser' in the global namespace.
+# b4_namespace_open would open an anonymous namespace and thus establish
+# internal linkage.  This would compile.  However, it's cryptic, and internal
+# linkage for the parser would be specified in all translation units that
+# include the header, which is always generated.  If we ever need to permit
+# internal linkage somehow, surely we can find a cleaner approach.
+m4_if(m4_bregexp(b4_namespace_ref, [^[   ]*$]), [-1], [],
+[b4_complain_at(b4_percent_define_get_loc([[namespace]]),
+                [[namespace reference is empty]])])
+
+# Instead of assuming the C++ compiler will do it, Bison should reject any
+# invalid b4_namepsace_ref that would be converted to a valid
+# b4_namespace_open.  The problem is that Bison doesn't always output
+# b4_namespace_ref to uncommented code but should reserve the ability to do so
+# in future releases without risking breaking any existing user grammars.
+# Specifically, don't allow empty names as b4_namespace_open would just convert
+# those into anonymous namespaces, and that might tempt some users.
+m4_if(m4_bregexp(b4_namespace_ref, [::[  ]*::]), [-1], [],
+[b4_complain_at(b4_percent_define_get_loc([[namespace]]),
+                [[namespace reference has consecutive "::"]])])
+m4_if(m4_bregexp(b4_namespace_ref, [::[  ]*$]), [-1], [],
+[b4_complain_at(b4_percent_define_get_loc([[namespace]]),
+                [[namespace reference has a trailing "::"]])])
+
+m4_define([b4_namespace_open],
+[b4_user_code([b4_percent_define_get_syncline([[namespace]])
+[namespace ]m4_bpatsubst(m4_dquote(m4_bpatsubst(m4_dquote(b4_namespace_ref),
+                                                [^\(.\)[         ]*::], [\1])),
+                         [::], [ { namespace ])[ {]])])
+
+m4_define([b4_namespace_close],
+[b4_user_code([b4_percent_define_get_syncline([[namespace]])
+m4_bpatsubst(m4_dquote(m4_bpatsubst(m4_dquote(b4_namespace_ref),
+                                    [^\(.\)[     ]*\(::\)?\([^][:]\|:[^][:]\)*],
+                                    [\1])),
+             [::\([^][:]\|:[^][:]\)*], [} ])[} // ]b4_namespace_ref])])
+
+
+# b4_token_enums(LIST-OF-PAIRS-TOKEN-NAME-TOKEN-NUMBER)
+# -----------------------------------------------------
+# Output the definition of the tokens as enums.
+m4_define([b4_token_enums],
+[/* Tokens.  */
+   enum yytokentype {
+m4_map_sep([     b4_token_enum], [,
+],
+           [$@])
+   };
+])
+
+
+## ----------------- ##
+## Semantic Values.  ##
+## ----------------- ##
+
+
+# b4_lhs_value([TYPE])
+# --------------------
+# Expansion of $<TYPE>$.
+m4_define([b4_lhs_value],
+[(yyval[]m4_ifval([$1], [.$1]))])
+
+
+# b4_rhs_value(RULE-LENGTH, NUM, [TYPE])
+# --------------------------------------
+# Expansion of $<TYPE>NUM, where the current rule has RULE-LENGTH
+# symbols on RHS.
+m4_define([b4_rhs_value],
+[(yysemantic_stack_@{($1) - ($2)@}m4_ifval([$3], [.$3]))])
+
+# b4_lhs_location()
+# -----------------
+# Expansion of @$.
+m4_define([b4_lhs_location],
+[(yyloc)])
+
+
+# b4_rhs_location(RULE-LENGTH, NUM)
+# ---------------------------------
+# Expansion of @NUM, where the current rule has RULE-LENGTH symbols
+# on RHS.
+m4_define([b4_rhs_location],
+[(yylocation_stack_@{($1) - ($2)@})])
+
+
+# b4_parse_param_decl
+# -------------------
+# Extra formal arguments of the constructor.
+# Change the parameter names from "foo" into "foo_yyarg", so that
+# there is no collision bw the user chosen attribute name, and the
+# argument name in the constructor.
+m4_define([b4_parse_param_decl],
+[m4_ifset([b4_parse_param],
+          [m4_map_sep([b4_parse_param_decl_1], [, ], [b4_parse_param])])])
+
+m4_define([b4_parse_param_decl_1],
+[$1_yyarg])
+
+
+
+# b4_parse_param_cons
+# -------------------
+# Extra initialisations of the constructor.
+m4_define([b4_parse_param_cons],
+          [m4_ifset([b4_parse_param],
+                    [
+      b4_cc_constructor_calls(b4_parse_param)])])
+m4_define([b4_cc_constructor_calls],
+          [m4_map_sep([b4_cc_constructor_call], [,
+      ], [$@])])
+m4_define([b4_cc_constructor_call],
+          [$2 ($2_yyarg)])
+
+# b4_parse_param_vars
+# -------------------
+# Extra instance variables.
+m4_define([b4_parse_param_vars],
+          [m4_ifset([b4_parse_param],
+                    [
+    /* User arguments.  */
+b4_cc_var_decls(b4_parse_param)])])
+m4_define([b4_cc_var_decls],
+          [m4_map_sep([b4_cc_var_decl], [
+], [$@])])
+m4_define([b4_cc_var_decl],
+          [    $1;])
diff --git a/tools/mhmake/src/bisondata/c.m4 b/tools/mhmake/src/bisondata/c.m4
new file mode 100644
index 000000000..2b44b7e49
--- /dev/null
+++ b/tools/mhmake/src/bisondata/c.m4
@@ -0,0 +1,477 @@
+                                                            -*- Autoconf -*-
+
+# C M4 Macros for Bison.
+# Copyright (C) 2002, 2004, 2005, 2006, 2007, 2008 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
+# 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
+# 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
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+## ---------------- ##
+## 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
+# b4_pull_flag if they use the values of the %define variables api.pure or
+# api.push_pull.
+m4_define([b4_identification],
+[[/* Identify Bison output.  */
+#define YYBISON 1
+
+/* Bison version.  */
+#define YYBISON_VERSION "]b4_version["
+
+/* Skeleton name.  */
+#define YYSKELETON_NAME ]b4_skeleton[]m4_ifdef([b4_pure_flag], [[
+
+/* Pure parsers.  */
+#define YYPURE ]b4_pure_flag])[]m4_ifdef([b4_push_flag], [[
+
+/* Push parsers.  */
+#define YYPUSH ]b4_push_flag])[]m4_ifdef([b4_pull_flag], [[
+
+/* Pull parsers.  */
+#define YYPULL ]b4_pull_flag])[
+
+/* Using locations.  */
+#define YYLSP_NEEDED ]b4_locations_flag[
+]])
+
+
+## ---------------- ##
+## Default values.  ##
+## ---------------- ##
+
+# If the %union is not named, its name is YYSTYPE.
+m4_define_default([b4_union_name], [YYSTYPE])
+
+# If the %name-prefix is not given, it is yy.
+m4_define_default([b4_prefix], [yy])
+
+## ------------------------ ##
+## Pure/impure interfaces.  ##
+## ------------------------ ##
+
+# b4_user_args
+# ------------
+m4_define([b4_user_args],
+[m4_ifset([b4_parse_param], [, b4_c_args(b4_parse_param)])])
+
+
+# b4_parse_param
+# --------------
+# If defined, b4_parse_param arrives double quoted, but below we prefer
+# it to be single quoted.
+m4_define([b4_parse_param],
+b4_parse_param)
+
+
+# b4_parse_param_for(DECL, FORMAL, BODY)
+# ---------------------------------------
+# Iterate over the user parameters, binding the declaration to DECL,
+# the formal name to FORMAL, and evaluating the BODY.
+m4_define([b4_parse_param_for],
+[m4_foreach([$1_$2], m4_defn([b4_parse_param]),
+[m4_pushdef([$1], m4_unquote(m4_car($1_$2)))dnl
+m4_pushdef([$2], m4_shift($1_$2))dnl
+$3[]dnl
+m4_popdef([$2])dnl
+m4_popdef([$1])dnl
+])])
+
+# b4_parse_param_use
+# ------------------
+# `YYUSE' all the parse-params.
+m4_define([b4_parse_param_use],
+[b4_parse_param_for([Decl], [Formal], [  YYUSE (Formal);
+])dnl
+])
+
+
+## ------------ ##
+## Data Types.  ##
+## ------------ ##
+
+# b4_int_type(MIN, MAX)
+# ---------------------
+# Return the smallest int type able to handle numbers ranging from
+# MIN to MAX (included).
+m4_define([b4_int_type],
+[m4_if(b4_ints_in($@,      [0],   [255]), [1], [unsigned char],
+       b4_ints_in($@,   [-128],   [127]), [1], [signed char],
+
+       b4_ints_in($@,      [0], [65535]), [1], [unsigned short int],
+       b4_ints_in($@, [-32768], [32767]), [1], [short int],
+
+       m4_eval([0 <= $1]),                [1], [unsigned int],
+
+                                               [int])])
+
+
+# b4_int_type_for(NAME)
+# ---------------------
+# Return the smallest int type able to handle numbers ranging from
+# `NAME_min' to `NAME_max' (included).
+m4_define([b4_int_type_for],
+[b4_int_type($1_min, $1_max)])
+
+
+
+## ---------##
+## Values.  ##
+## ---------##
+
+# b4_null
+---------
+# Return a null pointer constant.  NULL infringes on the user name
+# space in C, so use 0 rather than NULL.
+m4_define([b4_null], [0])
+
+
+
+
+## ------------------------- ##
+## Assigning token numbers.  ##
+## ------------------------- ##
+
+# b4_token_define(TOKEN-NAME, TOKEN-NUMBER)
+# -----------------------------------------
+# Output the definition of this token as #define.
+m4_define([b4_token_define],
+[#define $1 $2
+])
+
+
+# b4_token_defines(LIST-OF-PAIRS-TOKEN-NAME-TOKEN-NUMBER)
+# -------------------------------------------------------
+# Output the definition of the tokens (if there are) as #defines.
+m4_define([b4_token_defines],
+[m4_if([$#$1], [1], [],
+[/* Tokens.  */
+m4_map([b4_token_define], [$@])])
+])
+
+
+# b4_token_enum(TOKEN-NAME, TOKEN-NUMBER)
+# ---------------------------------------
+# Output the definition of this token as an enum.
+m4_define([b4_token_enum],
+[$1 = $2])
+
+
+# b4_token_enums(LIST-OF-PAIRS-TOKEN-NAME-TOKEN-NUMBER)
+# -----------------------------------------------------
+# Output the definition of the tokens (if there are) as enums.
+m4_define([b4_token_enums],
+[m4_if([$#$1], [1], [],
+[/* Tokens.  */
+#ifndef YYTOKENTYPE
+# define YYTOKENTYPE
+   /* Put the tokens into the symbol table, so that GDB and other debuggers
+      know about them.  */
+   enum yytokentype {
+m4_map_sep([     b4_token_enum], [,
+],
+           [$@])
+   };
+#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.
+m4_define([b4_token_enums_defines],
+[b4_token_enums($@)b4_yacc_if([b4_token_defines($@)], [])
+])
+
+
+
+## --------------------------------------------- ##
+## Defining C functions in both K&R and ANSI-C.  ##
+## --------------------------------------------- ##
+
+
+# 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
+])
+
+
+# b4_c_ansi_function_def(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
+# ---------------------------------------------------------------
+# Declare the function NAME in ANSI.
+m4_define([b4_c_ansi_function_def],
+[$2
+$1 (b4_c_ansi_formals(m4_shift2($@)))[]dnl
+])
+
+
+# b4_c_ansi_formals([DECL1, NAME1], ...)
+# --------------------------------------
+# Output the arguments ANSI-C definition.
+m4_define([b4_c_ansi_formals],
+[m4_if([$#], [0], [void],
+       [$#$1], [1], [void],
+               [m4_map_sep([b4_c_ansi_formal], [, ], [$@])])])
+
+m4_define([b4_c_ansi_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],
+[$2])
+
+
+# b4_c_knr_formal_decls([DECL1, NAME1], ...)
+# ------------------------------------------
+# Output the K&R argument declarations.
+m4_define([b4_c_knr_formal_decls],
+[m4_map_sep([b4_c_knr_formal_decl],
+            [
+],
+            [$@])])
+
+m4_define([b4_c_knr_formal_decl],
+[    $1;])
+
+
+
+## ------------------------------------------------------------ ##
+## Declaring (prototyping) C functions in both K&R and ANSI-C.  ##
+## ------------------------------------------------------------ ##
+
+
+# b4_c_function_decl(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
+# -----------------------------------------------------------
+# Declare the function NAME.
+m4_define([b4_c_function_decl],
+[#if defined __STDC__ || defined __cplusplus
+b4_c_ansi_function_decl($@)
+#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
+])
+
+
+
+
+## --------------------- ##
+## Calling C functions.  ##
+## --------------------- ##
+
+
+# b4_c_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
+])
+
+
+# b4_c_args([DECL1, NAME1], ...)
+# ------------------------------
+# Output the arguments NAME1, NAME2...
+m4_define([b4_c_args],
+[m4_map_sep([b4_c_arg], [, ], [$@])])
+
+m4_define([b4_c_arg],
+[$2])
+
+
+## ----------- ##
+## Synclines.  ##
+## ----------- ##
+
+# b4_sync_start(LINE, FILE)
+# -----------------------
+m4_define([b4_sync_start], [[#]line $1 $2])
+
+
+## -------------- ##
+## User actions.  ##
+## -------------- ##
+
+# b4_case(LABEL, STATEMENTS)
+# --------------------------
+m4_define([b4_case],
+[  case $1:
+$2
+    break;])
+
+# b4_symbol_actions(FILENAME, LINENO,
+#                   SYMBOL-TAG, SYMBOL-NUM,
+#                   SYMBOL-ACTION, SYMBOL-TYPENAME)
+# -------------------------------------------------
+m4_define([b4_symbol_actions],
+[m4_pushdef([b4_dollar_dollar],
+   [m4_ifval([$6], [(yyvaluep->$6)], [(*yyvaluep)])])dnl
+m4_pushdef([b4_at_dollar], [(*yylocationp)])dnl
+      case $4: /* $3 */
+b4_syncline([$2], [$1])
+        $5;
+b4_syncline([@oline@], [@ofile@])
+        break;
+m4_popdef([b4_at_dollar])dnl
+m4_popdef([b4_dollar_dollar])dnl
+])
+
+
+# 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],
+[[/*-----------------------------------------------.
+| Release the memory associated to this symbol.  |
+`-----------------------------------------------*/
+
+/*ARGSUSED*/
+]$1([yydestruct],
+    [static void],
+    [[const char *yymsg],    [yymsg]],
+    [[int yytype],           [yytype]],
+    [[YYSTYPE *yyvaluep],    [yyvaluep]][]dnl
+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)
+    yymsg = "Deleting";
+  YY_SYMBOL_PRINT (yymsg, yytype, yyvaluep, yylocationp);
+
+  switch (yytype)
+    {
+]m4_map([b4_symbol_actions], m4_defn([b4_symbol_destructors]))[
+      default:
+        break;
+    }
+}]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],
+[[
+/*--------------------------------.
+| Print this symbol on YYOUTPUT.  |
+`--------------------------------*/
+
+/*ARGSUSED*/
+]$1([yy_symbol_value_print],
+    [static void],
+               [[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 (!yyvaluep)
+    return;
+]b4_locations_if([  YYUSE (yylocationp);
+])dnl
+b4_parse_param_use[]dnl
+[# 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;
+    }
+}
+
+
+/*--------------------------------.
+| Print this symbol on YYOUTPUT.  |
+`--------------------------------*/
+
+]$1([yy_symbol_print],
+    [static void],
+               [[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]);
+
+]b4_locations_if([  YY_LOCATION_PRINT (yyoutput, *yylocationp);
+  YYFPRINTF (yyoutput, ": ");
+])dnl
+[  yy_symbol_value_print (yyoutput, yytype, yyvaluep]dnl
+b4_locations_if([, yylocationp])[]b4_user_args[);
+  YYFPRINTF (yyoutput, ")");
+}]dnl
+])
diff --git a/tools/mhmake/src/bisondata/lalr1.cc b/tools/mhmake/src/bisondata/lalr1.cc
new file mode 100644
index 000000000..25dd01938
--- /dev/null
+++ b/tools/mhmake/src/bisondata/lalr1.cc
@@ -0,0 +1,1169 @@
+# C++ skeleton for Bison
+
+# Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+# 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
+# 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
+# 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
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+m4_include(b4_pkgdatadir/[c++.m4])
+
+m4_define([b4_parser_class_name],
+          [b4_percent_define_get([[parser_class_name]])])
+
+m4_define([b4_parser_base_class_name],
+          [b4_percent_define_get([[parser_base_class_name]])])
+
+m4_define([b4_parser_class_constructor_init],
+          [b4_percent_define_get([[parser_class_constructor_init]])])
+
+m4_define([b4_parser_class_constructor_param],
+          [b4_percent_define_get([[parser_class_constructor_param]])])
+
+# The header is mandatory.
+b4_defines_if([],
+              [b4_fatal([b4_skeleton[: using %%defines is mandatory]])])
+
+# Backward compatibility.
+m4_define([b4_location_constructors])
+m4_include(b4_pkgdatadir/[location.cc])
+
+# We do want M4 expansion after # for CPP macros.
+m4_changecom()
+m4_divert_push(0)dnl
+b4_defines_if(
+[@output(b4_spec_defines_file@)
+b4_copyright([Skeleton interface for Bison LALR(1) parsers in C++],
+             [2002, 2003, 2004, 2005, 2006, 2007, 2008])
+dnl FIXME: This is wrong, we want computed header guards.
+[
+/* C++ LALR(1) parser skeleton written by Akim Demaille.  */
+
+#ifndef PARSER_HEADER_H
+# define PARSER_HEADER_H
+
+]b4_percent_code_get([[requires]])[
+
+#include <string>
+#include <iostream>
+#include "stack.hh"
+
+]b4_namespace_open[
+  class position;
+  class location;
+]b4_namespace_close[
+
+#include "location.hh"
+
+/* Enabling traces.  */
+#ifndef YYDEBUG
+# define YYDEBUG ]b4_debug_flag[
+#endif
+
+/* Enabling verbose error messages.  */
+#ifdef YYERROR_VERBOSE
+# undef YYERROR_VERBOSE
+# define YYERROR_VERBOSE 1
+#else
+# define YYERROR_VERBOSE ]b4_error_verbose_flag[
+#endif
+
+/* Enabling the token table.  */
+#ifndef YYTOKEN_TABLE
+# define YYTOKEN_TABLE ]b4_token_table[
+#endif
+
+/* YYLLOC_DEFAULT -- Set CURRENT to span from RHS[1] to RHS[N].
+   If N is 0, then set CURRENT to the empty location which ends
+   the previous symbol: RHS[0] (always defined).  */
+
+#ifndef YYLLOC_DEFAULT
+# define YYLLOC_DEFAULT(Current, Rhs, N)                \
+do {                                                    \
+  if (N)                                                \
+    {                                                   \
+      (Current).begin = (Rhs)[1].begin;                 \
+      (Current).end   = (Rhs)[N].end;                   \
+    }                                                   \
+  else                                                  \
+    {                                                   \
+      (Current).begin = (Current).end = (Rhs)[0].end;   \
+    }                                                   \
+} while (false)
+#endif
+
+]b4_namespace_open[
+
+  /// A Bison parser.
+  class ]b4_parser_class_name[ : public ]b4_parser_base_class_name[
+  {
+  public:
+    /// Symbol semantic values.
+#ifndef YYSTYPE
+]m4_ifdef([b4_stype],
+[    union semantic_type
+    {
+b4_user_stype
+    };],
+[m4_if(b4_tag_seen_flag, 0,
+[[    typedef int semantic_type;]],
+[[    typedef YYSTYPE semantic_type;]])])[
+#else
+    typedef YYSTYPE semantic_type;
+#endif
+    /// Symbol locations.
+    typedef ]b4_percent_define_get([[location_type]])[ location_type;
+    /// Tokens.
+    struct token
+    {
+      ]b4_token_enums(b4_tokens)[
+    };
+    /// Token type.
+    typedef token::yytokentype token_type;
+
+    /// Build a parser object.
+    ]b4_parser_class_name[ (]b4_parse_param_decl[ ]b4_parser_class_constructor_param[ );
+    virtual ~]b4_parser_class_name[ ();
+
+    /// Parse.
+    /// \returns  0 iff parsing succeeded.
+    virtual int parse ();
+
+#if YYDEBUG
+    /// The current debugging stream.
+    std::ostream& debug_stream () const;
+    /// Set the current debugging stream.
+    void set_debug_stream (std::ostream &);
+
+    /// Type for debugging levels.
+    typedef int debug_level_type;
+    /// The current debugging level.
+    debug_level_type debug_level () const;
+    /// Set the current debugging level.
+    void set_debug_level (debug_level_type l);
+#endif
+
+  private:
+    /// Report a syntax error.
+    /// \param loc    where the syntax error is found.
+    /// \param msg    a description of the syntax error.
+    virtual void error (const location_type& loc, const std::string& msg);
+
+    /// Generate an error message.
+    /// \param state   the state where the error occurred.
+    /// \param tok     the lookahead token.
+    virtual std::string yysyntax_error_ (int yystate]dnl
+b4_error_verbose_if([, int tok])[);
+
+#if YYDEBUG
+    /// \brief Report a symbol value on the debug stream.
+    /// \param yytype       The token type.
+    /// \param yyvaluep     Its semantic value.
+    /// \param yylocationp  Its location.
+    virtual void yy_symbol_value_print_ (int yytype,
+                                         const semantic_type* yyvaluep,
+                                         const location_type* yylocationp);
+    /// \brief Report a symbol on the debug stream.
+    /// \param yytype       The token type.
+    /// \param yyvaluep     Its semantic value.
+    /// \param yylocationp  Its location.
+    virtual void yy_symbol_print_ (int yytype,
+                                   const semantic_type* yyvaluep,
+                                   const location_type* yylocationp);
+#endif
+
+
+    /// State numbers.
+    typedef int state_type;
+    /// State stack type.
+    typedef stack<state_type>    state_stack_type;
+    /// Semantic value stack type.
+    typedef stack<semantic_type> semantic_stack_type;
+    /// location stack type.
+    typedef stack<location_type> location_stack_type;
+
+    /// The state stack.
+    state_stack_type yystate_stack_;
+    /// The semantic value stack.
+    semantic_stack_type yysemantic_stack_;
+    /// The location stack.
+    location_stack_type yylocation_stack_;
+
+    /// Internal symbol numbers.
+    typedef ]b4_int_type_for([b4_translate])[ token_number_type;
+    /* Tables.  */
+    /// For a state, the index in \a yytable_ of its portion.
+    static const ]b4_int_type_for([b4_pact])[ yypact_[];
+    static const ]b4_int_type(b4_pact_ninf, b4_pact_ninf)[ yypact_ninf_;
+
+    /// For a state, default rule to reduce.
+    /// Unless\a  yytable_ specifies something else to do.
+    /// Zero means the default is an error.
+    static const ]b4_int_type_for([b4_defact])[ yydefact_[];
+
+    static const ]b4_int_type_for([b4_pgoto])[ yypgoto_[];
+    static const ]b4_int_type_for([b4_defgoto])[ yydefgoto_[];
+
+    /// What to do in a state.
+    /// \a yytable_[yypact_[s]]: what to do in state \a s.
+    /// - if positive, shift that token.
+    /// - if negative, reduce the rule which number is the opposite.
+    /// - if zero, do what YYDEFACT says.
+    static const ]b4_int_type_for([b4_table])[ yytable_[];
+    static const ]b4_int_type(b4_table_ninf, b4_table_ninf)[ yytable_ninf_;
+
+    static const ]b4_int_type_for([b4_check])[ yycheck_[];
+
+    /// For a state, its accessing symbol.
+    static const ]b4_int_type_for([b4_stos])[ yystos_[];
+
+    /// For a rule, its LHS.
+    static const ]b4_int_type_for([b4_r1])[ yyr1_[];
+    /// For a rule, its RHS length.
+    static const ]b4_int_type_for([b4_r2])[ yyr2_[];
+
+#if YYDEBUG || YYERROR_VERBOSE || YYTOKEN_TABLE
+    /// For a symbol, its name in clear.
+    static const char* const yytname_[];
+#endif
+
+#if YYERROR_VERBOSE
+    /// Convert the symbol name \a n to a form suitable for a diagnostic.
+    virtual std::string yytnamerr_ (const char *n);
+#endif
+
+#if YYDEBUG
+    /// A type to store symbol numbers and -1.
+    typedef ]b4_int_type_for([b4_rhs])[ rhs_number_type;
+    /// A `-1'-separated list of the rules' RHS.
+    static const rhs_number_type yyrhs_[];
+    /// For each rule, the index of the first RHS symbol in \a yyrhs_.
+    static const ]b4_int_type_for([b4_prhs])[ yyprhs_[];
+    /// For each rule, its source line number.
+    static const ]b4_int_type_for([b4_rline])[ yyrline_[];
+    /// For each scanner token number, its symbol number.
+    static const ]b4_int_type_for([b4_toknum])[ yytoken_number_[];
+    /// Report on the debug stream that the rule \a r is going to be reduced.
+    virtual void yy_reduce_print_ (int r);
+    /// Print the state stack on the debug stream.
+    virtual void yystack_print_ ();
+
+    /* Debugging.  */
+    int yydebug_;
+    std::ostream* yycdebug_;
+#endif
+
+    /// Convert a scanner token number \a t to a symbol number.
+    token_number_type yytranslate_ (int t);
+
+    /// \brief Reclaim the memory associated to a symbol.
+    /// \param yymsg        Why this token is reclaimed.
+    /// \param yytype       The symbol type.
+    /// \param yyvaluep     Its semantic value.
+    /// \param yylocationp  Its location.
+    inline void yydestruct_ (const char* yymsg,
+                             int yytype,
+                             semantic_type* yyvaluep,
+                             location_type* yylocationp);
+
+    /// Pop \a n symbols the three stacks.
+    inline void yypop_ (unsigned int n = 1);
+
+    /* Constants.  */
+    static const int yyeof_;
+    /* LAST_ -- Last index in TABLE_.  */
+    static const int yylast_;
+    static const int yynnts_;
+    static const int yyempty_;
+    static const int yyfinal_;
+    static const int yyterror_;
+    static const int yyerrcode_;
+    static const int yyntokens_;
+    static const unsigned int yyuser_token_number_max_;
+    static const token_number_type yyundef_token_;
+]b4_parse_param_vars[
+  };
+]b4_namespace_close[
+
+]b4_percent_define_flag_if([[global_tokens_and_yystype]],
+[b4_token_defines(b4_tokens)
+
+#ifndef YYSTYPE
+ /* Redirection for backward compatibility.  */
+# define YYSTYPE b4_namespace_ref::b4_parser_class_name::semantic_type
+#endif
+])
+b4_percent_code_get([[provides]])[]dnl
+
+[#endif /* ! defined PARSER_HEADER_H */]
+])dnl
+@output(b4_parser_file_name@)
+b4_copyright([Skeleton implementation for Bison LALR(1) parsers in C++],
+             [2002, 2003, 2004, 2005, 2006, 2007, 2008])
+b4_percent_code_get([[top]])[]dnl
+m4_if(b4_prefix, [yy], [],
+[
+// Take the name prefix into account.
+#define yylex   b4_prefix[]lex])[
+
+/* First part of user declarations.  */
+]b4_user_pre_prologue
+
+b4_defines_if([[
+#include "@basename(]b4_spec_defines_file[@)"]])[
+
+/* User implementation prologue.  */
+]b4_user_post_prologue
+b4_percent_code_get[]dnl
+
+[#ifndef YY_
+# if YYENABLE_NLS
+#  if ENABLE_NLS
+#   include <libintl.h> /* FIXME: INFRINGES ON USER NAME SPACE */
+#   define YY_(msgid) dgettext ("bison-runtime", msgid)
+#  endif
+# endif
+# ifndef YY_
+#  define YY_(msgid) msgid
+# endif
+#endif
+
+/* Suppress unused-variable warnings by "using" E.  */
+#define YYUSE(e) ((void) (e))
+
+/* Enable debugging if requested.  */
+#if YYDEBUG
+
+/* A pseudo ostream that takes yydebug_ into account.  */
+# define YYCDEBUG if (yydebug_) (*yycdebug_)
+
+# define YY_SYMBOL_PRINT(Title, Type, Value, Location)  \
+do {                                                    \
+  if (yydebug_)                                         \
+    {                                                   \
+      *yycdebug_ << Title << ' ';                       \
+      yy_symbol_print_ ((Type), (Value), (Location));   \
+      *yycdebug_ << std::endl;                          \
+    }                                                   \
+} while (false)
+
+# define YY_REDUCE_PRINT(Rule)          \
+do {                                    \
+  if (yydebug_)                         \
+    yy_reduce_print_ (Rule);            \
+} while (false)
+
+# define YY_STACK_PRINT()               \
+do {                                    \
+  if (yydebug_)                         \
+    yystack_print_ ();                  \
+} while (false)
+
+#else /* !YYDEBUG */
+
+# define YYCDEBUG if (false) std::cerr
+# define YY_SYMBOL_PRINT(Title, Type, Value, Location)
+# define YY_REDUCE_PRINT(Rule)
+# define YY_STACK_PRINT()
+
+#endif /* !YYDEBUG */
+
+#define yyerrok         (yyerrstatus_ = 0)
+#define yyclearin       (yychar = yyempty_)
+
+#define YYACCEPT        goto yyacceptlab
+#define YYABORT         goto yyabortlab
+#define YYERROR         goto yyerrorlab
+#define YYRECOVERING()  (!!yyerrstatus_)
+
+]b4_namespace_open[
+#if YYERROR_VERBOSE
+
+  /* Return YYSTR after stripping away unnecessary quotes and
+     backslashes, so that it's suitable for yyerror.  The heuristic is
+     that double-quoting is unnecessary unless the string contains an
+     apostrophe, a comma, or backslash (other than backslash-backslash).
+     YYSTR is taken from yytname.  */
+  std::string
+  ]b4_parser_class_name[::yytnamerr_ (const char *yystr)
+  {
+    if (*yystr == '"')
+      {
+        std::string yyr = "";
+        char const *yyp = yystr;
+
+        for (;;)
+          switch (*++yyp)
+            {
+            case '\'':
+            case ',':
+              goto do_not_strip_quotes;
+
+            case '\\':
+              if (*++yyp != '\\')
+                goto do_not_strip_quotes;
+              /* Fall through.  */
+            default:
+              yyr += *yyp;
+              break;
+
+            case '"':
+              return yyr;
+            }
+      do_not_strip_quotes: ;
+      }
+
+    return yystr;
+  }
+
+#endif
+
+  /// Build a parser object.
+  ]b4_parser_class_name::b4_parser_class_name[ (]b4_parse_param_decl[ ]b4_parser_class_constructor_param[) ]b4_parser_class_constructor_init[ ]m4_ifset([b4_parse_param], [
+    :])[
+
+#if YYDEBUG
+    ]m4_ifset([b4_parse_param], [  ], [ :])[yydebug_ (false),
+      yycdebug_ (&std::cerr)]m4_ifset([b4_parse_param], [,])[
+#endif]b4_parse_param_cons[
+  {
+  }
+
+  ]b4_parser_class_name::~b4_parser_class_name[ ()
+  {
+  }
+
+#if YYDEBUG
+  /*--------------------------------.
+  | Print this symbol on YYOUTPUT.  |
+  `--------------------------------*/
+
+  inline void
+  ]b4_parser_class_name[::yy_symbol_value_print_ (int yytype,
+                           const semantic_type* yyvaluep, const location_type* yylocationp)
+  {
+    YYUSE (yylocationp);
+    YYUSE (yyvaluep);
+    switch (yytype)
+      {
+  ]m4_map([b4_symbol_actions], m4_defn([b4_symbol_printers]))dnl
+[       default:
+          break;
+      }
+  }
+
+
+  void
+  ]b4_parser_class_name[::yy_symbol_print_ (int yytype,
+                           const semantic_type* yyvaluep, const location_type* yylocationp)
+  {
+    *yycdebug_ << (yytype < yyntokens_ ? "token" : "nterm")
+               << ' ' << yytname_[yytype] << " ("
+               << *yylocationp << ": ";
+    yy_symbol_value_print_ (yytype, yyvaluep, yylocationp);
+    *yycdebug_ << ')';
+  }
+#endif
+
+  void
+  ]b4_parser_class_name[::yydestruct_ (const char* yymsg,
+                           int yytype, semantic_type* yyvaluep, location_type* yylocationp)
+  {
+    YYUSE (yylocationp);
+    YYUSE (yymsg);
+    YYUSE (yyvaluep);
+
+    YY_SYMBOL_PRINT (yymsg, yytype, yyvaluep, yylocationp);
+
+]m4_ifset([b4_symbol_actions], [  ], [
+    switch (yytype)
+      {
+  ]m4_map([b4_symbol_actions], m4_defn([b4_symbol_destructors]))[
+        default:
+          break;
+      }
+    ])[
+  }
+
+  void
+  ]b4_parser_class_name[::yypop_ (unsigned int n)
+  {
+    yystate_stack_.pop (n);
+    yysemantic_stack_.pop (n);
+    yylocation_stack_.pop (n);
+  }
+
+#if YYDEBUG
+  std::ostream&
+  ]b4_parser_class_name[::debug_stream () const
+  {
+    return *yycdebug_;
+  }
+
+  void
+  ]b4_parser_class_name[::set_debug_stream (std::ostream& o)
+  {
+    yycdebug_ = &o;
+  }
+
+
+  ]b4_parser_class_name[::debug_level_type
+  ]b4_parser_class_name[::debug_level () const
+  {
+    return yydebug_;
+  }
+
+  void
+  ]b4_parser_class_name[::set_debug_level (debug_level_type l)
+  {
+    yydebug_ = l;
+  }
+#endif
+
+  int
+  ]b4_parser_class_name[::parse ()
+  {
+    /// Lookahead and lookahead in internal form.
+    int yychar = yyempty_;
+    int yytoken = 0;
+
+    /* State.  */
+    int yyn;
+    int yylen = 0;
+    int yystate = 0;
+
+    /* Error handling.  */
+    int yynerrs_ = 0;
+    int yyerrstatus_ = 0;
+
+    /// Semantic value of the lookahead.
+    semantic_type yylval;
+    /// Location of the lookahead.
+    location_type yylloc;
+    /// The locations where the error started and ended.
+    location_type yyerror_range[2];
+
+    /// $$.
+    semantic_type yyval;
+    /// @@$.
+    location_type yyloc;
+
+    int yyresult;
+
+    YYCDEBUG << "Starting parse" << std::endl;
+
+]m4_ifdef([b4_initial_action], [
+m4_pushdef([b4_at_dollar],     [yylloc])dnl
+m4_pushdef([b4_dollar_dollar], [yylval])dnl
+    /* User initialization code.  */
+    b4_user_initial_action
+m4_popdef([b4_dollar_dollar])dnl
+m4_popdef([b4_at_dollar])])dnl
+
+  [  /* Initialize the stacks.  The initial state will be pushed in
+       yynewstate, since the latter expects the semantical and the
+       location values to have been already stored, initialize these
+       stacks with a primary value.  */
+    yystate_stack_ = state_stack_type (0);
+    yysemantic_stack_ = semantic_stack_type (0);
+    yylocation_stack_ = location_stack_type (0);
+    yysemantic_stack_.push (yylval);
+    yylocation_stack_.push (yylloc);
+
+    /* New state.  */
+  yynewstate:
+    yystate_stack_.push (yystate);
+    YYCDEBUG << "Entering state " << yystate << std::endl;
+
+    /* Accept?  */
+    if (yystate == yyfinal_)
+      goto yyacceptlab;
+
+    goto yybackup;
+
+    /* Backup.  */
+  yybackup:
+
+    /* Try to take a decision without lookahead.  */
+    yyn = yypact_[yystate];
+    if (yyn == yypact_ninf_)
+      goto yydefault;
+
+    /* Read a lookahead token.  */
+    if (yychar == yyempty_)
+      {
+        YYCDEBUG << "Reading a token: ";
+        yychar = ]b4_c_function_call([yylex], [int],
+                                     [[YYSTYPE*], [&yylval]][]dnl
+b4_locations_if([, [[location*], [&yylloc]]])dnl
+m4_ifdef([b4_lex_param], [, ]b4_lex_param))[;
+      }
+
+
+    /* Convert token to internal form.  */
+    if (yychar <= yyeof_)
+      {
+        yychar = yytoken = yyeof_;
+        YYCDEBUG << "Now at end of input." << std::endl;
+      }
+    else
+      {
+        yytoken = yytranslate_ (yychar);
+        YY_SYMBOL_PRINT ("Next token is", yytoken, &yylval, &yylloc);
+      }
+
+    /* If the proper action on seeing token YYTOKEN is to reduce or to
+       detect an error, take that action.  */
+    yyn += yytoken;
+    if (yyn < 0 || yylast_ < yyn || yycheck_[yyn] != yytoken)
+      goto yydefault;
+
+    /* Reduce or error.  */
+    yyn = yytable_[yyn];
+    if (yyn <= 0)
+      {
+        if (yyn == 0 || yyn == yytable_ninf_)
+        goto yyerrlab;
+        yyn = -yyn;
+        goto yyreduce;
+      }
+
+    /* Shift the lookahead token.  */
+    YY_SYMBOL_PRINT ("Shifting", yytoken, &yylval, &yylloc);
+
+    /* Discard the token being shifted.  */
+    yychar = yyempty_;
+
+    yysemantic_stack_.push (yylval);
+    yylocation_stack_.push (yylloc);
+
+    /* Count tokens shifted since error; after three, turn off error
+       status.  */
+    if (yyerrstatus_)
+      --yyerrstatus_;
+
+    yystate = yyn;
+    goto yynewstate;
+
+  /*-----------------------------------------------------------.
+  | yydefault -- do the default action for the current state.  |
+  `-----------------------------------------------------------*/
+  yydefault:
+    yyn = yydefact_[yystate];
+    if (yyn == 0)
+      goto yyerrlab;
+    goto yyreduce;
+
+  /*-----------------------------.
+  | yyreduce -- Do a reduction.  |
+  `-----------------------------*/
+  yyreduce:
+    yylen = yyr2_[yyn];
+    /* If YYLEN is nonzero, implement the default value of the action:
+       `$$ = $1'.  Otherwise, use the top of the stack.
+
+       Otherwise, the following line sets YYVAL to garbage.
+       This behavior is undocumented and Bison
+       users should not rely upon it.  */
+    if (yylen)
+      yyval = yysemantic_stack_[yylen - 1];
+    else
+      yyval = yysemantic_stack_[0];
+
+    {
+      slice<location_type, location_stack_type> slice (yylocation_stack_, yylen);
+      YYLLOC_DEFAULT (yyloc, slice, yylen);
+    }
+    YY_REDUCE_PRINT (yyn);
+    switch (yyn)
+      {
+        ]b4_user_actions[
+        default:
+          break;
+      }
+    YY_SYMBOL_PRINT ("-> $$ =", yyr1_[yyn], &yyval, &yyloc);
+
+    yypop_ (yylen);
+    yylen = 0;
+    YY_STACK_PRINT ();
+
+    yysemantic_stack_.push (yyval);
+    yylocation_stack_.push (yyloc);
+
+    /* Shift the result of the reduction.  */
+    yyn = yyr1_[yyn];
+    yystate = yypgoto_[yyn - yyntokens_] + yystate_stack_[0];
+    if (0 <= yystate && yystate <= yylast_
+        && yycheck_[yystate] == yystate_stack_[0])
+      yystate = yytable_[yystate];
+    else
+      yystate = yydefgoto_[yyn - yyntokens_];
+    goto yynewstate;
+
+  /*------------------------------------.
+  | yyerrlab -- here on detecting error |
+  `------------------------------------*/
+  yyerrlab:
+    /* If not already recovering from an error, report this error.  */
+    if (!yyerrstatus_)
+      {
+        ++yynerrs_;
+        error (yylloc, yysyntax_error_ (yystate]dnl
+b4_error_verbose_if([, yytoken])[));
+      }
+
+    yyerror_range[0] = yylloc;
+    if (yyerrstatus_ == 3)
+      {
+        /* If just tried and failed to reuse lookahead token after an
+         error, discard it.  */
+
+        if (yychar <= yyeof_)
+          {
+          /* Return failure if at end of input.  */
+          if (yychar == yyeof_)
+            YYABORT;
+          }
+        else
+          {
+            yydestruct_ ("Error: discarding", yytoken, &yylval, &yylloc);
+            yychar = yyempty_;
+          }
+      }
+
+    /* Else will try to reuse lookahead token after shifting the error
+       token.  */
+    goto yyerrlab1;
+
+
+  /*---------------------------------------------------.
+  | yyerrorlab -- error raised explicitly by YYERROR.  |
+  `---------------------------------------------------*/
+  yyerrorlab:
+
+    /* Pacify compilers like GCC when the user code never invokes
+       YYERROR and the label yyerrorlab therefore never appears in user
+       code.  */
+    if (false)
+      goto yyerrorlab;
+
+    yyerror_range[0] = yylocation_stack_[yylen - 1];
+    /* Do not reclaim the symbols of the rule which action triggered
+       this YYERROR.  */
+    yypop_ (yylen);
+    yylen = 0;
+    yystate = yystate_stack_[0];
+    goto yyerrlab1;
+
+  /*-------------------------------------------------------------.
+  | yyerrlab1 -- common code for both syntax error and YYERROR.  |
+  `-------------------------------------------------------------*/
+  yyerrlab1:
+    yyerrstatus_ = 3;   /* Each real token shifted decrements this.  */
+
+    for (;;)
+      {
+        yyn = yypact_[yystate];
+        if (yyn != yypact_ninf_)
+        {
+          yyn += yyterror_;
+          if (0 <= yyn && yyn <= yylast_ && yycheck_[yyn] == yyterror_)
+            {
+              yyn = yytable_[yyn];
+              if (0 < yyn)
+                break;
+            }
+        }
+
+        /* Pop the current state because it cannot handle the error token.  */
+        if (yystate_stack_.height () == 1)
+        YYABORT;
+
+        yyerror_range[0] = yylocation_stack_[0];
+        yydestruct_ ("Error: popping",
+                     yystos_[yystate],
+                     &yysemantic_stack_[0], &yylocation_stack_[0]);
+        yypop_ ();
+        yystate = yystate_stack_[0];
+        YY_STACK_PRINT ();
+      }
+
+    yyerror_range[1] = yylloc;
+    // Using YYLLOC is tempting, but would change the location of
+    // the lookahead.  YYLOC is available though.
+    YYLLOC_DEFAULT (yyloc, (yyerror_range - 1), 2);
+    yysemantic_stack_.push (yylval);
+    yylocation_stack_.push (yyloc);
+
+    /* Shift the error token.  */
+    YY_SYMBOL_PRINT ("Shifting", yystos_[yyn],
+                     &yysemantic_stack_[0], &yylocation_stack_[0]);
+
+    yystate = yyn;
+    goto yynewstate;
+
+    /* Accept.  */
+  yyacceptlab:
+    yyresult = 0;
+    goto yyreturn;
+
+    /* Abort.  */
+  yyabortlab:
+    yyresult = 1;
+    goto yyreturn;
+
+  yyreturn:
+    if (yychar != yyempty_)
+      yydestruct_ ("Cleanup: discarding lookahead", yytoken, &yylval, &yylloc);
+
+    /* Do not reclaim the symbols of the rule which action triggered
+       this YYABORT or YYACCEPT.  */
+    yypop_ (yylen);
+    while (yystate_stack_.height () != 1)
+      {
+        yydestruct_ ("Cleanup: popping",
+                   yystos_[yystate_stack_[0]],
+                   &yysemantic_stack_[0],
+                   &yylocation_stack_[0]);
+        yypop_ ();
+      }
+
+    return yyresult;
+  }
+
+  // Generate an error message.
+  std::string
+  ]b4_parser_class_name[::yysyntax_error_ (int yystate]dnl
+b4_error_verbose_if([, int tok])[)
+  {
+    std::string res;
+    YYUSE (yystate);
+#if YYERROR_VERBOSE
+    int yyn = yypact_[yystate];
+    if (yypact_ninf_ < yyn && yyn <= yylast_)
+      {
+        /* Start YYX at -YYN if negative to avoid negative indexes in
+           YYCHECK.  */
+        int yyxbegin = yyn < 0 ? -yyn : 0;
+
+        /* Stay within bounds of both yycheck and yytname.  */
+        int yychecklim = yylast_ - yyn + 1;
+        int yyxend = yychecklim < yyntokens_ ? yychecklim : yyntokens_;
+        int count = 0;
+        for (int x = yyxbegin; x < yyxend; ++x)
+          if (yycheck_[x + yyn] == x && x != yyterror_)
+            ++count;
+
+        // FIXME: This method of building the message is not compatible
+        // with internationalization.  It should work like yacc.c does it.
+        // That is, first build a string that looks like this:
+        // "syntax error, unexpected %s or %s or %s"
+        // Then, invoke YY_ on this string.
+        // Finally, use the string as a format to output
+        // yytname_[tok], etc.
+        // Until this gets fixed, this message appears in English only.
+        res = "syntax error, unexpected ";
+        res += yytnamerr_ (yytname_[tok]);
+        if (count < 5)
+          {
+            count = 0;
+            for (int x = yyxbegin; x < yyxend; ++x)
+              if (yycheck_[x + yyn] == x && x != yyterror_)
+                {
+                  res += (!count++) ? ", expecting " : " or ";
+                  res += yytnamerr_ (yytname_[x]);
+                }
+          }
+      }
+    else
+#endif
+      res = YY_("syntax error");
+    return res;
+  }
+
+
+  /* YYPACT[STATE-NUM] -- Index in YYTABLE of the portion describing
+     STATE-NUM.  */
+  const ]b4_int_type(b4_pact_ninf, b4_pact_ninf) b4_parser_class_name::yypact_ninf_ = b4_pact_ninf[;
+  const ]b4_int_type_for([b4_pact])[
+  ]b4_parser_class_name[::yypact_[] =
+  {
+    ]b4_pact[
+  };
+
+  /* YYDEFACT[S] -- default rule to reduce with in state S when YYTABLE
+     doesn't specify something else to do.  Zero means the default is an
+     error.  */
+  const ]b4_int_type_for([b4_defact])[
+  ]b4_parser_class_name[::yydefact_[] =
+  {
+    ]b4_defact[
+  };
+
+  /* YYPGOTO[NTERM-NUM].  */
+  const ]b4_int_type_for([b4_pgoto])[
+  ]b4_parser_class_name[::yypgoto_[] =
+  {
+    ]b4_pgoto[
+  };
+
+  /* YYDEFGOTO[NTERM-NUM].  */
+  const ]b4_int_type_for([b4_defgoto])[
+  ]b4_parser_class_name[::yydefgoto_[] =
+  {
+    ]b4_defgoto[
+  };
+
+  /* YYTABLE[YYPACT[STATE-NUM]].  What to do in state STATE-NUM.  If
+     positive, shift that token.  If negative, reduce the rule which
+     number is the opposite.  If zero, do what YYDEFACT says.  */
+  const ]b4_int_type(b4_table_ninf, b4_table_ninf) b4_parser_class_name::yytable_ninf_ = b4_table_ninf[;
+  const ]b4_int_type_for([b4_table])[
+  ]b4_parser_class_name[::yytable_[] =
+  {
+    ]b4_table[
+  };
+
+  /* YYCHECK.  */
+  const ]b4_int_type_for([b4_check])[
+  ]b4_parser_class_name[::yycheck_[] =
+  {
+    ]b4_check[
+  };
+
+  /* STOS_[STATE-NUM] -- The (internal number of the) accessing
+     symbol of state STATE-NUM.  */
+  const ]b4_int_type_for([b4_stos])[
+  ]b4_parser_class_name[::yystos_[] =
+  {
+    ]b4_stos[
+  };
+
+#if YYDEBUG
+  /* TOKEN_NUMBER_[YYLEX-NUM] -- Internal symbol number corresponding
+     to YYLEX-NUM.  */
+  const ]b4_int_type_for([b4_toknum])[
+  ]b4_parser_class_name[::yytoken_number_[] =
+  {
+    ]b4_toknum[
+  };
+#endif
+
+  /* YYR1[YYN] -- Symbol number of symbol that rule YYN derives.  */
+  const ]b4_int_type_for([b4_r1])[
+  ]b4_parser_class_name[::yyr1_[] =
+  {
+    ]b4_r1[
+  };
+
+  /* YYR2[YYN] -- Number of symbols composing right hand side of rule YYN.  */
+  const ]b4_int_type_for([b4_r2])[
+  ]b4_parser_class_name[::yyr2_[] =
+  {
+    ]b4_r2[
+  };
+
+#if YYDEBUG || YYERROR_VERBOSE || YYTOKEN_TABLE
+  /* YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
+     First, the terminals, then, starting at \a yyntokens_, nonterminals.  */
+  const char*
+  const ]b4_parser_class_name[::yytname_[] =
+  {
+    ]b4_tname[
+  };
+#endif
+
+#if YYDEBUG
+  /* YYRHS -- A `-1'-separated list of the rules' RHS.  */
+  const ]b4_parser_class_name[::rhs_number_type
+  ]b4_parser_class_name[::yyrhs_[] =
+  {
+    ]b4_rhs[
+  };
+
+  /* YYPRHS[YYN] -- Index of the first RHS symbol of rule number YYN in
+     YYRHS.  */
+  const ]b4_int_type_for([b4_prhs])[
+  ]b4_parser_class_name[::yyprhs_[] =
+  {
+    ]b4_prhs[
+  };
+
+  /* YYRLINE[YYN] -- Source line where rule number YYN was defined.  */
+  const ]b4_int_type_for([b4_rline])[
+  ]b4_parser_class_name[::yyrline_[] =
+  {
+    ]b4_rline[
+  };
+
+  // Print the state stack on the debug stream.
+  void
+  ]b4_parser_class_name[::yystack_print_ ()
+  {
+    *yycdebug_ << "Stack now";
+    for (state_stack_type::const_iterator i = yystate_stack_.begin ();
+         i != yystate_stack_.end (); ++i)
+      *yycdebug_ << ' ' << *i;
+    *yycdebug_ << std::endl;
+  }
+
+  // Report on the debug stream that the rule \a yyrule is going to be reduced.
+  void
+  ]b4_parser_class_name[::yy_reduce_print_ (int yyrule)
+  {
+    unsigned int yylno = yyrline_[yyrule];
+    int yynrhs = yyr2_[yyrule];
+    /* Print the symbols being reduced, and their result.  */
+    *yycdebug_ << "Reducing stack by rule " << yyrule - 1
+               << " (line " << yylno << "):" << std::endl;
+    /* The symbols being reduced.  */
+    for (int yyi = 0; yyi < yynrhs; yyi++)
+      YY_SYMBOL_PRINT ("   $" << yyi + 1 << " =",
+                       yyrhs_[yyprhs_[yyrule] + yyi],
+                       &]b4_rhs_value(yynrhs, yyi + 1)[,
+                       &]b4_rhs_location(yynrhs, yyi + 1)[);
+  }
+#endif // YYDEBUG
+
+  /* YYTRANSLATE(YYLEX) -- Bison symbol number corresponding to YYLEX.  */
+  ]b4_parser_class_name[::token_number_type
+  ]b4_parser_class_name[::yytranslate_ (int t)
+  {
+    static
+    const token_number_type
+    translate_table[] =
+    {
+      ]b4_translate[
+    };
+    if ((unsigned int) t <= yyuser_token_number_max_)
+      return translate_table[t];
+    else
+      return yyundef_token_;
+  }
+
+  const int ]b4_parser_class_name[::yyeof_ = 0;
+  const int ]b4_parser_class_name[::yylast_ = ]b4_last[;
+  const int ]b4_parser_class_name[::yynnts_ = ]b4_nterms_number[;
+  const int ]b4_parser_class_name[::yyempty_ = -2;
+  const int ]b4_parser_class_name[::yyfinal_ = ]b4_final_state_number[;
+  const int ]b4_parser_class_name[::yyterror_ = 1;
+  const int ]b4_parser_class_name[::yyerrcode_ = 256;
+  const int ]b4_parser_class_name[::yyntokens_ = ]b4_tokens_number[;
+
+  const unsigned int ]b4_parser_class_name[::yyuser_token_number_max_ = ]b4_user_token_number_max[;
+  const ]b4_parser_class_name[::token_number_type ]b4_parser_class_name[::yyundef_token_ = ]b4_undef_token_number[;
+
+]b4_namespace_close[
+
+]b4_epilogue
+dnl
+@output(b4_dir_prefix[]stack.hh@)
+b4_copyright([Stack handling for Bison parsers in C++],
+             [2002, 2003, 2004, 2005, 2006, 2007, 2008])[
+
+#ifndef BISON_STACK_HH
+# define BISON_STACK_HH
+
+#include <deque>
+
+]b4_namespace_open[
+  template <class T, class S = std::deque<T> >
+  class stack
+  {
+  public:
+
+    // Hide our reversed order.
+    typedef typename S::reverse_iterator iterator;
+    typedef typename S::const_reverse_iterator const_iterator;
+
+    stack () : seq_ ()
+    {
+    }
+
+    stack (unsigned int n) : seq_ (n)
+    {
+    }
+
+    inline
+    T&
+    operator [] (unsigned int i)
+    {
+      return seq_[i];
+    }
+
+    inline
+    const T&
+    operator [] (unsigned int i) const
+    {
+      return seq_[i];
+    }
+
+    inline
+    void
+    push (const T& t)
+    {
+      seq_.push_front (t);
+    }
+
+    inline
+    void
+    pop (unsigned int n = 1)
+    {
+      for (; n; --n)
+        seq_.pop_front ();
+    }
+
+    inline
+    unsigned int
+    height () const
+    {
+      return seq_.size ();
+    }
+
+    inline const_iterator begin () const { return seq_.rbegin (); }
+    inline const_iterator end () const { return seq_.rend (); }
+
+  private:
+
+    S seq_;
+  };
+
+  /// Present a slice of the top of a stack.
+  template <class T, class S = stack<T> >
+  class slice
+  {
+  public:
+
+    slice (const S& stack,
+           unsigned int range) : stack_ (stack),
+                                 range_ (range)
+    {
+    }
+
+    inline
+    const T&
+    operator [] (unsigned int i) const
+    {
+      return stack_[range_ - i];
+    }
+
+  private:
+
+    const S& stack_;
+    unsigned int range_;
+  };
+]b4_namespace_close[
+
+#endif // not BISON_STACK_HH[]dnl
+]
+m4_divert_pop(0)
diff --git a/tools/mhmake/src/bisondata/location.cc b/tools/mhmake/src/bisondata/location.cc
new file mode 100644
index 000000000..e142e5115
--- /dev/null
+++ b/tools/mhmake/src/bisondata/location.cc
@@ -0,0 +1,279 @@
+# C++ skeleton for Bison
+
+# Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007 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
+# 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
+# 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
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# We do want M4 expansion after # for CPP macros.
+m4_changecom()
+m4_divert_push(0)dnl
+@output(b4_dir_prefix[]position.hh@)
+b4_copyright([Positions for Bison parsers in C++],
+  [2002, 2003, 2004, 2005, 2006])[
+
+/**
+ ** \file position.hh
+ ** Define the ]b4_namespace_ref[::position class.
+ */
+
+#ifndef BISON_POSITION_HH
+# define BISON_POSITION_HH
+
+# include <iostream>
+# include <string>
+# include <algorithm>
+
+]b4_namespace_open[
+  /// Abstract a position.
+  class position
+  {
+  public:
+]m4_ifdef([b4_location_constructors], [
+    /// Construct a position.
+    position ()
+      : filename (0), line (]b4_location_initial_line[), column (]b4_location_initial_column[)
+    {
+    }
+
+])[
+    /// Initialization.
+    inline void initialize (]b4_percent_define_get([[filename_type]])[* fn)
+    {
+      filename = fn;
+      line = ]b4_location_initial_line[;
+      column = ]b4_location_initial_column[;
+    }
+
+    /** \name Line and Column related manipulators
+     ** \{ */
+  public:
+    /// (line related) Advance to the COUNT next lines.
+    inline void lines (int count = 1)
+    {
+      column = ]b4_location_initial_column[;
+      line += count;
+    }
+    /// (column related) Advance to the COUNT next columns.
+    inline void columns (int count = 1)
+    {
+      column = std::max (]b4_location_initial_column[u, column + count);
+    }
+    /** \} */
+
+  public:
+    /// File name to which this position refers.
+    ]b4_percent_define_get([[filename_type]])[* filename;
+    /// Current line number.
+    unsigned int line;
+    /// Current column number.
+    unsigned int column;
+  };
+
+  /// Add and assign a position.
+  inline const position&
+  operator+= (position& res, const int width)
+  {
+    res.columns (width);
+    return res;
+  }
+
+  /// Add two position objects.
+  inline const position
+  operator+ (const position& begin, const int width)
+  {
+    position res = begin;
+    return res += width;
+  }
+
+  /// Add and assign a position.
+  inline const position&
+  operator-= (position& res, const int width)
+  {
+    return res += -width;
+  }
+
+  /// Add two position objects.
+  inline const position
+  operator- (const position& begin, const int width)
+  {
+    return begin + -width;
+  }
+]b4_percent_define_flag_if([[define_location_comparison]], [[
+  /// Compare two position objects.
+  inline bool
+  operator== (const position& pos1, const position& pos2)
+  {
+    return
+      (pos1.filename == pos2.filename
+       || pos1.filename && pos2.filename && *pos1.filename == *pos2.filename)
+      && pos1.line == pos2.line && pos1.column == pos2.column;
+  }
+
+  /// Compare two position objects.
+  inline bool
+  operator!= (const position& pos1, const position& pos2)
+  {
+    return !(pos1 == pos2);
+  }
+]])[
+  /** \brief Intercept output stream redirection.
+   ** \param ostr the destination output stream
+   ** \param pos a reference to the position to redirect
+   */
+  inline std::ostream&
+  operator<< (std::ostream& ostr, const position& pos)
+  {
+    if (pos.filename)
+      ostr << *pos.filename << ':';
+    return ostr << pos.line << '.' << pos.column;
+  }
+
+]b4_namespace_close[
+#endif // not BISON_POSITION_HH]
+@output(b4_dir_prefix[]location.hh@)
+b4_copyright([Locations for Bison parsers in C++],
+  [2002, 2003, 2004, 2005, 2006])[
+
+/**
+ ** \file location.hh
+ ** Define the ]b4_namespace_ref[::location class.
+ */
+
+#ifndef BISON_LOCATION_HH
+# define BISON_LOCATION_HH
+
+# include <iostream>
+# include <string>
+# include "position.hh"
+
+]b4_namespace_open[
+
+  /// Abstract a location.
+  class location
+  {
+  public:
+]m4_ifdef([b4_location_constructors], [
+    /// Construct a location.
+    location ()
+      : begin (), end ()
+    {
+    }
+
+])[
+    /// Initialization.
+    inline void initialize (]b4_percent_define_get([[filename_type]])[* fn)
+    {
+      begin.initialize (fn);
+      end = begin;
+    }
+
+    /** \name Line and Column related manipulators
+     ** \{ */
+  public:
+    /// Reset initial location to final location.
+    inline void step ()
+    {
+      begin = end;
+    }
+
+    /// Extend the current location to the COUNT next columns.
+    inline void columns (unsigned int count = 1)
+    {
+      end += count;
+    }
+
+    /// Extend the current location to the COUNT next lines.
+    inline void lines (unsigned int count = 1)
+    {
+      end.lines (count);
+    }
+    inline void incline ()
+    {
+      lines(1);
+      step();
+    }
+    /** \} */
+
+
+  public:
+    /// Beginning of the located region.
+    position begin;
+    /// End of the located region.
+    position end;
+  };
+
+  /// Join two location objects to create a location.
+  inline const location operator+ (const location& begin, const location& end)
+  {
+    location res = begin;
+    res.end = end.end;
+    return res;
+  }
+
+  /// Add two location objects.
+  inline const location operator+ (const location& begin, unsigned int width)
+  {
+    location res = begin;
+    res.columns (width);
+    return res;
+  }
+
+  /// Add and assign a location.
+  inline location& operator+= (location& res, unsigned int width)
+  {
+    res.columns (width);
+    return res;
+  }
+]b4_percent_define_flag_if([[define_location_comparison]], [[
+  /// Compare two location objects.
+  inline bool
+  operator== (const location& loc1, const location& loc2)
+  {
+    return loc1.begin == loc2.begin && loc1.end == loc2.end;
+  }
+
+  /// Compare two location objects.
+  inline bool
+  operator!= (const location& loc1, const location& loc2)
+  {
+    return !(loc1 == loc2);
+  }
+]])[
+  /** \brief Intercept output stream redirection.
+   ** \param ostr the destination output stream
+   ** \param loc a reference to the location to redirect
+   **
+   ** Avoid duplicate information.
+   */
+  inline std::ostream& operator<< (std::ostream& ostr, const location& loc)
+  {
+    position last = loc.end - 1;
+    ostr << loc.begin;
+    if (last.filename
+        && (!loc.begin.filename
+            || *loc.begin.filename != *last.filename))
+      ostr << '-' << last;
+    else if (loc.begin.line != last.line)
+      ostr << '-' << last.line  << '.' << last.column;
+    else if (loc.begin.column != last.column)
+      ostr << '-' << last.column;
+    return ostr;
+  }
+
+]b4_namespace_close[
+
+#endif // not BISON_LOCATION_HH]
+m4_divert_pop(0)
+m4_changecom([#])
diff --git a/tools/mhmake/src/bisondata/m4sugar/foreach.m4 b/tools/mhmake/src/bisondata/m4sugar/foreach.m4
new file mode 100644
index 000000000..f6b724d77
--- /dev/null
+++ b/tools/mhmake/src/bisondata/m4sugar/foreach.m4
@@ -0,0 +1,400 @@
+#                                                  -*- Autoconf -*-
+# This file is part of Autoconf.
+# foreach-based replacements for recursive functions.
+# Speeds up GNU M4 1.4.x by avoiding quadratic $@ recursion, but penalizes
+# GNU M4 1.6 by requiring more memory and macro expansions.
+#
+# Copyright (C) 2008 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
+# 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
+# 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
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# As a special exception, the Free Software Foundation gives unlimited
+# permission to copy, distribute and modify the configure scripts that
+# are the output of Autoconf.  You need not follow the terms of the GNU
+# General Public License when using or distributing such scripts, even
+# though portions of the text of Autoconf appear in them.  The GNU
+# General Public License (GPL) does govern all other use of the material
+# that constitutes the Autoconf program.
+#
+# Certain portions of the Autoconf source text are designed to be copied
+# (in certain cases, depending on the input) into the output of
+# Autoconf.  We call these the "data" portions.  The rest of the Autoconf
+# source text consists of comments plus executable code that decides which
+# of the data portions to output in any given case.  We call these
+# comments and executable code the "non-data" portions.  Autoconf never
+# copies any of the non-data portions into its output.
+#
+# This special exception to the GPL applies to versions of Autoconf
+# released by the Free Software Foundation.  When you make and
+# distribute a modified version of Autoconf, you may extend this special
+# exception to the GPL to apply to your modified version as well, *unless*
+# your modified version has the potential to copy into its output some
+# of the text that was the non-data portion of the version that you started
+# with.  (In other words, unless your change moves or copies text from
+# the non-data portions to the data portions.)  If your modification has
+# such potential, you must delete any notice of this special exception
+# to the GPL from your modified version.
+#
+# Written by Eric Blake.
+#
+
+# In M4 1.4.x, every byte of $@ is rescanned.  This means that an
+# algorithm on n arguments that recurses with one less argument each
+# iteration will scan n * (n + 1) / 2 arguments, for O(n^2) time.  In
+# M4 1.6, this was fixed so that $@ is only scanned once, then
+# back-references are made to information stored about the scan.
+# Thus, n iterations need only scan n arguments, for O(n) time.
+# Additionally, in M4 1.4.x, recursive algorithms did not clean up
+# memory very well, requiring O(n^2) memory rather than O(n) for n
+# iterations.
+#
+# This file is designed to overcome the quadratic nature of $@
+# recursion by writing a variant of m4_foreach that uses m4_for rather
+# than $@ recursion to operate on the list.  This involves more macro
+# expansions, but avoids the need to rescan a quadratic number of
+# arguments, making these replacements very attractive for M4 1.4.x.
+# On the other hand, in any version of M4, expanding additional macros
+# costs additional time; therefore, in M4 1.6, where $@ recursion uses
+# fewer macros, these replacements actually pessimize performance.
+# Additionally, the use of $10 to mean the tenth argument violates
+# POSIX; although all versions of m4 1.4.x support this meaning, a
+# future m4 version may switch to take it as the first argument
+# concatenated with a literal 0, so the implementations in this file
+# are not future-proof.  Thus, this file is conditionally included as
+# part of m4_init(), only when it is detected that M4 probably has
+# quadratic behavior (ie. it lacks the macro __m4_version__).
+#
+# Please keep this file in sync with m4sugar.m4.
+
+# m4_foreach(VARIABLE, LIST, EXPRESSION)
+# --------------------------------------
+# Expand EXPRESSION assigning each value of the LIST to VARIABLE.
+# LIST should have the form `item_1, item_2, ..., item_n', i.e. the
+# whole list must *quoted*.  Quote members too if you don't want them
+# to be expanded.
+#
+# This version minimizes the number of times that $@ is evaluated by
+# using m4_for to generate a boilerplate into VARIABLE then passing $@
+# to that temporary macro.  Thus, the recursion is done in m4_for
+# without reparsing any user input, and is not quadratic.  For an idea
+# of how this works, note that m4_foreach(i,[1,2],[i]) defines i to be
+#   m4_define([$1],[$3])$2[]m4_define([$1],[$4])$2[]m4_popdef([i])
+# then calls i([i],[i],[1],[2]).
+m4_define([m4_foreach],
+[m4_if([$2], [], [], [_$0([$1], [$3], $2)])])
+
+m4_define([_m4_foreach],
+[m4_define([$1], m4_pushdef([$1])_m4_for([$1], [3], [$#], [1],
+    [$0_([1], [2], _m4_defn([$1]))])[m4_popdef([$1])])m4_indir([$1], $@)])
+
+m4_define([_m4_foreach_],
+[[m4_define([$$1], [$$3])$$2[]]])
+
+# m4_case(SWITCH, VAL1, IF-VAL1, VAL2, IF-VAL2, ..., DEFAULT)
+# -----------------------------------------------------------
+# Find the first VAL that SWITCH matches, and expand the corresponding
+# IF-VAL.  If there are no matches, expand DEFAULT.
+#
+# Use m4_for to create a temporary macro in terms of a boilerplate
+# m4_if with final cleanup.  If $# is even, we have DEFAULT; if it is
+# odd, then rounding the last $# up in the temporary macro is
+# harmless.  For example, both m4_case(1,2,3,4,5) and
+# m4_case(1,2,3,4,5,6) result in the intermediate _m4_case being
+#   m4_if([$1],[$2],[$3],[$1],[$4],[$5],_m4_popdef([_m4_case])[$6])
+m4_define([m4_case],
+[m4_if(m4_eval([$# <= 2]), [1], [$2],
+[m4_pushdef([_$0], [m4_if(]m4_for([_m4_count], [2], m4_decr([$#]), [2],
+     [_$0_([1], _m4_count, m4_incr(_m4_count))])[_m4_popdef(
+         [_$0])]m4_dquote($m4_eval([($# + 1) & ~1]))[)])_$0($@)])])
+
+m4_define([_m4_case_],
+[[[$$1],[$$2],[$$3],]])
+
+# m4_bmatch(SWITCH, RE1, VAL1, RE2, VAL2, ..., DEFAULT)
+# -----------------------------------------------------
+# m4 equivalent of
+#
+# if (SWITCH =~ RE1)
+#   VAL1;
+# elif (SWITCH =~ RE2)
+#   VAL2;
+# elif ...
+#   ...
+# else
+#   DEFAULT
+#
+# We build the temporary macro _m4_b:
+#   m4_define([_m4_b], _m4_defn([_m4_bmatch]))_m4_b([$1], [$2], [$3])...
+#   _m4_b([$1], [$m-1], [$m])_m4_b([], [], [$m+1]_m4_popdef([_m4_b]))
+# then invoke m4_unquote(_m4_b($@)), for concatenation with later text.
+m4_define([m4_bmatch],
+[m4_if([$#], 0, [m4_fatal([$0: too few arguments: $#])],
+       [$#], 1, [m4_fatal([$0: too few arguments: $#: $1])],
+       [$#], 2, [$2],
+       [m4_define([_m4_b], m4_pushdef([_m4_b])[m4_define([_m4_b],
+  _m4_defn([_$0]))]_m4_for([_m4_b], [3], m4_eval([($# + 1) / 2 * 2 - 1]),
+  [2], [_$0_([1], m4_decr(_m4_b), _m4_b)])[_m4_b([], [],]m4_dquote(
+  [$]m4_incr(_m4_b))[_m4_popdef([_m4_b]))])m4_unquote(_m4_b($@))])])
+
+m4_define([_m4_bmatch],
+[m4_if(m4_bregexp([$1], [$2]), [-1], [], [[$3]m4_define([$0])])])
+
+m4_define([_m4_bmatch_],
+[[_m4_b([$$1], [$$2], [$$3])]])
+
+
+# m4_cond(TEST1, VAL1, IF-VAL1, TEST2, VAL2, IF-VAL2, ..., [DEFAULT])
+# -------------------------------------------------------------------
+# Similar to m4_if, except that each TEST is expanded when encountered.
+# If the expansion of TESTn matches the string VALn, the result is IF-VALn.
+# The result is DEFAULT if no tests passed.  This macro allows
+# short-circuiting of expensive tests, where it pays to arrange quick
+# filter tests to run first.
+#
+# m4_cond already guarantees either 3*n or 3*n + 1 arguments, 1 <= n.
+# We only have to speed up _m4_cond, by building the temporary _m4_c:
+#   m4_define([_m4_c], _m4_defn([m4_unquote]))_m4_c([m4_if(($1), [($2)],
+#   [[$3]m4_define([_m4_c])])])_m4_c([m4_if(($4), [($5)],
+#   [[$6]m4_define([_m4_c])])])..._m4_c([m4_if(($m-2), [($m-1)],
+#   [[$m]m4_define([_m4_c])])])_m4_c([[$m+1]]_m4_popdef([_m4_c]))
+# We invoke m4_unquote(_m4_c($@)), for concatenation with later text.
+m4_define([_m4_cond],
+[m4_define([_m4_c], m4_pushdef([_m4_c])[m4_define([_m4_c],
+  _m4_defn([m4_unquote]))]_m4_for([_m4_c], [2], m4_eval([$# / 3 * 3 - 1]), [3],
+  [$0_(m4_decr(_m4_c), _m4_c, m4_incr(_m4_c))])[_m4_c(]m4_dquote(m4_dquote(
+  [$]m4_eval([$# / 3 * 3 + 1])))[_m4_popdef([_m4_c]))])m4_unquote(_m4_c($@))])
+
+m4_define([_m4_cond_],
+[[_m4_c([m4_if(($$1), [($$2)], [[$$3]m4_define([_m4_c])])])]])
+
+# m4_bpatsubsts(STRING, RE1, SUBST1, RE2, SUBST2, ...)
+# ----------------------------------------------------
+# m4 equivalent of
+#
+#   $_ = STRING;
+#   s/RE1/SUBST1/g;
+#   s/RE2/SUBST2/g;
+#   ...
+#
+# m4_bpatsubsts already validated an odd number of arguments; we only
+# need to speed up _m4_bpatsubsts.  To avoid nesting, we build the
+# temporary _m4_p:
+#   m4_define([_m4_p], [$1])m4_define([_m4_p],
+#   m4_bpatsubst(m4_dquote(_m4_defn([_m4_p])), [$2], [$3]))m4_define([_m4_p],
+#   m4_bpatsubst(m4_dquote(_m4_defn([_m4_p])), [$4], [$5]))m4_define([_m4_p],...
+#   m4_bpatsubst(m4_dquote(_m4_defn([_m4_p])), [$m-1], [$m]))m4_unquote(
+#   _m4_defn([_m4_p])_m4_popdef([_m4_p]))
+m4_define([_m4_bpatsubsts],
+[m4_define([_m4_p], m4_pushdef([_m4_p])[m4_define([_m4_p],
+  ]m4_dquote([$]1)[)]_m4_for([_m4_p], [3], [$#], [2], [$0_(m4_decr(_m4_p),
+  _m4_p)])[m4_unquote(_m4_defn([_m4_p])_m4_popdef([_m4_p]))])_m4_p($@)])
+
+m4_define([_m4_bpatsubsts_],
+[[m4_define([_m4_p],
+m4_bpatsubst(m4_dquote(_m4_defn([_m4_p])), [$$1], [$$2]))]])
+
+# m4_shiftn(N, ...)
+# -----------------
+# Returns ... shifted N times.  Useful for recursive "varargs" constructs.
+#
+# m4_shiftn already validated arguments; we only need to speed up
+# _m4_shiftn.  If N is 3, then we build the temporary _m4_s, defined as
+#   ,[$5],[$6],...,[$m]_m4_popdef([_m4_s])
+# before calling m4_shift(_m4_s($@)).
+m4_define([_m4_shiftn],
+[m4_if(m4_incr([$1]), [$#], [], [m4_define([_m4_s],
+           m4_pushdef([_m4_s])_m4_for([_m4_s], m4_eval([$1 + 2]), [$#], [1],
+  [[,]m4_dquote([$]_m4_s)])[_m4_popdef([_m4_s])])m4_shift(_m4_s($@))])])
+
+# m4_do(STRING, ...)
+# ------------------
+# This macro invokes all its arguments (in sequence, of course).  It is
+# useful for making your macros more structured and readable by dropping
+# unnecessary dnl's and have the macros indented properly.
+#
+# Here, we use the temporary macro _m4_do, defined as
+#   $1[]$2[]...[]$n[]_m4_popdef([_m4_do])
+m4_define([m4_do],
+[m4_if([$#], [0], [],
+       [m4_define([_$0], m4_pushdef([_$0])_m4_for([_$0], [1], [$#], [1],
+                  [$_$0[[]]])[_m4_popdef([_$0])])_$0($@)])])
+
+# m4_dquote_elt(ARGS)
+# -------------------
+# Return ARGS as an unquoted list of double-quoted arguments.
+#
+# m4_foreach to the rescue.  It's easier to shift off the leading comma.
+m4_define([m4_dquote_elt],
+[m4_shift(m4_foreach([_m4_elt], [$@], [,m4_dquote(_m4_defn([_m4_elt]))]))])
+
+# m4_reverse(ARGS)
+# ----------------
+# Output ARGS in reverse order.
+#
+# Invoke _m4_r($@) with the temporary _m4_r built as
+#   [$m], [$m-1], ..., [$2], [$1]_m4_popdef([_m4_r])
+m4_define([m4_reverse],
+[m4_if([$#], [0], [], [$#], [1], [[$1]],
+[m4_define([_m4_r], m4_dquote([$$#])m4_pushdef([_m4_r])_m4_for([_m4_r],
+      m4_decr([$#]), [1], [-1],
+    [[, ]m4_dquote([$]_m4_r)])[_m4_popdef([_m4_r])])_m4_r($@)])])
+
+
+# m4_map(MACRO, LIST)
+# -------------------
+# Invoke MACRO($1), MACRO($2) etc. where $1, $2... are the elements
+# of LIST.  $1, $2... must in turn be lists, appropriate for m4_apply.
+#
+# m4_map/m4_map_sep only execute once; the speedup comes in fixing
+# _m4_map.  The mismatch in () is intentional, since $1 supplies the
+# opening `(' (but it sure looks odd!).  Build the temporary _m4_m:
+#   $1, [$3])$1, [$4])...$1, [$m])_m4_popdef([_m4_m])
+m4_define([_m4_map],
+[m4_if([$#], [2], [],
+       [m4_define([_m4_m], m4_pushdef([_m4_m])_m4_for([_m4_m], [3], [$#], [1],
+   [$0_([1], _m4_m)])[_m4_popdef([_m4_m])])_m4_m($@)])])
+
+m4_define([_m4_map_],
+[[$$1, [$$2])]])
+
+# m4_transform(EXPRESSION, ARG...)
+# --------------------------------
+# Expand EXPRESSION([ARG]) for each argument.  More efficient than
+# m4_foreach([var], [ARG...], [EXPRESSION(m4_defn([var]))])
+#
+# Invoke the temporary macro _m4_transform, defined as:
+#   $1([$2])[]$1([$3])[]...$1([$m])[]_m4_popdef([_m4_transform])
+m4_define([m4_transform],
+[m4_if([$#], [0], [m4_fatal([$0: too few arguments: $#])],
+       [$#], [1], [],
+       [m4_define([_$0], m4_pushdef([_$0])_m4_for([_$0], [2], [$#], [1],
+   [_$0_([1], _$0)])[_m4_popdef([_$0])])_$0($@)])])
+
+m4_define([_m4_transform_],
+[[$$1([$$2])[]]])
+
+# m4_transform_pair(EXPRESSION, [END-EXPR = EXPRESSION], ARG...)
+# --------------------------------------------------------------
+# Perform a pairwise grouping of consecutive ARGs, by expanding
+# EXPRESSION([ARG1], [ARG2]).  If there are an odd number of ARGs, the
+# final argument is expanded with END-EXPR([ARGn]).
+#
+# Build the temporary macro _m4_transform_pair, with the $2([$m+1])
+# only output if $# is odd:
+#   $1([$3], [$4])[]$1([$5], [$6])[]...$1([$m-1],
+#   [$m])[]m4_default([$2], [$1])([$m+1])[]_m4_popdef([_m4_transform_pair])
+m4_define([m4_transform_pair],
+[m4_if([$#], [0], [m4_fatal([$0: too few arguments: $#])],
+       [$#], [1], [m4_fatal([$0: too few arguments: $#: $1])],
+       [$#], [2], [],
+       [$#], [3], [m4_default([$2], [$1])([$3])[]],
+       [m4_define([_$0], m4_pushdef([_$0])_m4_for([_$0], [3],
+   m4_eval([$# / 2 * 2 - 1]), [2], [_$0_([1], _$0, m4_incr(_$0))])_$0_end(
+   [1], [2], [$#])[_m4_popdef([_$0])])_$0($@)])])
+
+m4_define([_m4_transform_pair_],
+[[$$1([$$2], [$$3])[]]])
+
+m4_define([_m4_transform_pair_end],
+[m4_if(m4_eval([$3 & 1]), [1], [[m4_default([$$2], [$$1])([$$3])[]]])])
+
+# m4_join(SEP, ARG1, ARG2...)
+# ---------------------------
+# Produce ARG1SEPARG2...SEPARGn.  Avoid back-to-back SEP when a given ARG
+# is the empty string.  No expansion is performed on SEP or ARGs.
+#
+# Use a self-modifying separator, since we don't know how many
+# arguments might be skipped before a separator is first printed, but
+# be careful if the separator contains $.  m4_foreach to the rescue.
+m4_define([m4_join],
+[m4_pushdef([_m4_sep], [m4_define([_m4_sep], _m4_defn([m4_echo]))])]dnl
+[m4_foreach([_m4_arg], [m4_shift($@)],
+            [m4_ifset([_m4_arg], [_m4_sep([$1])_m4_defn([_m4_arg])])])]dnl
+[_m4_popdef([_m4_sep])])
+
+# m4_joinall(SEP, ARG1, ARG2...)
+# ------------------------------
+# Produce ARG1SEPARG2...SEPARGn.  An empty ARG results in back-to-back SEP.
+# No expansion is performed on SEP or ARGs.
+#
+# A bit easier than m4_join.  m4_foreach to the rescue.
+m4_define([m4_joinall],
+[[$2]m4_if(m4_eval([$# <= 2]), [1], [],
+           [m4_foreach([_m4_arg], [m4_shift2($@)],
+                       [[$1]_m4_defn([_m4_arg])])])])
+
+# m4_list_cmp(A, B)
+# -----------------
+# Compare the two lists of integer expressions A and B.
+#
+# m4_list_cmp takes care of any side effects; we only override
+# _m4_list_cmp_raw, where we can safely expand lists multiple times.
+# First, insert padding so that both lists are the same length; the
+# trailing +0 is necessary to handle a missing list.  Next, create a
+# temporary macro to perform pairwise comparisons until an inequality
+# is found.  For example, m4_list_cmp([1], [1,2]) creates _m4_cmp as
+#   m4_if(m4_eval([($1) != ($3)]), [1], [m4_cmp([$1], [$3])],
+#         m4_eval([($2) != ($4)]), [1], [m4_cmp([$2], [$4])],
+#         [0]_m4_popdef([_m4_cmp], [_m4_size]))
+# then calls _m4_cmp([1+0], [0], [1], [2+0])
+m4_define([_m4_list_cmp_raw],
+[m4_if([$1], [$2], 0, [m4_pushdef(
+     [_m4_size])_m4_list_cmp($1+0_m4_list_pad(m4_count($1), m4_count($2)),
+                             $2+0_m4_list_pad(m4_count($2), m4_count($1)))])])
+
+m4_define([_m4_list_pad],
+[m4_if(m4_eval($1 < $2), [1],
+       [_m4_for([_m4_size], m4_incr([$1]), [$2], [1], [,0])])])
+
+m4_define([_m4_list_cmp],
+[m4_define([_m4_size], m4_eval([$# >> 1]))]dnl
+[m4_define([_m4_cmp], m4_pushdef([_m4_cmp])[m4_if(]_m4_for([_m4_cmp],
+   [1], _m4_size, [1], [$0_(_m4_cmp, m4_eval(_m4_cmp + _m4_size))])[
+      [0]_m4_popdef([_m4_cmp], [_m4_size]))])_m4_cmp($@)])
+
+m4_define([_m4_list_cmp_],
+[[m4_eval([($$1) != ($$2)]), [1], [m4_cmp([$$1], [$$2])],
+]])
+
+# m4_max(EXPR, ...)
+# m4_min(EXPR, ...)
+# -----------------
+# Return the decimal value of the maximum (or minimum) in a series of
+# integer expressions.
+#
+# m4_foreach to the rescue; we only need to replace _m4_minmax.  Here,
+# we need a temporary macro to track the best answer so far, so that
+# the foreach expression is tractable.
+m4_define([_m4_minmax],
+[m4_pushdef([_m4_best], m4_eval([$2]))m4_foreach([_m4_arg], [m4_shift2($@)],
+    [m4_define([_m4_best], $1(_m4_best, _m4_defn([_m4_arg])))])]dnl
+[_m4_best[]_m4_popdef([_m4_best])])
+
+# m4_set_add_all(SET, VALUE...)
+# -----------------------------
+# Add each VALUE into SET.  This is O(n) in the number of VALUEs, and
+# can be faster than calling m4_set_add for each VALUE.
+#
+# m4_foreach to the rescue.  If no deletions have occurred, then avoid
+# the speed penalty of m4_set_add.
+m4_define([m4_set_add_all],
+[m4_if([$#], [0], [], [$#], [1], [],
+       [m4_define([_m4_set_size($1)], m4_eval(m4_set_size([$1])
+          + m4_len(m4_foreach([_m4_arg], [m4_shift($@)],
+    m4_ifdef([_m4_set_cleanup($1)],
+             [[m4_set_add([$1], _m4_defn([_m4_arg]))]],
+             [[m4_ifdef([_m4_set([$1],]_m4_defn([_m4_arg])[)], [],
+                        [m4_define([_m4_set([$1],]_m4_defn([_m4_arg])[)],
+                                   [1])m4_pushdef([_m4_set([$1])],
+        _m4_defn([_m4_arg]))-])]])))))])])
diff --git a/tools/mhmake/src/bisondata/m4sugar/m4sugar.m4 b/tools/mhmake/src/bisondata/m4sugar/m4sugar.m4
new file mode 100644
index 000000000..291267c33
--- /dev/null
+++ b/tools/mhmake/src/bisondata/m4sugar/m4sugar.m4
@@ -0,0 +1,2789 @@
+divert(-1)#                                                  -*- Autoconf -*-
+# This file is part of Autoconf.
+# Base M4 layer.
+# Requires GNU M4.
+#
+# Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
+# 2008 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
+# 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
+# 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
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# As a special exception, the Free Software Foundation gives unlimited
+# permission to copy, distribute and modify the configure scripts that
+# are the output of Autoconf.  You need not follow the terms of the GNU
+# General Public License when using or distributing such scripts, even
+# though portions of the text of Autoconf appear in them.  The GNU
+# General Public License (GPL) does govern all other use of the material
+# that constitutes the Autoconf program.
+#
+# Certain portions of the Autoconf source text are designed to be copied
+# (in certain cases, depending on the input) into the output of
+# Autoconf.  We call these the "data" portions.  The rest of the Autoconf
+# source text consists of comments plus executable code that decides which
+# of the data portions to output in any given case.  We call these
+# comments and executable code the "non-data" portions.  Autoconf never
+# copies any of the non-data portions into its output.
+#
+# This special exception to the GPL applies to versions of Autoconf
+# released by the Free Software Foundation.  When you make and
+# distribute a modified version of Autoconf, you may extend this special
+# exception to the GPL to apply to your modified version as well, *unless*
+# your modified version has the potential to copy into its output some
+# of the text that was the non-data portion of the version that you started
+# with.  (In other words, unless your change moves or copies text from
+# the non-data portions to the data portions.)  If your modification has
+# such potential, you must delete any notice of this special exception
+# to the GPL from your modified version.
+#
+# Written by Akim Demaille.
+#
+
+# Set the quotes, whatever the current quoting system.
+changequote()
+changequote([, ])
+
+# Some old m4's don't support m4exit.  But they provide
+# equivalent functionality by core dumping because of the
+# long macros we define.
+ifdef([__gnu__], ,
+[errprint(M4sugar requires GNU M4. Install it before installing M4sugar or
+set the M4 environment variable to its absolute file name.)
+m4exit(2)])
+
+
+## ------------------------------- ##
+## 1. Simulate --prefix-builtins.  ##
+## ------------------------------- ##
+
+# m4_define
+# m4_defn
+# m4_undefine
+define([m4_define],   defn([define]))
+define([m4_defn],     defn([defn]))
+define([m4_undefine], defn([undefine]))
+
+m4_undefine([define])
+m4_undefine([defn])
+m4_undefine([undefine])
+
+
+# m4_copy(SRC, DST)
+# -----------------
+# Define DST as the definition of SRC.
+# What's the difference between:
+# 1. m4_copy([from], [to])
+# 2. m4_define([to], [from($@)])
+# Well, obviously 1 is more expensive in space.  Maybe 2 is more expensive
+# in time, but because of the space cost of 1, it's not that obvious.
+# Nevertheless, one huge difference is the handling of `$0'.  If `from'
+# uses `$0', then with 1, `to''s `$0' is `to', while it is `from' in 2.
+# The user would certainly prefer to see `to'.
+m4_define([m4_copy],
+[m4_define([$2], m4_defn([$1]))])
+
+
+# m4_rename(SRC, DST)
+# -------------------
+# Rename the macro SRC to DST.
+m4_define([m4_rename],
+[m4_copy([$1], [$2])m4_undefine([$1])])
+
+
+# m4_rename_m4(MACRO-NAME)
+# ------------------------
+# Rename MACRO-NAME to m4_MACRO-NAME.
+m4_define([m4_rename_m4],
+[m4_rename([$1], [m4_$1])])
+
+
+# m4_copy_unm4(m4_MACRO-NAME)
+# ---------------------------
+# Copy m4_MACRO-NAME to MACRO-NAME.
+m4_define([m4_copy_unm4],
+[m4_copy([$1], m4_bpatsubst([$1], [^m4_\(.*\)], [[\1]]))])
+
+
+# Some m4 internals have names colliding with tokens we might use.
+# Rename them a` la `m4 --prefix-builtins'.  Conditionals first, since
+# some subsequent renames are conditional.
+m4_rename_m4([ifdef])
+m4_rename([ifelse], [m4_if])
+
+m4_rename_m4([builtin])
+m4_rename_m4([changecom])
+m4_rename_m4([changequote])
+m4_ifdef([changeword],dnl conditionally available in 1.4.x
+[m4_undefine([changeword])])
+m4_rename_m4([debugfile])
+m4_rename_m4([debugmode])
+m4_rename_m4([decr])
+m4_undefine([divert])
+m4_rename_m4([divnum])
+m4_rename_m4([dumpdef])
+m4_rename_m4([errprint])
+m4_rename_m4([esyscmd])
+m4_rename_m4([eval])
+m4_rename_m4([format])
+m4_undefine([include])
+m4_rename_m4([incr])
+m4_rename_m4([index])
+m4_rename_m4([indir])
+m4_rename_m4([len])
+m4_rename([m4exit], [m4_exit])
+m4_undefine([m4wrap])
+m4_ifdef([mkstemp],dnl added in M4 1.4.8
+[m4_rename_m4([mkstemp])
+m4_copy([m4_mkstemp], [m4_maketemp])
+m4_undefine([maketemp])],
+[m4_rename_m4([maketemp])
+m4_copy([m4_maketemp], [m4_mkstemp])])
+m4_rename([patsubst], [m4_bpatsubst])
+m4_rename_m4([popdef])
+m4_rename_m4([pushdef])
+m4_rename([regexp], [m4_bregexp])
+m4_rename_m4([shift])
+m4_undefine([sinclude])
+m4_rename_m4([substr])
+m4_ifdef([symbols],dnl present only in alpha-quality 1.4o
+[m4_rename_m4([symbols])])
+m4_rename_m4([syscmd])
+m4_rename_m4([sysval])
+m4_rename_m4([traceoff])
+m4_rename_m4([traceon])
+m4_rename_m4([translit])
+m4_undefine([undivert])
+
+
+## ------------------- ##
+## 2. Error messages.  ##
+## ------------------- ##
+
+
+# m4_location
+# -----------
+m4_define([m4_location],
+[__file__:__line__])
+
+
+# m4_errprintn(MSG)
+# -----------------
+# Same as `errprint', but with the missing end of line.
+m4_define([m4_errprintn],
+[m4_errprint([$1
+])])
+
+
+# m4_warning(MSG)
+# ---------------
+# Warn the user.
+m4_define([m4_warning],
+[m4_errprintn(m4_location[: warning: $1])])
+
+
+# m4_fatal(MSG, [EXIT-STATUS])
+# ----------------------------
+# Fatal the user.                                                      :)
+m4_define([m4_fatal],
+[m4_errprintn(m4_location[: error: $1])dnl
+m4_expansion_stack_dump()dnl
+m4_exit(m4_if([$2],, 1, [$2]))])
+
+
+# m4_assert(EXPRESSION, [EXIT-STATUS = 1])
+# ----------------------------------------
+# This macro ensures that EXPRESSION evaluates to true, and exits if
+# EXPRESSION evaluates to false.
+m4_define([m4_assert],
+[m4_if(m4_eval([$1]), 0,
+       [m4_fatal([assert failed: $1], [$2])])])
+
+
+
+## ------------- ##
+## 3. Warnings.  ##
+## ------------- ##
+
+
+# _m4_warn(CATEGORY, MESSAGE, STACK-TRACE)
+# ----------------------------------------
+# Report a MESSAGE to the user if the CATEGORY of warnings is enabled.
+# This is for traces only.
+# The STACK-TRACE is a \n-separated list of "LOCATION: MESSAGE".
+#
+# Within m4, the macro is a no-op.  This macro really matters
+# when autom4te post-processes the trace output.
+m4_define([_m4_warn], [])
+
+
+# m4_warn(CATEGORY, MESSAGE)
+# --------------------------
+# Report a MESSAGE to the user if the CATEGORY of warnings is enabled.
+m4_define([m4_warn],
+[_m4_warn([$1], [$2],
+m4_ifdef([m4_expansion_stack],
+         [_m4_defn([m4_expansion_stack])
+m4_location[: the top level]]))dnl
+])
+
+
+
+## ------------------- ##
+## 4. File inclusion.  ##
+## ------------------- ##
+
+
+# We also want to neutralize include (and sinclude for symmetry),
+# but we want to extend them slightly: warn when a file is included
+# several times.  This is, in general, a dangerous operation, because
+# too many people forget to quote the first argument of m4_define.
+#
+# For instance in the following case:
+#   m4_define(foo, [bar])
+# then a second reading will turn into
+#   m4_define(bar, [bar])
+# which is certainly not what was meant.
+
+# m4_include_unique(FILE)
+# -----------------------
+# Declare that the FILE was loading; and warn if it has already
+# been included.
+m4_define([m4_include_unique],
+[m4_ifdef([m4_include($1)],
+          [m4_warn([syntax], [file `$1' included several times])])dnl
+m4_define([m4_include($1)])])
+
+
+# m4_include(FILE)
+# ----------------
+# Like the builtin include, but warns against multiple inclusions.
+m4_define([m4_include],
+[m4_include_unique([$1])dnl
+m4_builtin([include], [$1])])
+
+
+# m4_sinclude(FILE)
+# -----------------
+# Like the builtin sinclude, but warns against multiple inclusions.
+m4_define([m4_sinclude],
+[m4_include_unique([$1])dnl
+m4_builtin([sinclude], [$1])])
+
+
+
+## ------------------------------------ ##
+## 5. Additional branching constructs.  ##
+## ------------------------------------ ##
+
+# Both `m4_ifval' and `m4_ifset' tests against the empty string.  The
+# difference is that `m4_ifset' is specialized on macros.
+#
+# In case of arguments of macros, eg. $1, it makes little difference.
+# In the case of a macro `FOO', you don't want to check `m4_ifval(FOO,
+# TRUE)', because if `FOO' expands with commas, there is a shifting of
+# the arguments.  So you want to run `m4_ifval([FOO])', but then you just
+# compare the *string* `FOO' against `', which, of course fails.
+#
+# So you want the variation `m4_ifset' that expects a macro name as $1.
+# If this macro is both defined and defined to a non empty value, then
+# it runs TRUE, etc.
+
+
+# m4_ifval(COND, [IF-TRUE], [IF-FALSE])
+# -------------------------------------
+# If COND is not the empty string, expand IF-TRUE, otherwise IF-FALSE.
+# Comparable to m4_ifdef.
+m4_define([m4_ifval],
+[m4_if([$1], [], [$3], [$2])])
+
+
+# m4_n(TEXT)
+# ----------
+# If TEXT is not empty, return TEXT and a new line, otherwise nothing.
+m4_define([m4_n],
+[m4_if([$1],
+       [], [],
+           [$1
+])])
+
+
+# m4_ifvaln(COND, [IF-TRUE], [IF-FALSE])
+# --------------------------------------
+# Same as `m4_ifval', but add an extra newline to IF-TRUE or IF-FALSE
+# unless that argument is empty.
+m4_define([m4_ifvaln],
+[m4_if([$1],
+       [],   [m4_n([$3])],
+             [m4_n([$2])])])
+
+
+# m4_ifset(MACRO, [IF-TRUE], [IF-FALSE])
+# --------------------------------------
+# If MACRO has no definition, or of its definition is the empty string,
+# expand IF-FALSE, otherwise IF-TRUE.
+m4_define([m4_ifset],
+[m4_ifdef([$1],
+          [m4_ifval(_m4_defn([$1]), [$2], [$3])],
+          [$3])])
+
+
+# m4_ifndef(NAME, [IF-NOT-DEFINED], [IF-DEFINED])
+# -----------------------------------------------
+m4_define([m4_ifndef],
+[m4_ifdef([$1], [$3], [$2])])
+
+
+# m4_case(SWITCH, VAL1, IF-VAL1, VAL2, IF-VAL2, ..., DEFAULT)
+# -----------------------------------------------------------
+# m4 equivalent of
+# switch (SWITCH)
+# {
+#   case VAL1:
+#     IF-VAL1;
+#     break;
+#   case VAL2:
+#     IF-VAL2;
+#     break;
+#   ...
+#   default:
+#     DEFAULT;
+#     break;
+# }.
+# All the values are optional, and the macro is robust to active
+# symbols properly quoted.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_case],
+[m4_if([$#], 0, [],
+       [$#], 1, [],
+       [$#], 2, [$2],
+       [$1], [$2], [$3],
+       [$0([$1], m4_shift3($@))])])
+
+
+# m4_bmatch(SWITCH, RE1, VAL1, RE2, VAL2, ..., DEFAULT)
+# -----------------------------------------------------
+# m4 equivalent of
+#
+# if (SWITCH =~ RE1)
+#   VAL1;
+# elif (SWITCH =~ RE2)
+#   VAL2;
+# elif ...
+#   ...
+# else
+#   DEFAULT
+#
+# All the values are optional, and the macro is robust to active symbols
+# properly quoted.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_bmatch],
+[m4_if([$#], 0, [m4_fatal([$0: too few arguments: $#])],
+       [$#], 1, [m4_fatal([$0: too few arguments: $#: $1])],
+       [$#], 2, [$2],
+       [m4_if(m4_bregexp([$1], [$2]), -1, [$0([$1], m4_shift3($@))],
+              [$3])])])
+
+
+# m4_car(LIST)
+# m4_cdr(LIST)
+# ------------
+# Manipulate m4 lists.
+m4_define([m4_car], [[$1]])
+m4_define([m4_cdr],
+[m4_if([$#], 0, [m4_fatal([$0: cannot be called without arguments])],
+       [$#], 1, [],
+       [m4_dquote(m4_shift($@))])])
+
+# _m4_cdr(LIST)
+# -------------
+# Like m4_cdr, except include a leading comma unless only one element
+# remains.  Why?  Because comparing a large list against [] is more
+# expensive in expansion time than comparing the number of arguments; so
+# _m4_cdr can be used to reduce the number of arguments when it is time
+# to end recursion.
+m4_define([_m4_cdr],
+[m4_if([$#], 1, [],
+       [, m4_dquote(m4_shift($@))])])
+
+
+
+# m4_cond(TEST1, VAL1, IF-VAL1, TEST2, VAL2, IF-VAL2, ..., [DEFAULT])
+# -------------------------------------------------------------------
+# Similar to m4_if, except that each TEST is expanded when encountered.
+# If the expansion of TESTn matches the string VALn, the result is IF-VALn.
+# The result is DEFAULT if no tests passed.  This macro allows
+# short-circuiting of expensive tests, where it pays to arrange quick
+# filter tests to run first.
+#
+# For an example, consider a previous implementation of _AS_QUOTE_IFELSE:
+#
+#    m4_if(m4_index([$1], [\]), [-1], [$2],
+#          m4_eval(m4_index([$1], [\\]) >= 0), [1], [$2],
+#          m4_eval(m4_index([$1], [\$]) >= 0), [1], [$2],
+#          m4_eval(m4_index([$1], [\`]) >= 0), [1], [$3],
+#          m4_eval(m4_index([$1], [\"]) >= 0), [1], [$3],
+#          [$2])
+#
+# Here, m4_index is computed 5 times, and m4_eval 4, even if $1 contains
+# no backslash.  It is more efficient to do:
+#
+#    m4_cond([m4_index([$1], [\])], [-1], [$2],
+#            [m4_eval(m4_index([$1], [\\]) >= 0)], [1], [$2],
+#            [m4_eval(m4_index([$1], [\$]) >= 0)], [1], [$2],
+#            [m4_eval(m4_index([$1], [\`]) >= 0)], [1], [$3],
+#            [m4_eval(m4_index([$1], [\"]) >= 0)], [1], [$3],
+#            [$2])
+#
+# In the common case of $1 with no backslash, only one m4_index expansion
+# occurs, and m4_eval is avoided altogether.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_cond],
+[m4_if([$#], [0], [m4_fatal([$0: cannot be called without arguments])],
+       [$#], [1], [$1],
+       m4_eval([$# % 3]), [2], [m4_fatal([$0: missing an argument])],
+       [_$0($@)])])
+
+m4_define([_m4_cond],
+[m4_if(($1), [($2)], [$3],
+       [$#], [3], [],
+       [$#], [4], [$4],
+       [$0(m4_shift3($@))])])
+
+
+## ---------------------------------------- ##
+## 6. Enhanced version of some primitives.  ##
+## ---------------------------------------- ##
+
+# m4_bpatsubsts(STRING, RE1, SUBST1, RE2, SUBST2, ...)
+# ----------------------------------------------------
+# m4 equivalent of
+#
+#   $_ = STRING;
+#   s/RE1/SUBST1/g;
+#   s/RE2/SUBST2/g;
+#   ...
+#
+# All the values are optional, and the macro is robust to active symbols
+# properly quoted.
+#
+# I would have liked to name this macro `m4_bpatsubst', unfortunately,
+# due to quotation problems, I need to double quote $1 below, therefore
+# the anchors are broken :(  I can't let users be trapped by that.
+#
+# Recall that m4_shift3 always results in an argument.  Hence, we need
+# to distinguish between a final deletion vs. ending recursion.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_bpatsubsts],
+[m4_if([$#], 0, [m4_fatal([$0: too few arguments: $#])],
+       [$#], 1, [m4_fatal([$0: too few arguments: $#: $1])],
+       [$#], 2, [m4_unquote(m4_builtin([patsubst], [[$1]], [$2]))],
+       [$#], 3, [m4_unquote(m4_builtin([patsubst], [[$1]], [$2], [$3]))],
+       [_$0($@m4_if(m4_eval($# & 1), 0, [,]))])])
+m4_define([_m4_bpatsubsts],
+[m4_if([$#], 2, [$1],
+       [$0(m4_builtin([patsubst], [[$1]], [$2], [$3]),
+           m4_shift3($@))])])
+
+
+# m4_define_default(MACRO, VALUE)
+# -------------------------------
+# If MACRO is undefined, set it to VALUE.
+m4_define([m4_define_default],
+[m4_ifndef([$1], [m4_define($@)])])
+
+
+# m4_default(EXP1, EXP2)
+# ----------------------
+# Returns EXP1 if non empty, otherwise EXP2.
+#
+# This macro is called on hot paths, so inline the contents of m4_ifval,
+# for one less round of expansion.
+m4_define([m4_default],
+[m4_if([$1], [], [$2], [$1])])
+
+
+# m4_defn(NAME)
+# -------------
+# Like the original, except guarantee a warning when using something which is
+# undefined (unlike M4 1.4.x).  This replacement is not a full-featured
+# replacement: if any of the defined macros contain unbalanced quoting, but
+# when pasted together result in a well-quoted string, then only native m4
+# support is able to get it correct.  But that's where quadrigraphs come in
+# handy, if you really need unbalanced quotes inside your macros.
+#
+# This macro is called frequently, so minimize the amount of additional
+# expansions by skipping m4_ifndef.  Better yet, if __m4_version__ exists,
+# (added in M4 1.6), then let m4 do the job for us (see m4_init).
+#
+# _m4_defn is for internal use only - it bypasses the wrapper, so it
+# must only be used on one argument at a time, and only on macros
+# known to be defined.  Make sure this still works if the user renames
+# m4_defn but not _m4_defn.
+m4_copy([m4_defn], [_m4_defn])
+m4_define([m4_defn],
+[m4_if([$#], [0], [[$0]],
+       [$#], [1], [m4_ifdef([$1], [_m4_defn([$1])],
+                            [m4_fatal([$0: undefined macro: $1])])],
+       [m4_foreach([_m4_macro], [$@], [$0(_m4_defn([_m4_macro]))])])])
+
+
+# _m4_dumpdefs_up(NAME)
+# ---------------------
+m4_define([_m4_dumpdefs_up],
+[m4_ifdef([$1],
+          [m4_pushdef([_m4_dumpdefs], _m4_defn([$1]))dnl
+m4_dumpdef([$1])dnl
+_m4_popdef([$1])dnl
+_m4_dumpdefs_up([$1])])])
+
+
+# _m4_dumpdefs_down(NAME)
+# -----------------------
+m4_define([_m4_dumpdefs_down],
+[m4_ifdef([_m4_dumpdefs],
+          [m4_pushdef([$1], _m4_defn([_m4_dumpdefs]))dnl
+_m4_popdef([_m4_dumpdefs])dnl
+_m4_dumpdefs_down([$1])])])
+
+
+# m4_dumpdefs(NAME)
+# -----------------
+# Similar to `m4_dumpdef(NAME)', but if NAME was m4_pushdef'ed, display its
+# value stack (most recent displayed first).
+m4_define([m4_dumpdefs],
+[_m4_dumpdefs_up([$1])dnl
+_m4_dumpdefs_down([$1])])
+
+
+# m4_popdef(NAME)
+# ---------------
+# Like the original, except guarantee a warning when using something which is
+# undefined (unlike M4 1.4.x).
+#
+# This macro is called frequently, so minimize the amount of additional
+# expansions by skipping m4_ifndef.  Better yet, if __m4_version__ exists,
+# (added in M4 1.6), then let m4 do the job for us (see m4_init).
+#
+# _m4_popdef is for internal use only - it bypasses the wrapper, so it
+# must only be used on macros known to be defined.  Make sure this
+# still works if the user renames m4_popdef but not _m4_popdef.
+m4_copy([m4_popdef], [_m4_popdef])
+m4_define([m4_popdef],
+[m4_if([$#], [0], [[$0]],
+       [$#], [1], [m4_ifdef([$1], [_m4_popdef([$1])],
+                            [m4_fatal([$0: undefined macro: $1])])],
+       [m4_foreach([_m4_macro], [$@], [$0(_m4_defn([_m4_macro]))])])])
+
+
+# m4_shiftn(N, ...)
+# -----------------
+# Returns ... shifted N times.  Useful for recursive "varargs" constructs.
+#
+# Autoconf does not use this macro, because it is inherently slower than
+# calling the common cases of m4_shift2 or m4_shift3 directly.  But it
+# might as well be fast for other clients, such as Libtool.  One way to
+# do this is to expand $@ only once in _m4_shiftn (otherwise, for long
+# lists, the expansion of m4_if takes twice as much memory as what the
+# list itself occupies, only to throw away the unused branch).  The end
+# result is strictly equivalent to
+#   m4_if([$1], 1, [m4_shift(,m4_shift(m4_shift($@)))],
+#         [_m4_shiftn(m4_decr([$1]), m4_shift(m4_shift($@)))])
+# but with the final `m4_shift(m4_shift($@)))' shared between the two
+# paths.  The first leg uses a no-op m4_shift(,$@) to balance out the ().
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_shiftn],
+[m4_assert(0 < $1 && $1 < $#)_$0($@)])
+
+m4_define([_m4_shiftn],
+[m4_if([$1], 1, [m4_shift(],
+       [$0(m4_decr([$1])]), m4_shift(m4_shift($@)))])
+
+# m4_shift2(...)
+# m4_shift3(...)
+# -----------------
+# Returns ... shifted twice, and three times.  Faster than m4_shiftn.
+m4_define([m4_shift2], [m4_shift(m4_shift($@))])
+m4_define([m4_shift3], [m4_shift(m4_shift(m4_shift($@)))])
+
+# _m4_shift2(...)
+# _m4_shift3(...)
+# ---------------
+# Like m4_shift2 or m4_shift3, except include a leading comma unless shifting
+# consumes all arguments.  Why?  Because in recursion, it is nice to
+# distinguish between 1 element left and 0 elements left, based on how many
+# arguments this shift expands to.
+m4_define([_m4_shift2],
+[m4_if([$#], [2], [],
+       [, m4_shift(m4_shift($@))])])
+m4_define([_m4_shift3],
+[m4_if([$#], [3], [],
+       [, m4_shift(m4_shift(m4_shift($@)))])])
+
+
+# m4_undefine(NAME)
+# -----------------
+# Like the original, except guarantee a warning when using something which is
+# undefined (unlike M4 1.4.x).
+#
+# This macro is called frequently, so minimize the amount of additional
+# expansions by skipping m4_ifndef.  Better yet, if __m4_version__ exists,
+# (added in M4 1.6), then let m4 do the job for us (see m4_init).
+#
+# _m4_undefine is for internal use only - it bypasses the wrapper, so
+# it must only be used on macros known to be defined.  Make sure this
+# still works if the user renames m4_undefine but not _m4_undefine.
+m4_copy([m4_undefine], [_m4_undefine])
+m4_define([m4_undefine],
+[m4_if([$#], [0], [[$0]],
+       [$#], [1], [m4_ifdef([$1], [_m4_undefine([$1])],
+                            [m4_fatal([$0: undefined macro: $1])])],
+       [m4_foreach([_m4_macro], [$@], [$0(_m4_defn([_m4_macro]))])])])
+
+# _m4_wrap(PRE, POST)
+# -------------------
+# Helper macro for m4_wrap and m4_wrap_lifo.  Allows nested calls to
+# m4_wrap within wrapped text.  Use _m4_defn and _m4_popdef for speed.
+m4_define([_m4_wrap],
+[m4_ifdef([$0_text],
+          [m4_define([$0_text], [$1]_m4_defn([$0_text])[$2])],
+          [m4_builtin([m4wrap], [m4_unquote(
+  _m4_defn([$0_text])_m4_popdef([$0_text]))])m4_define([$0_text], [$1$2])])])
+
+# m4_wrap(TEXT)
+# -------------
+# Append TEXT to the list of hooks to be executed at the end of input.
+# Whereas the order of the original may be LIFO in the underlying m4,
+# this version is always FIFO.
+m4_define([m4_wrap],
+[_m4_wrap([], [$1[]])])
+
+# m4_wrap_lifo(TEXT)
+# ------------------
+# Prepend TEXT to the list of hooks to be executed at the end of input.
+# Whereas the order of m4_wrap may be FIFO in the underlying m4, this
+# version is always LIFO.
+m4_define([m4_wrap_lifo],
+[_m4_wrap([$1[]])])
+
+## ------------------------- ##
+## 7. Quoting manipulation.  ##
+## ------------------------- ##
+
+
+# m4_apply(MACRO, LIST)
+# ---------------------
+# Invoke MACRO, with arguments provided from the quoted list of
+# comma-separated quoted arguments.  If LIST is empty, invoke MACRO
+# without arguments.  The expansion will not be concatenated with
+# subsequent text.
+m4_define([m4_apply],
+[m4_if([$2], [], [$1], [$1($2)])[]])
+
+# _m4_apply(MACRO, LIST)
+# ----------------------
+# Like m4_apply, except do nothing if LIST is empty.
+m4_define([_m4_apply],
+[m4_if([$2], [], [], [$1($2)[]])])
+
+
+# m4_count(ARGS)
+# --------------
+# Return a count of how many ARGS are present.
+m4_define([m4_count], [$#])
+
+
+# m4_do(STRING, ...)
+# ------------------
+# This macro invokes all its arguments (in sequence, of course).  It is
+# useful for making your macros more structured and readable by dropping
+# unnecessary dnl's and have the macros indented properly.  No concatenation
+# occurs after a STRING; use m4_unquote(m4_join(,STRING)) for that.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_do],
+[m4_if([$#], 0, [],
+       [$#], 1, [$1[]],
+       [$1[]$0(m4_shift($@))])])
+
+
+# m4_dquote(ARGS)
+# ---------------
+# Return ARGS as a quoted list of quoted arguments.
+m4_define([m4_dquote],  [[$@]])
+
+
+# m4_dquote_elt(ARGS)
+# -------------------
+# Return ARGS as an unquoted list of double-quoted arguments.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_dquote_elt],
+[m4_if([$#], [0], [],
+       [$#], [1], [[[$1]]],
+       [[[$1]],$0(m4_shift($@))])])
+
+
+# m4_echo(ARGS)
+# -------------
+# Return the ARGS, with the same level of quoting.  Whitespace after
+# unquoted commas are consumed.
+m4_define([m4_echo], [$@])
+
+
+# m4_expand(ARG)
+# --------------
+# Return the expansion of ARG as a single string.  Unlike m4_quote($1), this
+# correctly preserves whitespace following single-quoted commas that appeared
+# within ARG.
+#
+#   m4_define([active], [ACT, IVE])
+#   m4_define([active2], [[ACT, IVE]])
+#   m4_quote(active, active2)
+#   => ACT,IVE,ACT, IVE
+#   m4_expand([active, active2])
+#   => ACT, IVE, ACT, IVE
+#
+# Unfortunately, due to limitations in m4, ARG must expand to something
+# with balanced quotes (use quadrigraphs to get around this).  The input
+# is not likely to have unbalanced -=<{(/)}>=- quotes, and it is possible
+# to have unbalanced (), provided it was specified with proper [] quotes.
+#
+# Exploit that extra () will group unquoted commas and the following
+# whitespace, then convert () to [].  m4_bpatsubst can't handle newlines
+# inside $1, and m4_substr strips quoting.  So we (ab)use m4_changequote.
+m4_define([m4_expand], [_$0(-=<{($1)}>=-)])
+m4_define([_m4_expand],
+[m4_changequote([-=<{(], [)}>=-])$1m4_changequote([, ])])
+
+
+# m4_ignore(ARGS)
+# ---------------
+# Expands to nothing.  Useful for conditionally ignoring an arbitrary
+# number of arguments (see _m4_list_cmp for an example).
+m4_define([m4_ignore])
+
+
+# m4_make_list(ARGS)
+# ------------------
+# Similar to m4_dquote, this creates a quoted list of quoted ARGS.  This
+# version is less efficient than m4_dquote, but separates each argument
+# with a comma and newline, rather than just comma, for readability.
+# When developing an m4sugar algorithm, you could temporarily use
+#   m4_pushdef([m4_dquote],m4_defn([m4_make_list]))
+# around your code to make debugging easier.
+m4_define([m4_make_list], [m4_join([,
+], m4_dquote_elt($@))])
+
+
+# m4_noquote(STRING)
+# ------------------
+# Return the result of ignoring all quotes in STRING and invoking the
+# macros it contains.  Amongst other things, this is useful for enabling
+# macro invocations inside strings with [] blocks (for instance regexps
+# and help-strings).  On the other hand, since all quotes are disabled,
+# any macro expanded during this time that relies on nested [] quoting
+# will likely crash and burn.  This macro is seldom useful; consider
+# m4_unquote or m4_expand instead.
+m4_define([m4_noquote],
+[m4_changequote([-=<{(],[)}>=-])$1-=<{()}>=-m4_changequote([,])])
+
+
+# m4_quote(ARGS)
+# --------------
+# Return ARGS as a single argument.  Any whitespace after unquoted commas
+# is stripped.  There is always output, even when there were no arguments.
+#
+# It is important to realize the difference between `m4_quote(exp)' and
+# `[exp]': in the first case you obtain the quoted *result* of the
+# expansion of EXP, while in the latter you just obtain the string
+# `exp'.
+m4_define([m4_quote],  [[$*]])
+
+
+# _m4_quote(ARGS)
+# ---------------
+# Like m4_quote, except that when there are no arguments, there is no
+# output.  For conditional scenarios (such as passing _m4_quote as the
+# macro name in m4_mapall), this feature can be used to distinguish between
+# one argument of the empty string vs. no arguments.  However, in the
+# normal case with arguments present, this is less efficient than m4_quote.
+m4_define([_m4_quote],
+[m4_if([$#], [0], [], [[$*]])])
+
+
+# m4_reverse(ARGS)
+# ----------------
+# Output ARGS in reverse order.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_reverse],
+[m4_if([$#], [0], [], [$#], [1], [[$1]],
+       [$0(m4_shift($@)), [$1]])])
+
+
+# m4_unquote(ARGS)
+# ----------------
+# Remove one layer of quotes from each ARG, performing one level of
+# expansion.  For one argument, m4_unquote([arg]) is more efficient than
+# m4_do([arg]), but for multiple arguments, the difference is that
+# m4_unquote separates arguments with commas while m4_do concatenates.
+# Follow this macro with [] if concatenation with subsequent text is
+# undesired.
+m4_define([m4_unquote], [$*])
+
+
+## -------------------------- ##
+## 8. Implementing m4 loops.  ##
+## -------------------------- ##
+
+
+# m4_for(VARIABLE, FIRST, LAST, [STEP = +/-1], EXPRESSION)
+# --------------------------------------------------------
+# Expand EXPRESSION defining VARIABLE to FROM, FROM + 1, ..., TO with
+# increments of STEP.  Both limits are included, and bounds are
+# checked for consistency.  The algorithm is robust to indirect
+# VARIABLE names.  Changing VARIABLE inside EXPRESSION will not impact
+# the number of iterations.
+#
+# Uses _m4_defn for speed, and avoid dnl in the macro body.
+m4_define([m4_for],
+[m4_pushdef([$1], m4_eval([$2]))]dnl
+[m4_cond([m4_eval(([$3]) > ([$2]))], 1,
+           [m4_pushdef([_m4_step], m4_eval(m4_default([$4],
+              1)))m4_assert(_m4_step > 0)_$0([$1], _m4_defn([$1]),
+  m4_eval((([$3]) - ([$2])) / _m4_step * _m4_step + ([$2])),
+  _m4_step, [$5])],
+         [m4_eval(([$3]) < ([$2]))], 1,
+           [m4_pushdef([_m4_step], m4_eval(m4_default([$4],
+              -1)))m4_assert(_m4_step < 0)_$0([$1], _m4_defn([$1]),
+  m4_eval((([$2]) - ([$3])) / -(_m4_step) * _m4_step + ([$2])),
+  _m4_step, [$5])],
+         [m4_pushdef([_m4_step])$5])[]]dnl
+[m4_popdef([_m4_step], [$1])])
+
+
+# _m4_for(VARIABLE, COUNT, LAST, STEP, EXPRESSION)
+# ------------------------------------------------
+# Core of the loop, no consistency checks, all arguments are plain
+# numbers.  Define VARIABLE to COUNT, expand EXPRESSION, then alter
+# COUNT by STEP and iterate if COUNT is not LAST.
+m4_define([_m4_for],
+[m4_define([$1], [$2])$5[]m4_if([$2], [$3], [],
+      [$0([$1], m4_eval([$2 + $4]), [$3], [$4], [$5])])])
+
+
+# Implementing `foreach' loops in m4 is much more tricky than it may
+# seem.  For example, the old M4 1.4.4 manual had an incorrect example,
+# which looked like this (when translated to m4sugar):
+#
+# | # foreach(VAR, (LIST), STMT)
+# | m4_define([foreach],
+# |   [m4_pushdef([$1])_foreach([$1], [$2], [$3])m4_popdef([$1])])
+# | m4_define([_arg1], [$1])
+# | m4_define([_foreach],
+# |   [m4_if([$2], [()], ,
+# |     [m4_define([$1], _arg1$2)$3[]_foreach([$1], (m4_shift$2), [$3])])])
+#
+# But then if you run
+#
+# | m4_define(a, 1)
+# | m4_define(b, 2)
+# | m4_define(c, 3)
+# | foreach([f], [([a], [(b], [c)])], [echo f
+# | ])
+#
+# it gives
+#
+#  => echo 1
+#  => echo (2,3)
+#
+# which is not what is expected.
+#
+# Of course the problem is that many quotes are missing.  So you add
+# plenty of quotes at random places, until you reach the expected
+# result.  Alternatively, if you are a quoting wizard, you directly
+# reach the following implementation (but if you really did, then
+# apply to the maintenance of m4sugar!).
+#
+# | # foreach(VAR, (LIST), STMT)
+# | m4_define([foreach], [m4_pushdef([$1])_foreach($@)m4_popdef([$1])])
+# | m4_define([_arg1], [[$1]])
+# | m4_define([_foreach],
+# |  [m4_if($2, [()], ,
+# |    [m4_define([$1], [_arg1$2])$3[]_foreach([$1], [(m4_shift$2)], [$3])])])
+#
+# which this time answers
+#
+#  => echo a
+#  => echo (b
+#  => echo c)
+#
+# Bingo!
+#
+# Well, not quite.
+#
+# With a better look, you realize that the parens are more a pain than
+# a help: since anyway you need to quote properly the list, you end up
+# with always using an outermost pair of parens and an outermost pair
+# of quotes.  Rejecting the parens both eases the implementation, and
+# simplifies the use:
+#
+# | # foreach(VAR, (LIST), STMT)
+# | m4_define([foreach], [m4_pushdef([$1])_foreach($@)m4_popdef([$1])])
+# | m4_define([_arg1], [$1])
+# | m4_define([_foreach],
+# |  [m4_if($2, [], ,
+# |    [m4_define([$1], [_arg1($2)])$3[]_foreach([$1], [m4_shift($2)], [$3])])])
+#
+#
+# Now, just replace the `$2' with `m4_quote($2)' in the outer `m4_if'
+# to improve robustness, and you come up with a nice implementation
+# that doesn't require extra parentheses in the user's LIST.
+#
+# But wait -  now the algorithm is quadratic, because every recursion of
+# the algorithm keeps the entire LIST and merely adds another m4_shift to
+# the quoted text.  If the user has a lot of elements in LIST, you can
+# bring the system to its knees with the memory m4 then requires, or trip
+# the m4 --nesting-limit recursion factor.  The only way to avoid
+# quadratic growth is ensure m4_shift is expanded prior to the recursion.
+# Hence the design below.
+#
+# The M4 manual now includes a chapter devoted to this issue, with
+# the lessons learned from m4sugar.  And still, this design is only
+# optimal for M4 1.6; see foreach.m4 for yet more comments on why
+# M4 1.4.x uses yet another implementation.
+
+
+# m4_foreach(VARIABLE, LIST, EXPRESSION)
+# --------------------------------------
+#
+# Expand EXPRESSION assigning each value of the LIST to VARIABLE.
+# LIST should have the form `item_1, item_2, ..., item_n', i.e. the
+# whole list must *quoted*.  Quote members too if you don't want them
+# to be expanded.
+#
+# This macro is robust to active symbols:
+#      | m4_define(active, [ACT, IVE])
+#      | m4_foreach(Var, [active, active], [-Var-])
+#     => -ACT--IVE--ACT--IVE-
+#
+#      | m4_foreach(Var, [[active], [active]], [-Var-])
+#     => -ACT, IVE--ACT, IVE-
+#
+#      | m4_foreach(Var, [[[active]], [[active]]], [-Var-])
+#     => -active--active-
+#
+# This macro is called frequently, so avoid extra expansions such as
+# m4_ifval and dnl.  Also, since $2 might be quite large, try to use it
+# as little as possible in _m4_foreach; each extra use requires that much
+# more memory for expansion.  So, rather than directly compare $2 against
+# [] and use m4_car/m4_cdr for recursion, we instead unbox the list (which
+# requires swapping the argument order in the helper), insert an ignored
+# third argument, and use m4_shift3 to detect when recursion is complete.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_foreach],
+[m4_if([$2], [], [],
+       [m4_pushdef([$1])_$0([$1], [$3], [], $2)m4_popdef([$1])])])
+
+m4_define([_m4_foreach],
+[m4_if([$#], [3], [],
+       [m4_define([$1], [$4])$2[]$0([$1], [$2], m4_shift3($@))])])
+
+
+# m4_foreach_w(VARIABLE, LIST, EXPRESSION)
+# ----------------------------------------
+#
+# Like m4_foreach, but the list is whitespace separated.
+#
+# This macro is robust to active symbols:
+#    m4_foreach_w([Var], [ active
+#    b  act\
+#    ive  ], [-Var-])end
+#    => -active--b--active-end
+#
+m4_define([m4_foreach_w],
+[m4_foreach([$1], m4_split(m4_normalize([$2]), [ ]), [$3])])
+
+
+# m4_map(MACRO, LIST)
+# m4_mapall(MACRO, LIST)
+# ----------------------
+# Invoke MACRO($1), MACRO($2) etc. where $1, $2... are the elements of
+# LIST.  $1, $2... must in turn be lists, appropriate for m4_apply.
+# If LIST contains an empty sublist, m4_map skips the expansion of
+# MACRO, while m4_mapall expands MACRO with no arguments.
+#
+# Since LIST may be quite large, we want to minimize how often it
+# appears in the expansion.  Rather than use m4_car/m4_cdr iteration,
+# we unbox the list, ignore the second argument, and use m4_shift2 to
+# detect the end of recursion.  The mismatch in () is intentional; see
+# _m4_map.  For m4_map, an empty list behaves like an empty sublist
+# and gets ignored; for m4_mapall, we must special-case the empty
+# list.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_map],
+[_m4_map([_m4_apply([$1]], [], $2)])
+
+m4_define([m4_mapall],
+[m4_if([$2], [], [],
+       [_m4_map([m4_apply([$1]], [], $2)])])
+
+
+# m4_map_sep(MACRO, SEPARATOR, LIST)
+# m4_mapall_sep(MACRO, SEPARATOR, LIST)
+# -------------------------------------
+# Invoke MACRO($1), SEPARATOR, MACRO($2), ..., MACRO($N) where $1,
+# $2... $N are the elements of LIST, and are in turn lists appropriate
+# for m4_apply.  SEPARATOR is expanded, in order to allow the creation
+# of a list of arguments by using a single-quoted comma as the
+# separator.  For each empty sublist, m4_map_sep skips the expansion
+# of MACRO and SEPARATOR, while m4_mapall_sep expands MACRO with no
+# arguments.
+#
+# For m4_mapall_sep, merely expand the first iteration without the
+# separator, then include separator as part of subsequent recursion;
+# but avoid extra expansion of LIST's side-effects via a helper macro.
+# For m4_map_sep, things are trickier - we don't know if the first
+# list element is an empty sublist, so we must define a self-modifying
+# helper macro and use that as the separator instead.
+m4_define([m4_map_sep],
+[m4_pushdef([m4_Sep], [m4_define([m4_Sep], _m4_defn([m4_unquote]))])]dnl
+[_m4_map([_m4_apply([m4_Sep([$2])[]$1]], [], $3)m4_popdef([m4_Sep])])
+
+m4_define([m4_mapall_sep],
+[m4_if([$3], [], [], [_$0([$1], [$2], $3)])])
+
+m4_define([_m4_mapall_sep],
+[m4_apply([$1], [$3])_m4_map([m4_apply([$2[]$1]], m4_shift2($@))])
+
+# _m4_map(PREFIX, IGNORED, SUBLIST, ...)
+# --------------------------------------
+# Common implementation for all four m4_map variants.  The mismatch in
+# the number of () is intentional.  PREFIX must supply a form of
+# m4_apply, the open `(', and the MACRO to be applied.  Each iteration
+# then appends `,', the current SUBLIST and the closing `)', then
+# recurses to the next SUBLIST.  IGNORED is an aid to ending recursion
+# efficiently.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([_m4_map],
+[m4_if([$#], [2], [],
+       [$1, [$3])$0([$1], m4_shift2($@))])])
+
+# m4_transform(EXPRESSION, ARG...)
+# --------------------------------
+# Expand EXPRESSION([ARG]) for each argument.  More efficient than
+# m4_foreach([var], [ARG...], [EXPRESSION(m4_defn([var]))])
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_transform],
+[m4_if([$#], [0], [m4_fatal([$0: too few arguments: $#])],
+       [$#], [1], [],
+       [$#], [2], [$1([$2])[]],
+       [$1([$2])[]$0([$1], m4_shift2($@))])])
+
+
+# m4_transform_pair(EXPRESSION, [END-EXPR = EXPRESSION], ARG...)
+# --------------------------------------------------------------
+# Perform a pairwise grouping of consecutive ARGs, by expanding
+# EXPRESSION([ARG1], [ARG2]).  If there are an odd number of ARGs, the
+# final argument is expanded with END-EXPR([ARGn]).
+#
+# For example:
+#   m4_define([show], [($*)m4_newline])dnl
+#   m4_transform_pair([show], [], [a], [b], [c], [d], [e])dnl
+#   => (a,b)
+#   => (c,d)
+#   => (e)
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_transform_pair],
+[m4_if([$#], [0], [m4_fatal([$0: too few arguments: $#])],
+       [$#], [1], [m4_fatal([$0: too few arguments: $#: $1])],
+       [$#], [2], [],
+       [$#], [3], [m4_default([$2], [$1])([$3])[]],
+       [$#], [4], [$1([$3], [$4])[]],
+       [$1([$3], [$4])[]$0([$1], [$2], m4_shift(m4_shift3($@)))])])
+
+
+## --------------------------- ##
+## 9. More diversion support.  ##
+## --------------------------- ##
+
+
+# _m4_divert(DIVERSION-NAME or NUMBER)
+# ------------------------------------
+# If DIVERSION-NAME is the name of a diversion, return its number,
+# otherwise if it is a NUMBER return it.
+m4_define([_m4_divert],
+[m4_ifdef([_m4_divert($1)],
+          [m4_indir([_m4_divert($1)])],
+          [$1])])
+
+# KILL is only used to suppress output.
+m4_define([_m4_divert(KILL)],           -1)
+
+# The empty diversion name is a synonym for 0.
+m4_define([_m4_divert()],                0)
+
+
+# _m4_divert_n_stack
+# ------------------
+# Print m4_divert_stack with newline prepended, if it's nonempty.
+m4_define([_m4_divert_n_stack],
+[m4_ifdef([m4_divert_stack], [
+_m4_defn([m4_divert_stack])])])
+
+
+# m4_divert(DIVERSION-NAME)
+# -------------------------
+# Change the diversion stream to DIVERSION-NAME.
+m4_define([m4_divert],
+[m4_define([m4_divert_stack], m4_location[: $0: $1]_m4_divert_n_stack)]dnl
+[m4_builtin([divert], _m4_divert([$1]))])
+
+
+# m4_divert_push(DIVERSION-NAME)
+# ------------------------------
+# Change the diversion stream to DIVERSION-NAME, while stacking old values.
+m4_define([m4_divert_push],
+[m4_pushdef([m4_divert_stack], m4_location[: $0: $1]_m4_divert_n_stack)]dnl
+[m4_pushdef([_m4_divert_diversion], [$1])]dnl
+[m4_builtin([divert], _m4_divert([$1]))])
+
+
+# m4_divert_pop([DIVERSION-NAME])
+# -------------------------------
+# Change the diversion stream to its previous value, unstacking it.
+# If specified, verify we left DIVERSION-NAME.
+# When we pop the last value from the stack, we divert to -1.
+m4_define([m4_divert_pop],
+[m4_ifndef([_m4_divert_diversion],
+           [m4_fatal([too many m4_divert_pop])])]dnl
+[m4_if([$1], [], [],
+       [$1], _m4_defn([_m4_divert_diversion]), [],
+       [m4_fatal([$0($1): diversion mismatch: ]_m4_divert_n_stack)])]dnl
+[_m4_popdef([m4_divert_stack], [_m4_divert_diversion])]dnl
+[m4_builtin([divert],
+            m4_ifdef([_m4_divert_diversion],
+                     [_m4_divert(_m4_defn([_m4_divert_diversion]))],
+                     -1))])
+
+
+# m4_divert_text(DIVERSION-NAME, CONTENT)
+# ---------------------------------------
+# Output CONTENT into DIVERSION-NAME (which may be a number actually).
+# An end of line is appended for free to CONTENT.
+m4_define([m4_divert_text],
+[m4_divert_push([$1])$2
+m4_divert_pop([$1])])
+
+
+# m4_divert_once(DIVERSION-NAME, CONTENT)
+# ---------------------------------------
+# Output CONTENT into DIVERSION-NAME once, if not already there.
+# An end of line is appended for free to CONTENT.
+m4_define([m4_divert_once],
+[m4_expand_once([m4_divert_text([$1], [$2])])])
+
+
+# m4_undivert(DIVERSION-NAME)
+# ---------------------------
+# Undivert DIVERSION-NAME.  Unlike the M4 version, this only takes a single
+# diversion identifier, and should not be used to undivert files.
+m4_define([m4_undivert],
+[m4_builtin([undivert], _m4_divert([$1]))])
+
+
+## --------------------------------------------- ##
+## 10. Defining macros with bells and whistles.  ##
+## --------------------------------------------- ##
+
+# `m4_defun' is basically `m4_define' but it equips the macro with the
+# needed machinery for `m4_require'.  A macro must be m4_defun'd if
+# either it is m4_require'd, or it m4_require's.
+#
+# Two things deserve attention and are detailed below:
+#  1. Implementation of m4_require
+#  2. Keeping track of the expansion stack
+#
+# 1. Implementation of m4_require
+# ===============================
+#
+# Of course m4_defun AC_PROVIDE's the macro, so that a macro which has
+# been expanded is not expanded again when m4_require'd, but the
+# difficult part is the proper expansion of macros when they are
+# m4_require'd.
+#
+# The implementation is based on two ideas, (i) using diversions to
+# prepare the expansion of the macro and its dependencies (by Franc,ois
+# Pinard), and (ii) expand the most recently m4_require'd macros _after_
+# the previous macros (by Axel Thimm).
+#
+#
+# The first idea: why use diversions?
+# -----------------------------------
+#
+# When a macro requires another, the other macro is expanded in new
+# diversion, GROW.  When the outer macro is fully expanded, we first
+# undivert the most nested diversions (GROW - 1...), and finally
+# undivert GROW.  To understand why we need several diversions,
+# consider the following example:
+#
+# | m4_defun([TEST1], [Test...REQUIRE([TEST2])1])
+# | m4_defun([TEST2], [Test...REQUIRE([TEST3])2])
+# | m4_defun([TEST3], [Test...3])
+#
+# Because m4_require is not required to be first in the outer macros, we
+# must keep the expansions of the various levels of m4_require separated.
+# Right before executing the epilogue of TEST1, we have:
+#
+#          GROW - 2: Test...3
+#          GROW - 1: Test...2
+#          GROW:     Test...1
+#          BODY:
+#
+# Finally the epilogue of TEST1 undiverts GROW - 2, GROW - 1, and
+# GROW into the regular flow, BODY.
+#
+#          GROW - 2:
+#          GROW - 1:
+#          GROW:
+#          BODY:        Test...3; Test...2; Test...1
+#
+# (The semicolons are here for clarification, but of course are not
+# emitted.)  This is what Autoconf 2.0 (I think) to 2.13 (I'm sure)
+# implement.
+#
+#
+# The second idea: first required first out
+# -----------------------------------------
+#
+# The natural implementation of the idea above is buggy and produces
+# very surprising results in some situations.  Let's consider the
+# following example to explain the bug:
+#
+# | m4_defun([TEST1],  [REQUIRE([TEST2a])REQUIRE([TEST2b])])
+# | m4_defun([TEST2a], [])
+# | m4_defun([TEST2b], [REQUIRE([TEST3])])
+# | m4_defun([TEST3],  [REQUIRE([TEST2a])])
+# |
+# | AC_INIT
+# | TEST1
+#
+# The dependencies between the macros are:
+#
+#                3 --- 2b
+#               /        \              is m4_require'd by
+#              /          \       left -------------------- right
+#           2a ------------ 1
+#
+# If you strictly apply the rules given in the previous section you get:
+#
+#          GROW - 2: TEST3
+#          GROW - 1: TEST2a; TEST2b
+#          GROW:     TEST1
+#          BODY:
+#
+# (TEST2a, although required by TEST3 is not expanded in GROW - 3
+# because is has already been expanded before in GROW - 1, so it has
+# been AC_PROVIDE'd, so it is not expanded again) so when you undivert
+# the stack of diversions, you get:
+#
+#          GROW - 2:
+#          GROW - 1:
+#          GROW:
+#          BODY:        TEST3; TEST2a; TEST2b; TEST1
+#
+# i.e., TEST2a is expanded after TEST3 although the latter required the
+# former.
+#
+# Starting from 2.50, we use an implementation provided by Axel Thimm.
+# The idea is simple: the order in which macros are emitted must be the
+# same as the one in which macros are expanded.  (The bug above can
+# indeed be described as: a macro has been AC_PROVIDE'd before its
+# dependent, but it is emitted after: the lack of correlation between
+# emission and expansion order is guilty).
+#
+# How to do that?  You keep the stack of diversions to elaborate the
+# macros, but each time a macro is fully expanded, emit it immediately.
+#
+# In the example above, when TEST2a is expanded, but it's epilogue is
+# not run yet, you have:
+#
+#          GROW - 2:
+#          GROW - 1: TEST2a
+#          GROW:     Elaboration of TEST1
+#          BODY:
+#
+# The epilogue of TEST2a emits it immediately:
+#
+#          GROW - 2:
+#          GROW - 1:
+#          GROW:     Elaboration of TEST1
+#          BODY:     TEST2a
+#
+# TEST2b then requires TEST3, so right before the epilogue of TEST3, you
+# have:
+#
+#          GROW - 2: TEST3
+#          GROW - 1: Elaboration of TEST2b
+#          GROW:     Elaboration of TEST1
+#          BODY:      TEST2a
+#
+# The epilogue of TEST3 emits it:
+#
+#          GROW - 2:
+#          GROW - 1: Elaboration of TEST2b
+#          GROW:     Elaboration of TEST1
+#          BODY:     TEST2a; TEST3
+#
+# TEST2b is now completely expanded, and emitted:
+#
+#          GROW - 2:
+#          GROW - 1:
+#          GROW:     Elaboration of TEST1
+#          BODY:     TEST2a; TEST3; TEST2b
+#
+# and finally, TEST1 is finished and emitted:
+#
+#          GROW - 2:
+#          GROW - 1:
+#          GROW:
+#          BODY:     TEST2a; TEST3; TEST2b: TEST1
+#
+# The idea is simple, but the implementation is a bit evolved.  If you
+# are like me, you will want to see the actual functioning of this
+# implementation to be convinced.  The next section gives the full
+# details.
+#
+#
+# The Axel Thimm implementation at work
+# -------------------------------------
+#
+# We consider the macros above, and this configure.ac:
+#
+#           AC_INIT
+#           TEST1
+#
+# You should keep the definitions of _m4_defun_pro, _m4_defun_epi, and
+# m4_require at hand to follow the steps.
+#
+# This implements tries not to assume that the current diversion is
+# BODY, so as soon as a macro (m4_defun'd) is expanded, we first
+# record the current diversion under the name _m4_divert_dump (denoted
+# DUMP below for short).  This introduces an important difference with
+# the previous versions of Autoconf: you cannot use m4_require if you
+# are not inside an m4_defun'd macro, and especially, you cannot
+# m4_require directly from the top level.
+#
+# We have not tried to simulate the old behavior (better yet, we
+# diagnose it), because it is too dangerous: a macro m4_require'd from
+# the top level is expanded before the body of `configure', i.e., before
+# any other test was run.  I let you imagine the result of requiring
+# AC_STDC_HEADERS for instance, before AC_PROG_CC was actually run....
+#
+# After AC_INIT was run, the current diversion is BODY.
+# * AC_INIT was run
+#   DUMP:                undefined
+#   diversion stack:     BODY |-
+#
+# * TEST1 is expanded
+# The prologue of TEST1 sets _m4_divert_dump, which is the diversion
+# where the current elaboration will be dumped, to the current
+# diversion.  It also m4_divert_push to GROW, where the full
+# expansion of TEST1 and its dependencies will be elaborated.
+#   DUMP:        BODY
+#   BODY:        empty
+#   diversions:  GROW, BODY |-
+#
+# * TEST1 requires TEST2a
+# _m4_require_call m4_divert_pushes another temporary diversion,
+# GROW - 1, and expands TEST2a in there.
+#   DUMP:        BODY
+#   BODY:        empty
+#   GROW - 1:    TEST2a
+#   diversions:  GROW - 1, GROW, BODY |-
+# Than the content of the temporary diversion is moved to DUMP and the
+# temporary diversion is popped.
+#   DUMP:        BODY
+#   BODY:        TEST2a
+#   diversions:  GROW, BODY |-
+#
+# * TEST1 requires TEST2b
+# Again, _m4_require_call pushes GROW - 1 and heads to expand TEST2b.
+#   DUMP:        BODY
+#   BODY:        TEST2a
+#   diversions:  GROW - 1, GROW, BODY |-
+#
+# * TEST2b requires TEST3
+# _m4_require_call pushes GROW - 2 and expands TEST3 here.
+# (TEST3 requires TEST2a, but TEST2a has already been m4_provide'd, so
+# nothing happens.)
+#   DUMP:        BODY
+#   BODY:        TEST2a
+#   GROW - 2:    TEST3
+#   diversions:  GROW - 2, GROW - 1, GROW, BODY |-
+# Than the diversion is appended to DUMP, and popped.
+#   DUMP:        BODY
+#   BODY:        TEST2a; TEST3
+#   diversions:  GROW - 1, GROW, BODY |-
+#
+# * TEST1 requires TEST2b (contd.)
+# The content of TEST2b is expanded...
+#   DUMP:        BODY
+#   BODY:        TEST2a; TEST3
+#   GROW - 1:    TEST2b,
+#   diversions:  GROW - 1, GROW, BODY |-
+# ... and moved to DUMP.
+#   DUMP:        BODY
+#   BODY:        TEST2a; TEST3; TEST2b
+#   diversions:  GROW, BODY |-
+#
+# * TEST1 is expanded: epilogue
+# TEST1's own content is in GROW...
+#   DUMP:        BODY
+#   BODY:        TEST2a; TEST3; TEST2b
+#   GROW:        TEST1
+#   diversions:  BODY |-
+# ... and it's epilogue moves it to DUMP and then undefines DUMP.
+#   DUMP:       undefined
+#   BODY:       TEST2a; TEST3; TEST2b; TEST1
+#   diversions: BODY |-
+#
+#
+# 2. Keeping track of the expansion stack
+# =======================================
+#
+# When M4 expansion goes wrong it is often extremely hard to find the
+# path amongst macros that drove to the failure.  What is needed is
+# the stack of macro `calls'. One could imagine that GNU M4 would
+# maintain a stack of macro expansions, unfortunately it doesn't, so
+# we do it by hand.  This is of course extremely costly, but the help
+# this stack provides is worth it.  Nevertheless to limit the
+# performance penalty this is implemented only for m4_defun'd macros,
+# not for define'd macros.
+#
+# The scheme is simplistic: each time we enter an m4_defun'd macros,
+# we prepend its name in m4_expansion_stack, and when we exit the
+# macro, we remove it (thanks to pushdef/popdef).
+#
+# In addition, we want to detect circular m4_require dependencies.
+# Each time we expand a macro FOO we define _m4_expanding(FOO); and
+# m4_require(BAR) simply checks whether _m4_expanding(BAR) is defined.
+
+
+# m4_expansion_stack_push(TEXT)
+# -----------------------------
+m4_define([m4_expansion_stack_push],
+[m4_pushdef([m4_expansion_stack],
+            [$1]m4_ifdef([m4_expansion_stack], [
+_m4_defn([m4_expansion_stack])]))])
+
+
+# m4_expansion_stack_pop
+# ----------------------
+m4_define([m4_expansion_stack_pop],
+[m4_popdef([m4_expansion_stack])])
+
+
+# m4_expansion_stack_dump
+# -----------------------
+# Dump the expansion stack.
+m4_define([m4_expansion_stack_dump],
+[m4_ifdef([m4_expansion_stack],
+          [m4_errprintn(_m4_defn([m4_expansion_stack]))])dnl
+m4_errprintn(m4_location[: the top level])])
+
+
+# _m4_divert(GROW)
+# ----------------
+# This diversion is used by the m4_defun/m4_require machinery.  It is
+# important to keep room before GROW because for each nested
+# AC_REQUIRE we use an additional diversion (i.e., two m4_require's
+# will use GROW - 2.  More than 3 levels has never seemed to be
+# needed.)
+#
+# ...
+# - GROW - 2
+#   m4_require'd code, 2 level deep
+# - GROW - 1
+#   m4_require'd code, 1 level deep
+# - GROW
+#   m4_defun'd macros are elaborated here.
+
+m4_define([_m4_divert(GROW)],       10000)
+
+
+# _m4_defun_pro(MACRO-NAME)
+# -------------------------
+# The prologue for Autoconf macros.
+#
+# This is called frequently, so minimize the number of macro invocations
+# by avoiding dnl and m4_defn overhead.
+m4_define([_m4_defun_pro],
+m4_do([[m4_ifdef([m4_expansion_stack], [], [_m4_defun_pro_outer[]])]],
+      [[m4_expansion_stack_push(_m4_defn(
+          [m4_location($1)])[: $1 is expanded from...])]],
+      [[m4_pushdef([_m4_expanding($1)])]]))
+
+m4_define([_m4_defun_pro_outer],
+[m4_copy([_m4_divert_diversion], [_m4_divert_dump])m4_divert_push([GROW])])
+
+# _m4_defun_epi(MACRO-NAME)
+# -------------------------
+# The Epilogue for Autoconf macros.  MACRO-NAME only helps tracing
+# the PRO/EPI pairs.
+#
+# This is called frequently, so minimize the number of macro invocations
+# by avoiding dnl and m4_popdef overhead.
+m4_define([_m4_defun_epi],
+m4_do([[_m4_popdef([_m4_expanding($1)])]],
+      [[m4_expansion_stack_pop()]],
+      [[m4_ifdef([m4_expansion_stack], [], [_m4_defun_epi_outer[]])]],
+      [[m4_provide([$1])]]))
+
+m4_define([_m4_defun_epi_outer],
+[_m4_undefine([_m4_divert_dump])m4_divert_pop([GROW])m4_undivert([GROW])])
+
+
+# m4_defun(NAME, EXPANSION)
+# -------------------------
+# Define a macro which automatically provides itself.  Add machinery
+# so the macro automatically switches expansion to the diversion
+# stack if it is not already using it.  In this case, once finished,
+# it will bring back all the code accumulated in the diversion stack.
+# This, combined with m4_require, achieves the topological ordering of
+# macros.  We don't use this macro to define some frequently called
+# macros that are not involved in ordering constraints, to save m4
+# processing.
+m4_define([m4_defun],
+[m4_define([m4_location($1)], m4_location)dnl
+m4_define([$1],
+          [_m4_defun_pro([$1])$2[]_m4_defun_epi([$1])])])
+
+
+# m4_defun_once(NAME, EXPANSION)
+# ------------------------------
+# As m4_defun, but issues the EXPANSION only once, and warns if used
+# several times.
+m4_define([m4_defun_once],
+[m4_define([m4_location($1)], m4_location)dnl
+m4_define([$1],
+          [m4_provide_if([$1],
+                         [m4_warn([syntax], [$1 invoked multiple times])],
+                         [_m4_defun_pro([$1])$2[]_m4_defun_epi([$1])])])])
+
+
+# m4_pattern_forbid(ERE, [WHY])
+# -----------------------------
+# Declare that no token matching the forbidden extended regular
+# expression ERE should be seen in the output unless...
+m4_define([m4_pattern_forbid], [])
+
+
+# m4_pattern_allow(ERE)
+# ---------------------
+# ... that token also matches the allowed extended regular expression ERE.
+# Both used via traces.
+m4_define([m4_pattern_allow], [])
+
+
+## --------------------------------- ##
+## 11. Dependencies between macros.  ##
+## --------------------------------- ##
+
+
+# m4_before(THIS-MACRO-NAME, CALLED-MACRO-NAME)
+# ---------------------------------------------
+# Issue a warning if CALLED-MACRO-NAME was called before THIS-MACRO-NAME.
+m4_define([m4_before],
+[m4_provide_if([$2],
+               [m4_warn([syntax], [$2 was called before $1])])])
+
+
+# m4_require(NAME-TO-CHECK, [BODY-TO-EXPAND = NAME-TO-CHECK])
+# -----------------------------------------------------------
+# If NAME-TO-CHECK has never been expanded (actually, if it is not
+# m4_provide'd), expand BODY-TO-EXPAND *before* the current macro
+# expansion.  Once expanded, emit it in _m4_divert_dump.  Keep track
+# of the m4_require chain in m4_expansion_stack.
+#
+# The normal cases are:
+#
+# - NAME-TO-CHECK == BODY-TO-EXPAND
+#   Which you can use for regular macros with or without arguments, e.g.,
+#     m4_require([AC_PROG_CC], [AC_PROG_CC])
+#     m4_require([AC_CHECK_HEADERS(limits.h)], [AC_CHECK_HEADERS(limits.h)])
+#   which is just the same as
+#     m4_require([AC_PROG_CC])
+#     m4_require([AC_CHECK_HEADERS(limits.h)])
+#
+# - BODY-TO-EXPAND == m4_indir([NAME-TO-CHECK])
+#   In the case of macros with irregular names.  For instance:
+#     m4_require([AC_LANG_COMPILER(C)], [indir([AC_LANG_COMPILER(C)])])
+#   which means `if the macro named `AC_LANG_COMPILER(C)' (the parens are
+#   part of the name, it is not an argument) has not been run, then
+#   call it.'
+#   Had you used
+#     m4_require([AC_LANG_COMPILER(C)], [AC_LANG_COMPILER(C)])
+#   then m4_require would have tried to expand `AC_LANG_COMPILER(C)', i.e.,
+#   call the macro `AC_LANG_COMPILER' with `C' as argument.
+#
+#   You could argue that `AC_LANG_COMPILER', when it receives an argument
+#   such as `C' should dispatch the call to `AC_LANG_COMPILER(C)'.  But this
+#   `extension' prevents `AC_LANG_COMPILER' from having actual arguments that
+#   it passes to `AC_LANG_COMPILER(C)'.
+#
+# This is called frequently, so minimize the number of macro invocations
+# by avoiding dnl and other overhead on the common path.
+m4_define([m4_require],
+m4_do([[m4_ifdef([_m4_expanding($1)],
+                 [m4_fatal([$0: circular dependency of $1])])]],
+      [[m4_ifdef([_m4_divert_dump], [],
+                 [m4_fatal([$0($1): cannot be used outside of an ]dnl
+m4_bmatch([$0], [^AC_], [[AC_DEFUN]], [[m4_defun]])['d macro])])]],
+      [[m4_provide_if([$1],
+                      [],
+                      [_m4_require_call([$1], [$2])])]]))
+
+
+# _m4_require_call(NAME-TO-CHECK, [BODY-TO-EXPAND = NAME-TO-CHECK])
+# -----------------------------------------------------------------
+# If m4_require decides to expand the body, it calls this macro.
+#
+# This is called frequently, so minimize the number of macro invocations
+# by avoiding dnl and other overhead on the common path.
+m4_define([_m4_require_call],
+m4_do([[m4_define([_m4_divert_grow], m4_decr(_m4_divert_grow))]],
+      [[m4_divert_push(_m4_divert_grow)]],
+      [[m4_default([$2], [$1])
+m4_provide_if([$1],
+              [],
+              [m4_warn([syntax],
+                       [$1 is m4_require'd but not m4_defun'd])])]],
+      [[m4_divert(_m4_defn([_m4_divert_dump]))]],
+      [[m4_undivert(_m4_divert_grow)]],
+      [[m4_divert_pop(_m4_divert_grow)]],
+      [[m4_define([_m4_divert_grow], m4_incr(_m4_divert_grow))]]))
+
+
+# _m4_divert_grow
+# ---------------
+# The counter for _m4_require_call.
+m4_define([_m4_divert_grow], _m4_divert([GROW]))
+
+
+# m4_expand_once(TEXT, [WITNESS = TEXT])
+# --------------------------------------
+# If TEXT has never been expanded, expand it *here*.  Use WITNESS as
+# as a memory that TEXT has already been expanded.
+m4_define([m4_expand_once],
+[m4_provide_if(m4_ifval([$2], [[$2]], [[$1]]),
+               [],
+               [m4_provide(m4_ifval([$2], [[$2]], [[$1]]))[]$1])])
+
+
+# m4_provide(MACRO-NAME)
+# ----------------------
+m4_define([m4_provide],
+[m4_define([m4_provide($1)])])
+
+
+# m4_provide_if(MACRO-NAME, IF-PROVIDED, IF-NOT-PROVIDED)
+# -------------------------------------------------------
+# If MACRO-NAME is provided do IF-PROVIDED, else IF-NOT-PROVIDED.
+# The purpose of this macro is to provide the user with a means to
+# check macros which are provided without letting her know how the
+# information is coded.
+m4_define([m4_provide_if],
+[m4_ifdef([m4_provide($1)],
+          [$2], [$3])])
+
+
+## --------------------- ##
+## 12. Text processing.  ##
+## --------------------- ##
+
+
+# m4_cr_letters
+# m4_cr_LETTERS
+# m4_cr_Letters
+# -------------
+m4_define([m4_cr_letters], [abcdefghijklmnopqrstuvwxyz])
+m4_define([m4_cr_LETTERS], [ABCDEFGHIJKLMNOPQRSTUVWXYZ])
+m4_define([m4_cr_Letters],
+m4_defn([m4_cr_letters])dnl
+m4_defn([m4_cr_LETTERS])dnl
+)
+
+
+# m4_cr_digits
+# ------------
+m4_define([m4_cr_digits], [0123456789])
+
+
+# m4_cr_alnum
+# -----------
+m4_define([m4_cr_alnum],
+m4_defn([m4_cr_Letters])dnl
+m4_defn([m4_cr_digits])dnl
+)
+
+
+# m4_cr_symbols1
+# m4_cr_symbols2
+# -------------------------------
+m4_define([m4_cr_symbols1],
+m4_defn([m4_cr_Letters])dnl
+_)
+
+m4_define([m4_cr_symbols2],
+m4_defn([m4_cr_symbols1])dnl
+m4_defn([m4_cr_digits])dnl
+)
+
+# m4_cr_all
+# ---------
+# The character range representing everything, with `-' as the last
+# character, since it is special to m4_translit.  Use with care, because
+# it contains characters special to M4 (fortunately, both ASCII and EBCDIC
+# have [] in order, so m4_defn([m4_cr_all]) remains a valid string).  It
+# also contains characters special to terminals, so it should never be
+# displayed in an error message.  Also, attempts to map [ and ] to other
+# characters via m4_translit must deal with the fact that m4_translit does
+# not add quotes to the output.
+#
+# It is mainly useful in generating inverted character range maps, for use
+# in places where m4_translit is faster than an equivalent m4_bpatsubst;
+# the regex `[^a-z]' is equivalent to:
+#  m4_translit(m4_dquote(m4_defn([m4_cr_all])), [a-z])
+m4_define([m4_cr_all],
+m4_translit(m4_dquote(m4_format(m4_dquote(m4_for(
+  ,1,255,,[[%c]]))m4_for([i],1,255,,[,i]))), [-])-)
+
+
+# _m4_define_cr_not(CATEGORY)
+# ---------------------------
+# Define m4_cr_not_CATEGORY as the inverse of m4_cr_CATEGORY.
+m4_define([_m4_define_cr_not],
+[m4_define([m4_cr_not_$1],
+           m4_translit(m4_dquote(m4_defn([m4_cr_all])),
+                       m4_defn([m4_cr_$1])))])
+
+
+# m4_cr_not_letters
+# m4_cr_not_LETTERS
+# m4_cr_not_Letters
+# m4_cr_not_digits
+# m4_cr_not_alnum
+# m4_cr_not_symbols1
+# m4_cr_not_symbols2
+# ------------------
+# Inverse character sets
+_m4_define_cr_not([letters])
+_m4_define_cr_not([LETTERS])
+_m4_define_cr_not([Letters])
+_m4_define_cr_not([digits])
+_m4_define_cr_not([alnum])
+_m4_define_cr_not([symbols1])
+_m4_define_cr_not([symbols2])
+
+
+# m4_newline
+# ----------
+# Expands to a newline.  Exists for formatting reasons.
+m4_define([m4_newline], [
+])
+
+
+# m4_re_escape(STRING)
+# --------------------
+# Escape RE active characters in STRING.
+m4_define([m4_re_escape],
+[m4_bpatsubst([$1],
+              [[][*+.?\^$]], [\\\&])])
+
+
+# m4_re_string
+# ------------
+# Regexp for `[a-zA-Z_0-9]*'
+# m4_dquote provides literal [] for the character class.
+m4_define([m4_re_string],
+m4_dquote(m4_defn([m4_cr_symbols2]))dnl
+[*]dnl
+)
+
+
+# m4_re_word
+# ----------
+# Regexp for `[a-zA-Z_][a-zA-Z_0-9]*'
+m4_define([m4_re_word],
+m4_dquote(m4_defn([m4_cr_symbols1]))dnl
+m4_defn([m4_re_string])dnl
+)
+
+
+# m4_tolower(STRING)
+# m4_toupper(STRING)
+# ------------------
+# These macros convert STRING to lowercase or uppercase.
+#
+# Rather than expand the m4_defn each time, we inline them up front.
+m4_define([m4_tolower],
+[m4_translit([$1], ]m4_dquote(m4_defn([m4_cr_LETTERS]))[,
+                   ]m4_dquote(m4_defn([m4_cr_letters]))[)])
+m4_define([m4_toupper],
+[m4_translit([$1], ]m4_dquote(m4_defn([m4_cr_letters]))[,
+                   ]m4_dquote(m4_defn([m4_cr_LETTERS]))[)])
+
+
+# m4_split(STRING, [REGEXP])
+# --------------------------
+#
+# Split STRING into an m4 list of quoted elements.  The elements are
+# quoted with [ and ].  Beginning spaces and end spaces *are kept*.
+# Use m4_strip to remove them.
+#
+# REGEXP specifies where to split.  Default is [\t ]+.
+#
+# If STRING is empty, the result is an empty list.
+#
+# Pay attention to the m4_changequotes.  When m4 reads the definition of
+# m4_split, it still has quotes set to [ and ].  Luckily, these are matched
+# in the macro body, so the definition is stored correctly.  Use the same
+# alternate quotes as m4_noquote; it must be unlikely to appear in $1.
+#
+# Also, notice that $1 is quoted twice, since we want the result to
+# be quoted.  Then you should understand that the argument of
+# patsubst is -=<{(STRING)}>=- (i.e., with additional -=<{( and )}>=-).
+#
+# This macro is safe on active symbols, i.e.:
+#   m4_define(active, ACTIVE)
+#   m4_split([active active ])end
+#   => [active], [active], []end
+#
+# Optimize on regex of ` ' (space), since m4_foreach_w already guarantees
+# that the list contains single space separators, and a common case is
+# splitting a single-element list.  This macro is called frequently,
+# so avoid unnecessary dnl inside the definition.
+m4_define([m4_split],
+[m4_if([$1], [], [],
+       [$2], [ ], [m4_if(m4_index([$1], [ ]), [-1], [[[$1]]], [_$0($@)])],
+       [$2], [], [_$0([$1], [[   ]+])],
+       [_$0($@)])])
+
+m4_define([_m4_split],
+[m4_changequote([-=<{(],[)}>=-])]dnl
+[[m4_bpatsubst(-=<{(-=<{($1)}>=-)}>=-, -=<{($2)}>=-,
+               -=<{(], [)}>=-)]m4_changequote([, ])])
+
+
+
+# m4_flatten(STRING)
+# ------------------
+# If STRING contains end of lines, replace them with spaces.  If there
+# are backslashed end of lines, remove them.  This macro is safe with
+# active symbols.
+#    m4_define(active, ACTIVE)
+#    m4_flatten([active
+#    act\
+#    ive])end
+#    => active activeend
+#
+# In m4, m4_bpatsubst is expensive, so first check for a newline.
+m4_define([m4_flatten],
+[m4_if(m4_index([$1], [
+]), [-1], [[$1]],
+       [m4_translit(m4_bpatsubst([[[$1]]], [\\
+]), [
+], [ ])])])
+
+
+# m4_strip(STRING)
+# ----------------
+# Expands into STRING with tabs and spaces singled out into a single
+# space, and removing leading and trailing spaces.
+#
+# This macro is robust to active symbols.
+#    m4_define(active, ACTIVE)
+#    m4_strip([  active <tab> <tab>active ])end
+#    => active activeend
+#
+# First, notice that we guarantee trailing space.  Why?  Because regular
+# expressions are greedy, and `.* ?' would always group the space into the
+# .* portion.  The algorithm is simpler by avoiding `?' at the end.  The
+# algorithm correctly strips everything if STRING is just ` '.
+#
+# Then notice the second pattern: it is in charge of removing the
+# leading/trailing spaces.  Why not just `[^ ]'?  Because they are
+# applied to over-quoted strings, i.e. more or less [STRING], due
+# to the limitations of m4_bpatsubsts.  So the leading space in STRING
+# is the *second* character; equally for the trailing space.
+m4_define([m4_strip],
+[m4_bpatsubsts([$1 ],
+               [[        ]+], [ ],
+               [^. ?\(.*\) .$], [[[\1]]])])
+
+
+# m4_normalize(STRING)
+# --------------------
+# Apply m4_flatten and m4_strip to STRING.
+#
+# The argument is quoted, so that the macro is robust to active symbols:
+#
+#    m4_define(active, ACTIVE)
+#    m4_normalize([  act\
+#    ive
+#    active ])end
+#    => active activeend
+
+m4_define([m4_normalize],
+[m4_strip(m4_flatten([$1]))])
+
+
+
+# m4_join(SEP, ARG1, ARG2...)
+# ---------------------------
+# Produce ARG1SEPARG2...SEPARGn.  Avoid back-to-back SEP when a given ARG
+# is the empty string.  No expansion is performed on SEP or ARGs.
+#
+# Since the number of arguments to join can be arbitrarily long, we
+# want to avoid having more than one $@ in the macro definition;
+# otherwise, the expansion would require twice the memory of the already
+# long list.  Hence, m4_join merely looks for the first non-empty element,
+# and outputs just that element; while _m4_join looks for all non-empty
+# elements, and outputs them following a separator.  The final trick to
+# note is that we decide between recursing with $0 or _$0 based on the
+# nested m4_if ending with `_'.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_join],
+[m4_if([$#], [1], [],
+       [$#], [2], [[$2]],
+       [m4_if([$2], [], [], [[$2]_])$0([$1], m4_shift2($@))])])
+m4_define([_m4_join],
+[m4_if([$#$2], [2], [],
+       [m4_if([$2], [], [], [[$1$2]])$0([$1], m4_shift2($@))])])
+
+# m4_joinall(SEP, ARG1, ARG2...)
+# ------------------------------
+# Produce ARG1SEPARG2...SEPARGn.  An empty ARG results in back-to-back SEP.
+# No expansion is performed on SEP or ARGs.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_joinall], [[$2]_$0([$1], m4_shift($@))])
+m4_define([_m4_joinall],
+[m4_if([$#], [2], [], [[$1$3]$0([$1], m4_shift2($@))])])
+
+# m4_combine([SEPARATOR], PREFIX-LIST, [INFIX], SUFFIX...)
+# --------------------------------------------------------
+# Produce the pairwise combination of every element in the quoted,
+# comma-separated PREFIX-LIST with every element from the SUFFIX arguments.
+# Each pair is joined with INFIX, and pairs are separated by SEPARATOR.
+# No expansion occurs on SEPARATOR, INFIX, or elements of either list.
+#
+# For example:
+#   m4_combine([, ], [[a], [b], [c]], [-], [1], [2], [3])
+#   => a-1, a-2, a-3, b-1, b-2, b-3, c-1, c-2, c-3
+#
+# In order to have the correct number of SEPARATORs, we use a temporary
+# variable that redefines itself after the first use.  We must use defn
+# rather than overquoting in case PREFIX or SUFFIX contains $1, but use
+# _m4_defn for speed.  Likewise, we compute the m4_shift3 only once,
+# rather than in each iteration of the outer m4_foreach.
+m4_define([m4_combine],
+[m4_if(m4_eval([$# > 3]), [1],
+       [m4_pushdef([m4_Separator], [m4_define([m4_Separator],
+                                    _m4_defn([m4_echo]))])]]dnl
+[[m4_foreach([m4_Prefix], [$2],
+             [m4_foreach([m4_Suffix], ]m4_dquote(m4_dquote(m4_shift3($@)))[,
+        [m4_Separator([$1])[]_m4_defn([m4_Prefix])[$3]_m4_defn(
+                                                      [m4_Suffix])])])]]dnl
+[[_m4_popdef([m4_Separator])])])
+
+
+# m4_append(MACRO-NAME, STRING, [SEPARATOR])
+# ------------------------------------------
+# Redefine MACRO-NAME to hold its former content plus `SEPARATOR`'STRING'
+# at the end.  It is valid to use this macro with MACRO-NAME undefined,
+# in which case no SEPARATOR is added.  Be aware that the criterion is
+# `not being defined', and not `not being empty'.
+#
+# Note that neither STRING nor SEPARATOR are expanded here; rather, when
+# you expand MACRO-NAME, they will be expanded at that point in time.
+#
+# This macro is robust to active symbols.  It can be used to grow
+# strings.
+#
+#    | m4_define(active, ACTIVE)dnl
+#    | m4_append([sentence], [This is an])dnl
+#    | m4_append([sentence], [ active ])dnl
+#    | m4_append([sentence], [symbol.])dnl
+#    | sentence
+#    | m4_undefine([active])dnl
+#    | sentence
+#    => This is an ACTIVE symbol.
+#    => This is an active symbol.
+#
+# It can be used to define hooks.
+#
+#    | m4_define(active, ACTIVE)dnl
+#    | m4_append([hooks], [m4_define([act1], [act2])])dnl
+#    | m4_append([hooks], [m4_define([act2], [active])])dnl
+#    | m4_undefine([active])dnl
+#    | act1
+#    | hooks
+#    | act1
+#    => act1
+#    =>
+#    => active
+#
+# It can also be used to create lists, although this particular usage was
+# broken prior to autoconf 2.62.
+#    | m4_append([list], [one], [, ])dnl
+#    | m4_append([list], [two], [, ])dnl
+#    | m4_append([list], [three], [, ])dnl
+#    | list
+#    | m4_dquote(list)
+#    => one, two, three
+#    => [one],[two],[three]
+#
+# Note that m4_append can benefit from amortized O(n) m4 behavior, if
+# the underlying m4 implementation is smart enough to avoid copying existing
+# contents when enlarging a macro's definition into any pre-allocated storage
+# (m4 1.4.x unfortunately does not implement this optimization).  We do
+# not implement m4_prepend, since it is inherently O(n^2) (pre-allocated
+# storage only occurs at the end of a macro, so the existing contents must
+# always be moved).
+#
+# Use _m4_defn for speed.
+m4_define([m4_append],
+[m4_define([$1], m4_ifdef([$1], [_m4_defn([$1])[$3]])[$2])])
+
+
+# m4_append_uniq(MACRO-NAME, STRING, [SEPARATOR], [IF-UNIQ], [IF-DUP])
+# --------------------------------------------------------------------
+# Like `m4_append', but append only if not yet present.  Additionally,
+# expand IF-UNIQ if STRING was appended, or IF-DUP if STRING was already
+# present.  Also, warn if SEPARATOR is not empty and occurs within STRING,
+# as the algorithm no longer guarantees uniqueness.
+#
+# Note that while m4_append can be O(n) (depending on the quality of the
+# underlying M4 implementation), m4_append_uniq is inherently O(n^2)
+# because each append operation searches the entire string.
+m4_define([m4_append_uniq],
+[m4_ifval([$3], [m4_if(m4_index([$2], [$3]), [-1], [],
+                       [m4_warn([syntax],
+                                [$0: `$2' contains `$3'])])])_$0($@)])
+m4_define([_m4_append_uniq],
+[m4_ifdef([$1],
+          [m4_if(m4_index([$3]_m4_defn([$1])[$3], [$3$2$3]), [-1],
+                 [m4_append([$1], [$2], [$3])$4], [$5])],
+          [m4_define([$1], [$2])$4])])
+
+# m4_append_uniq_w(MACRO-NAME, STRINGS)
+# -------------------------------------
+# For each of the words in the whitespace separated list STRINGS, append
+# only the unique strings to the definition of MACRO-NAME.
+#
+# Use _m4_defn for speed.
+m4_define([m4_append_uniq_w],
+[m4_foreach_w([m4_Word], [$2],
+              [_m4_append_uniq([$1], _m4_defn([m4_Word]), [ ])])])
+
+
+# m4_text_wrap(STRING, [PREFIX], [FIRST-PREFIX], [WIDTH])
+# -------------------------------------------------------
+# Expands into STRING wrapped to hold in WIDTH columns (default = 79).
+# If PREFIX is given, each line is prefixed with it.  If FIRST-PREFIX is
+# specified, then the first line is prefixed with it.  As a special case,
+# if the length of FIRST-PREFIX is greater than that of PREFIX, then
+# FIRST-PREFIX will be left alone on the first line.
+#
+# No expansion occurs on the contents STRING, PREFIX, or FIRST-PREFIX,
+# although quadrigraphs are correctly recognized.
+#
+# Typical outputs are:
+#
+# m4_text_wrap([Short string */], [   ], [/* ], 20)
+#  => /* Short string */
+#
+# m4_text_wrap([Much longer string */], [   ], [/* ], 20)
+#  => /* Much longer
+#  =>    string */
+#
+# m4_text_wrap([Short doc.], [          ], [  --short ], 30)
+#  =>   --short Short doc.
+#
+# m4_text_wrap([Short doc.], [          ], [  --too-wide ], 30)
+#  =>   --too-wide
+#  =>           Short doc.
+#
+# m4_text_wrap([Super long documentation.], [          ], [  --too-wide ], 30)
+#  =>   --too-wide
+#  =>      Super long
+#  =>      documentation.
+#
+# FIXME: there is no checking of a longer PREFIX than WIDTH, but do
+# we really want to bother with people trying each single corner
+# of a software?
+#
+# This macro does not leave a trailing space behind the last word of a line,
+# which complicates it a bit.  The algorithm is otherwise stupid and simple:
+# all the words are preceded by m4_Separator which is defined to empty for
+# the first word, and then ` ' (single space) for all the others.
+#
+# The algorithm uses a helper that uses $2 through $4 directly, rather than
+# using local variables, to avoid m4_defn overhead, or expansion swallowing
+# any $.  It also bypasses m4_popdef overhead with _m4_popdef since no user
+# macro expansion occurs in the meantime.  Also, the definition is written
+# with m4_do, to avoid time wasted on dnl during expansion (since this is
+# already a time-consuming macro).
+m4_define([m4_text_wrap],
+[_$0([$1], [$2], m4_if([$3], [], [[$2]], [[$3]]),
+     m4_if([$4], [], [79], [[$4]]))])
+m4_define([_m4_text_wrap],
+m4_do(dnl set up local variables, to avoid repeated calculations
+[[m4_pushdef([m4_Indent], m4_qlen([$2]))]],
+[[m4_pushdef([m4_Cursor], m4_qlen([$3]))]],
+[[m4_pushdef([m4_Separator], [m4_define([m4_Separator], [ ])])]],
+dnl expand the first prefix, then check its length vs. regular prefix
+dnl same length: nothing special
+dnl prefix1 longer: output on line by itself, and reset cursor
+dnl prefix1 shorter: pad to length of prefix, and reset cursor
+[[[$3]m4_cond([m4_Cursor], m4_Indent, [],
+              [m4_eval(m4_Cursor > m4_Indent)], [1], [
+[$2]m4_define([m4_Cursor], m4_Indent)],
+              [m4_format([%*s], m4_max([0],
+  m4_eval(m4_Indent - m4_Cursor)), [])m4_define([m4_Cursor], m4_Indent)])]],
+dnl now, for each word, compute the curser after the word is output, then
+dnl check if the cursor would exceed the wrap column
+dnl if so, reset cursor, and insert newline and prefix
+dnl if not, insert the separator (usually a space)
+dnl either way, insert the word
+[[m4_foreach_w([m4_Word], [$1],
+  [m4_define([m4_Cursor],
+             m4_eval(m4_Cursor + m4_qlen(_m4_defn([m4_Word]))
+                     + 1))m4_if(m4_eval(m4_Cursor > ([$4])),
+      [1], [m4_define([m4_Cursor],
+                      m4_eval(m4_Indent + m4_qlen(_m4_defn([m4_Word])) + 1))
+[$2]],
+      [m4_Separator[]])_m4_defn([m4_Word])])]],
+dnl finally, clean up the local variabls
+[[_m4_popdef([m4_Separator], [m4_Cursor], [m4_Indent])]]))
+
+
+# m4_text_box(MESSAGE, [FRAME-CHARACTER = `-'])
+# ---------------------------------------------
+# Turn MESSAGE into:
+#  ## ------- ##
+#  ## MESSAGE ##
+#  ## ------- ##
+# using FRAME-CHARACTER in the border.
+m4_define([m4_text_box],
+[m4_pushdef([m4_Border],
+            m4_translit(m4_format([%*s], m4_qlen(m4_expand([$1])), []),
+                        [ ], m4_if([$2], [], [[-]], [[$2]])))dnl
+@%:@@%:@ m4_Border @%:@@%:@
+@%:@@%:@ $1 @%:@@%:@
+@%:@@%:@ m4_Border @%:@@%:@_m4_popdef([m4_Border])dnl
+])
+
+
+# m4_qlen(STRING)
+# ---------------
+# Expands to the length of STRING after autom4te converts all quadrigraphs.
+#
+# Avoid bpatsubsts for the common case of no quadrigraphs.
+m4_define([m4_qlen],
+[m4_if(m4_index([$1], [@]), [-1], [m4_len([$1])],
+       [m4_len(m4_bpatsubst([[$1]],
+                            [@\(\(<:\|:>\|S|\|%:\|\{:\|:\}\)\(@\)\|&t@\)],
+                            [\3]))])])
+
+
+# m4_qdelta(STRING)
+# -----------------
+# Expands to the net change in the length of STRING from autom4te converting the
+# quadrigraphs in STRING.  This number is always negative or zero.
+m4_define([m4_qdelta],
+[m4_eval(m4_qlen([$1]) - m4_len([$1]))])
+
+
+
+## ----------------------- ##
+## 13. Number processing.  ##
+## ----------------------- ##
+
+# m4_cmp(A, B)
+# ------------
+# Compare two integer expressions.
+# A < B -> -1
+# A = B ->  0
+# A > B ->  1
+m4_define([m4_cmp],
+[m4_eval((([$1]) > ([$2])) - (([$1]) < ([$2])))])
+
+
+# m4_list_cmp(A, B)
+# -----------------
+#
+# Compare the two lists of integer expressions A and B.  For instance:
+#   m4_list_cmp([1, 0],     [1])    ->  0
+#   m4_list_cmp([1, 0],     [1, 0]) ->  0
+#   m4_list_cmp([1, 2],     [1, 0]) ->  1
+#   m4_list_cmp([1, 2, 3],  [1, 2]) ->  1
+#   m4_list_cmp([1, 2, -3], [1, 2]) -> -1
+#   m4_list_cmp([1, 0],     [1, 2]) -> -1
+#   m4_list_cmp([1],        [1, 2]) -> -1
+#   m4_define([xa], [oops])dnl
+#   m4_list_cmp([[0xa]],    [5+5])  -> 0
+#
+# Rather than face the overhead of m4_case, we use a helper function whose
+# expansion includes the name of the macro to invoke on the tail, either
+# m4_ignore or m4_unquote.  This is particularly useful when comparing
+# long lists, since less text is being expanded for deciding when to end
+# recursion.  The recursion is between a pair of macros that alternate
+# which list is trimmed by one element; this is more efficient than
+# calling m4_cdr on both lists from a single macro.  Guarantee exactly
+# one expansion of both lists' side effects.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_list_cmp],
+[_$0_raw(m4_dquote($1), m4_dquote($2))])
+
+m4_define([_m4_list_cmp_raw],
+[m4_if([$1], [$2], [0], [_m4_list_cmp_1([$1], $2)])])
+
+m4_define([_m4_list_cmp],
+[m4_if([$1], [], [0m4_ignore], [$2], [0], [m4_unquote], [$2m4_ignore])])
+
+m4_define([_m4_list_cmp_1],
+[_m4_list_cmp_2([$2], [m4_shift2($@)], $1)])
+
+m4_define([_m4_list_cmp_2],
+[_m4_list_cmp([$1$3], m4_cmp([$3+0], [$1+0]))(
+  [_m4_list_cmp_1(m4_dquote(m4_shift3($@)), $2)])])
+
+# m4_max(EXPR, ...)
+# m4_min(EXPR, ...)
+# -----------------
+# Return the decimal value of the maximum (or minimum) in a series of
+# integer expressions.
+#
+# M4 1.4.x doesn't provide ?:.  Hence this huge m4_eval.  Avoid m4_eval
+# if both arguments are identical, but be aware of m4_max(0xa, 10) (hence
+# the use of <=, not just <, in the second multiply).
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_max],
+[m4_if([$#], [0], [m4_fatal([too few arguments to $0])],
+       [$#], [1], [m4_eval([$1])],
+       [$#$1], [2$2], [m4_eval([$1])],
+       [$#], [2], [_$0($@)],
+       [_m4_minmax([_$0], $@)])])
+
+m4_define([_m4_max],
+[m4_eval((([$1]) > ([$2])) * ([$1]) + (([$1]) <= ([$2])) * ([$2]))])
+
+m4_define([m4_min],
+[m4_if([$#], [0], [m4_fatal([too few arguments to $0])],
+       [$#], [1], [m4_eval([$1])],
+       [$#$1], [2$2], [m4_eval([$1])],
+       [$#], [2], [_$0($@)],
+       [_m4_minmax([_$0], $@)])])
+
+m4_define([_m4_min],
+[m4_eval((([$1]) < ([$2])) * ([$1]) + (([$1]) >= ([$2])) * ([$2]))])
+
+# _m4_minmax(METHOD, ARG1, ARG2...)
+# ---------------------------------
+# Common recursion code for m4_max and m4_min.  METHOD must be _m4_max
+# or _m4_min, and there must be at least two arguments to combine.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([_m4_minmax],
+[m4_if([$#], [3], [$1([$2], [$3])],
+       [$0([$1], $1([$2], [$3]), m4_shift3($@))])])
+
+
+# m4_sign(A)
+# ----------
+# The sign of the integer expression A.
+m4_define([m4_sign],
+[m4_eval((([$1]) > 0) - (([$1]) < 0))])
+
+
+
+## ------------------------ ##
+## 14. Version processing.  ##
+## ------------------------ ##
+
+
+# m4_version_unletter(VERSION)
+# ----------------------------
+# Normalize beta version numbers with letters to numeric expressions, which
+# can then be handed to m4_eval for the purpose of comparison.
+#
+#   Nl -> (N+1).-1.(l#)
+#
+# for example:
+#   [2.14a] -> [2.14+1.-1.[0r36:a]] -> 2.15.-1.10
+#   [2.14b] -> [2.15+1.-1.[0r36:b]] -> 2.15.-1.11
+#   [2.61aa.b] -> [2.61+1.-1.[0r36:aa],+1.-1.[0r36:b]] -> 2.62.-1.370.1.-1.11
+#
+# This macro expects reasonable version numbers, but can handle double
+# letters and does not expand any macros.  Original version strings can
+# use both `.' and `-' separators.
+#
+# Inline constant expansions, to avoid m4_defn overhead.
+# _m4_version_unletter is the real workhorse used by m4_version_compare,
+# but since [0r36:a] is less readable than 10, we provide a wrapper for
+# human use.
+m4_define([m4_version_unletter],
+[m4_map_sep([m4_eval], [.],
+            m4_dquote(m4_dquote_elt(m4_unquote(_$0([$1])))))])
+m4_define([_m4_version_unletter],
+[m4_bpatsubst(m4_translit([[[$1]]], [.-], [,,]),]dnl
+m4_dquote(m4_dquote(m4_defn([m4_cr_Letters])))[[+],
+              [+1,-1,[0r36:\&]])])
+
+
+# m4_version_compare(VERSION-1, VERSION-2)
+# ----------------------------------------
+# Compare the two version numbers and expand into
+#  -1 if VERSION-1 < VERSION-2
+#   0 if           =
+#   1 if           >
+#
+# Since _m4_version_unletter does not output side effects, we can
+# safely bypass the overhead of m4_version_cmp.
+m4_define([m4_version_compare],
+[_m4_list_cmp_raw(_m4_version_unletter([$1]), _m4_version_unletter([$2]))])
+
+
+# m4_PACKAGE_NAME
+# m4_PACKAGE_TARNAME
+# m4_PACKAGE_VERSION
+# m4_PACKAGE_STRING
+# m4_PACKAGE_BUGREPORT
+# --------------------
+# If m4sugar/version.m4 is present, then define version strings.  This
+# file is optional, provided by Autoconf but absent in Bison.
+m4_sinclude([m4sugar/version.m4])
+
+
+# m4_version_prereq(VERSION, [IF-OK], [IF-NOT = FAIL])
+# ----------------------------------------------------
+# Check this Autoconf version against VERSION.
+m4_define([m4_version_prereq],
+m4_ifdef([m4_PACKAGE_VERSION],
+[[m4_if(m4_version_compare(]m4_dquote(m4_defn([m4_PACKAGE_VERSION]))[, [$1]),
+        [-1],
+        [m4_default([$3],
+                    [m4_fatal([Autoconf version $1 or higher is required],
+                              [63])])],
+        [$2])]],
+[[m4_fatal([m4sugar/version.m4 not found])]]))
+
+
+## ------------------ ##
+## 15. Set handling.  ##
+## ------------------ ##
+
+# Autoconf likes to create arbitrarily large sets; for example, as of
+# this writing, the configure.ac for coreutils tracks a set of more
+# than 400 AC_SUBST.  How do we track all of these set members,
+# without introducing duplicates?  We could use m4_append_uniq, with
+# the set NAME residing in the contents of the macro NAME.
+# Unfortunately, m4_append_uniq is quadratic for set creation, because
+# it costs O(n) to search the string for each of O(n) insertions; not
+# to mention that with m4 1.4.x, even using m4_append is slow, costing
+# O(n) rather than O(1) per insertion.  Other set operations, not used
+# by Autoconf but still possible by manipulation of the definition
+# tracked in macro NAME, include O(n) deletion of one element and O(n)
+# computation of set size.  Because the set is exposed to the user via
+# the definition of a single macro, we cannot cache any data about the
+# set without risking the cache being invalidated by the user
+# redefining NAME.
+#
+# Can we do better?  Yes, because m4 gives us an O(1) search function
+# for free: ifdef.  Additionally, even m4 1.4.x gives us an O(1)
+# insert operation for free: pushdef.  But to use these, we must
+# represent the set via a group of macros; to keep the set consistent,
+# we must hide the set so that the user can only manipulate it through
+# accessor macros.  The contents of the set are maintained through two
+# access points; _m4_set([name]) is a pushdef stack of values in the
+# set, useful for O(n) traversal of the set contents; while the
+# existence of _m4_set([name],value) with no particular value is
+# useful for O(1) querying of set membership.  And since the user
+# cannot externally manipulate the set, we are free to add additional
+# caching macros for other performance improvements.  Deletion can be
+# O(1) per element rather than O(n), by reworking the definition of
+# _m4_set([name],value) to be 0 or 1 based on current membership, and
+# adding _m4_set_cleanup(name) to defer the O(n) cleanup of
+# _m4_set([name]) until we have another reason to do an O(n)
+# traversal.  The existence of _m4_set_cleanup(name) can then be used
+# elsewhere to determine if we must dereference _m4_set([name],value),
+# or assume that definition implies set membership.  Finally, size can
+# be tracked in an O(1) fashion with _m4_set_size(name).
+#
+# The quoting in _m4_set([name],value) is chosen so that there is no
+# ambiguity with a set whose name contains a comma, and so that we can
+# supply the value via _m4_defn([_m4_set([name])]) without needing any
+# quote manipulation.
+
+# m4_set_add(SET, VALUE, [IF-UNIQ], [IF-DUP])
+# -------------------------------------------
+# Add VALUE as an element of SET.  Expand IF-UNIQ on the first
+# addition, and IF-DUP if it is already in the set.  Addition of one
+# element is O(1), such that overall set creation is O(n).
+#
+# We do not want to add a duplicate for a previously deleted but
+# unpruned element, but it is just as easy to check existence directly
+# as it is to query _m4_set_cleanup($1).
+m4_define([m4_set_add],
+[m4_ifdef([_m4_set([$1],$2)],
+          [m4_if(m4_indir([_m4_set([$1],$2)]), [0],
+                 [m4_define([_m4_set([$1],$2)],
+                            [1])_m4_set_size([$1], [m4_incr])$3], [$4])],
+          [m4_define([_m4_set([$1],$2)],
+                     [1])m4_pushdef([_m4_set([$1])],
+                                    [$2])_m4_set_size([$1], [m4_incr])$3])])
+
+# m4_set_add_all(SET, VALUE...)
+# -----------------------------
+# Add each VALUE into SET.  This is O(n) in the number of VALUEs, and
+# can be faster than calling m4_set_add for each VALUE.
+#
+# Implement two recursion helpers; the check variant is slower but
+# handles the case where an element has previously been removed but
+# not pruned.  The recursion helpers ignore their second argument, so
+# that we can use the faster m4_shift2 and 2 arguments, rather than
+# _m4_shift2 and one argument, as the signal to end recursion.
+#
+# Please keep foreach.m4 in sync with any adjustments made here.
+m4_define([m4_set_add_all],
+[m4_define([_m4_set_size($1)], m4_eval(m4_set_size([$1])
+  + m4_len(m4_ifdef([_m4_set_cleanup($1)], [_$0_check], [_$0])([$1], $@))))])
+
+m4_define([_m4_set_add_all],
+[m4_if([$#], [2], [],
+       [m4_ifdef([_m4_set([$1],$3)], [],
+                 [m4_define([_m4_set([$1],$3)], [1])m4_pushdef([_m4_set([$1])],
+           [$3])-])$0([$1], m4_shift2($@))])])
+
+m4_define([_m4_set_add_all_check],
+[m4_if([$#], [2], [],
+       [m4_set_add([$1], [$3])$0([$1], m4_shift2($@))])])
+
+# m4_set_contains(SET, VALUE, [IF-PRESENT], [IF-ABSENT])
+# ------------------------------------------------------
+# Expand IF-PRESENT if SET contains VALUE, otherwise expand IF-ABSENT.
+# This is always O(1).
+m4_define([m4_set_contains],
+[m4_ifdef([_m4_set_cleanup($1)],
+          [m4_if(m4_ifdef([_m4_set([$1],$2)],
+                    [m4_indir([_m4_set([$1],$2)])], [0]), [1], [$3], [$4])],
+          [m4_ifdef([_m4_set([$1],$2)], [$3], [$4])])])
+
+# m4_set_contents(SET, [SEP])
+# ---------------------------
+# Expand to a single string containing all the elements in SET,
+# separated by SEP, without modifying SET.  No provision is made for
+# disambiguating set elements that contain non-empty SEP as a
+# sub-string, or for recognizing a set that contains only the empty
+# string.  Order of the output is not guaranteed.  If any elements
+# have been previously removed from the set, this action will prune
+# the unused memory.  This is O(n) in the size of the set before
+# pruning.
+#
+# Use _m4_popdef for speed.  The existence of _m4_set_cleanup($1)
+# determines which version of _1 helper we use.
+m4_define([m4_set_contents],
+[m4_ifdef([_m4_set_cleanup($1)], [_$0_1c], [_$0_1])([$1])_$0_2([$1],
+    [_m4_defn([_m4_set_($1)])], [[$2]])])
+
+# _m4_set_contents_1(SET)
+# _m4_set_contents_1c(SET)
+# _m4_set_contents_2(SET, SEP, PREP)
+# ----------------------------------
+# Expand to a list of quoted elements currently in the set, separated
+# by SEP, and moving PREP in front of SEP on recursion.  To avoid
+# nesting limit restrictions, the algorithm must be broken into two
+# parts; _1 destructively copies the stack in reverse into
+# _m4_set_($1), producing no output; then _2 destructively copies
+# _m4_set_($1) back into the stack in reverse.  SEP is expanded while
+# _m4_set_($1) contains the current element, so a SEP containing
+# _m4_defn([_m4_set_($1)]) can produce output in the order the set was
+# created.  Behavior is undefined if SEP tries to recursively list or
+# modify SET in any way other than calling m4_set_remove on the
+# current element.  Use _1 if all entries in the stack are guaranteed
+# to be in the set, and _1c to prune removed entries.  Uses _m4_defn
+# and _m4_popdef for speed.
+m4_define([_m4_set_contents_1],
+[m4_ifdef([_m4_set([$1])], [m4_pushdef([_m4_set_($1)],
+    _m4_defn([_m4_set([$1])]))_m4_popdef([_m4_set([$1])])$0([$1])])])
+
+m4_define([_m4_set_contents_1c],
+[m4_ifdef([_m4_set([$1])],
+          [m4_set_contains([$1], _m4_defn([_m4_set([$1])]),
+                   [m4_pushdef([_m4_set_($1)], _m4_defn([_m4_set([$1])]))],
+                   [_m4_popdef([_m4_set([$1],]_m4_defn(
+      [_m4_set([$1])])[)])])_m4_popdef([_m4_set([$1])])$0([$1])],
+          [_m4_popdef([_m4_set_cleanup($1)])])])
+
+m4_define([_m4_set_contents_2],
+[m4_ifdef([_m4_set_($1)], [m4_pushdef([_m4_set([$1])],
+    _m4_defn([_m4_set_($1)]))$2[]_m4_popdef([_m4_set_($1)])$0([$1], [$3$2])])])
+
+# m4_set_delete(SET)
+# ------------------
+# Delete all elements in SET, and reclaim any memory occupied by the
+# set.  This is O(n) in the set size.
+#
+# Use _m4_defn and _m4_popdef for speed.
+m4_define([m4_set_delete],
+[m4_ifdef([_m4_set([$1])],
+          [_m4_popdef([_m4_set([$1],]_m4_defn([_m4_set([$1])])[)],
+                      [_m4_set([$1])])$0([$1])],
+          [m4_ifdef([_m4_set_cleanup($1)],
+                    [_m4_popdef([_m4_set_cleanup($1)])])m4_ifdef(
+                    [_m4_set_size($1)],
+                    [_m4_popdef([_m4_set_size($1)])])])])
+
+# m4_set_difference(SET1, SET2)
+# -----------------------------
+# Produce a LIST of quoted elements that occur in SET1 but not SET2.
+# Output a comma prior to any elements, to distinguish the empty
+# string from no elements.  This can be directly used as a series of
+# arguments, such as for m4_join, or wrapped inside quotes for use in
+# m4_foreach.  Order of the output is not guaranteed.
+#
+# Short-circuit the idempotence relation.  Use _m4_defn for speed.
+m4_define([m4_set_difference],
+[m4_if([$1], [$2], [],
+       [m4_set_foreach([$1], [_m4_element],
+                       [m4_set_contains([$2], _m4_defn([_m4_element]), [],
+                                        [,_m4_defn([_m4_element])])])])])
+
+# m4_set_dump(SET, [SEP])
+# -----------------------
+# Expand to a single string containing all the elements in SET,
+# separated by SEP, then delete SET.  In general, if you only need to
+# list the contents once, this is faster than m4_set_contents.  No
+# provision is made for disambiguating set elements that contain
+# non-empty SEP as a sub-string.  Order of the output is not
+# guaranteed.  This is O(n) in the size of the set before pruning.
+#
+# Use _m4_popdef for speed.  Use existence of _m4_set_cleanup($1) to
+# decide if more expensive recursion is needed.
+m4_define([m4_set_dump],
+[m4_ifdef([_m4_set_size($1)],
+          [_m4_popdef([_m4_set_size($1)])])m4_ifdef([_m4_set_cleanup($1)],
+    [_$0_check], [_$0])([$1], [], [$2])])
+
+# _m4_set_dump(SET, SEP, PREP)
+# _m4_set_dump_check(SET, SEP, PREP)
+# ----------------------------------
+# Print SEP and the current element, then delete the element and
+# recurse with empty SEP changed to PREP.  The check variant checks
+# whether the element has been previously removed.  Use _m4_defn and
+# _m4_popdef for speed.
+m4_define([_m4_set_dump],
+[m4_ifdef([_m4_set([$1])],
+          [[$2]_m4_defn([_m4_set([$1])])_m4_popdef([_m4_set([$1],]_m4_defn(
+                [_m4_set([$1])])[)], [_m4_set([$1])])$0([$1], [$2$3])])])
+
+m4_define([_m4_set_dump_check],
+[m4_ifdef([_m4_set([$1])],
+          [m4_set_contains([$1], _m4_defn([_m4_set([$1])]),
+                           [[$2]_m4_defn([_m4_set([$1])])])_m4_popdef(
+    [_m4_set([$1],]_m4_defn([_m4_set([$1])])[)],
+    [_m4_set([$1])])$0([$1], [$2$3])],
+          [_m4_popdef([_m4_set_cleanup($1)])])])
+
+# m4_set_empty(SET, [IF-EMPTY], [IF-ELEMENTS])
+# --------------------------------------------
+# Expand IF-EMPTY if SET has no elements, otherwise IF-ELEMENTS.
+m4_define([m4_set_empty],
+[m4_ifdef([_m4_set_size($1)],
+          [m4_if(m4_indir([_m4_set_size($1)]), [0], [$2], [$3])], [$2])])
+
+# m4_set_foreach(SET, VAR, ACTION)
+# --------------------------------
+# For each element of SET, define VAR to the element and expand
+# ACTION.  ACTION should not recursively list SET's contents, add
+# elements to SET, nor delete any element from SET except the one
+# currently in VAR.  The order that the elements are visited in is not
+# guaranteed.  This is faster than the corresponding m4_foreach([VAR],
+#   m4_indir([m4_dquote]m4_set_listc([SET])), [ACTION])
+m4_define([m4_set_foreach],
+[m4_pushdef([$2])m4_ifdef([_m4_set_cleanup($1)],
+    [_m4_set_contents_1c], [_m4_set_contents_1])([$1])_m4_set_contents_2([$1],
+       [m4_define([$2], _m4_defn([_m4_set_($1)]))$3[]])m4_popdef([$2])])
+
+# m4_set_intersection(SET1, SET2)
+# -------------------------------
+# Produce a LIST of quoted elements that occur in both SET1 or SET2.
+# Output a comma prior to any elements, to distinguish the empty
+# string from no elements.  This can be directly used as a series of
+# arguments, such as for m4_join, or wrapped inside quotes for use in
+# m4_foreach.  Order of the output is not guaranteed.
+#
+# Iterate over the smaller set, and short-circuit the idempotence
+# relation.  Use _m4_defn for speed.
+m4_define([m4_set_intersection],
+[m4_if([$1], [$2], [m4_set_listc([$1])],
+       m4_eval(m4_set_size([$2]) < m4_set_size([$1])), [1], [$0([$2], [$1])],
+       [m4_set_foreach([$1], [_m4_element],
+                       [m4_set_contains([$2], _m4_defn([_m4_element]),
+                                        [,_m4_defn([_m4_element])])])])])
+
+# m4_set_list(SET)
+# m4_set_listc(SET)
+# -----------------
+# Produce a LIST of quoted elements of SET.  This can be directly used
+# as a series of arguments, such as for m4_join or m4_set_add_all, or
+# wrapped inside quotes for use in m4_foreach or m4_map.  With
+# m4_set_list, there is no way to distinguish an empty set from a set
+# containing only the empty string; with m4_set_listc, a leading comma
+# is output if there are any elements.
+m4_define([m4_set_list],
+[m4_ifdef([_m4_set_cleanup($1)], [_m4_set_contents_1c],
+          [_m4_set_contents_1])([$1])_m4_set_contents_2([$1],
+               [_m4_defn([_m4_set_($1)])], [,])])
+
+m4_define([m4_set_listc],
+[m4_ifdef([_m4_set_cleanup($1)], [_m4_set_contents_1c],
+          [_m4_set_contents_1])([$1])_m4_set_contents_2([$1],
+               [,_m4_defn([_m4_set_($1)])])])
+
+# m4_set_remove(SET, VALUE, [IF-PRESENT], [IF-ABSENT])
+# ----------------------------------------------------
+# If VALUE is an element of SET, delete it and expand IF-PRESENT.
+# Otherwise expand IF-ABSENT.  Deleting a single value is O(1),
+# although it leaves memory occupied until the next O(n) traversal of
+# the set which will compact the set.
+#
+# Optimize if the element being removed is the most recently added,
+# since defining _m4_set_cleanup($1) slows down so many other macros.
+# In particular, this plays well with m4_set_foreach.
+m4_define([m4_set_remove],
+[m4_set_contains([$1], [$2], [_m4_set_size([$1],
+    [m4_decr])m4_if(_m4_defn([_m4_set([$1])]), [$2],
+                    [_m4_popdef([_m4_set([$1],$2)], [_m4_set([$1])])],
+                    [m4_define([_m4_set_cleanup($1)])m4_define(
+                      [_m4_set([$1],$2)], [0])])$3], [$4])])
+
+# m4_set_size(SET)
+# ----------------
+# Expand to the number of elements currently in SET.  This operation
+# is O(1), and thus more efficient than m4_count(m4_set_list([SET])).
+m4_define([m4_set_size],
+[m4_ifdef([_m4_set_size($1)], [m4_indir([_m4_set_size($1)])], [0])])
+
+# _m4_set_size(SET, ACTION)
+# -------------------------
+# ACTION must be either m4_incr or m4_decr, and the size of SET is
+# changed accordingly.  If the set is empty, ACTION must not be
+# m4_decr.
+m4_define([_m4_set_size],
+[m4_define([_m4_set_size($1)],
+           m4_ifdef([_m4_set_size($1)], [$2(m4_indir([_m4_set_size($1)]))],
+                    [1]))])
+
+# m4_set_union(SET1, SET2)
+# ------------------------
+# Produce a LIST of double quoted elements that occur in either SET1
+# or SET2, without duplicates.  Output a comma prior to any elements,
+# to distinguish the empty string from no elements.  This can be
+# directly used as a series of arguments, such as for m4_join, or
+# wrapped inside quotes for use in m4_foreach.  Order of the output is
+# not guaranteed.
+#
+# We can rely on the fact that m4_set_listc prunes SET1, so we don't
+# need to check _m4_set([$1],element) for 0.  Use _m4_defn for speed.
+# Short-circuit the idempotence relation.
+m4_define([m4_set_union],
+[m4_set_listc([$1])m4_if([$1], [$2], [], [m4_set_foreach([$2], [_m4_element],
+  [m4_ifdef([_m4_set([$1],]_m4_defn([_m4_element])[)], [],
+            [,_m4_defn([_m4_element])])])])])
+
+
+## ------------------- ##
+## 16. File handling.  ##
+## ------------------- ##
+
+
+# It is a real pity that M4 comes with no macros to bind a diversion
+# to a file.  So we have to deal without, which makes us a lot more
+# fragile than we should.
+
+
+# m4_file_append(FILE-NAME, CONTENT)
+# ----------------------------------
+m4_define([m4_file_append],
+[m4_syscmd([cat >>$1 <<_m4eof
+$2
+_m4eof
+])
+m4_if(m4_sysval, [0], [],
+      [m4_fatal([$0: cannot write: $1])])])
+
+
+
+## ------------------------ ##
+## 17. Setting M4sugar up.  ##
+## ------------------------ ##
+
+
+# m4_init
+# -------
+# Initialize the m4sugar language.
+m4_define([m4_init],
+[# All the M4sugar macros start with `m4_', except `dnl' kept as is
+# for sake of simplicity.
+m4_pattern_forbid([^_?m4_])
+m4_pattern_forbid([^dnl$])
+
+# If __m4_version__ is defined, we assume that we are being run by M4
+# 1.6 or newer, and thus that $@ recursion is linear and debugmode(d)
+# is available for faster checks of dereferencing undefined macros.
+# But if it is missing, we assume we are being run by M4 1.4.x, that
+# $@ recursion is quadratic, and that we need foreach-based
+# replacement macros.  Use the raw builtin to avoid tripping up
+# include tracing.
+m4_ifdef([__m4_version__],
+[m4_debugmode([+d])
+m4_copy([_m4_defn], [m4_defn])
+m4_copy([_m4_popdef], [m4_popdef])
+m4_copy([_m4_undefine], [m4_undefine])],
+[m4_builtin([include], [m4sugar/foreach.m4])])
+
+# _m4_divert_diversion should be defined:
+m4_divert_push([KILL])
+
+# Check the divert push/pop perfect balance.
+m4_wrap([m4_divert_pop([])
+         m4_ifdef([_m4_divert_diversion],
+           [m4_fatal([$0: unbalanced m4_divert_push:]_m4_divert_n_stack)])[]])
+])