ax_lua.m4

# ===========================================================================
#                               ax_lua.m4
# ===========================================================================
#
# SYNOPSIS
#
#   AX_PROG_LUA[([MINIMUM-VERSION], [TOO-BIG-VERSION],
#                [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])]
#   AX_LUA_HEADERS[([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])]
#   AX_LUA_LIBS[([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])]
#   AX_LUA_READLINE[([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])]
#
# DESCRIPTION
#
#   Detect a Lua interpreter, optionally specifying a minimum and maximum
#   version number. Set up important Lua paths, such as the directories in
#   which to install scripts and modules (shared libraries).
#
#   Also detect Lua headers and libraries. The Lua version contained in the
#   header is checked to match the Lua interpreter version exactly. When
#   searching for Lua libraries, the version number is used as a suffix. This
#   is done with the goal of supporting multiple Lua installs (5.1 and 5.2
#   side-by-side).
#
#
#   *** A note on compatibility with previous versions: This file has been
#   mostly rewritten for serial 18. Most developers should be able to use
#   these macros without needing to modify configure.ac. Care has been taken
#   to preserve each macro's behaviour, but there are some differences:
#
#   1) AX_WITH_LUA is deprecated; it now expands to the exact same thing as
#   AX_PROG_LUA with no arguments.
#
#   2) AX_LUA_HEADERS now checks that the version number defined in lua.h
#   matches the interpreter version. AX_LUA_HEADERS_VERSION is therefore
#   unnecessary, so it is deprecated and does not expand to anything.
#
#   3) The configure flag --with-lua-suffix no longer exists; the user
#   should instead specify the LUA precious variable on the command line.
#   See the AX_PROG_LUA description for details.
#
#   Please read the macro descriptions for more information. ***
#
#
#
#   AX_PROG_LUA[([MINIMUM-VERSION], [TOO-BIG-VERSION],
#                [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])]
#   -------------------------------------------------------
#
#   Search for the Lua interpreter, and set up important Lua paths.
#   Adds precious variable LUA, which may contain the path of the Lua
#   interpreter. If LUA is blank, the user's path is searched for an
#   suitable interpreter.
#
#   If MINIMUM-VERSION is supplied, then only Lua interpreters with a version
#   number greater or equal to MINIMUM-VERSION will be accepted. If TOO-BIG-
#   VERSION is also supplied, then only Lua interpreters with a version
#   number greater or equal to MINIMUM-VERSION and less than TOO-BIG-VERSION
#   will be accepted.
#
#   Version comparisions require the AX_COMPARE_VERSION macro, which is
#   provided by ax_compare_version.m4 from the Autoconf Archive.
#
#   The Lua version number, LUA_VERSION, is found from the interpreter, and
#   substituted. LUA_PLATFORM is also found, but not currently supported (no
#   standard representation).
#
#   Finally, the macro finds four paths:
#
#     luadir             Directory to install Lua scripts.
#     pkgluadir          $luadir/$PACKAGE
#     luaexecdir         Directory to install Lua modules.
#     pkgluaexecdir      $luaexecdir/$PACKAGE
#
#   These paths a found based on $prefix, $exec_prefix, Lua's package.path,
#   and package.cpath. The first path of package.path beginning with $prefix
#   is selected as luadir. The first path of package.cpath beginning with
#   $exec_prefix is used as luaexecdir. This should work on all reasonable
#   Lua installations. If a path cannot be determined, a default path is
#   used. Of course, the user can override these later when invoking make.
#
#     luadir             Default: $prefix/share/lua/$LUA_VERSION
#     luaexecdir         Default: $exec_prefix/lib/lua/$LUA_VERSION
#
#   These directories can be used by Automake as install destinations.
#   The variable name minus 'dir' needs to be used as a prefix to the
#   appropriate Automake primary, e.g. lua_SCRIPS or luaexec_LIBRARIES.
#
#   If an acceptable Lua interpreter is found, then ACTION-IF-FOUND is
#   performed, otherwise ACTION-IF-NOT-FOUND is preformed. If ACTION-IF-NOT-
#   FOUND is blank, then it will default to printing an error. To prevent
#   the default behavior, give ':' as an action.
#
#
#   AX_LUA_HEADERS[([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])]
#   ----------------------------------------------------------
#
#   Search for Lua headers. Requires that AX_PROG_LUA be expanded before this
#   macro. Adds precious variable LUA_INCLUDE, which may contain Lua specific
#   include flags, e.g. -I/usr/include/lua5.1. If LUA_INCLUDE is blank, then
#   this macro will attempt to find suitable flags.
#
#   LUA_INCLUDE can be used by Automake to compile Lua modules or executables
#   with embedded interpreters. The *_CPPFLAGS variables should be used for
#   this purpose, e.g. myprog_CPPFLAGS = $(LUA_INCLUDE).
#
#   This macro searches for the header lua.h (and others). The search is
#   performed with a combination of CPPFLAGS, CPATH, etc, and LUA_INCLUDE.
#   If the search is unsuccessful, then some common directories are tried. If
#   the headers are then found, then LUA_INCLUDE is set accordingly.
#
#   The paths automatically searched are:
#
#     * /usr/include/luaX.Y
#     * /usr/include/lua/X.Y
#     * /usr/include/luaXY
#     * /usr/local/include/luaX.Y
#     * /usr/local/include/lua/X.Y
#     * /usr/local/include/luaXY
#
#   (Where X.Y is the Lua version number, e.g. 5.1.)
#
#   The Lua version number found in the headers is always checked to match
#   the Lua interpreter's version number. Lua headers with mismatched
#   version numbers are not accepted.
#
#   If headers are found, then ACTION-IF-FOUND is performed, otherwise
#   ACTION-IF-NOT-FOUND is performed. If ACTION-IF-NOT-FOUND is blank,
#   then it will default to printing an error. To prevent the default
#   behavior, set the action to ':'.
#
#
#   AX_LUA_LIBS[([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])]
#   -------------------------------------------------------
#
#   Search for Lua libraries. Requires that AX_PROG_LUA be expanded before
#   this macro. Adds precious variable LUA_LIB, which may contain Lua specific
#   linker flags, e.g. -llua5.1. If LUA_LIB is blank, then this macro will
#   attempt to find suitable flags.
#
#   LUA_LIB can be used by Automake to link Lua modules or executables with
#   embedded interpreters. The *_LIBADD and *_LDADD variables should be used
#   for this purpose, e.g. mymod_LIBADD = $(LUA_LIB).
#
#   This macro searches for the Lua library. More technically, it searches
#   for a library containing the function lua_load. The search is performed
#   with a combination of LIBS, LIBRARY_PATH, and LUA_LIB.
#
#   If the search determines that some linker flags are missing, then those
#   flags will be added to LUA_LIB.
#
#   If libraries are found, then ACTION-IF-FOUND is performed, otherwise
#   ACTION-IF-NOT-FOUND is performed. If ACTION-IF-NOT-FOUND is blank,
#   then it will default to printing an error. To prevent the default
#   behavior, set the action to ':'.
#
#
#   AX_LUA_READLINE[([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])]
#   -----------------------------------------------------------
#
#   Search for readline headers and libraries. Requires the AX_LIB_READLINE
#   macro, which is provided by ax_lib_readline.m4 from the Autoconf Archive.
#
#   If a readline compatible library is found, then ACTION-IF-FOUND is
#   performed, otherwise ACTION-IF-NOT-FOUND is performed.
#
#
# LICENSE
#
#   Copyright (C) 2013 Tim Perkins <tprk77@gmail.com>
#   Copyright (C) 2013 Reuben Thomas <rrt@sc3d.org>
#
#   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 respective Autoconf Macro's copyright owner
#   gives unlimited permission to copy, distribute and modify the configure
#   scripts that are the output of Autoconf when processing the Macro. 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 the
#   Macro appear in them. The GNU General Public License (GPL) does govern
#   all other use of the material that constitutes the Autoconf Macro.
#
#   This special exception to the GPL applies to versions of the Autoconf
#   Macro released by the Autoconf Archive. When you make and distribute a
#   modified version of the Autoconf Macro, you may extend this special
#   exception to the GPL to apply to your modified version as well.
#
# THANKS
#
#   This file was inspired by Andrew Dalke's and James Henstridge's python.m4
#   and Tom Payne's, Matthieu Moy's, and Reuben Thomas's ax_lua.m4 (serial
#   17). Basically, this file is a mashup of those two files. I like to think
#   it combines the best of the two!

#serial 18


dnl =========================================================================
dnl AX_PROG_LUA([MINIMUM-VERSION], [TOO-BIG-VERSION],
dnl             [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])
dnl =========================================================================
AC_DEFUN([AX_PROG_LUA],
[
  dnl Make LUA a precious variable.
  AC_ARG_VAR([LUA], [The Lua interpreter, e.g. /usr/bin/lua5.1])

  dnl Find a Lua interpreter.
  m4_define_default([_AX_LUA_INTERPRETER_LIST],
    [lua lua5.2 lua5.1 lua50])

  m4_if([$1], [],
  [ dnl No version check is needed. Find any Lua interpreter.
    AS_IF([test "x$LUA" = 'x'],
      [AC_PATH_PROGS([LUA], [_AX_LUA_INTERPRETER_LIST], [:])])
    ax_display_LUA='lua'

    dnl At least check if this is a Lua interpreter.
    AC_MSG_CHECKING([if $LUA is a Lua interprester])
    _AX_LUA_CHK_IS_INTRP([$LUA],
      [AC_MSG_RESULT([yes])],
      [ AC_MSG_RESULT([no])
        AC_MSG_WARN([not a Lua interpreter])
      ])
  ],
  [ dnl A version check is needed.
    AS_IF([test "x$LUA" != 'x'],
    [ dnl Check if this is a Lua interpreter.
      AC_MSG_CHECKING([if $LUA is a Lua interprester])
      _AX_LUA_CHK_IS_INTRP([$LUA],
        [AC_MSG_RESULT([yes])],
        [ AC_MSG_RESULT([no])
          AC_MSG_WARN([not a Lua interpreter])
        ])
      dnl Check the version.
      m4_if([$2], [],
        [_ax_check_text="whether $LUA version >= $1"],
        [_ax_check_text="whether $LUA version >= $1, < $2"])
      AC_MSG_CHECKING([$_ax_check_text])
      _AX_LUA_CHK_VER([$LUA], [$1], [$2],
        [AC_MSG_RESULT([yes])],
        [ AC_MSG_RESULT([no])
          AC_MSG_WARN([version is out of range for specified LUA])])
      ax_display_LUA=$LUA
    ],
    [ dnl Try each interpreter until we find one that satisfies VERSION.
      m4_if([$2], [],
        [_ax_check_text="for a Lua interpreter with version >= $1"],
        [_ax_check_text="for a Lua interpreter with version >= $1, < $2"])
      AC_CACHE_CHECK([$_ax_check_text],
        [ax_cv_pathless_LUA],
        [ for ax_cv_pathless_LUA in _AX_LUA_INTERPRETER_LIST none; do
            test "x$ax_cv_pathless_LUA" = 'xnone' && break
            _AX_LUA_CHK_IS_INTRP([$ax_cv_pathless_LUA], [], [continue])
            _AX_LUA_CHK_VER([$ax_cv_pathless_LUA], [$1], [$2], [break])
          done
        ])
      dnl Set $LUA to the absolute path of $ax_cv_pathless_LUA.
      AS_IF([test "x$ax_cv_pathless_LUA" = 'xnone'],
        [LUA=':'],
        [AC_PATH_PROG([LUA], [$ax_cv_pathless_LUA])])
      ax_display_LUA=$ax_cv_pathless_LUA
    ])
  ])

  AS_IF([test "x$LUA" = 'x:'],
  [ dnl Run any user-specified action, or abort.
    m4_default([$4], [AC_MSG_WARN([cannot find suitable Lua interpreter])])
  ],
  [ dnl Query Lua for its version number.
    AC_CACHE_CHECK([for $ax_display_LUA version], [ax_cv_lua_version],
      [ ax_cv_lua_version=`$LUA -e "print(_VERSION)" | \
          sed "s|^Lua \(.*\)|\1|" | \
          grep -o "^@<:@0-9@:>@\+\\.@<:@0-9@:>@\+"`
      ])
    AS_IF([test "x$ax_cv_lua_version" = 'x'],
      [AC_MSG_WARN([invalid Lua version number])])
    AC_SUBST([LUA_VERSION], [$ax_cv_lua_version])
    AC_SUBST([LUA_SHORT_VERSION], [`echo "$LUA_VERSION" | sed 's|\.||'`])

    dnl The following check is not supported:
    dnl At times (like when building shared libraries) you may want to know
    dnl which OS platform Lua thinks this is.
    AC_CACHE_CHECK([for $ax_display_LUA platform], [ax_cv_lua_platform],
      [ax_cv_lua_platform=`$LUA -e "print('unknown')"`])
    AC_SUBST([LUA_PLATFORM], [$ax_cv_lua_platform])

    dnl Use the values of $prefix and $exec_prefix for the corresponding
    dnl values of LUA_PREFIX and LUA_EXEC_PREFIX. These are made distinct
    dnl variables so they can be overridden if need be. However, the general
    dnl consensus is that you shouldn't need this ability.
    AC_SUBST([LUA_PREFIX], ['${prefix}'])
    AC_SUBST([LUA_EXEC_PREFIX], ['${exec_prefix}'])

    dnl Lua provides no way to query the script directory, and instead
    dnl provides LUA_PATH. However, we should be able to make a safe educated
    dnl guess. If the built-in search path contains a directory which is
    dnl prefixed by $prefix, then we can store scripts there. The first
    dnl matching path will be used.
    AC_CACHE_CHECK([for $ax_display_LUA script directory],
      [ax_cv_lua_luadir],
      [ AS_IF([test "x$prefix" = 'xNONE'],
          [ax_lua_prefix=$ac_default_prefix],
          [ax_lua_prefix=$prefix])

        dnl Initialize to the default path.
        ax_cv_lua_luadir="$LUA_PREFIX/share/lua/$LUA_VERSION"

        dnl Try to find a path with the prefix.
        _AX_LUA_FND_PRFX_PTH([$LUA], [$ax_lua_prefix], [package.path])
        AS_IF([test "x$ax_lua_prefixed_path" != 'x'],
        [ dnl Fix the prefix.
          _ax_strip_prefix=`echo "$ax_lua_prefix" | sed 's|.|.|g'`
          ax_cv_lua_luadir=`echo "$ax_lua_prefixed_path" | \
            sed "s,^$_ax_strip_prefix,$LUA_PREFIX,"`
        ])
      ])
    AC_SUBST([luadir], [$ax_cv_lua_luadir])
    AC_SUBST([pkgluadir], [\${luadir}/$PACKAGE])

    dnl Lua provides no way to query the module directory, and instead
    dnl provides LUA_PATH. However, we should be able to make a safe educated
    dnl guess. If the built-in search path contains a directory which is
    dnl prefixed by $exec_prefix, then we can store modules there. The first
    dnl matching path will be used.
    AC_CACHE_CHECK([for $ax_display_LUA module directory],
      [ax_cv_lua_luaexecdir],
      [ AS_IF([test "x$exec_prefix" = 'xNONE'],
          [ax_lua_exec_prefix=$ax_lua_prefix],
          [ax_lua_exec_prefix=$exec_prefix])

        dnl Initialize to the default path.
        ax_cv_lua_luaexecdir="$LUA_EXEC_PREFIX/lib/lua/$LUA_VERSION"

        dnl Try to find a path with the prefix.
        _AX_LUA_FND_PRFX_PTH([$LUA],
          [$ax_lua_exec_prefix], [package.cpathd])
        AS_IF([test "x$ax_lua_prefixed_path" != 'x'],
        [ dnl Fix the prefix.
          _ax_strip_prefix=`echo "$ax_lua_exec_prefix" | sed 's|.|.|g'`
          ax_cv_lua_luaexecdir=`echo "$ax_lua_prefixed_path" | \
            sed "s,^$_ax_strip_prefix,$LUA_EXEC_PREFIX,"`
        ])
      ])
    AC_SUBST([luaexecdir], [$ax_cv_lua_luaexecdir])
    AC_SUBST([pkgluaexecdir], [\${luaexecdir}/$PACKAGE])

    dnl Run any user specified action.
    $3
  ])
])

dnl AX_WITH_LUA is now the same thing as AX_PROG_LUA.
AC_DEFUN([AX_WITH_LUA],
[
  AC_MSG_WARN([[$0 is deprecated, please use AX_PROG_LUA]])
  AX_PROG_LUA
])


dnl =========================================================================
dnl _AX_LUA_CHK_IS_INTRP(PROG, [ACTION-IF-TRUE], [ACTION-IF-FALSE])
dnl =========================================================================
AC_DEFUN([_AX_LUA_CHK_IS_INTRP],
[
  dnl Just print _VERSION because all Lua interpreters have this global.
  AS_IF([$1 -e "print('Hello ' .. _VERSION .. '!')" &>/dev/null],
    [$2], [$3])
])


dnl =========================================================================
dnl _AX_LUA_CHK_VER(PROG, MINIMUM-VERSION, [TOO-BIG-VERSION],
dnl                 [ACTION-IF-TRUE], [ACTION-IF-FALSE])
dnl =========================================================================
AC_DEFUN([_AX_LUA_CHK_VER],
[
  _ax_test_ver=`$1 -e "print(_VERSION)" 2>/dev/null | \
    sed "s|^Lua \(.*\)|\1|" | grep -o "^@<:@0-9@:>@\+\\.@<:@0-9@:>@\+"`
  AS_IF([test "x$_ax_test_ver" = 'x'],
    [_ax_test_ver='0'])
  AX_COMPARE_VERSION([$_ax_test_ver], [ge], [$2])
  m4_if([$3], [], [],
    [ AS_IF([$ax_compare_version],
        [AX_COMPARE_VERSION([$_ax_test_ver], [lt], [$3])])
    ])
  AS_IF([$ax_compare_version], [$4], [$5])
])


dnl =========================================================================
dnl _AX_LUA_FND_PRFX_PTH(PROG, PREFIX, LUA-PATH-VARIABLE)
dnl =========================================================================
AC_DEFUN([_AX_LUA_FND_PRFX_PTH],
[
  dnl Invokes the Lua interpreter PROG to print the path variable
  dnl LUA-PATH-VARIABLE, usually package.path or package.cpath. Paths are
  dnl then matched against PREFIX. The first path to begin with PREFIX is set
  dnl to ax_lua_prefixed_path.

  ax_lua_prefixed_path=''
  _ax_package_paths=`$1 -e 'print($3)' 2>/dev/null | sed 's|;|\n|g'`
  dnl Try the paths in order, looking for the prefix.
  for _ax_package_path in $_ax_package_paths; do
    dnl Copy the path, up to the use of a Lua wildcard.
    _ax_path_parts=`echo "$_ax_package_path" | sed 's|/|\n|g'`
    _ax_reassembled=''
    for _ax_path_part in $_ax_path_parts; do
      echo "$_ax_path_part" | grep '\?' >/dev/null && break
      _ax_reassembled="$_ax_reassembled/$_ax_path_part"
    done
    dnl Check the path against the prefix.
    _ax_package_path=$_ax_reassembled
    if echo "$_ax_package_path" | grep "^$2" >/dev/null; then
      dnl Found it.
      ax_lua_prefixed_path=$_ax_package_path
      break
    fi
  done
])


dnl =========================================================================
dnl AX_LUA_HEADERS([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])
dnl =========================================================================
AC_DEFUN([AX_LUA_HEADERS],
[
  dnl Check for LUA_VERSION.
  AC_MSG_CHECKING([if LUA_VERSION is defined])
  AS_IF([test "x$LUA_VERSION" != 'x'],
    [AC_MSG_RESULT([yes])],
    [ AC_MSG_RESULT([no])
      AC_MSG_WARN([cannot check Lua headers without knowing LUA_VERSION])
    ])

  dnl Make LUA_INCLUDE a precious variable.
  AC_ARG_VAR([LUA_INCLUDE], [The Lua includes, e.g. -I/usr/include/lua5.1])

  dnl Some default directories to search.
  LUA_SHORT_VERSION=`echo "$LUA_VERSION" | sed 's|\.||'`
  m4_define_default([_AX_LUA_INCLUDE_LIST],
    [ /usr/local/include/lua$LUA_VERSION \
      /usr/local/include/lua/$LUA_VERSION \
      /usr/local/include/lua$LUA_SHORT_VERSION \
      /usr/include/lua$LUA_VERSION \
      /usr/include/lua/$LUA_VERSION \
      /usr/include/lua$LUA_SHORT_VERSION \
    ])

  dnl Try to find the headers.
  _ax_lua_saved_cppflags=$CPPFLAGS
  CPPFLAGS="$CPPFLAGS $LUA_INCLUDE"
  AC_CHECK_HEADERS([lua.h lualib.h lauxlib.h luaconf.h luajit.h])
  CPPFLAGS=$_ax_lua_saved_cppflags

  dnl Try some other directories if LUA_INCLUDE was not set.
  AS_IF([test "x$LUA_INCLUDE" = 'x' &&
         test "x$ac_cv_header_lua_h" != 'xyes'],
    [ dnl Try some common include paths.
      for _ax_include_path in _AX_LUA_INCLUDE_LIST; do
        AC_MSG_CHECKING([for Lua headers in])
        AC_MSG_RESULT([$_ax_include_path])

        test ! -d "$_ax_include_path" && continue
        AS_UNSET([ac_cv_header_lua_h])
        AS_UNSET([ac_cv_header_lualib_h])
        AS_UNSET([ac_cv_header_lauxlib_h])
        AS_UNSET([ac_cv_header_luaconf_h])
        AS_UNSET([ac_cv_header_luajit_h])

        _ax_lua_saved_cppflags=$CPPFLAGS
        CPPFLAGS="$CPPFLAGS -I$_ax_include_path"
        AC_CHECK_HEADERS([lua.h lualib.h lauxlib.h luaconf.h luajit.h])
        CPPFLAGS=$_ax_lua_saved_cppflags

        AS_IF([test "x$ac_cv_header_lua_h" = 'xyes'],
          [ ac_cv_lua_include="-I$_ax_include_path"
            break
          ])
      done
    ])

  dnl Retrieve our cached include value
  if test x"$ac_cv_lua_include" != 'x' && test x"$LUA_INCLUDE" = 'x'; then
    LUA_INCLUDE="$ac_cv_lua_include"
  fi

  AS_IF([test "x$ac_cv_header_lua_h" = 'xyes'],
    [ dnl Make a program to print LUA_VERSION defined in the header.
      dnl TODO This probably shouldn't be a runtime test.

      AC_CACHE_CHECK([for Lua header version],
        [ax_cv_lua_header_version],
        [ _ax_lua_saved_cppflags=$CPPFLAGS
          CPPFLAGS="$CPPFLAGS $LUA_INCLUDE"
          AC_RUN_IFELSE(
            [ AC_LANG_SOURCE([[
#include <lua.h>
#include <stdlib.h>
#include <stdio.h>
int main(int argc, char ** argv)
{
  if(argc > 1) printf("%s", LUA_VERSION);
  exit(EXIT_SUCCESS);
}
]])
            ],
            [ ax_cv_lua_header_version=`./conftest$EXEEXT p | \
                sed "s|^Lua \(.*\)|\1|" | \
                grep -o "^@<:@0-9@:>@\+\\.@<:@0-9@:>@\+"`
            ],
            [ax_cv_lua_header_version='unknown'])
          CPPFLAGS=$_ax_lua_saved_cppflags
        ])

      dnl Give the caller a chance to specify a header version
      dnl This is because LuaJIT headers return version 5.1.4 for the above
      dnl test.
      if test "x$LUA_COMPAT_VERSION" != 'x'; then
        LUA_VERSION=$LUA_COMPAT_VERSION
      fi

      dnl Compare this to the previously found LUA_VERSION.
      AC_MSG_CHECKING([if Lua header version matches $LUA_VERSION])
      AS_IF([test "x$ax_cv_lua_header_version" = "x$LUA_VERSION"],
        [ AC_MSG_RESULT([yes])
          ax_header_version_match='yes'
        ],
        [ AC_MSG_RESULT([no])
          ax_header_version_match='no'
        ])
    ])

  dnl Was LUA_INCLUDE specified?
  AS_IF([test "x$ax_header_version_match" != 'xyes' &&
         test "x$LUA_INCLUDE" != 'x'],
    [AC_MSG_WARN([cannot find headers for specified LUA_INCLUDE])])

  dnl Test the final result and run user code.
  AS_IF([test "x$ax_header_version_match" = 'xyes'], [$1],
    [m4_default([$2], [AC_MSG_WARN([cannot find Lua includes])])])
])

dnl AX_LUA_HEADERS_VERSION no longer exists, use AX_LUA_HEADERS.
AC_DEFUN([AX_LUA_HEADERS_VERSION],
[
  AC_MSG_WARN([[$0 is deprecated, please use AX_LUA_HEADERS]])
])


dnl =========================================================================
dnl AX_LUA_LIBS([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])
dnl =========================================================================
AC_DEFUN([AX_LUA_LIBS],
[
  dnl TODO Should this macro also check various -L flags?

  dnl Check for LUA_VERSION.
  AC_MSG_CHECKING([if LUA_VERSION is defined])
  AS_IF([test "x$LUA_VERSION" != 'x'],
    [AC_MSG_RESULT([yes])],
    [ AC_MSG_RESULT([no])
      AC_MSG_WARN([cannot check Lua libs without knowing LUA_VERSION])
    ])

  dnl Make LUA_LIB a precious variable.
  AC_ARG_VAR([LUA_LIB], [The Lua library, e.g. -llua5.1])

  AS_IF([test "x$LUA_LIB" != 'x'],
  [ dnl Check that LUA_LIBS works.
    _ax_lua_saved_libs=$LIBS
    LIBS="$LIBS $LUA_LIB"
    AC_SEARCH_LIBS([lua_load], [],
      [_ax_found_lua_libs='yes'],
      [_ax_found_lua_libs='no'])
    LIBS=$_ax_lua_saved_libs

    dnl Check the result.
    AS_IF([test "x$_ax_found_lua_libs" != 'xyes'],
      [AC_MSG_WARN([cannot find libs for specified LUA_LIB])])
  ],
  [ dnl First search for extra libs.
    _ax_lua_extra_libs=''

    _ax_lua_saved_libs=$LIBS
    LIBS="$LIBS $LUA_LIB"
    AC_SEARCH_LIBS([exp], [m])
    AC_SEARCH_LIBS([dlopen], [dl])
    LIBS=$_ax_lua_saved_libs

    AS_IF([test "x$ac_cv_search_exp" != 'xno' &&
           test "x$ac_cv_search_exp" != 'xnone required'],
      [_ax_lua_extra_libs="$_ax_lua_extra_libs $ac_cv_search_exp"])

    AS_IF([test "x$ac_cv_search_dlopen" != 'xno' &&
           test "x$ac_cv_search_dlopen" != 'xnone required'],
      [_ax_lua_extra_libs="$_ax_lua_extra_libs $ac_cv_search_dlopen"])

    dnl Try to find the Lua libs.
    _ax_lua_saved_libs=$LIBS
    LIBS="$LIBS $LUA_LIB"
    AC_SEARCH_LIBS([lua_load], [lua$LUA_VERSION lua$LUA_SHORT_VERSION lua],
      [_ax_found_lua_libs='yes'],
      [_ax_found_lua_libs='no'],
      [$_ax_lua_extra_libs])
    LIBS=$_ax_lua_saved_libs

    AS_IF([test "x$ac_cv_search_lua_load" != 'xno' &&
           test "x$ac_cv_search_lua_load" != 'xnone required'],
      [LUA_LIB="$ac_cv_search_lua_load $_ax_lua_extra_libs"])
  ])

  dnl Test the result and run user code.
  AS_IF([test "x$_ax_found_lua_libs" = 'xyes'], [$1],
    [m4_default([$2], [AC_MSG_WARN([cannot find Lua libs])])])
])


dnl =========================================================================
dnl AX_LUA_READLINE([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])
dnl =========================================================================
AC_DEFUN([AX_LUA_READLINE],
[
  AX_LIB_READLINE
  AS_IF([test "x$ac_cv_header_readline_readline_h" != 'x' &&
         test "x$ac_cv_header_readline_history_h" != 'x'],
    [ LUA_LIBS_CFLAGS="-DLUA_USE_READLINE $LUA_LIBS_CFLAGS"
      $1
    ],
    [$2])
])