# 00gnulib.m4 serial 3

dnl Copyright (C) 2009-2017 Free Software Foundation, Inc.

dnl This file is free software; the Free Software Foundation

dnl gives unlimited permission to copy and/or distribute it,

dnl with or without modifications, as long as this notice is preserved.

dnl This file must be named something that sorts before all other

dnl gnulib-provided .m4 files.  It is needed until such time as we can

dnl assume Autoconf 2.64, with its improved AC_DEFUN_ONCE and

dnl m4_divert semantics.

# Until autoconf 2.63, handling of the diversion stack required m4_init

# to be called first; but this does not happen with aclocal.  Wrapping

# the entire execution in another layer of the diversion stack fixes this.

# Worse, prior to autoconf 2.62, m4_wrap depended on the underlying m4

# for whether it was FIFO or LIFO; in order to properly balance with

# m4_init, we need to undo our push just before anything wrapped within

# the m4_init body.  The way to ensure this is to wrap both sides of

# m4_init with a one-shot macro that does the pop at the right time.

m4_ifndef([_m4_divert_diversion],

[m4_divert_push([KILL])

m4_define([gl_divert_fixup], [m4_divert_pop()m4_define([$0])])

m4_define([m4_init],

  [gl_divert_fixup()]m4_defn([m4_init])[gl_divert_fixup()])])

# AC_DEFUN_ONCE([NAME], VALUE)

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

# Define NAME to expand to VALUE on the first use (whether by direct

# expansion, or by AC_REQUIRE), and to nothing on all subsequent uses.

# Avoid bugs in AC_REQUIRE in Autoconf 2.63 and earlier.  This

# definition is slower than the version in Autoconf 2.64, because it

# can only use interfaces that existed since 2.59; but it achieves the

# same effect.  Quoting is necessary to avoid confusing Automake.

m4_version_prereq([2.63.263], [],

[m4_define([AC][_DEFUN_ONCE],

  [AC][_DEFUN([$1],

    [AC_REQUIRE([_gl_DEFUN_ONCE([$1])],

      [m4_indir([_gl_DEFUN_ONCE([$1])])])])]dnl

[AC][_DEFUN([_gl_DEFUN_ONCE([$1])], [$2])])])

# gl_00GNULIB

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

# Witness macro that this file has been included.  Needed to force

# Automake to include this file prior to all other gnulib .m4 files.

AC_DEFUN([gl_00GNULIB])