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dnl Copyright (C) 2002-2003, 2005-2006, 2008 Free Software Foundation, Inc.
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dnl This file is free software, distributed under the terms of the GNU
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dnl General Public License. As a special exception to the GNU General
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dnl Public License, this file may be distributed as part of a program
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dnl that contains a configuration script generated by Autoconf, under
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dnl the same distribution terms as the rest of that program.
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dnl This file defines some "once only" variants of standard autoconf macros.
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dnl AC_CHECK_HEADERS_ONCE like AC_CHECK_HEADERS
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dnl AC_CHECK_FUNCS_ONCE like AC_CHECK_FUNCS
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dnl AC_CHECK_DECLS_ONCE like AC_CHECK_DECLS
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dnl AC_REQUIRE([AC_FUNC_STRCOLL]) like AC_FUNC_STRCOLL
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dnl The advantage is that the check for each of the headers/functions/decls
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dnl will be put only once into the 'configure' file. It keeps the size of
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dnl the 'configure' file down, and avoids redundant output when 'configure'
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dnl The drawback is that the checks cannot be conditionalized. If you write
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dnl if some_condition; then gl_CHECK_HEADERS(stdlib.h); fi
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dnl inside an AC_DEFUNed function, the gl_CHECK_HEADERS macro call expands to
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dnl empty, and the check will be inserted before the body of the AC_DEFUNed
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dnl The original code implemented AC_CHECK_HEADERS_ONCE and AC_CHECK_FUNCS_ONCE
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dnl in terms of AC_DEFUN and AC_REQUIRE. This implementation uses diversions to
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dnl named sections DEFAULTS and INIT_PREPARE in order to check all requested
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dnl headers at once, thus reducing the size of 'configure'. It is known to work
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dnl with autoconf 2.57..2.62 at least . The size reduction is ca. 9%.
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dnl Autoconf version 2.59 plus gnulib is required; this file is not needed
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dnl with Autoconf 2.60 or greater. But note that autoconf's implementation of
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dnl AC_CHECK_DECLS_ONCE expects a comma-separated list of symbols as first
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# AC_CHECK_HEADERS_ONCE(HEADER1 HEADER2 ...) is a once-only variant of
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# AC_CHECK_HEADERS(HEADER1 HEADER2 ...).
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AC_DEFUN([AC_CHECK_HEADERS_ONCE], [
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m4_foreach_w([gl_HEADER_NAME], [$1], [
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AC_DEFUN([gl_CHECK_HEADER_]m4_quote(translit(gl_HEADER_NAME,
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m4_divert_text([INIT_PREPARE],
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[gl_header_list="$gl_header_list gl_HEADER_NAME"])
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AH_TEMPLATE(AS_TR_CPP([HAVE_]m4_defn([gl_HEADER_NAME])),
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[Define to 1 if you have the <]m4_defn([gl_HEADER_NAME])[> header file.])
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AC_REQUIRE([gl_CHECK_HEADER_]m4_quote(translit(gl_HEADER_NAME,
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m4_define([gl_HEADERS_EXPANSION], [
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m4_divert_text([DEFAULTS], [gl_header_list=])
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AC_CHECK_HEADERS([$gl_header_list])
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m4_define([gl_HEADERS_EXPANSION], [])
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# AC_CHECK_FUNCS_ONCE(FUNC1 FUNC2 ...) is a once-only variant of
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# AC_CHECK_FUNCS(FUNC1 FUNC2 ...).
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AC_DEFUN([AC_CHECK_FUNCS_ONCE], [
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m4_foreach_w([gl_FUNC_NAME], [$1], [
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AC_DEFUN([gl_CHECK_FUNC_]m4_defn([gl_FUNC_NAME]), [
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m4_divert_text([INIT_PREPARE],
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[gl_func_list="$gl_func_list gl_FUNC_NAME"])
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AH_TEMPLATE(AS_TR_CPP([HAVE_]m4_defn([gl_FUNC_NAME])),
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[Define to 1 if you have the `]m4_defn([gl_FUNC_NAME])[' function.])
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AC_REQUIRE([gl_CHECK_FUNC_]m4_defn([gl_FUNC_NAME]))
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m4_define([gl_FUNCS_EXPANSION], [
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m4_divert_text([DEFAULTS], [gl_func_list=])
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AC_CHECK_FUNCS([$gl_func_list])
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m4_define([gl_FUNCS_EXPANSION], [])
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# AC_CHECK_DECLS_ONCE(DECL1 DECL2 ...) is a once-only variant of
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# AC_CHECK_DECLS(DECL1, DECL2, ...).
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AC_DEFUN([AC_CHECK_DECLS_ONCE], [
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m4_foreach_w([gl_DECL_NAME], [$1], [
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AC_DEFUN([gl_CHECK_DECL_]m4_defn([gl_DECL_NAME]), [
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AC_CHECK_DECLS(m4_defn([gl_DECL_NAME]))
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AC_REQUIRE([gl_CHECK_DECL_]m4_defn([gl_DECL_NAME]))
added
removed
m4/onceonly.m4
