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1 # onceonly.m4 serial 6
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2 dnl Copyright (C) 2002-2003, 2005-2006, 2008-2010 Free Software Foundation,
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3 dnl Inc.
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4 dnl This file is free software, distributed under the terms of the GNU
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5 dnl General Public License. As a special exception to the GNU General
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6 dnl Public License, this file may be distributed as part of a program
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7 dnl that contains a configuration script generated by Autoconf, under
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8 dnl the same distribution terms as the rest of that program.
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9
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10 dnl This file defines some "once only" variants of standard autoconf macros.
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11 dnl AC_CHECK_HEADERS_ONCE like AC_CHECK_HEADERS
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12 dnl AC_CHECK_FUNCS_ONCE like AC_CHECK_FUNCS
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13 dnl AC_CHECK_DECLS_ONCE like AC_CHECK_DECLS
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14 dnl AC_REQUIRE([AC_FUNC_STRCOLL]) like AC_FUNC_STRCOLL
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15 dnl The advantage is that the check for each of the headers/functions/decls
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16 dnl will be put only once into the 'configure' file. It keeps the size of
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17 dnl the 'configure' file down, and avoids redundant output when 'configure'
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18 dnl is run.
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19 dnl The drawback is that the checks cannot be conditionalized. If you write
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20 dnl if some_condition; then gl_CHECK_HEADERS(stdlib.h); fi
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21 dnl inside an AC_DEFUNed function, the gl_CHECK_HEADERS macro call expands to
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22 dnl empty, and the check will be inserted before the body of the AC_DEFUNed
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23 dnl function.
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24
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25 dnl The original code implemented AC_CHECK_HEADERS_ONCE and AC_CHECK_FUNCS_ONCE
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26 dnl in terms of AC_DEFUN and AC_REQUIRE. This implementation uses diversions to
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27 dnl named sections DEFAULTS and INIT_PREPARE in order to check all requested
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28 dnl headers at once, thus reducing the size of 'configure'. It is known to work
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29 dnl with autoconf 2.57..2.62 at least . The size reduction is ca. 9%.
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30
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31 dnl Autoconf version 2.59 plus gnulib is required; this file is not needed
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32 dnl with Autoconf 2.60 or greater. But note that autoconf's implementation of
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33 dnl AC_CHECK_DECLS_ONCE expects a comma-separated list of symbols as first
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34 dnl argument!
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35 AC_PREREQ([2.59])
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36
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37 # AC_CHECK_HEADERS_ONCE(HEADER1 HEADER2 ...) is a once-only variant of
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38 # AC_CHECK_HEADERS(HEADER1 HEADER2 ...).
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39 AC_DEFUN([AC_CHECK_HEADERS_ONCE], [
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40 :
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41 m4_foreach_w([gl_HEADER_NAME], [$1], [
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42 AC_DEFUN([gl_CHECK_HEADER_]m4_quote(translit(gl_HEADER_NAME,
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43 [./-], [___])), [
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44 m4_divert_text([INIT_PREPARE],
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45 [gl_header_list="$gl_header_list gl_HEADER_NAME"])
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46 gl_HEADERS_EXPANSION
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47 AH_TEMPLATE(AS_TR_CPP([HAVE_]m4_defn([gl_HEADER_NAME])),
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48 [Define to 1 if you have the <]m4_defn([gl_HEADER_NAME])[> header file.])
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49 ])
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50 AC_REQUIRE([gl_CHECK_HEADER_]m4_quote(translit(gl_HEADER_NAME,
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51 [./-], [___])))
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52 ])
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53 ])
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54 m4_define([gl_HEADERS_EXPANSION], [
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55 m4_divert_text([DEFAULTS], [gl_header_list=])
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56 AC_CHECK_HEADERS([$gl_header_list])
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57 m4_define([gl_HEADERS_EXPANSION], [])
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58 ])
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59
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60 # AC_CHECK_FUNCS_ONCE(FUNC1 FUNC2 ...) is a once-only variant of
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61 # AC_CHECK_FUNCS(FUNC1 FUNC2 ...).
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62 AC_DEFUN([AC_CHECK_FUNCS_ONCE], [
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63 :
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64 m4_foreach_w([gl_FUNC_NAME], [$1], [
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65 AC_DEFUN([gl_CHECK_FUNC_]m4_defn([gl_FUNC_NAME]), [
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66 m4_divert_text([INIT_PREPARE],
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67 [gl_func_list="$gl_func_list gl_FUNC_NAME"])
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68 gl_FUNCS_EXPANSION
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69 AH_TEMPLATE(AS_TR_CPP([HAVE_]m4_defn([gl_FUNC_NAME])),
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70 [Define to 1 if you have the `]m4_defn([gl_FUNC_NAME])[' function.])
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71 ])
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72 AC_REQUIRE([gl_CHECK_FUNC_]m4_defn([gl_FUNC_NAME]))
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73 ])
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74 ])
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75 m4_define([gl_FUNCS_EXPANSION], [
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76 m4_divert_text([DEFAULTS], [gl_func_list=])
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77 AC_CHECK_FUNCS([$gl_func_list])
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78 m4_define([gl_FUNCS_EXPANSION], [])
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79 ])
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80
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81 # AC_CHECK_DECLS_ONCE(DECL1 DECL2 ...) is a once-only variant of
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82 # AC_CHECK_DECLS(DECL1, DECL2, ...).
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83 AC_DEFUN([AC_CHECK_DECLS_ONCE], [
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84 :
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85 m4_foreach_w([gl_DECL_NAME], [$1], [
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86 AC_DEFUN([gl_CHECK_DECL_]m4_defn([gl_DECL_NAME]), [
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87 AC_CHECK_DECLS(m4_defn([gl_DECL_NAME]))
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88 ])
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89 AC_REQUIRE([gl_CHECK_DECL_]m4_defn([gl_DECL_NAME]))
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90 ])
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91 ])
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