gnulib/import/m4/extensions.m4

   1 # serial 22  -*- Autoconf -*-
   2 # Enable extensions on systems that normally disable them.
   3
   4 # Copyright (C) 2003, 2006-2021 Free Software Foundation, Inc.
   5 # This file is free software; the Free Software Foundation
   6 # gives unlimited permission to copy and/or distribute it,
   7 # with or without modifications, as long as this notice is preserved.
   8
   9 dnl Define to empty for the benefit of Autoconf 2.69 and earlier, so that
  10 dnl AC_USE_SYSTEM_EXTENSIONS (below) can be used unchanged from Autoconf 2.70+.
  11 m4_ifndef([AC_CHECK_INCLUDES_DEFAULT],
  12   [AC_DEFUN([AC_CHECK_INCLUDES_DEFAULT], [])])
  13
  14 # This definition of AC_USE_SYSTEM_EXTENSIONS is stolen from git
  15 # Autoconf.  Perhaps we can remove this once we can assume Autoconf
  16 # is recent-enough everywhere, but since Autoconf mutates rapidly
  17 # enough in this area it's likely we'll need to redefine
  18 # AC_USE_SYSTEM_EXTENSIONS for quite some time.
  19
  20 # If autoconf reports a warning
  21 #     warning: AC_COMPILE_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS
  22 # or  warning: AC_RUN_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS
  23 # the fix is
  24 #   1) to ensure that AC_USE_SYSTEM_EXTENSIONS is never directly invoked
  25 #      but always AC_REQUIREd,
  26 #   2) to ensure that for each occurrence of
  27 #        AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
  28 #      or
  29 #        AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
  30 #      the corresponding gnulib module description has 'extensions' among
  31 #      its dependencies. This will ensure that the gl_USE_SYSTEM_EXTENSIONS
  32 #      invocation occurs in gl_EARLY, not in gl_INIT.
  33
  34 m4_version_prereq([2.70.1], [], [
  35
  36 # AC_USE_SYSTEM_EXTENSIONS
  37 # ------------------------
  38 # Enable extensions on systems that normally disable them,
  39 # typically due to standards-conformance issues.
  40 # We unconditionally define as many of the known feature-enabling
  41 # as possible, reserving conditional behavior for macros that are
  42 # known to cause problems on some platforms (such as __EXTENSIONS__).
  43 AC_DEFUN_ONCE([AC_USE_SYSTEM_EXTENSIONS],
  44 [AC_BEFORE([$0], [AC_PREPROC_IFELSE])dnl
  45 AC_BEFORE([$0], [AC_COMPILE_IFELSE])dnl
  46 AC_BEFORE([$0], [AC_LINK_IFELSE])dnl
  47 AC_BEFORE([$0], [AC_RUN_IFELSE])dnl
  48 AC_BEFORE([$0], [AC_CHECK_INCLUDES_DEFAULT])dnl
  49 dnl #undef in AH_VERBATIM gets replaced with #define by AC_DEFINE.
  50 dnl Use a different key than __EXTENSIONS__, as that name broke existing
  51 dnl configure.ac when using autoheader 2.62.
  52 dnl The macros below are in alphabetical order ignoring leading _ or __
  53 dnl prefixes.
  54 AH_VERBATIM([USE_SYSTEM_EXTENSIONS],
  55 [/* Enable extensions on AIX 3, Interix.  */
  56 #ifndef _ALL_SOURCE
  57 # undef _ALL_SOURCE
  58 #endif
  59 /* Enable general extensions on macOS.  */
  60 #ifndef _DARWIN_C_SOURCE
  61 # undef _DARWIN_C_SOURCE
  62 #endif
  63 /* Enable general extensions on Solaris.  */
  64 #ifndef __EXTENSIONS__
  65 # undef __EXTENSIONS__
  66 #endif
  67 /* Enable GNU extensions on systems that have them.  */
  68 #ifndef _GNU_SOURCE
  69 # undef _GNU_SOURCE
  70 #endif
  71 /* Enable X/Open compliant socket functions that do not require linking
  72    with -lxnet on HP-UX 11.11.  */
  73 #ifndef _HPUX_ALT_XOPEN_SOCKET_API
  74 # undef _HPUX_ALT_XOPEN_SOCKET_API
  75 #endif
  76 /* Identify the host operating system as Minix.
  77    This macro does not affect the system headers' behavior.
  78    A future release of Autoconf may stop defining this macro.  */
  79 #ifndef _MINIX
  80 # undef _MINIX
  81 #endif
  82 /* Enable general extensions on NetBSD.
  83    Enable NetBSD compatibility extensions on Minix.  */
  84 #ifndef _NETBSD_SOURCE
  85 # undef _NETBSD_SOURCE
  86 #endif
  87 /* Enable OpenBSD compatibility extensions on NetBSD.
  88    Oddly enough, this does nothing on OpenBSD.  */
  89 #ifndef _OPENBSD_SOURCE
  90 # undef _OPENBSD_SOURCE
  91 #endif
  92 /* Define to 1 if needed for POSIX-compatible behavior.  */
  93 #ifndef _POSIX_SOURCE
  94 # undef _POSIX_SOURCE
  95 #endif
  96 /* Define to 2 if needed for POSIX-compatible behavior.  */
  97 #ifndef _POSIX_1_SOURCE
  98 # undef _POSIX_1_SOURCE
  99 #endif
 100 /* Enable POSIX-compatible threading on Solaris.  */
 101 #ifndef _POSIX_PTHREAD_SEMANTICS
 102 # undef _POSIX_PTHREAD_SEMANTICS
 103 #endif
 104 /* Enable extensions specified by ISO/IEC TS 18661-5:2014.  */
 105 #ifndef __STDC_WANT_IEC_60559_ATTRIBS_EXT__
 106 # undef __STDC_WANT_IEC_60559_ATTRIBS_EXT__
 107 #endif
 108 /* Enable extensions specified by ISO/IEC TS 18661-1:2014.  */
 109 #ifndef __STDC_WANT_IEC_60559_BFP_EXT__
 110 # undef __STDC_WANT_IEC_60559_BFP_EXT__
 111 #endif
 112 /* Enable extensions specified by ISO/IEC TS 18661-2:2015.  */
 113 #ifndef __STDC_WANT_IEC_60559_DFP_EXT__
 114 # undef __STDC_WANT_IEC_60559_DFP_EXT__
 115 #endif
 116 /* Enable extensions specified by ISO/IEC TS 18661-4:2015.  */
 117 #ifndef __STDC_WANT_IEC_60559_FUNCS_EXT__
 118 # undef __STDC_WANT_IEC_60559_FUNCS_EXT__
 119 #endif
 120 /* Enable extensions specified by ISO/IEC TS 18661-3:2015.  */
 121 #ifndef __STDC_WANT_IEC_60559_TYPES_EXT__
 122 # undef __STDC_WANT_IEC_60559_TYPES_EXT__
 123 #endif
 124 /* Enable extensions specified by ISO/IEC TR 24731-2:2010.  */
 125 #ifndef __STDC_WANT_LIB_EXT2__
 126 # undef __STDC_WANT_LIB_EXT2__
 127 #endif
 128 /* Enable extensions specified by ISO/IEC 24747:2009.  */
 129 #ifndef __STDC_WANT_MATH_SPEC_FUNCS__
 130 # undef __STDC_WANT_MATH_SPEC_FUNCS__
 131 #endif
 132 /* Enable extensions on HP NonStop.  */
 133 #ifndef _TANDEM_SOURCE
 134 # undef _TANDEM_SOURCE
 135 #endif
 136 /* Enable X/Open extensions.  Define to 500 only if necessary
 137    to make mbstate_t available.  */
 138 #ifndef _XOPEN_SOURCE
 139 # undef _XOPEN_SOURCE
 140 #endif
 141 ])dnl
 142
 143   AC_REQUIRE([AC_CHECK_INCLUDES_DEFAULT])dnl
 144   _AC_CHECK_HEADER_ONCE([wchar.h])
 145   _AC_CHECK_HEADER_ONCE([minix/config.h])
 146
 147 dnl Defining __EXTENSIONS__ may break the system headers on some systems.
 148 dnl (FIXME: Which ones?)
 149   AC_CACHE_CHECK([whether it is safe to define __EXTENSIONS__],
 150     [ac_cv_safe_to_define___extensions__],
 151     [AC_COMPILE_IFELSE(
 152        [AC_LANG_PROGRAM([[
 153 #         define __EXTENSIONS__ 1
 154           ]AC_INCLUDES_DEFAULT])],
 155        [ac_cv_safe_to_define___extensions__=yes],
 156        [ac_cv_safe_to_define___extensions__=no])])
 157
 158 dnl HP-UX 11.11 defines mbstate_t only if _XOPEN_SOURCE is defined to
 159 dnl 500, regardless of whether compiling with -Ae or -D_HPUX_SOURCE=1.
 160 dnl But defining _XOPEN_SOURCE may turn *off* extensions on platforms
 161 dnl not covered by turn-on-extensions macros (notably Dragonfly, Free,
 162 dnl and OpenBSD, which don't have any equivalent of _NETBSD_SOURCE) so
 163 dnl it should only be defined when necessary.
 164   AC_CACHE_CHECK([whether _XOPEN_SOURCE should be defined],
 165     [ac_cv_should_define__xopen_source],
 166     [ac_cv_should_define__xopen_source=no
 167     AS_IF([test $ac_cv_header_wchar_h = yes],
 168       [AC_COMPILE_IFELSE(
 169         [AC_LANG_PROGRAM([[
 170           #include <wchar.h>
 171           mbstate_t x;]])],
 172         [],
 173         [AC_COMPILE_IFELSE(
 174           [AC_LANG_PROGRAM([[
 175             #define _XOPEN_SOURCE 500
 176             #include <wchar.h>
 177             mbstate_t x;]])],
 178           [ac_cv_should_define__xopen_source=yes])])])])
 179
 180   AC_DEFINE([_ALL_SOURCE])
 181   AC_DEFINE([_DARWIN_C_SOURCE])
 182   AC_DEFINE([_GNU_SOURCE])
 183   AC_DEFINE([_HPUX_ALT_XOPEN_SOCKET_API])
 184   AC_DEFINE([_NETBSD_SOURCE])
 185   AC_DEFINE([_OPENBSD_SOURCE])
 186   AC_DEFINE([_POSIX_PTHREAD_SEMANTICS])
 187   AC_DEFINE([__STDC_WANT_IEC_60559_ATTRIBS_EXT__])
 188   AC_DEFINE([__STDC_WANT_IEC_60559_BFP_EXT__])
 189   AC_DEFINE([__STDC_WANT_IEC_60559_DFP_EXT__])
 190   AC_DEFINE([__STDC_WANT_IEC_60559_FUNCS_EXT__])
 191   AC_DEFINE([__STDC_WANT_IEC_60559_TYPES_EXT__])
 192   AC_DEFINE([__STDC_WANT_LIB_EXT2__])
 193   AC_DEFINE([__STDC_WANT_MATH_SPEC_FUNCS__])
 194   AC_DEFINE([_TANDEM_SOURCE])
 195   AS_IF([test $ac_cv_header_minix_config_h = yes],
 196     [MINIX=yes
 197     AC_DEFINE([_MINIX])
 198     AC_DEFINE([_POSIX_SOURCE])
 199     AC_DEFINE([_POSIX_1_SOURCE], [2])],
 200     [MINIX=])
 201   AS_IF([test $ac_cv_safe_to_define___extensions__ = yes],
 202     [AC_DEFINE([__EXTENSIONS__])])
 203   AS_IF([test $ac_cv_should_define__xopen_source = yes],
 204     [AC_DEFINE([_XOPEN_SOURCE], [500])])
 205 ])# AC_USE_SYSTEM_EXTENSIONS
 206 ])
 207
 208 # gl_USE_SYSTEM_EXTENSIONS
 209 # ------------------------
 210 # Enable extensions on systems that normally disable them,
 211 # typically due to standards-conformance issues.
 212 AC_DEFUN_ONCE([gl_USE_SYSTEM_EXTENSIONS],
 213 [
 214   AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
 215
 216   dnl On OpenBSD 6.8 with GCC, the include files contain a couple of
 217   dnl definitions that are only activated with an explicit -D_ISOC11_SOURCE.
 218   dnl That's because this version of GCC (4.2.1) supports the option
 219   dnl '-std=gnu99' but not the option '-std=gnu11'.
 220   AC_REQUIRE([AC_CANONICAL_HOST])
 221   case "$host_os" in
 222     openbsd*)
 223       AC_DEFINE([_ISOC11_SOURCE], [1],
 224         [Define to enable the declarations of ISO C 11 types and functions.])
 225       ;;
 226   esac
 227 ])