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1# serial 12  -*- Autoconf -*-
2# Enable extensions on systems that normally disable them.
3
4# Copyright (C) 2003, 2006-2012 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# This definition of AC_USE_SYSTEM_EXTENSIONS is stolen from CVS
10# Autoconf.  Perhaps we can remove this once we can assume Autoconf
11# 2.62 or later everywhere, but since CVS Autoconf mutates rapidly
12# enough in this area it's likely we'll need to redefine
13# AC_USE_SYSTEM_EXTENSIONS for quite some time.
14
15# If autoconf reports a warning
16#     warning: AC_COMPILE_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS
17# or  warning: AC_RUN_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS
18# the fix is
19#   1) to ensure that AC_USE_SYSTEM_EXTENSIONS is never directly invoked
20#      but always AC_REQUIREd,
21#   2) to ensure that for each occurrence of
22#        AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
23#      or
24#        AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
25#      the corresponding gnulib module description has 'extensions' among
26#      its dependencies. This will ensure that the gl_USE_SYSTEM_EXTENSIONS
27#      invocation occurs in gl_EARLY, not in gl_INIT.
28
29# AC_USE_SYSTEM_EXTENSIONS
30# ------------------------
31# Enable extensions on systems that normally disable them,
32# typically due to standards-conformance issues.
33# Remember that #undef in AH_VERBATIM gets replaced with #define by
34# AC_DEFINE.  The goal here is to define all known feature-enabling
35# macros, then, if reports of conflicts are made, disable macros that
36# cause problems on some platforms (such as __EXTENSIONS__).
37AC_DEFUN_ONCE([AC_USE_SYSTEM_EXTENSIONS],
38[AC_BEFORE([$0], [AC_COMPILE_IFELSE])dnl
39AC_BEFORE([$0], [AC_RUN_IFELSE])dnl
40
41  AC_REQUIRE([AC_CANONICAL_HOST])
42
43  AC_CHECK_HEADER([minix/config.h], [MINIX=yes], [MINIX=])
44  if test "$MINIX" = yes; then
45    AC_DEFINE([_POSIX_SOURCE], [1],
46      [Define to 1 if you need to in order for 'stat' and other
47       things to work.])
48    AC_DEFINE([_POSIX_1_SOURCE], [2],
49      [Define to 2 if the system does not provide POSIX.1 features
50       except with this defined.])
51    AC_DEFINE([_MINIX], [1],
52      [Define to 1 if on MINIX.])
53  fi
54
55  dnl HP-UX 11.11 defines mbstate_t only if _XOPEN_SOURCE is defined to 500,
56  dnl regardless of whether the flags -Ae or _D_HPUX_SOURCE=1 are already
57  dnl provided.
58  case "$host_os" in
59    hpux*)
60      AC_DEFINE([_XOPEN_SOURCE], [500],
61        [Define to 500 only on HP-UX.])
62      ;;
63  esac
64
65  AH_VERBATIM([__EXTENSIONS__],
66[/* Enable extensions on AIX 3, Interix.  */
67#ifndef _ALL_SOURCE
68# undef _ALL_SOURCE
69#endif
70/* Enable general extensions on Mac OS X.  */
71#ifndef _DARWIN_C_SOURCE
72# undef _DARWIN_C_SOURCE
73#endif
74/* Enable GNU extensions on systems that have them.  */
75#ifndef _GNU_SOURCE
76# undef _GNU_SOURCE
77#endif
78/* Enable threading extensions on Solaris.  */
79#ifndef _POSIX_PTHREAD_SEMANTICS
80# undef _POSIX_PTHREAD_SEMANTICS
81#endif
82/* Enable extensions on HP NonStop.  */
83#ifndef _TANDEM_SOURCE
84# undef _TANDEM_SOURCE
85#endif
86/* Enable general extensions on Solaris.  */
87#ifndef __EXTENSIONS__
88# undef __EXTENSIONS__
89#endif
90])
91  AC_CACHE_CHECK([whether it is safe to define __EXTENSIONS__],
92    [ac_cv_safe_to_define___extensions__],
93    [AC_COMPILE_IFELSE(
94       [AC_LANG_PROGRAM([[
95#         define __EXTENSIONS__ 1
96          ]AC_INCLUDES_DEFAULT])],
97       [ac_cv_safe_to_define___extensions__=yes],
98       [ac_cv_safe_to_define___extensions__=no])])
99  test $ac_cv_safe_to_define___extensions__ = yes &&
100    AC_DEFINE([__EXTENSIONS__])
101  AC_DEFINE([_ALL_SOURCE])
102  AC_DEFINE([_DARWIN_C_SOURCE])
103  AC_DEFINE([_GNU_SOURCE])
104  AC_DEFINE([_POSIX_PTHREAD_SEMANTICS])
105  AC_DEFINE([_TANDEM_SOURCE])
106])# AC_USE_SYSTEM_EXTENSIONS
107
108# gl_USE_SYSTEM_EXTENSIONS
109# ------------------------
110# Enable extensions on systems that normally disable them,
111# typically due to standards-conformance issues.
112AC_DEFUN_ONCE([gl_USE_SYSTEM_EXTENSIONS],
113[
114  dnl Require this macro before AC_USE_SYSTEM_EXTENSIONS.
115  dnl gnulib does not need it. But if it gets required by third-party macros
116  dnl after AC_USE_SYSTEM_EXTENSIONS is required, autoconf 2.62..2.63 emit a
117  dnl warning: "AC_COMPILE_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS".
118  dnl Note: We can do this only for one of the macros AC_AIX, AC_GNU_SOURCE,
119  dnl AC_MINIX. If people still use AC_AIX or AC_MINIX, they are out of luck.
120  AC_REQUIRE([AC_GNU_SOURCE])
121
122  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
123])
124