1# serial 9  -*- Autoconf -*-
2# Enable extensions on systems that normally disable them.
3
4# Copyright (C) 2003, 2006-2010 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 GNU extensions on systems that have them.  */
71#ifndef _GNU_SOURCE
72# undef _GNU_SOURCE
73#endif
74/* Enable threading extensions on Solaris.  */
75#ifndef _POSIX_PTHREAD_SEMANTICS
76# undef _POSIX_PTHREAD_SEMANTICS
77#endif
78/* Enable extensions on HP NonStop.  */
79#ifndef _TANDEM_SOURCE
80# undef _TANDEM_SOURCE
81#endif
82/* Enable general extensions on Solaris.  */
83#ifndef __EXTENSIONS__
84# undef __EXTENSIONS__
85#endif
86])
87  AC_CACHE_CHECK([whether it is safe to define __EXTENSIONS__],
88    [ac_cv_safe_to_define___extensions__],
89    [AC_COMPILE_IFELSE(
90       [AC_LANG_PROGRAM([[
91#         define __EXTENSIONS__ 1
92          ]AC_INCLUDES_DEFAULT])],
93       [ac_cv_safe_to_define___extensions__=yes],
94       [ac_cv_safe_to_define___extensions__=no])])
95  test $ac_cv_safe_to_define___extensions__ = yes &&
96    AC_DEFINE([__EXTENSIONS__])
97  AC_DEFINE([_ALL_SOURCE])
98  AC_DEFINE([_GNU_SOURCE])
99  AC_DEFINE([_POSIX_PTHREAD_SEMANTICS])
100  AC_DEFINE([_TANDEM_SOURCE])
101])# AC_USE_SYSTEM_EXTENSIONS
102
103# gl_USE_SYSTEM_EXTENSIONS
104# ------------------------
105# Enable extensions on systems that normally disable them,
106# typically due to standards-conformance issues.
107AC_DEFUN_ONCE([gl_USE_SYSTEM_EXTENSIONS],
108[
109  dnl Require this macro before AC_USE_SYSTEM_EXTENSIONS.
110  dnl gnulib does not need it. But if it gets required by third-party macros
111  dnl after AC_USE_SYSTEM_EXTENSIONS is required, autoconf 2.62..2.63 emit a
112  dnl warning: "AC_COMPILE_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS".
113  dnl Note: We can do this only for one of the macros AC_AIX, AC_GNU_SOURCE,
114  dnl AC_MINIX. If people still use AC_AIX or AC_MINIX, they are out of luck.
115  AC_REQUIRE([AC_GNU_SOURCE])
116
117  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
118])
119