1# serial 13  -*- Autoconf -*-
2# Enable extensions on systems that normally disable them.
3
4# Copyright (C) 2003, 2006-2014 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 git
10# Autoconf.  Perhaps we can remove this once we can assume Autoconf
11# 2.70 or later everywhere, but since 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#
34# Remember that #undef in AH_VERBATIM gets replaced with #define by
35# AC_DEFINE.  The goal here is to define all known feature-enabling
36# macros, then, if reports of conflicts are made, disable macros that
37# cause problems on some platforms (such as __EXTENSIONS__).
38AC_DEFUN_ONCE([AC_USE_SYSTEM_EXTENSIONS],
39[AC_BEFORE([$0], [AC_COMPILE_IFELSE])dnl
40AC_BEFORE([$0], [AC_RUN_IFELSE])dnl
41
42  AC_CHECK_HEADER([minix/config.h], [MINIX=yes], [MINIX=])
43  if test "$MINIX" = yes; then
44    AC_DEFINE([_POSIX_SOURCE], [1],
45      [Define to 1 if you need to in order for 'stat' and other
46       things to work.])
47    AC_DEFINE([_POSIX_1_SOURCE], [2],
48      [Define to 2 if the system does not provide POSIX.1 features
49       except with this defined.])
50    AC_DEFINE([_MINIX], [1],
51      [Define to 1 if on MINIX.])
52    AC_DEFINE([_NETBSD_SOURCE], [1],
53      [Define to 1 to make NetBSD features available.  MINIX 3 needs this.])
54  fi
55
56dnl Use a different key than __EXTENSIONS__, as that name broke existing
57dnl configure.ac when using autoheader 2.62.
58  AH_VERBATIM([USE_SYSTEM_EXTENSIONS],
59[/* Enable extensions on AIX 3, Interix.  */
60#ifndef _ALL_SOURCE
61# undef _ALL_SOURCE
62#endif
63/* Enable general extensions on OS X.  */
64#ifndef _DARWIN_C_SOURCE
65# undef _DARWIN_C_SOURCE
66#endif
67/* Enable GNU extensions on systems that have them.  */
68#ifndef _GNU_SOURCE
69# undef _GNU_SOURCE
70#endif
71/* Enable threading extensions on Solaris.  */
72#ifndef _POSIX_PTHREAD_SEMANTICS
73# undef _POSIX_PTHREAD_SEMANTICS
74#endif
75/* Enable extensions on HP NonStop.  */
76#ifndef _TANDEM_SOURCE
77# undef _TANDEM_SOURCE
78#endif
79/* Enable X/Open extensions if necessary.  HP-UX 11.11 defines
80   mbstate_t only if _XOPEN_SOURCE is defined to 500, regardless of
81   whether compiling with -Ae or -D_HPUX_SOURCE=1.  */
82#ifndef _XOPEN_SOURCE
83# undef _XOPEN_SOURCE
84#endif
85/* Enable general extensions on Solaris.  */
86#ifndef __EXTENSIONS__
87# undef __EXTENSIONS__
88#endif
89])
90  AC_CACHE_CHECK([whether it is safe to define __EXTENSIONS__],
91    [ac_cv_safe_to_define___extensions__],
92    [AC_COMPILE_IFELSE(
93       [AC_LANG_PROGRAM([[
94#         define __EXTENSIONS__ 1
95          ]AC_INCLUDES_DEFAULT])],
96       [ac_cv_safe_to_define___extensions__=yes],
97       [ac_cv_safe_to_define___extensions__=no])])
98  test $ac_cv_safe_to_define___extensions__ = yes &&
99    AC_DEFINE([__EXTENSIONS__])
100  AC_DEFINE([_ALL_SOURCE])
101  AC_DEFINE([_DARWIN_C_SOURCE])
102  AC_DEFINE([_GNU_SOURCE])
103  AC_DEFINE([_POSIX_PTHREAD_SEMANTICS])
104  AC_DEFINE([_TANDEM_SOURCE])
105  AC_CACHE_CHECK([whether _XOPEN_SOURCE should be defined],
106    [ac_cv_should_define__xopen_source],
107    [ac_cv_should_define__xopen_source=no
108     AC_COMPILE_IFELSE(
109       [AC_LANG_PROGRAM([[
110          #include <wchar.h>
111          mbstate_t x;]])],
112       [],
113       [AC_COMPILE_IFELSE(
114          [AC_LANG_PROGRAM([[
115             #define _XOPEN_SOURCE 500
116             #include <wchar.h>
117             mbstate_t x;]])],
118          [ac_cv_should_define__xopen_source=yes])])])
119  test $ac_cv_should_define__xopen_source = yes &&
120    AC_DEFINE([_XOPEN_SOURCE], [500])
121])# AC_USE_SYSTEM_EXTENSIONS
122
123# gl_USE_SYSTEM_EXTENSIONS
124# ------------------------
125# Enable extensions on systems that normally disable them,
126# typically due to standards-conformance issues.
127AC_DEFUN_ONCE([gl_USE_SYSTEM_EXTENSIONS],
128[
129  dnl Require this macro before AC_USE_SYSTEM_EXTENSIONS.
130  dnl gnulib does not need it. But if it gets required by third-party macros
131  dnl after AC_USE_SYSTEM_EXTENSIONS is required, autoconf 2.62..2.63 emit a
132  dnl warning: "AC_COMPILE_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS".
133  dnl Note: We can do this only for one of the macros AC_AIX, AC_GNU_SOURCE,
134  dnl AC_MINIX. If people still use AC_AIX or AC_MINIX, they are out of luck.
135  AC_REQUIRE([AC_GNU_SOURCE])
136
137  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
138])
139