diff options
Diffstat (limited to 'm4/extensions.m4')
| -rw-r--r-- | m4/extensions.m4 | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/m4/extensions.m4 b/m4/extensions.m4 index e71845f..4976079 100644 --- a/m4/extensions.m4 +++ b/m4/extensions.m4 @@ -1,10 +1,13 @@ # Enable extensions on systems that normally disable them. -# Copyright (C) 2003 Free Software Foundation, Inc. +# Copyright (C) 2003, 2006 Free Software Foundation, Inc. # This file is free software; the Free Software Foundation # gives unlimited permission to copy and/or distribute it, # with or without modifications, as long as this notice is preserved. +# This file is only needed in autoconf <= 2.59. Newer versions of autoconf +# have a macro AC_USE_SYSTEM_EXTENSIONS with identical semantics. + # gl_USE_SYSTEM_EXTENSIONS # ------------------------ # Enable extensions on systems that normally disable them, @@ -25,6 +28,15 @@ AC_DEFUN([gl_USE_SYSTEM_EXTENSIONS], [ #ifndef _POSIX_PTHREAD_SEMANTICS # undef _POSIX_PTHREAD_SEMANTICS #endif]) - AC_DEFINE([__EXTENSIONS__]) + AC_CACHE_CHECK([whether it is safe to define __EXTENSIONS__], + [ac_cv_safe_to_define___extensions__], + [AC_COMPILE_IFELSE( + [AC_LANG_PROGRAM([ + #define __EXTENSIONS__ 1 + AC_INCLUDES_DEFAULT])], + [ac_cv_safe_to_define___extensions__=yes], + [ac_cv_safe_to_define___extensions__=no])]) + test $ac_cv_safe_to_define___extensions__ = yes && + AC_DEFINE([__EXTENSIONS__]) AC_DEFINE([_POSIX_PTHREAD_SEMANTICS]) ]) |