autoconf: Posix Variants

1 
1 5.12 Posix Variants
1 ===================
1 
1 The following macro makes it possible to use features of Posix that are
1 extensions to C, as well as platform extensions not defined by Posix.
1 
1  -- Macro: AC_USE_SYSTEM_EXTENSIONS
1      This macro was introduced in Autoconf 2.60.  If possible, enable
1      extensions to C or Posix on hosts that normally disable the
1      extensions, typically due to standards-conformance namespace
1      issues.  This should be called before any macros that run the C
1      compiler.  The following preprocessor macros are defined where
1      appropriate:
1 
1     `_GNU_SOURCE'
1           Enable extensions on GNU/Linux.
1 
1     `__EXTENSIONS__'
1           Enable general extensions on Solaris.
1 
1     `_POSIX_PTHREAD_SEMANTICS'
1           Enable threading extensions on Solaris.
1 
1     `_TANDEM_SOURCE'
1           Enable extensions for the HP NonStop platform.
1 
1     `_ALL_SOURCE'
1           Enable extensions for AIX 3, and for Interix.
1 
1     `_POSIX_SOURCE'
1           Enable Posix functions for Minix.
1 
1     `_POSIX_1_SOURCE'
1           Enable additional Posix functions for Minix.
1 
1     `_MINIX'
1           Identify Minix platform.  This particular preprocessor macro
1           is obsolescent, and may be removed in a future release of
1           Autoconf.
1