extensions.m4

bison 2.0 主要可以用来做语法分析用的

# Enable extensions on systems that normally disable them.

# Copyright (C) 2003 Free Software Foundation, Inc.

# This file is free software, distributed under the terms of the GNU
# General Public License.  As a special exception to the GNU General
# Public License, this file may be distributed as part of a program
# that contains a configuration script generated by Autoconf, under
# the same distribution terms as the rest of that program.

# gl_USE_SYSTEM_EXTENSIONS
# ------------------------
# Enable extensions on systems that normally disable them,
# typically due to standards-conformance issues.
AC_DEFUN([gl_USE_SYSTEM_EXTENSIONS], [
  AC_BEFORE([$0], [AC_COMPILE_IFELSE])
  AC_BEFORE([$0], [AC_RUN_IFELSE])

  AC_REQUIRE([AC_GNU_SOURCE])
  AC_REQUIRE([AC_AIX])
  AC_REQUIRE([AC_MINIX])

  AH_VERBATIM([__EXTENSIONS__],
[/* Enable extensions on Solaris.  */
#ifndef __EXTENSIONS__
# undef __EXTENSIONS__
#endif])
  AC_DEFINE([__EXTENSIONS__])
])