ax_cxx_have_empty_iostream.m4

# ===============================================================================
#  https://www.gnu.org/software/autoconf-archive/ax_cxx_have_empty_iostream.html
# ===============================================================================
#
# SYNOPSIS
#
#   AX_CXX_HAVE_EMPTY_IOSTREAM
#
# DESCRIPTION
#
#   Check if the compiler allow the empty iostream constructor. Ok before
#   gcc3, not after.
#
# LICENSE
#
#   Copyright (c) 2008 Alain BARBET <alian@cpan.org>
#
#   This program is free software; you can redistribute it and/or modify it
#   under the terms of the GNU General Public License as published by the
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#
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#   WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
#   Public License for more details.
#
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#serial 7

AU_ALIAS([AC_CXX_HAVE_EMPTY_IOSTREAM], [AX_CXX_HAVE_EMPTY_IOSTREAM])
AC_DEFUN([AX_CXX_HAVE_EMPTY_IOSTREAM],
[AC_CACHE_CHECK(whether the compiler allow empty iostream,
ax_cv_cxx_have_empty_iostream,
[AC_REQUIRE([AX_CXX_NAMESPACES])
  AC_LANG_PUSH([C++])
  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <iostream>
#ifdef HAVE_NAMESPACES
using namespace std;
#endif]], [[iostream iostr; return 0;]])],
  [ax_cv_cxx_have_empty_iostream=yes], [ax_cv_cxx_have_empty_iostream=no])
  AC_LANG_POP([C++])
])
if test "$ax_cv_cxx_have_empty_iostream" = yes; then
   AC_DEFINE(HAVE_EMPTY_IOSTREAM,,[define if the compiler allow empty
iostream])
fi
])