ax_cxx_have_ext_hash_set.m4

# =============================================================================
#  https://www.gnu.org/software/autoconf-archive/ax_cxx_have_ext_hash_set.html
# =============================================================================
#
# SYNOPSIS
#
#   AX_CXX_HAVE_EXT_HASH_SET
#
# DESCRIPTION
#
#   Check if the compiler has ext/hash_set Eg:
#
#     #if defined(HAVE_EXT_HASH_SET)
#     #include <ext/hash_set>
#     #else
#     #if defined(HAVE_STL)
#     #include <hash_set>
#     #else
#     # Can't find hash_set header !
#     #endif
#     #endif
#
# 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
#   Free Software Foundation; either version 2 of the License, or (at your
#   option) any later version.
#
#   This program is distributed in the hope that it will be useful, but
#   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.
#
#   You should have received a copy of the GNU General Public License along
#   with this program. If not, see <https://www.gnu.org/licenses/>.
#
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#   gives unlimited permission to copy, distribute and modify the configure
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#   exception to the GPL to apply to your modified version as well.

#serial 7

AU_ALIAS([AC_CXX_HAVE_EXT_HASH_SET], [AX_CXX_HAVE_EXT_HASH_SET])
AC_DEFUN([AX_CXX_HAVE_EXT_HASH_SET],
[AC_CACHE_CHECK(whether the compiler has ext/hash_set,
ax_cv_cxx_have_ext_hash_set,
[AC_REQUIRE([AX_CXX_NAMESPACES])
  AC_LANG_PUSH([C++])
  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <ext/hash_set>
#ifdef HAVE_NAMESPACES
using namespace std;
#endif]], [[hash_set<int> t; return 0;]])],
  [ax_cv_cxx_have_ext_hash_set=yes], [ax_cv_cxx_have_ext_hash_set=no])
  AC_LANG_POP([C++])
])
if test "$ax_cv_cxx_have_ext_hash_set" = yes; then
   AC_DEFINE(HAVE_EXT_HASH_SET,,[define if the compiler has ext/hash_set])
fi
])