##### http://autoconf-archive.cryp.to/ac_cxx_explicit.html
#
# SYNOPSIS
#
#   AC_CXX_EXPLICIT
#
# DESCRIPTION
#
#   If the compiler can be asked to prevent using implicitly one
#   argument constructors as converting constructors with the explicit
#   keyword, define HAVE_EXPLICIT.
#
# LAST MODIFICATION
#
#   2004-02-04
#
# COPYLEFT
#
#   Copyright (c) 2004 Todd Veldhuizen
#   Copyright (c) 2004 Luc Maisonobe <luc@spaceroots.org>
#
#   Copying and distribution of this file, with or without
#   modification, are permitted in any medium without royalty provided
#   the copyright notice and this notice are preserved.

AC_DEFUN([AC_CXX_EXPLICIT],
[AC_CACHE_CHECK(whether the compiler supports the explicit keyword,
ac_cv_cxx_explicit,
[AC_LANG_SAVE
 AC_LANG_CPLUSPLUS
 AC_TRY_COMPILE([class A{public:explicit A(double){}};],
[double c = 5.0;A x(c);return 0;],
 ac_cv_cxx_explicit=yes, ac_cv_cxx_explicit=no)
 AC_LANG_RESTORE
])
if test "$ac_cv_cxx_explicit" = yes; then
  AC_DEFINE(HAVE_EXPLICIT,,[define if the compiler supports the explicit keyword])
fi
])