Add additional tests.

test/implicit_cast_fail2.cpp

@@ -0,0 +1,19 @@
+//
+// Test that implicit_cast requires a template argument
+//
+// Copyright 2014 Peter Dimov
+//
+// Distributed under the Boost Software License, Version 1.0.
+//
+// See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt
+//
+
+#include <boost/implicit_cast.hpp>
+
+int main()
+{
+    int x = boost::implicit_cast( 1 );
+    (void)x;
+
+    return 0;
+}