// Copyright Louis Dionne 2013-2017 // Distributed under the Boost Software License, Version 1.0. // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) #include namespace hana = boost::hana; template struct base_template { // Can't write this because the assertion would always fire up: // static_assert(false, "..."); // So instead we write this: static_assert(hana::detail::wrong>::value, "base_template does not have a valid default definition"); }; template <> struct base_template { // something useful }; int main() { }