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SFINAE-fail mp_eval_if when F<U...> is invalid

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Peter Dimov
2017-05-18 15:22:05 +03:00
parent 37bbb15375
commit 611ea810bd
3 changed files with 55 additions and 21 deletions
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test/mp_eval_if_sf.cpp
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// Copyright 2017 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/mp11/utility.hpp>
#include <boost/core/lightweight_test_trait.hpp>
#include <type_traits>
using boost::mp11::mp_eval_if;
using boost::mp11::mp_identity_t;
template<class C, class... A> using eval_if = mp_eval_if<C, void, mp_identity_t, A...>;
int main()
{
using boost::mp11::mp_valid;
BOOST_TEST_TRAIT_TRUE((mp_valid<eval_if, std::true_type>));
BOOST_TEST_TRAIT_TRUE((mp_valid<eval_if, std::true_type, void>));
BOOST_TEST_TRAIT_TRUE((mp_valid<eval_if, std::true_type, void, void>));
BOOST_TEST_TRAIT_TRUE((mp_valid<eval_if, std::true_type, void, void, void>));
BOOST_TEST_TRAIT_FALSE((mp_valid<eval_if, std::false_type>));
BOOST_TEST_TRAIT_TRUE((mp_valid<eval_if, std::false_type, void>));
BOOST_TEST_TRAIT_FALSE((mp_valid<eval_if, std::false_type, void, void>));
BOOST_TEST_TRAIT_FALSE((mp_valid<eval_if, std::false_type, void, void, void>));
return boost::report_errors();
}