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38 lines
1.1 KiB
C++
38 lines
1.1 KiB
C++
// Copyright Louis Dionne 2013-2016
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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#include <boost/hana/assert.hpp>
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#include <boost/hana/not.hpp>
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#include <boost/hana/optional.hpp>
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#include <boost/hana/traits.hpp>
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#include <boost/hana/type.hpp>
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#include <type_traits>
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#include <utility>
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namespace hana = boost::hana;
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template <typename ...>
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using void_t = void;
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template <typename T, typename = void>
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struct has_type : std::false_type { };
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template <typename T>
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struct has_type<T, void_t<typename T::type>>
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: std::true_type
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{ };
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auto common_type_impl = hana::sfinae([](auto t, auto u) -> decltype(hana::type_c<
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decltype(true ? hana::traits::declval(t) : hana::traits::declval(u))
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>) { return {}; });
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template <typename T, typename U>
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using common_type2 = decltype(common_type_impl(hana::type_c<T>, hana::type_c<U>));
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static_assert(!has_type<common_type2<int, int*>>{}, "");
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static_assert(std::is_same<common_type2<int, float>::type, float>{}, "");
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int main() { }
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