35 lines
1.0 KiB
C++
35 lines
1.0 KiB
C++
// Copyright Louis Dionne 2013-2017
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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/pair.hpp>
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#include <type_traits>
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namespace hana = boost::hana;
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struct empty1 { };
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struct empty2 { };
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struct empty3 { };
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struct empty4 { };
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// Make sure the storage of a pair is compressed
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static_assert(sizeof(hana::pair<empty1, int>) == sizeof(int), "");
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static_assert(sizeof(hana::pair<int, empty1>) == sizeof(int), "");
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// Also make sure that a pair with only empty members is empty too. This is
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// important to ensure, for example, that a tuple of pairs of empty objects
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// will get the EBO.
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static_assert(std::is_empty<hana::pair<empty1, empty2>>{}, "");
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// Make sure that a pair of empty pairs is still empty.
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static_assert(std::is_empty<
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hana::pair<hana::pair<empty1, empty2>, empty3>
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>{}, "");
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static_assert(std::is_empty<
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hana::pair<hana::pair<empty1, empty2>, hana::pair<empty3, empty4>>
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>{}, "");
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int main() { }
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