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Diffstat (limited to 'src/boost/libs/hana/test/pair/empty_storage.cpp')
-rw-r--r-- | src/boost/libs/hana/test/pair/empty_storage.cpp | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/src/boost/libs/hana/test/pair/empty_storage.cpp b/src/boost/libs/hana/test/pair/empty_storage.cpp new file mode 100644 index 000000000..000041485 --- /dev/null +++ b/src/boost/libs/hana/test/pair/empty_storage.cpp @@ -0,0 +1,34 @@ +// 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 <boost/hana/pair.hpp> + +#include <type_traits> +namespace hana = boost::hana; + + +struct empty1 { }; +struct empty2 { }; +struct empty3 { }; +struct empty4 { }; + +// Make sure the storage of a pair is compressed +static_assert(sizeof(hana::pair<empty1, int>) == sizeof(int), ""); +static_assert(sizeof(hana::pair<int, empty1>) == sizeof(int), ""); + +// Also make sure that a pair with only empty members is empty too. This is +// important to ensure, for example, that a tuple of pairs of empty objects +// will get the EBO. +static_assert(std::is_empty<hana::pair<empty1, empty2>>{}, ""); + +// Make sure that a pair of empty pairs is still empty. +static_assert(std::is_empty< + hana::pair<hana::pair<empty1, empty2>, empty3> +>{}, ""); + +static_assert(std::is_empty< + hana::pair<hana::pair<empty1, empty2>, hana::pair<empty3, empty4>> +>{}, ""); + +int main() { } |