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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:45:59 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:45:59 +0000 |
commit | 19fcec84d8d7d21e796c7624e521b60d28ee21ed (patch) | |
tree | 42d26aa27d1e3f7c0b8bd3fd14e7d7082f5008dc /src/boost/libs/hana/test/tuple/usability_of_types.cpp | |
parent | Initial commit. (diff) | |
download | ceph-upstream.tar.xz ceph-upstream.zip |
Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/boost/libs/hana/test/tuple/usability_of_types.cpp')
-rw-r--r-- | src/boost/libs/hana/test/tuple/usability_of_types.cpp | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/src/boost/libs/hana/test/tuple/usability_of_types.cpp b/src/boost/libs/hana/test/tuple/usability_of_types.cpp new file mode 100644 index 000000000..261b47ad0 --- /dev/null +++ b/src/boost/libs/hana/test/tuple/usability_of_types.cpp @@ -0,0 +1,41 @@ +// 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/at.hpp> +#include <boost/hana/back.hpp> +#include <boost/hana/front.hpp> +#include <boost/hana/integral_constant.hpp> +#include <boost/hana/tuple.hpp> +#include <boost/hana/type.hpp> + +#include <type_traits> +namespace hana = boost::hana; + + +// The fact that a reference to a `type<...>` is returned from `front(types)` +// and friends used to break the `decltype(front(types))::type` pattern, +// because we would be trying to fetch `::type` inside a reference. To work +// around this, a unary `operator+` turning a lvalue `type` into a rvalue +// `type` was added. + +struct T; struct U; struct V; + +int main() { + auto check = [](auto types) { + static_assert(std::is_same< + typename decltype(+hana::front(types))::type, T + >{}, ""); + + static_assert(std::is_same< + typename decltype(+hana::at(types, hana::size_c<1>))::type, U + >{}, ""); + + static_assert(std::is_same< + typename decltype(+hana::back(types))::type, V + >{}, ""); + }; + + check(hana::make_tuple(hana::type_c<T>, hana::type_c<U>, hana::type_c<V>)); + check(hana::tuple_t<T, U, V>); +} |