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[Tests] Workaround missing EBO in Clang for Windows

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This commit is contained in:
Louis Dionne
2015-11-11 17:31:37 -05:00
parent c8850d83e8
commit 76a0ac16a4
1 changed files with 31 additions and 22 deletions
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53
test/tuple/empty_member.cpp
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@@ -8,28 +8,37 @@ Distributed under the Boost Software License, Version 1.0.
namespace hana = boost::hana;
//
// We disable this test when the compiler does not support the empty base
// class optimization (EBO). Compilers normally support it, but Clang for
// Windows emulates the broken behaviour of MSVC, and does not support the
// EBO for more than one base class. See https://goo.gl/5FE3R6 for more info.
//
template <typename T>
struct holder { T value; };
template <typename ...T>
struct inherit : T... { };
struct A { };
struct B { };
static constexpr bool EBO_is_supported = sizeof(inherit<A, holder<int>>) == sizeof(int);
int main() {
{
using T = hana::tuple<int, A>;
static_assert((sizeof(T) == sizeof(int)), "");
}
{
using T = hana::tuple<A, int>;
static_assert((sizeof(T) == sizeof(int)), "");
}
{
using T = hana::tuple<A, int, B>;
static_assert((sizeof(T) == sizeof(int)), "");
}
{
using T = hana::tuple<A, B, int>;
static_assert((sizeof(T) == sizeof(int)), "");
}
{
using T = hana::tuple<int, A, B>;
static_assert((sizeof(T) == sizeof(int)), "");
}
}
template <bool = EBO_is_supported, typename EmptyA = A, typename EmptyB = B>
struct test {
static_assert((sizeof(hana::tuple<int, EmptyA>) == sizeof(int)), "");
static_assert((sizeof(hana::tuple<EmptyA, int>) == sizeof(int)), "");
static_assert((sizeof(hana::tuple<EmptyA, int, EmptyB>) == sizeof(int)), "");
static_assert((sizeof(hana::tuple<EmptyA, EmptyB, int>) == sizeof(int)), "");
static_assert((sizeof(hana::tuple<int, EmptyA, EmptyB>) == sizeof(int)), "");
};
template <>
struct test<false> {
// Nothing to test
};
template struct test<>;
int main() { }