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re PR libstdc++/80187 (C++ variant should be trivially copy constructible if possible)

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PR libstdc++/80187
	* include/std/variant (variant::variant, variant::~variant,
	variant::operator=): Implement triviality forwarding for four
	special member functions.
	* testsuite/20_util/variant/compile.cc: Tests.

From-SVN: r249706
This commit is contained in:
Tim Shen 2017-06-27 18:19:03 +00:00 • committed by Tim Shen
parent 8c2805bbbb
commit 7050372474
3 changed files with 341 additions and 82 deletions
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8
libstdc++-v3/ChangeLog
View file

@ -1,3 +1,11 @@
2017-06-27 Tim Shen <timshen@google.com>
PR libstdc++/80187
* include/std/variant (variant::variant, variant::~variant,
variant::operator=): Implement triviality forwarding for four
special member functions.
* testsuite/20_util/variant/compile.cc: Tests.
2017-06-27 Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/81221

312
libstdc++-v3/include/std/variant
View file

@ -295,6 +295,46 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__variant::__ref_cast<_Tp>(__t));
}
template<typename... _Types>
struct _Traits
{
static constexpr bool _S_default_ctor =
is_default_constructible_v<typename _Nth_type<0, _Types...>::type>;
static constexpr bool _S_copy_ctor =
(is_copy_constructible_v<_Types> && ...);
static constexpr bool _S_move_ctor =
(is_move_constructible_v<_Types> && ...);
static constexpr bool _S_copy_assign =
_S_copy_ctor && _S_move_ctor
&& (is_copy_assignable_v<_Types> && ...);
static constexpr bool _S_move_assign =
_S_move_ctor
&& (is_move_assignable_v<_Types> && ...);
static constexpr bool _S_trivial_dtor =
(is_trivially_destructible_v<_Types> && ...);
static constexpr bool _S_trivial_copy_ctor =
(is_trivially_copy_constructible_v<_Types> && ...);
static constexpr bool _S_trivial_move_ctor =
(is_trivially_move_constructible_v<_Types> && ...);
static constexpr bool _S_trivial_copy_assign =
_S_trivial_dtor && (is_trivially_copy_assignable_v<_Types> && ...);
static constexpr bool _S_trivial_move_assign =
_S_trivial_dtor && (is_trivially_move_assignable_v<_Types> && ...);
// The following nothrow traits are for non-trivial SMFs. Trivial SMFs
// are always nothrow.
static constexpr bool _S_nothrow_default_ctor =
is_nothrow_default_constructible_v<
typename _Nth_type<0, _Types...>::type>;
static constexpr bool _S_nothrow_copy_ctor = false;
static constexpr bool _S_nothrow_move_ctor =
(is_nothrow_move_constructible_v<_Types> && ...);
static constexpr bool _S_nothrow_copy_assign = false;
static constexpr bool _S_nothrow_move_assign =
_S_nothrow_move_ctor && (is_nothrow_move_assignable_v<_Types> && ...);
};
// Defines members and ctors.
template<typename... _Types>
union _Variadic_union { };
@ -360,6 +400,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
~_Variant_storage()
{ _M_reset(); }
void*
_M_storage() const
{
return const_cast<void*>(static_cast<const void*>(
std::addressof(_M_u)));
}
constexpr bool
_M_valid() const noexcept
{
return this->_M_index != __index_type(variant_npos);
}
_Variadic_union<_Types...> _M_u;
using __index_type = __select_index<_Types...>;
__index_type _M_index;
@ -379,59 +432,108 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
void _M_reset()
{ _M_index = variant_npos; }
void*
_M_storage() const
{
return const_cast<void*>(static_cast<const void*>(
std::addressof(_M_u)));
}
constexpr bool
_M_valid() const noexcept
{
return this->_M_index != __index_type(variant_npos);
}
_Variadic_union<_Types...> _M_u;
using __index_type = __select_index<_Types...>;
__index_type _M_index;
};
// Helps SFINAE on special member functions. Otherwise it can live in variant
// class.
template<typename... _Types>
struct _Variant_base :
_Variant_storage<(std::is_trivially_destructible_v<_Types> && ...),
_Types...>
using _Variant_storage_alias =
_Variant_storage<_Traits<_Types...>::_S_trivial_dtor, _Types...>;
// The following are (Copy|Move) (ctor|assign) layers for forwarding
// triviality and handling non-trivial SMF behaviors.
template<bool, typename... _Types>
struct _Copy_ctor_base : _Variant_storage_alias<_Types...>
{
using _Storage =
_Variant_storage<(std::is_trivially_destructible_v<_Types> && ...),
_Types...>;
using _Base = _Variant_storage_alias<_Types...>;
using _Base::_Base;
constexpr
_Variant_base()
noexcept(is_nothrow_default_constructible_v<
variant_alternative_t<0, variant<_Types...>>>)
: _Variant_base(in_place_index<0>) { }
_Variant_base(const _Variant_base& __rhs)
_Copy_ctor_base(const _Copy_ctor_base& __rhs)
noexcept(_Traits<_Types...>::_S_nothrow_copy_ctor)
{
if (__rhs._M_valid())
{
static constexpr void (*_S_vtable[])(void*, void*) =
{ &__erased_ctor<_Types&, const _Types&>... };
_S_vtable[__rhs._M_index](_M_storage(), __rhs._M_storage());
_S_vtable[__rhs._M_index](this->_M_storage(), __rhs._M_storage());
this->_M_index = __rhs._M_index;
}
}
_Variant_base(_Variant_base&& __rhs)
noexcept((is_nothrow_move_constructible_v<_Types> && ...))
_Copy_ctor_base(_Copy_ctor_base&&) = default;
_Copy_ctor_base& operator=(const _Copy_ctor_base&) = default;
_Copy_ctor_base& operator=(_Copy_ctor_base&&) = default;
};
template<typename... _Types>
struct _Copy_ctor_base<true, _Types...> : _Variant_storage_alias<_Types...>
{
using _Base = _Variant_storage_alias<_Types...>;
using _Base::_Base;
};
template<typename... _Types>
using _Copy_ctor_alias =
_Copy_ctor_base<_Traits<_Types...>::_S_trivial_copy_ctor, _Types...>;
template<bool, typename... _Types>
struct _Move_ctor_base : _Copy_ctor_alias<_Types...>
{
using _Base = _Copy_ctor_alias<_Types...>;
using _Base::_Base;
_Move_ctor_base(_Move_ctor_base&& __rhs)
noexcept(_Traits<_Types...>::_S_nothrow_move_ctor)
{
if (__rhs._M_valid())
{
static constexpr void (*_S_vtable[])(void*, void*) =
{ &__erased_ctor<_Types&, _Types&&>... };
_S_vtable[__rhs._M_index](_M_storage(), __rhs._M_storage());
_S_vtable[__rhs._M_index](this->_M_storage(), __rhs._M_storage());
this->_M_index = __rhs._M_index;
}
}
template<size_t _Np, typename... _Args>
constexpr explicit
_Variant_base(in_place_index_t<_Np> __i, _Args&&... __args)
: _Storage(__i, std::forward<_Args>(__args)...)
{ }
_Move_ctor_base(const _Move_ctor_base&) = default;
_Move_ctor_base& operator=(const _Move_ctor_base&) = default;
_Move_ctor_base& operator=(_Move_ctor_base&&) = default;
};
_Variant_base&
operator=(const _Variant_base& __rhs)
template<typename... _Types>
struct _Move_ctor_base<true, _Types...> : _Copy_ctor_alias<_Types...>
{
using _Base = _Copy_ctor_alias<_Types...>;
using _Base::_Base;
};
template<typename... _Types>
using _Move_ctor_alias =
_Move_ctor_base<_Traits<_Types...>::_S_trivial_move_ctor, _Types...>;
template<bool, typename... _Types>
struct _Copy_assign_base : _Move_ctor_alias<_Types...>
{
using _Base = _Move_ctor_alias<_Types...>;
using _Base::_Base;
_Copy_assign_base&
operator=(const _Copy_assign_base& __rhs)
noexcept(_Traits<_Types...>::_S_nothrow_copy_assign)
{
if (this->_M_index == __rhs._M_index)
{
@ -439,16 +541,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
static constexpr void (*_S_vtable[])(void*, void*) =
{ &__erased_assign<_Types&, const _Types&>... };
_S_vtable[__rhs._M_index](_M_storage(), __rhs._M_storage());
_S_vtable[__rhs._M_index](this->_M_storage(), __rhs._M_storage());
}
}
else
{
_Variant_base __tmp(__rhs);
this->~_Variant_base();
_Copy_assign_base __tmp(__rhs);
this->~_Copy_assign_base();
__try
{
::new (this) _Variant_base(std::move(__tmp));
::new (this) _Copy_assign_base(std::move(__tmp));
}
__catch (...)
{
@ -460,12 +562,35 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return *this;
}
void _M_destructive_move(_Variant_base&& __rhs)
_Copy_assign_base(const _Copy_assign_base&) = default;
_Copy_assign_base(_Copy_assign_base&&) = default;
_Copy_assign_base& operator=(_Copy_assign_base&&) = default;
};
template<typename... _Types>
struct _Copy_assign_base<true, _Types...> : _Move_ctor_alias<_Types...>
{
using _Base = _Move_ctor_alias<_Types...>;
using _Base::_Base;
};
template<typename... _Types>
using _Copy_assign_alias =
_Copy_assign_base<_Traits<_Types...>::_S_trivial_copy_assign,
_Types...>;
template<bool, typename... _Types>
struct _Move_assign_base : _Copy_assign_alias<_Types...>
{
using _Base = _Copy_assign_alias<_Types...>;
using _Base::_Base;
void _M_destructive_move(_Move_assign_base&& __rhs)
{
this->~_Variant_base();
this->~_Move_assign_base();
__try
{
::new (this) _Variant_base(std::move(__rhs));
::new (this) _Move_assign_base(std::move(__rhs));
}
__catch (...)
{
@ -474,40 +599,74 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
}
_Variant_base&
operator=(_Variant_base&& __rhs)
noexcept((is_nothrow_move_constructible_v<_Types> && ...)
&& (is_nothrow_move_assignable_v<_Types> && ...))
_Move_assign_base&
operator=(_Move_assign_base&& __rhs)
noexcept(_Traits<_Types...>::_S_nothrow_move_assign)
{
if (this->_M_index == __rhs._M_index)
{
if (__rhs._M_valid())
{
static constexpr void (*_S_vtable[])(void*, void*) =
{ &__erased_assign<_Types&, _Types&&>... };
_S_vtable[__rhs._M_index](_M_storage(), __rhs._M_storage());
{ &__erased_assign<_Types&, const _Types&>... };
_S_vtable[__rhs._M_index](this->_M_storage(), __rhs._M_storage());
}
}
else
{
_M_destructive_move(std::move(__rhs));
_Move_assign_base __tmp(__rhs);
this->~_Move_assign_base();
__try
{
::new (this) _Move_assign_base(std::move(__tmp));
}
__catch (...)
{
this->_M_index = variant_npos;
__throw_exception_again;
}
}
__glibcxx_assert(this->_M_index == __rhs._M_index);
return *this;
}
void*
_M_storage() const
{
return const_cast<void*>(static_cast<const void*>(
std::addressof(_Storage::_M_u)));
}
_Move_assign_base(const _Move_assign_base&) = default;
_Move_assign_base(_Move_assign_base&&) = default;
_Move_assign_base& operator=(const _Move_assign_base&) = default;
};
constexpr bool
_M_valid() const noexcept
{
return this->_M_index !=
typename _Storage::__index_type(variant_npos);
}
template<typename... _Types>
struct _Move_assign_base<true, _Types...> : _Copy_assign_alias<_Types...>
{
using _Base = _Copy_assign_alias<_Types...>;
using _Base::_Base;
};
template<typename... _Types>
using _Move_assign_alias =
_Move_assign_base<_Traits<_Types...>::_S_trivial_move_assign,
_Types...>;
template<typename... _Types>
struct _Variant_base : _Move_assign_alias<_Types...>
{
using _Base = _Move_assign_alias<_Types...>;
constexpr
_Variant_base()
noexcept(_Traits<_Types...>::_S_nothrow_default_ctor)
: _Variant_base(in_place_index<0>) { }
template<size_t _Np, typename... _Args>
constexpr explicit
_Variant_base(in_place_index_t<_Np> __i, _Args&&... __args)
: _Base(__i, std::forward<_Args>(__args)...)
{ }
_Variant_base(const _Variant_base&) = default;
_Variant_base(_Variant_base&&) = default;
_Variant_base& operator=(const _Variant_base&) = default;
_Variant_base& operator=(_Variant_base&&) = default;
};
// For how many times does _Tp appear in _Tuple?
@ -882,16 +1041,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
class variant
: private __detail::__variant::_Variant_base<_Types...>,
private _Enable_default_constructor<
is_default_constructible_v<
variant_alternative_t<0, variant<_Types...>>>, variant<_Types...>>,
__detail::__variant::_Traits<_Types...>::_S_default_ctor,
variant<_Types...>>,
private _Enable_copy_move<
(is_copy_constructible_v<_Types> && ...),
(is_copy_constructible_v<_Types> && ...)
&& (is_move_constructible_v<_Types> && ...)
&& (is_copy_assignable_v<_Types> && ...),
(is_move_constructible_v<_Types> && ...),
(is_move_constructible_v<_Types> && ...)
&& (is_move_assignable_v<_Types> && ...),
__detail::__variant::_Traits<_Types...>::_S_copy_ctor,
__detail::__variant::_Traits<_Types...>::_S_copy_assign,
__detail::__variant::_Traits<_Types...>::_S_move_ctor,
__detail::__variant::_Traits<_Types...>::_S_move_assign,
variant<_Types...>>
{
private:
@ -904,9 +1060,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
using _Base = __detail::__variant::_Variant_base<_Types...>;
using _Default_ctor_enabler =
_Enable_default_constructor<
is_default_constructible_v<
variant_alternative_t<0, variant<_Types...>>>, variant<_Types...>>;
_Enable_default_constructor<
__detail::__variant::_Traits<_Types...>::_S_default_ctor,
variant<_Types...>>;
template<typename _Tp>
static constexpr bool
@ -933,12 +1089,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static constexpr size_t __index_of =
__detail::__variant::__index_of_v<_Tp, _Types...>;
using _Traits = __detail::__variant::_Traits<_Types...>;
public:
constexpr variant()
noexcept(is_nothrow_default_constructible_v<__to_type<0>>) = default;
variant(const variant&) = default;
variant(variant&&)
noexcept((is_nothrow_move_constructible_v<_Types> && ...)) = default;
variant() = default;
variant(const variant& __rhs) = default;
variant(variant&&) = default;
variant& operator=(const variant&) = default;
variant& operator=(variant&&) = default;
~variant() = default;
template<typename _Tp,
typename = enable_if_t<!is_same_v<decay_t<_Tp>, variant>>,
@ -947,7 +1106,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr
variant(_Tp&& __t)
noexcept(is_nothrow_constructible_v<__accepted_type<_Tp&&>, _Tp&&>)
: variant(in_place_index<__accepted_index<_Tp&&>>, std::forward<_Tp>(__t))
: variant(in_place_index<__accepted_index<_Tp&&>>,
std::forward<_Tp>(__t))
{ __glibcxx_assert(holds_alternative<__accepted_type<_Tp&&>>(*this)); }
template<typename _Tp, typename... _Args,
@ -955,7 +1115,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
&& is_constructible_v<_Tp, _Args&&...>>>
constexpr explicit
variant(in_place_type_t<_Tp>, _Args&&... __args)
: variant(in_place_index<__index_of<_Tp>>, std::forward<_Args>(__args)...)
: variant(in_place_index<__index_of<_Tp>>,
std::forward<_Args>(__args)...)
{ __glibcxx_assert(holds_alternative<_Tp>(*this)); }
template<typename _Tp, typename _Up, typename... _Args,
@ -988,13 +1149,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_Default_ctor_enabler(_Enable_default_constructor_tag{})
{ __glibcxx_assert(index() == _Np); }
~variant() = default;
variant& operator=(const variant&) = default;
variant& operator=(variant&&)
noexcept((is_nothrow_move_constructible_v<_Types> && ...)
&& (is_nothrow_move_assignable_v<_Types> && ...)) = default;
template<typename _Tp>
enable_if_t<__exactly_once<__accepted_type<_Tp&&>>
&& is_constructible_v<__accepted_type<_Tp&&>, _Tp&&>
@ -1089,7 +1243,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr size_t index() const noexcept
{
if (this->_M_index ==
typename _Base::_Storage::__index_type(variant_npos))
typename _Base::__index_type(variant_npos))
return variant_npos;
return this->_M_index;
}

103
libstdc++-v3/testsuite/20_util/variant/compile.cc
View file

@ -88,10 +88,12 @@ void copy_ctor()
{
static_assert(is_copy_constructible_v<variant<int, string>>, "");
static_assert(!is_copy_constructible_v<variant<AllDeleted, string>>, "");
static_assert(is_trivially_copy_constructible_v<variant<int>>, "");
static_assert(!is_trivially_copy_constructible_v<variant<std::string>>, "");
{
variant<int> a;
static_assert(!noexcept(variant<int>(a)), "");
static_assert(noexcept(variant<int>(a)), "");
}
{
variant<string> a;
@ -103,7 +105,7 @@ void copy_ctor()
}
{
variant<int, char> a;
static_assert(!noexcept(variant<int, char>(a)), "");
static_assert(noexcept(variant<int, char>(a)), "");
}
}
@ -111,6 +113,8 @@ void move_ctor()
{
static_assert(is_move_constructible_v<variant<int, string>>, "");
static_assert(!is_move_constructible_v<variant<AllDeleted, string>>, "");
static_assert(is_trivially_move_constructible_v<variant<int>>, "");
static_assert(!is_trivially_move_constructible_v<variant<std::string>>, "");
static_assert(!noexcept(variant<int, Empty>(declval<variant<int, Empty>>())), "");
static_assert(noexcept(variant<int, DefaultNoexcept>(declval<variant<int, DefaultNoexcept>>())), "");
}
@ -148,13 +152,15 @@ void copy_assign()
{
static_assert(is_copy_assignable_v<variant<int, string>>, "");
static_assert(!is_copy_assignable_v<variant<AllDeleted, string>>, "");
static_assert(is_trivially_copy_assignable_v<variant<int>>, "");
static_assert(!is_trivially_copy_assignable_v<variant<string>>, "");
{
variant<Empty> a;
static_assert(!noexcept(a = a), "");
}
{
variant<DefaultNoexcept> a;
static_assert(!noexcept(a = a), "");
static_assert(noexcept(a = a), "");
}
}
@ -162,6 +168,8 @@ void move_assign()
{
static_assert(is_move_assignable_v<variant<int, string>>, "");
static_assert(!is_move_assignable_v<variant<AllDeleted, string>>, "");
static_assert(is_trivially_move_assignable_v<variant<int>>, "");
static_assert(!is_trivially_move_assignable_v<variant<string>>, "");
{
variant<Empty> a;
static_assert(!noexcept(a = std::move(a)), "");
@ -454,3 +462,92 @@ void test_emplace()
static_assert(!has_type_emplace<variant<AllDeleted>, AllDeleted>(0), "");
static_assert(!has_index_emplace<variant<AllDeleted>, 0>(0), "");
}
void test_triviality()
{
#define TEST_TEMPLATE(DT, CC, MC, CA, MA, CC_VAL, MC_VAL, CA_VAL, MA_VAL) \
{ \
struct A \
{ \
~A() DT; \
A(const A&) CC; \
A(A&&) MC; \
A& operator=(const A&) CA; \
A& operator=(A&&) MA; \
}; \
static_assert(CC_VAL == is_trivially_copy_constructible_v<variant<A>>, ""); \
static_assert(MC_VAL == is_trivially_move_constructible_v<variant<A>>, ""); \
static_assert(CA_VAL == is_trivially_copy_assignable_v<variant<A>>, ""); \
static_assert(MA_VAL == is_trivially_move_assignable_v<variant<A>>, ""); \
}
TEST_TEMPLATE(=default, =default, =default, =default, =default, true, true, true, true)
TEST_TEMPLATE(=default, =default, =default, =default, {}, true, true, true, false)
TEST_TEMPLATE(=default, =default, =default, {}, =default, true, true, false, true)
TEST_TEMPLATE(=default, =default, =default, {}, {}, true, true, false, false)
TEST_TEMPLATE(=default, =default, {}, =default, =default, true, false, true, true)
TEST_TEMPLATE(=default, =default, {}, =default, {}, true, false, true, false)
TEST_TEMPLATE(=default, =default, {}, {}, =default, true, false, false, true)
TEST_TEMPLATE(=default, =default, {}, {}, {}, true, false, false, false)
TEST_TEMPLATE(=default, {}, =default, =default, =default, false, true, true, true)
TEST_TEMPLATE(=default, {}, =default, =default, {}, false, true, true, false)
TEST_TEMPLATE(=default, {}, =default, {}, =default, false, true, false, true)
TEST_TEMPLATE(=default, {}, =default, {}, {}, false, true, false, false)
TEST_TEMPLATE(=default, {}, {}, =default, =default, false, false, true, true)
TEST_TEMPLATE(=default, {}, {}, =default, {}, false, false, true, false)
TEST_TEMPLATE(=default, {}, {}, {}, =default, false, false, false, true)
TEST_TEMPLATE(=default, {}, {}, {}, {}, false, false, false, false)
TEST_TEMPLATE( {}, =default, =default, =default, =default, false, false, false, false)
TEST_TEMPLATE( {}, =default, =default, =default, {}, false, false, false, false)
TEST_TEMPLATE( {}, =default, =default, {}, =default, false, false, false, false)
TEST_TEMPLATE( {}, =default, =default, {}, {}, false, false, false, false)
TEST_TEMPLATE( {}, =default, {}, =default, =default, false, false, false, false)
TEST_TEMPLATE( {}, =default, {}, =default, {}, false, false, false, false)
TEST_TEMPLATE( {}, =default, {}, {}, =default, false, false, false, false)
TEST_TEMPLATE( {}, =default, {}, {}, {}, false, false, false, false)
TEST_TEMPLATE( {}, {}, =default, =default, =default, false, false, false, false)
TEST_TEMPLATE( {}, {}, =default, =default, {}, false, false, false, false)
TEST_TEMPLATE( {}, {}, =default, {}, =default, false, false, false, false)
TEST_TEMPLATE( {}, {}, =default, {}, {}, false, false, false, false)
TEST_TEMPLATE( {}, {}, {}, =default, =default, false, false, false, false)
TEST_TEMPLATE( {}, {}, {}, =default, {}, false, false, false, false)
TEST_TEMPLATE( {}, {}, {}, {}, =default, false, false, false, false)
TEST_TEMPLATE( {}, {}, {}, {}, {}, false, false, false, false)
#undef TEST_TEMPLATE
#define TEST_TEMPLATE(CC, MC, CA, MA) \
{ \
struct A \
{ \
A(const A&) CC; \
A(A&&) MC; \
A& operator=(const A&) CA; \
A& operator=(A&&) MA; \
}; \
static_assert(!is_trivially_copy_constructible_v<variant<AllDeleted, A>>, ""); \
static_assert(!is_trivially_move_constructible_v<variant<AllDeleted, A>>, ""); \
static_assert(!is_trivially_copy_assignable_v<variant<AllDeleted, A>>, ""); \
static_assert(!is_trivially_move_assignable_v<variant<AllDeleted, A>>, ""); \
}
TEST_TEMPLATE(=default, =default, =default, =default)
TEST_TEMPLATE(=default, =default, =default, {})
TEST_TEMPLATE(=default, =default, {}, =default)
TEST_TEMPLATE(=default, =default, {}, {})
TEST_TEMPLATE(=default, {}, =default, =default)
TEST_TEMPLATE(=default, {}, =default, {})
TEST_TEMPLATE(=default, {}, {}, =default)
TEST_TEMPLATE(=default, {}, {}, {})
TEST_TEMPLATE( {}, =default, =default, =default)
TEST_TEMPLATE( {}, =default, =default, {})
TEST_TEMPLATE( {}, =default, {}, =default)
TEST_TEMPLATE( {}, =default, {}, {})
TEST_TEMPLATE( {}, {}, =default, =default)
TEST_TEMPLATE( {}, {}, =default, {})
TEST_TEMPLATE( {}, {}, {}, =default)
TEST_TEMPLATE( {}, {}, {}, {})
#undef TEST_TEMPLATE
static_assert(is_trivially_copy_constructible_v<variant<DefaultNoexcept, int, char, float, double>>, "");
static_assert(is_trivially_move_constructible_v<variant<DefaultNoexcept, int, char, float, double>>, "");
static_assert(is_trivially_copy_assignable_v<variant<DefaultNoexcept, int, char, float, double>>, "");
static_assert(is_trivially_move_assignable_v<variant<DefaultNoexcept, int, char, float, double>>, "");
}