/* Essentially an internal optional implementation :)
(C) 2017-2021 Niall Douglas (24 commits)
File Created: June 2017
Boost Software License - Version 1.0 - August 17th, 2003
Permission is hereby granted, free of charge, to any person or organization
obtaining a copy of the software and accompanying documentation covered by
this license (the "Software") to use, reproduce, display, distribute,
execute, and transmit the Software, and to prepare derivative works of the
Software, and to permit third-parties to whom the Software is furnished to
do so, all subject to the following:
The copyright notices in the Software and this entire statement, including
the above license grant, this restriction and the following disclaimer,
must be included in all copies of the Software, in whole or in part, and
all derivative works of the Software, unless such copies or derivative
works are solely in the form of machine-executable object code generated by
a source language processor.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
*/
#ifndef BOOST_OUTCOME_VALUE_STORAGE_HPP
#define BOOST_OUTCOME_VALUE_STORAGE_HPP
#include "../config.hpp"
#include
BOOST_OUTCOME_V2_NAMESPACE_EXPORT_BEGIN
namespace detail
{
template struct strong_swap_impl
{
constexpr strong_swap_impl(bool &allgood, T &a, T &b)
{
allgood = true;
using std::swap;
swap(a, b);
}
};
template struct strong_placement_impl
{
template constexpr strong_placement_impl(bool &allgood, T *a, T *b, F &&f)
{
allgood = true;
new(a) T(static_cast(*b));
b->~T();
f();
}
};
#ifndef BOOST_NO_EXCEPTIONS
template struct strong_swap_impl
{
strong_swap_impl(bool &allgood, T &a, T &b)
{
allgood = true;
T v(static_cast(a));
try
{
a = static_cast(b);
}
catch(...)
{
// Try to put back a
try
{
a = static_cast(v);
// fall through as all good
}
catch(...)
{
// failed to completely restore
allgood = false;
// throw away second exception
}
throw; // rethrow original exception
}
// b has been moved to a, try to move v to b
try
{
b = static_cast(v);
}
catch(...)
{
// Try to restore a to b, and v to a
try
{
b = static_cast(a);
a = static_cast(v);
// fall through as all good
}
catch(...)
{
// failed to completely restore
allgood = false;
// throw away second exception
}
throw; // rethrow original exception
}
}
};
template struct strong_placement_impl
{
template strong_placement_impl(bool &allgood, T *a, T *b, F &&f)
{
new(a) T(static_cast(*b));
try
{
b->~T();
f();
}
catch(...)
{
// Try to put back a, but only if we are still good
if(allgood)
{
try
{
new(b) T(static_cast(*a));
// fall through as all good
}
catch(...)
{
// failed to completely restore
allgood = false;
// throw away second exception
}
throw; // rethrow original exception
}
}
}
};
#endif
} // namespace detail
/*!
*/
BOOST_OUTCOME_TEMPLATE(class T)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(std::is_move_constructible::value &&std::is_move_assignable::value))
constexpr inline void strong_swap(bool &allgood, T &a, T &b) noexcept(detail::is_nothrow_swappable::value)
{
detail::strong_swap_impl::value>(allgood, a, b);
}
/*!
*/
BOOST_OUTCOME_TEMPLATE(class T, class F)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(std::is_move_constructible::value &&std::is_move_assignable::value))
constexpr inline void strong_placement(bool &allgood, T *a, T *b, F &&f) noexcept(std::is_nothrow_move_constructible::value)
{
detail::strong_placement_impl::value>(allgood, a, b, static_cast(f));
}
namespace detail
{
template
constexpr
#ifdef _MSC_VER
__declspec(noreturn)
#elif defined(__GNUC__) || defined(__clang__)
__attribute__((noreturn))
#endif
void make_ub(T && /*unused*/)
{
assert(false); // NOLINT
#if defined(__GNUC__) || defined(__clang__)
__builtin_unreachable();
#elif defined(_MSC_VER)
__assume(0);
#endif
}
/* Outcome v1 used a C bitfield whose values were tracked by compiler optimisers nicely,
but that produces ICEs when used in constexpr.
Outcome v2.0-v2.1 used a 32 bit integer and manually set and cleared bits. Unfortunately
only GCC's optimiser tracks bit values during constant folding, and only per byte, and
even then unreliably. https://wg21.link/P1886 "Error speed benchmarking" showed just how
poorly clang and MSVC fails to optimise outcome-using code, if you manually set bits.
Outcome v2.2 therefore uses an enum with fixed values, and constexpr manipulation functions
to change the value to one of the enum's values. This is stupid to look at in source code,
but it make clang's optimiser do the right thing, so it's worth it.
*/
#define BOOST_OUTCOME_USE_CONSTEXPR_ENUM_STATUS 0
enum class status : uint16_t
{
// WARNING: These bits are not tracked by abi-dumper, but changing them will break ABI!
none = 0,
have_value = (1U << 0U),
have_error = (1U << 1U),
have_exception = (2U << 1U),
have_error_exception = (3U << 1U),
// failed to complete a strong swap
have_lost_consistency = (1U << 3U),
have_value_lost_consistency = (1U << 0U) | (1U << 3U),
have_error_lost_consistency = (1U << 1U) | (1U << 3U),
have_exception_lost_consistency = (2U << 1U) | (1U << 3U),
have_error_exception_lost_consistency = (3U << 1U) | (1U << 3U),
// can errno be set from this error?
have_error_is_errno = (1U << 4U),
have_error_error_is_errno = (1U << 1U) | (1U << 4U),
have_error_exception_error_is_errno = (3U << 1U) | (1U << 4U),
have_error_lost_consistency_error_is_errno = (1U << 1U) | (1U << 3U) | (1U << 4U),
have_error_exception_lost_consistency_error_is_errno = (3U << 1U) | (1U << 3U) | (1U << 4U),
// value has been moved from
have_moved_from = (1U << 5U)
};
struct status_bitfield_type
{
status status_value{status::none};
uint16_t spare_storage_value{0}; // hooks::spare_storage()
constexpr status_bitfield_type() = default;
constexpr status_bitfield_type(status v) noexcept
: status_value(v)
{
} // NOLINT
constexpr status_bitfield_type(status v, uint16_t s) noexcept
: status_value(v)
, spare_storage_value(s)
{
}
constexpr status_bitfield_type(const status_bitfield_type &) = default;
constexpr status_bitfield_type(status_bitfield_type &&) = default;
constexpr status_bitfield_type &operator=(const status_bitfield_type &) = default;
constexpr status_bitfield_type &operator=(status_bitfield_type &&) = default;
//~status_bitfield_type() = default; // Do NOT uncomment this, it breaks older clangs!
constexpr bool have_value() const noexcept
{
#if BOOST_OUTCOME_USE_CONSTEXPR_ENUM_STATUS
return (status_value == status::have_value) //
|| (status_value == status::have_value_lost_consistency) //
;
#else
return (static_cast(status_value) & static_cast(status::have_value)) != 0;
#endif
}
constexpr bool have_error() const noexcept
{
#if BOOST_OUTCOME_USE_CONSTEXPR_ENUM_STATUS
return (status_value == status::have_error) //
|| (status_value == status::have_error_exception) //
|| (status_value == status::have_error_lost_consistency) //
|| (status_value == status::have_error_exception_lost_consistency) //
|| (status_value == status::have_error_error_is_errno) //
|| (status_value == status::have_error_exception_error_is_errno) //
|| (status_value == status::have_error_lost_consistency_error_is_errno) //
|| (status_value == status::have_error_exception_lost_consistency_error_is_errno) //
;
#else
return (static_cast(status_value) & static_cast(status::have_error)) != 0;
#endif
}
constexpr bool have_exception() const noexcept
{
#if BOOST_OUTCOME_USE_CONSTEXPR_ENUM_STATUS
return (status_value == status::have_exception) //
|| (status_value == status::have_error_exception) //
|| (status_value == status::have_exception_lost_consistency) //
|| (status_value == status::have_error_exception_lost_consistency) //
|| (status_value == status::have_error_exception_error_is_errno) //
|| (status_value == status::have_error_exception_lost_consistency_error_is_errno) //
;
#else
return (static_cast(status_value) & static_cast(status::have_exception)) != 0;
#endif
}
constexpr bool have_lost_consistency() const noexcept
{
#if BOOST_OUTCOME_USE_CONSTEXPR_ENUM_STATUS
return (status_value == status::have_value_lost_consistency) //
|| (status_value == status::have_error_lost_consistency) //
|| (status_value == status::have_exception_lost_consistency) //
|| (status_value == status::have_error_lost_consistency_error_is_errno) //
|| (status_value == status::have_error_exception_lost_consistency_error_is_errno) //
;
#else
return (static_cast(status_value) & static_cast(status::have_lost_consistency)) != 0;
#endif
}
constexpr bool have_error_is_errno() const noexcept
{
#if BOOST_OUTCOME_USE_CONSTEXPR_ENUM_STATUS
return (status_value == status::have_error_error_is_errno) //
|| (status_value == status::have_error_exception_error_is_errno) //
|| (status_value == status::have_error_lost_consistency_error_is_errno) //
|| (status_value == status::have_error_exception_lost_consistency_error_is_errno) //
;
#else
return (static_cast(status_value) & static_cast(status::have_error_is_errno)) != 0;
#endif
}
constexpr bool have_moved_from() const noexcept
{
#if BOOST_OUTCOME_USE_CONSTEXPR_ENUM_STATUS
#error Fixme
#else
return (static_cast(status_value) & static_cast(status::have_moved_from)) != 0;
#endif
}
constexpr status_bitfield_type &set_have_value(bool v) noexcept
{
#if BOOST_OUTCOME_USE_CONSTEXPR_ENUM_STATUS
switch(status_value)
{
case status::none:
if(v)
{
status_value = status::have_value;
}
break;
case status::have_value:
if(!v)
{
status_value = status::none;
}
break;
case status::have_error:
if(v)
{
make_ub(*this);
}
break;
case status::have_exception:
if(v)
{
make_ub(*this);
}
break;
case status::have_error_exception:
if(v)
{
make_ub(*this);
}
break;
case status::have_value_lost_consistency:
if(!v)
{
status_value = status::none;
}
break;
case status::have_error_lost_consistency:
if(v)
{
make_ub(*this);
}
break;
case status::have_exception_lost_consistency:
if(v)
{
make_ub(*this);
}
break;
case status::have_error_exception_lost_consistency:
if(v)
{
make_ub(*this);
}
break;
case status::have_error_error_is_errno:
if(v)
{
make_ub(*this);
}
break;
case status::have_error_exception_error_is_errno:
if(v)
{
make_ub(*this);
}
break;
case status::have_error_lost_consistency_error_is_errno:
if(v)
{
make_ub(*this);
}
break;
case status::have_error_exception_lost_consistency_error_is_errno:
if(v)
{
make_ub(*this);
}
break;
}
#else
status_value = static_cast(v ? (static_cast(status_value) | static_cast(status::have_value)) :
(static_cast(status_value) & ~static_cast(status::have_value)));
#endif
return *this;
}
constexpr status_bitfield_type &set_have_error(bool v) noexcept
{
#if BOOST_OUTCOME_USE_CONSTEXPR_ENUM_STATUS
switch(status_value)
{
case status::none:
if(v)
{
status_value = status::have_error;
}
break;
case status::have_value:
if(v)
{
make_ub(*this);
}
break;
case status::have_error:
if(!v)
{
status_value = status::none;
}
break;
case status::have_exception:
if(v)
{
status_value = status::have_error_exception;
}
break;
case status::have_error_exception:
if(!v)
{
status_value = status::have_exception;
}
break;
case status::have_value_lost_consistency:
if(v)
{
make_ub(*this);
}
break;
case status::have_error_lost_consistency:
if(!v)
{
status_value = status::none;
}
break;
case status::have_exception_lost_consistency:
if(v)
{
status_value = status::have_error_exception_lost_consistency;
}
break;
case status::have_error_exception_lost_consistency:
if(!v)
{
status_value = status::have_exception_lost_consistency;
}
break;
case status::have_error_error_is_errno:
if(!v)
{
status_value = status::none;
}
break;
case status::have_error_exception_error_is_errno:
if(!v)
{
status_value = status::have_exception;
}
break;
case status::have_error_lost_consistency_error_is_errno:
if(!v)
{
status_value = status::none;
}
break;
case status::have_error_exception_lost_consistency_error_is_errno:
if(!v)
{
status_value = status::have_exception_lost_consistency;
}
break;
}
#else
status_value = static_cast(v ? (static_cast(status_value) | static_cast(status::have_error)) :
(static_cast(status_value) & ~static_cast(status::have_error)));
#endif
return *this;
}
constexpr status_bitfield_type &set_have_exception(bool v) noexcept
{
#if BOOST_OUTCOME_USE_CONSTEXPR_ENUM_STATUS
switch(status_value)
{
case status::none:
if(v)
{
status_value = status::have_exception;
}
break;
case status::have_value:
if(v)
{
make_ub(*this);
}
break;
case status::have_error:
if(v)
{
status_value = status::have_error_exception;
}
break;
case status::have_exception:
if(!v)
{
status_value = status::none;
}
break;
case status::have_error_exception:
if(!v)
{
status_value = status::have_error;
}
break;
case status::have_value_lost_consistency:
if(v)
{
make_ub(*this);
}
break;
case status::have_error_lost_consistency:
if(v)
{
status_value = status::have_error_exception_lost_consistency;
}
break;
case status::have_exception_lost_consistency:
if(!v)
{
status_value = status::none;
}
break;
case status::have_error_exception_lost_consistency:
if(!v)
{
status_value = status::have_error_lost_consistency;
}
break;
case status::have_error_error_is_errno:
if(v)
{
status_value = status::have_error_exception_error_is_errno;
}
break;
case status::have_error_exception_error_is_errno:
if(!v)
{
status_value = status::have_error_error_is_errno;
}
break;
case status::have_error_lost_consistency_error_is_errno:
if(v)
{
status_value = status::have_error_exception_lost_consistency_error_is_errno;
}
break;
case status::have_error_exception_lost_consistency_error_is_errno:
if(!v)
{
status_value = status::have_error_lost_consistency_error_is_errno;
}
break;
}
#else
status_value = static_cast(v ? (static_cast(status_value) | static_cast(status::have_exception)) :
(static_cast(status_value) & ~static_cast(status::have_exception)));
#endif
return *this;
}
constexpr status_bitfield_type &set_have_error_is_errno(bool v) noexcept
{
#if BOOST_OUTCOME_USE_CONSTEXPR_ENUM_STATUS
switch(status_value)
{
case status::none:
make_ub(*this);
break;
case status::have_value:
make_ub(*this);
break;
case status::have_error:
if(v)
{
status_value = status::have_error_error_is_errno;
}
break;
case status::have_exception:
make_ub(*this);
break;
case status::have_error_exception:
if(v)
{
status_value = status::have_error_exception_error_is_errno;
}
break;
case status::have_value_lost_consistency:
make_ub(*this);
break;
case status::have_error_lost_consistency:
if(v)
{
status_value = status::have_error_lost_consistency_error_is_errno;
}
break;
case status::have_exception_lost_consistency:
make_ub(*this);
break;
case status::have_error_exception_lost_consistency:
if(v)
{
status_value = status::have_error_exception_lost_consistency_error_is_errno;
}
break;
case status::have_error_error_is_errno:
if(!v)
{
status_value = status::have_error;
}
break;
case status::have_error_exception_error_is_errno:
if(!v)
{
status_value = status::have_error_exception;
}
break;
case status::have_error_lost_consistency_error_is_errno:
if(!v)
{
status_value = status::have_error_lost_consistency;
}
break;
case status::have_error_exception_lost_consistency_error_is_errno:
if(!v)
{
status_value = status::have_error_exception_lost_consistency;
}
break;
}
#else
status_value = static_cast(v ? (static_cast(status_value) | static_cast(status::have_error_is_errno)) :
(static_cast(status_value) & ~static_cast(status::have_error_is_errno)));
#endif
return *this;
}
constexpr status_bitfield_type &set_have_lost_consistency(bool v) noexcept
{
#if BOOST_OUTCOME_USE_CONSTEXPR_ENUM_STATUS
switch(status_value)
{
case status::none:
if(v)
{
make_ub(*this);
}
break;
case status::have_value:
if(v)
{
status_value = status::have_value_lost_consistency;
}
break;
case status::have_error:
if(v)
{
status_value = status::have_error_lost_consistency;
}
break;
case status::have_exception:
if(v)
{
status_value = status::have_exception_lost_consistency;
}
break;
case status::have_error_exception:
if(v)
{
status_value = status::have_error_exception_lost_consistency;
}
break;
case status::have_value_lost_consistency:
if(!v)
{
status_value = status::have_value;
}
break;
case status::have_error_lost_consistency:
if(!v)
{
status_value = status::have_error;
}
break;
case status::have_exception_lost_consistency:
if(!v)
{
status_value = status::have_exception;
}
break;
case status::have_error_exception_lost_consistency:
if(!v)
{
status_value = status::have_error_exception;
}
break;
case status::have_error_error_is_errno:
if(v)
{
status_value = status::have_error_lost_consistency_error_is_errno;
}
break;
case status::have_error_exception_error_is_errno:
if(v)
{
status_value = status::have_error_exception_lost_consistency_error_is_errno;
}
break;
case status::have_error_lost_consistency_error_is_errno:
if(!v)
{
status_value = status::have_error_exception_error_is_errno;
}
break;
case status::have_error_exception_lost_consistency_error_is_errno:
if(!v)
{
status_value = status::have_error_exception_error_is_errno;
}
break;
}
#else
status_value = static_cast(v ? (static_cast(status_value) | static_cast(status::have_lost_consistency)) :
(static_cast(status_value) & ~static_cast(status::have_lost_consistency)));
#endif
return *this;
}
constexpr status_bitfield_type &set_have_moved_from(bool v) noexcept
{
#if BOOST_OUTCOME_USE_CONSTEXPR_ENUM_STATUS
#error Fixme
#else
status_value = static_cast(v ? (static_cast(status_value) | static_cast(status::have_moved_from)) :
(static_cast(status_value) & ~static_cast(status::have_moved_from)));
#endif
return *this;
}
};
#if !defined(NDEBUG)
// Check is trivial in all ways except default constructibility
static_assert(sizeof(status_bitfield_type) == 4, "status_bitfield_type is not sized 4 bytes!");
static_assert(std::is_trivially_copyable::value, "status_bitfield_type is not trivially copyable!");
static_assert(std::is_trivially_assignable::value, "status_bitfield_type is not trivially assignable!");
static_assert(std::is_trivially_destructible::value, "status_bitfield_type is not trivially destructible!");
static_assert(std::is_trivially_copy_constructible::value, "status_bitfield_type is not trivially copy constructible!");
static_assert(std::is_trivially_move_constructible::value, "status_bitfield_type is not trivially move constructible!");
static_assert(std::is_trivially_copy_assignable::value, "status_bitfield_type is not trivially copy assignable!");
static_assert(std::is_trivially_move_assignable::value, "status_bitfield_type is not trivially move assignable!");
// Also check is standard layout
static_assert(std::is_standard_layout::value, "status_bitfield_type is not a standard layout type!");
#endif
template constexpr inline void _set_error_is_errno(State & /*unused*/) {}
#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable : 4127) // conditional expression is constant
#pragma warning(disable : 4624) // destructor was implicitly defined as deleted
#endif
// Used if both T and E are trivial
template struct value_storage_trivial
{
using value_type = T;
using error_type = E;
// Disable in place construction if they are the same type
struct disable_in_place_value_type
{
};
struct disable_in_place_error_type
{
};
using _value_type = std::conditional_t::value, disable_in_place_value_type, value_type>;
using _error_type = std::conditional_t::value, disable_in_place_error_type, error_type>;
using _value_type_ = devoid;
using _error_type_ = devoid;
union {
empty_type _empty;
_value_type_ _value;
_error_type_ _error;
};
status_bitfield_type _status;
constexpr value_storage_trivial() noexcept
: _empty{}
{
}
value_storage_trivial(const value_storage_trivial &) = default; // NOLINT
value_storage_trivial(value_storage_trivial &&) = default; // NOLINT
value_storage_trivial &operator=(const value_storage_trivial &) = default; // NOLINT
value_storage_trivial &operator=(value_storage_trivial &&) = default; // NOLINT
~value_storage_trivial() = default;
constexpr explicit value_storage_trivial(status_bitfield_type status)
: _empty()
, _status(status)
{
}
template
constexpr explicit value_storage_trivial(in_place_type_t<_value_type> /*unused*/,
Args &&... args) noexcept(detail::is_nothrow_constructible<_value_type_, Args...>)
: _value(static_cast(args)...)
, _status(status::have_value)
{
}
template
constexpr value_storage_trivial(in_place_type_t<_value_type> /*unused*/, std::initializer_list il,
Args &&... args) noexcept(detail::is_nothrow_constructible<_value_type_, std::initializer_list, Args...>)
: _value(il, static_cast(args)...)
, _status(status::have_value)
{
}
template
constexpr explicit value_storage_trivial(in_place_type_t<_error_type> /*unused*/,
Args &&... args) noexcept(detail::is_nothrow_constructible<_error_type_, Args...>)
: _error(static_cast(args)...)
, _status(status::have_error)
{
_set_error_is_errno(*this);
}
template
constexpr value_storage_trivial(in_place_type_t<_error_type> /*unused*/, std::initializer_list il,
Args &&... args) noexcept(detail::is_nothrow_constructible<_error_type_, std::initializer_list, Args...>)
: _error(il, static_cast(args)...)
, _status(status::have_error)
{
_set_error_is_errno(*this);
}
struct nonvoid_converting_constructor_tag
{
};
template
static constexpr bool enable_nonvoid_converting_constructor =
!(std::is_same, value_type>::value && std::is_same, error_type>::value) //
&& detail::is_constructible && detail::is_constructible;
BOOST_OUTCOME_TEMPLATE(class U, class V)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_nonvoid_converting_constructor))
constexpr explicit value_storage_trivial(const value_storage_trivial &o, nonvoid_converting_constructor_tag /*unused*/ = {}) noexcept(
detail::is_nothrow_constructible<_value_type_, U> &&detail::is_nothrow_constructible<_error_type_, V>)
: value_storage_trivial(o._status.have_value() ?
value_storage_trivial(in_place_type, o._value) :
(o._status.have_error() ? value_storage_trivial(in_place_type, o._error) : value_storage_trivial())) // NOLINT
{
_status = o._status;
}
BOOST_OUTCOME_TEMPLATE(class U, class V)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_nonvoid_converting_constructor))
constexpr explicit value_storage_trivial(value_storage_trivial &&o, nonvoid_converting_constructor_tag /*unused*/ = {}) noexcept(
detail::is_nothrow_constructible<_value_type_, U> &&detail::is_nothrow_constructible<_error_type_, V>)
: value_storage_trivial(
o._status.have_value() ?
value_storage_trivial(in_place_type, static_cast(o._value)) :
(o._status.have_error() ? value_storage_trivial(in_place_type, static_cast(o._error)) : value_storage_trivial())) // NOLINT
{
_status = o._status;
}
struct void_value_converting_constructor_tag
{
};
template
static constexpr bool enable_void_value_converting_constructor =
std::is_default_constructible::value &&detail::is_constructible;
BOOST_OUTCOME_TEMPLATE(class V)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_void_value_converting_constructor))
constexpr explicit value_storage_trivial(const value_storage_trivial &o, void_value_converting_constructor_tag /*unused*/ = {}) noexcept(
std::is_nothrow_default_constructible<_value_type_>::value &&detail::is_nothrow_constructible<_error_type_, V>)
: value_storage_trivial(o._status.have_value() ?
value_storage_trivial(in_place_type) :
(o._status.have_error() ? value_storage_trivial(in_place_type, o._error) : value_storage_trivial())) // NOLINT
{
_status = o._status;
}
BOOST_OUTCOME_TEMPLATE(class V)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_void_value_converting_constructor))
constexpr explicit value_storage_trivial(value_storage_trivial &&o, void_value_converting_constructor_tag /*unused*/ = {}) noexcept(
std::is_nothrow_default_constructible<_value_type_>::value &&detail::is_nothrow_constructible<_error_type_, V>)
: value_storage_trivial(
o._status.have_value() ?
value_storage_trivial(in_place_type) :
(o._status.have_error() ? value_storage_trivial(in_place_type, static_cast(o._error)) : value_storage_trivial())) // NOLINT
{
_status = o._status;
}
struct void_error_converting_constructor_tag
{
};
template
static constexpr bool enable_void_error_converting_constructor =
std::is_default_constructible::value &&detail::is_constructible;
BOOST_OUTCOME_TEMPLATE(class U)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_void_error_converting_constructor))
constexpr explicit value_storage_trivial(const value_storage_trivial &o, void_error_converting_constructor_tag /*unused*/ = {}) noexcept(
detail::is_nothrow_constructible<_value_type_, U> &&std::is_nothrow_default_constructible<_error_type_>::value)
: value_storage_trivial(o._status.have_value() ?
value_storage_trivial(in_place_type, o._value) :
(o._status.have_error() ? value_storage_trivial(in_place_type) : value_storage_trivial())) // NOLINT
{
_status = o._status;
}
BOOST_OUTCOME_TEMPLATE(class U)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_void_error_converting_constructor))
constexpr explicit value_storage_trivial(value_storage_trivial &&o, void_error_converting_constructor_tag /*unused*/ = {}) noexcept(
detail::is_nothrow_constructible<_value_type_, U> &&std::is_nothrow_default_constructible<_error_type_>::value)
: value_storage_trivial(o._status.have_value() ?
value_storage_trivial(in_place_type, static_cast(o._value)) :
(o._status.have_error() ? value_storage_trivial(in_place_type) : value_storage_trivial())) // NOLINT
{
_status = o._status;
}
constexpr void swap(value_storage_trivial &o) noexcept
{
// storage is trivial, so just use assignment
auto temp = static_cast(*this);
*this = static_cast(o);
o = static_cast(temp);
}
};
// Used if T is non-trivial
template struct value_storage_nontrivial
{
using value_type = T;
using error_type = E;
struct disable_in_place_value_type
{
};
struct disable_in_place_error_type
{
};
using _value_type = std::conditional_t::value, disable_in_place_value_type, value_type>;
using _error_type = std::conditional_t::value, disable_in_place_error_type, error_type>;
using _value_type_ = devoid;
using _error_type_ = devoid;
union {
empty_type _empty1;
_value_type_ _value;
};
status_bitfield_type _status;
union {
empty_type _empty2;
_error_type_ _error;
};
value_storage_nontrivial() noexcept
: _empty1{}
, _empty2{}
{
}
value_storage_nontrivial &operator=(const value_storage_nontrivial &) = default; // if reaches here, copy assignment is trivial
value_storage_nontrivial &operator=(value_storage_nontrivial &&) = default; // NOLINT if reaches here, move assignment is trivial
value_storage_nontrivial(value_storage_nontrivial &&o) noexcept(
std::is_nothrow_move_constructible<_value_type_>::value &&std::is_nothrow_move_constructible<_error_type_>::value) // NOLINT
{
if(o._status.have_value())
{
new(&_value) _value_type_(static_cast<_value_type_ &&>(o._value)); // NOLINT
}
else if(o._status.have_error())
{
new(&_error) _error_type_(static_cast<_error_type_ &&>(o._error)); // NOLINT
}
_status = o._status;
o._status.set_have_moved_from(true);
}
value_storage_nontrivial(const value_storage_nontrivial &o) noexcept(
std::is_nothrow_copy_constructible<_value_type_>::value &&std::is_nothrow_copy_constructible<_error_type_>::value)
{
if(o._status.have_value())
{
new(&_value) _value_type_(o._value); // NOLINT
}
else if(o._status.have_error())
{
new(&_error) _error_type_(o._error); // NOLINT
}
_status = o._status;
}
explicit value_storage_nontrivial(status_bitfield_type status)
: _empty1()
, _status(status)
, _empty2()
{
}
template
explicit value_storage_nontrivial(in_place_type_t<_value_type> /*unused*/,
Args &&... args) noexcept(detail::is_nothrow_constructible<_value_type_, Args...>)
: _value(static_cast(args)...) // NOLINT
, _status(status::have_value)
{
}
template
value_storage_nontrivial(in_place_type_t<_value_type> /*unused*/, std::initializer_list il,
Args &&... args) noexcept(detail::is_nothrow_constructible<_value_type_, std::initializer_list, Args...>)
: _value(il, static_cast(args)...)
, _status(status::have_value)
{
}
template
explicit value_storage_nontrivial(in_place_type_t<_error_type> /*unused*/,
Args &&... args) noexcept(detail::is_nothrow_constructible<_error_type_, Args...>)
: _status(status::have_error)
, _error(static_cast(args)...) // NOLINT
{
_set_error_is_errno(*this);
}
template
value_storage_nontrivial(in_place_type_t<_error_type> /*unused*/, std::initializer_list il,
Args &&... args) noexcept(detail::is_nothrow_constructible<_error_type_, std::initializer_list, Args...>)
: _status(status::have_error)
, _error(il, static_cast(args)...)
{
_set_error_is_errno(*this);
}
struct nonvoid_converting_constructor_tag
{
};
template
static constexpr bool enable_nonvoid_converting_constructor =
!(std::is_same, value_type>::value && std::is_same, error_type>::value) //
&& detail::is_constructible && detail::is_constructible;
BOOST_OUTCOME_TEMPLATE(class U, class V)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_nonvoid_converting_constructor))
constexpr explicit value_storage_nontrivial(const value_storage_trivial &o, nonvoid_converting_constructor_tag /*unused*/ = {}) noexcept(
detail::is_nothrow_constructible<_value_type_, U> &&detail::is_nothrow_constructible<_error_type_, V>)
: value_storage_nontrivial(o._status.have_value() ?
value_storage_nontrivial(in_place_type, o._value) :
(o._status.have_error() ? value_storage_nontrivial(in_place_type, o._error) : value_storage_nontrivial()))
{
_status = o._status;
}
BOOST_OUTCOME_TEMPLATE(class U, class V)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_nonvoid_converting_constructor))
constexpr explicit value_storage_nontrivial(value_storage_trivial &&o, nonvoid_converting_constructor_tag /*unused*/ = {}) noexcept(
detail::is_nothrow_constructible<_value_type_, U> &&detail::is_nothrow_constructible<_error_type_, V>)
: value_storage_nontrivial(
o._status.have_value() ?
value_storage_nontrivial(in_place_type, static_cast(o._value)) :
(o._status.have_error() ? value_storage_nontrivial(in_place_type, static_cast(o._error)) : value_storage_nontrivial()))
{
_status = o._status;
}
BOOST_OUTCOME_TEMPLATE(class U, class V)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_nonvoid_converting_constructor))
constexpr explicit value_storage_nontrivial(const value_storage_nontrivial &o, nonvoid_converting_constructor_tag /*unused*/ = {}) noexcept(
detail::is_nothrow_constructible<_value_type_, U> &&detail::is_nothrow_constructible<_error_type_, V>)
: value_storage_nontrivial(o._status.have_value() ?
value_storage_nontrivial(in_place_type, o._value) :
(o._status.have_error() ? value_storage_nontrivial(in_place_type, o._error) : value_storage_nontrivial()))
{
_status = o._status;
}
BOOST_OUTCOME_TEMPLATE(class U, class V)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_nonvoid_converting_constructor))
constexpr explicit value_storage_nontrivial(value_storage_nontrivial &&o, nonvoid_converting_constructor_tag /*unused*/ = {}) noexcept(
detail::is_nothrow_constructible<_value_type_, U> &&detail::is_nothrow_constructible<_error_type_, V>)
: value_storage_nontrivial(
o._status.have_value() ?
value_storage_nontrivial(in_place_type, static_cast(o._value)) :
(o._status.have_error() ? value_storage_nontrivial(in_place_type, static_cast(o._error)) : value_storage_nontrivial()))
{
_status = o._status;
}
struct void_value_converting_constructor_tag
{
};
template
static constexpr bool enable_void_value_converting_constructor =
std::is_default_constructible::value &&detail::is_constructible;
BOOST_OUTCOME_TEMPLATE(class V)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_void_value_converting_constructor))
explicit value_storage_nontrivial(const value_storage_trivial &o, void_value_converting_constructor_tag /*unused*/ = {}) noexcept(
std::is_nothrow_default_constructible<_value_type_>::value &&detail::is_nothrow_constructible<_error_type_, V>)
{
if(o._status.have_value())
{
new(&_value) _value_type_(); // NOLINT
}
else if(o._status.have_error())
{
new(&_error) _error_type_(o._error); // NOLINT
}
_status = o._status;
}
BOOST_OUTCOME_TEMPLATE(class V)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_void_value_converting_constructor))
explicit value_storage_nontrivial(value_storage_trivial &&o, void_value_converting_constructor_tag /*unused*/ = {}) noexcept(
std::is_nothrow_default_constructible<_value_type_>::value &&detail::is_nothrow_constructible<_error_type_, V>)
{
if(o._status.have_value())
{
new(&_value) _value_type_(); // NOLINT
}
else if(o._status.have_error())
{
new(&_error) _error_type_(static_cast<_error_type_ &&>(o._error)); // NOLINT
}
_status = o._status;
o._status.set_have_moved_from(true);
}
struct void_error_converting_constructor_tag
{
};
template
static constexpr bool enable_void_error_converting_constructor =
std::is_default_constructible::value &&detail::is_constructible;
BOOST_OUTCOME_TEMPLATE(class U)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_void_error_converting_constructor))
explicit value_storage_nontrivial(const value_storage_trivial &o, void_error_converting_constructor_tag /*unused*/ = {}) noexcept(
detail::is_nothrow_constructible<_value_type_, U> &&std::is_nothrow_default_constructible<_error_type_>::value)
{
if(o._status.have_value())
{
new(&_value) _value_type_(o._value); // NOLINT
}
else if(o._status.have_error())
{
new(&_error) _error_type_(); // NOLINT
}
_status = o._status;
}
BOOST_OUTCOME_TEMPLATE(class U)
BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_void_error_converting_constructor))
explicit value_storage_nontrivial(value_storage_trivial &&o, void_error_converting_constructor_tag /*unused*/ = {}) noexcept(
detail::is_nothrow_constructible<_value_type_, U> &&std::is_nothrow_default_constructible<_error_type_>::value)
{
if(o._status.have_value())
{
new(&_value) _value_type_(static_cast<_value_type_ &&>(o._value)); // NOLINT
}
else if(o._status.have_error())
{
new(&_error) _error_type_(); // NOLINT
}
_status = o._status;
o._status.set_have_moved_from(true);
}
~value_storage_nontrivial() noexcept(std::is_nothrow_destructible<_value_type_>::value &&std::is_nothrow_destructible<_error_type_>::value)
{
if(this->_status.have_value())
{
if(!trait::is_move_bitcopying::value || !this->_status.have_moved_from())
{
this->_value.~_value_type_(); // NOLINT
}
this->_status.set_have_value(false);
}
else if(this->_status.have_error())
{
if(!trait::is_move_bitcopying::value || !this->_status.have_moved_from())
{
this->_error.~_error_type_(); // NOLINT
}
this->_status.set_have_error(false);
}
}
constexpr void
swap(value_storage_nontrivial &o) noexcept(detail::is_nothrow_swappable<_value_type_>::value &&detail::is_nothrow_swappable<_error_type_>::value)
{
using std::swap;
// empty/empty
if(!_status.have_value() && !o._status.have_value() && !_status.have_error() && !o._status.have_error())
{
swap(_status, o._status);
return;
}
// value/value
if(_status.have_value() && o._status.have_value())
{
struct _
{
status_bitfield_type &a, &b;
bool all_good{false};
~_()
{
if(!all_good)
{
// We lost one of the values
a.set_have_lost_consistency(true);
b.set_have_lost_consistency(true);
}
}
} _{_status, o._status};
strong_swap(_.all_good, _value, o._value);
swap(_status, o._status);
return;
}
// error/error
if(_status.have_error() && o._status.have_error())
{
struct _
{
status_bitfield_type &a, &b;
bool all_good{false};
~_()
{
if(!all_good)
{
// We lost one of the values
a.set_have_lost_consistency(true);
b.set_have_lost_consistency(true);
}
}
} _{_status, o._status};
strong_swap(_.all_good, _error, o._error);
swap(_status, o._status);
return;
}
// Could be value/empty, error/empty, etc
if(_status.have_value() && !o._status.have_error())
{
// Move construct me into other
new(&o._value) _value_type_(static_cast<_value_type_ &&>(_value)); // NOLINT
if(!trait::is_move_bitcopying::value)
{
this->_value.~value_type(); // NOLINT
}
swap(_status, o._status);
return;
}
if(o._status.have_value() && !_status.have_error())
{
// Move construct other into me
new(&_value) _value_type_(static_cast<_value_type_ &&>(o._value)); // NOLINT
if(!trait::is_move_bitcopying::value)
{
o._value.~value_type(); // NOLINT
}
swap(_status, o._status);
return;
}
if(_status.have_error() && !o._status.have_value())
{
// Move construct me into other
new(&o._error) _error_type_(static_cast<_error_type_ &&>(_error)); // NOLINT
if(!trait::is_move_bitcopying::value)
{
this->_error.~error_type(); // NOLINT
}
swap(_status, o._status);
return;
}
if(o._status.have_error() && !_status.have_value())
{
// Move construct other into me
new(&_error) _error_type_(static_cast<_error_type_ &&>(o._error)); // NOLINT
if(!trait::is_move_bitcopying::value)
{
o._error.~error_type(); // NOLINT
}
swap(_status, o._status);
return;
}
// It can now only be value/error, or error/value
struct _
{
status_bitfield_type &a, &b;
_value_type_ *value, *o_value;
_error_type_ *error, *o_error;
bool all_good{true};
~_()
{
if(!all_good)
{
// We lost one of the values
a.set_have_lost_consistency(true);
b.set_have_lost_consistency(true);
}
}
} _{_status, o._status, &_value, &o._value, &_error, &o._error};
if(_status.have_value() && o._status.have_error())
{
strong_placement(_.all_good, _.o_value, _.value, [&_] { //
strong_placement(_.all_good, _.error, _.o_error, [&_] { //
swap(_.a, _.b); //
});
});
return;
}
if(_status.have_error() && o._status.have_value())
{
strong_placement(_.all_good, _.o_error, _.error, [&_] { //
strong_placement(_.all_good, _.value, _.o_value, [&_] { //
swap(_.a, _.b); //
});
});
return;
}
// Should never reach here
make_ub(_value);
}
};
template struct value_storage_delete_copy_constructor : Base // NOLINT
{
using Base::Base;
using value_type = typename Base::value_type;
using error_type = typename Base::error_type;
value_storage_delete_copy_constructor() = default;
value_storage_delete_copy_constructor(const value_storage_delete_copy_constructor &) = delete;
value_storage_delete_copy_constructor(value_storage_delete_copy_constructor &&) = default; // NOLINT
};
template struct value_storage_delete_copy_assignment : Base // NOLINT
{
using Base::Base;
using value_type = typename Base::value_type;
using error_type = typename Base::error_type;
value_storage_delete_copy_assignment() = default;
value_storage_delete_copy_assignment(const value_storage_delete_copy_assignment &) = default;
value_storage_delete_copy_assignment(value_storage_delete_copy_assignment &&) = default; // NOLINT
value_storage_delete_copy_assignment &operator=(const value_storage_delete_copy_assignment &o) = delete;
value_storage_delete_copy_assignment &operator=(value_storage_delete_copy_assignment &&o) = default; // NOLINT
};
template struct value_storage_delete_move_assignment : Base // NOLINT
{
using Base::Base;
using value_type = typename Base::value_type;
using error_type = typename Base::error_type;
value_storage_delete_move_assignment() = default;
value_storage_delete_move_assignment(const value_storage_delete_move_assignment &) = default;
value_storage_delete_move_assignment(value_storage_delete_move_assignment &&) = default; // NOLINT
value_storage_delete_move_assignment &operator=(const value_storage_delete_move_assignment &o) = default;
value_storage_delete_move_assignment &operator=(value_storage_delete_move_assignment &&o) = delete;
};
template struct value_storage_delete_move_constructor : Base // NOLINT
{
using Base::Base;
using value_type = typename Base::value_type;
using error_type = typename Base::error_type;
value_storage_delete_move_constructor() = default;
value_storage_delete_move_constructor(const value_storage_delete_move_constructor &) = default;
value_storage_delete_move_constructor(value_storage_delete_move_constructor &&) = delete;
};
template struct value_storage_nontrivial_move_assignment : Base // NOLINT
{
using Base::Base;
using value_type = typename Base::value_type;
using error_type = typename Base::error_type;
value_storage_nontrivial_move_assignment() = default;
value_storage_nontrivial_move_assignment(const value_storage_nontrivial_move_assignment &) = default;
value_storage_nontrivial_move_assignment(value_storage_nontrivial_move_assignment &&) = default; // NOLINT
value_storage_nontrivial_move_assignment &operator=(const value_storage_nontrivial_move_assignment &o) = default;
value_storage_nontrivial_move_assignment &operator=(value_storage_nontrivial_move_assignment &&o) noexcept(
std::is_nothrow_move_assignable::value &&std::is_nothrow_move_assignable::value) // NOLINT
{
using _value_type_ = typename Base::_value_type_;
using _error_type_ = typename Base::_error_type_;
if(!this->_status.have_value() && !this->_status.have_error() && !o._status.have_value() && !o._status.have_error())
{
this->_status = o._status;
o._status.set_have_moved_from(true);
return *this;
}
if(this->_status.have_value() && o._status.have_value())
{
this->_value = static_cast<_value_type_&&>(o._value); // NOLINT
this->_status = o._status;
o._status.set_have_moved_from(true);
return *this;
}
if(this->_status.have_error() && o._status.have_error())
{
this->_error = static_cast<_error_type_&&>(o._error); // NOLINT
this->_status = o._status;
o._status.set_have_moved_from(true);
return *this;
}
if(this->_status.have_value() && !o._status.have_value() && !o._status.have_error())
{
if(!trait::is_move_bitcopying::value || this->_status.have_moved_from())
{
this->_value.~_value_type_(); // NOLINT
}
this->_status = o._status;
o._status.set_have_moved_from(true);
return *this;
}
if(!this->_status.have_value() && !this->_status.have_error() && o._status.have_value())
{
new(&this->_value) _value_type_(static_cast<_value_type_&&>(o._value)); // NOLINT
this->_status = o._status;
o._status.set_have_moved_from(true);
return *this;
}
if(this->_status.have_error() && !o._status.have_value() && !o._status.have_error())
{
if(!trait::is_move_bitcopying::value || this->_status.have_moved_from())
{
this->_error.~_error_type_(); // NOLINT
}
this->_status = o._status;
o._status.set_have_moved_from(true);
return *this;
}
if(!this->_status.have_value() && !this->_status.have_error() && o._status.have_error())
{
new(&this->_error) _error_type_(static_cast<_error_type_&&>(o._error)); // NOLINT
this->_status = o._status;
o._status.set_have_moved_from(true);
return *this;
}
if(this->_status.have_value() && o._status.have_error())
{
if(!trait::is_move_bitcopying::value || this->_status.have_moved_from())
{
this->_value.~_value_type_(); // NOLINT
}
new(&this->_error) _error_type_(static_cast<_error_type_&&>(o._error)); // NOLINT
this->_status = o._status;
o._status.set_have_moved_from(true);
return *this;
}
if(this->_status.have_error() && o._status.have_value())
{
if(!trait::is_move_bitcopying::value || this->_status.have_moved_from())
{
this->_error.~_error_type_(); // NOLINT
}
new(&this->_value) _value_type_(static_cast<_value_type_&&>(o._value)); // NOLINT
this->_status = o._status;
o._status.set_have_moved_from(true);
return *this;
}
// Should never reach here
make_ub(this->_value);
}
};
template struct value_storage_nontrivial_copy_assignment : Base // NOLINT
{
using Base::Base;
using value_type = typename Base::value_type;
using error_type = typename Base::error_type;
value_storage_nontrivial_copy_assignment() = default;
value_storage_nontrivial_copy_assignment(const value_storage_nontrivial_copy_assignment &) = default;
value_storage_nontrivial_copy_assignment(value_storage_nontrivial_copy_assignment &&) = default; // NOLINT
value_storage_nontrivial_copy_assignment &operator=(value_storage_nontrivial_copy_assignment &&o) = default; // NOLINT
value_storage_nontrivial_copy_assignment &operator=(const value_storage_nontrivial_copy_assignment &o) noexcept(
std::is_nothrow_copy_assignable::value &&std::is_nothrow_copy_assignable::value)
{
using _value_type_ = typename Base::_value_type_;
using _error_type_ = typename Base::_error_type_;
if(!this->_status.have_value() && !this->_status.have_error() && !o._status.have_value()
&& !o._status.have_error())
{
this->_status = o._status;
return *this;
}
if(this->_status.have_value() && o._status.have_value())
{
this->_value = o._value; // NOLINT
this->_status = o._status;
return *this;
}
if(this->_status.have_error() && o._status.have_error())
{
this->_error = o._error; // NOLINT
this->_status = o._status;
return *this;
}
if(this->_status.have_value() && !o._status.have_value() && !o._status.have_error())
{
if(!trait::is_move_bitcopying::value || this->_status.have_moved_from())
{
this->_value.~_value_type_(); // NOLINT
}
this->_status = o._status;
return *this;
}
if(!this->_status.have_value() && !this->_status.have_error() && o._status.have_value())
{
new(&this->_value) _value_type_(o._value); // NOLINT
this->_status = o._status;
return *this;
}
if(this->_status.have_error() && !o._status.have_value() && !o._status.have_error())
{
if(!trait::is_move_bitcopying::value || this->_status.have_moved_from())
{
this->_error.~_error_type_(); // NOLINT
}
this->_status = o._status;
return *this;
}
if(!this->_status.have_value() && !this->_status.have_error() && o._status.have_error())
{
new(&this->_error) _error_type_(o._error); // NOLINT
this->_status = o._status;
return *this;
}
if(this->_status.have_value() && o._status.have_error())
{
if(!trait::is_move_bitcopying::value || this->_status.have_moved_from())
{
this->_value.~_value_type_(); // NOLINT
}
new(&this->_error) _error_type_(o._error); // NOLINT
this->_status = o._status;
return *this;
}
if(this->_status.have_error() && o._status.have_value())
{
if(!trait::is_move_bitcopying::value || this->_status.have_moved_from())
{
this->_error.~_error_type_(); // NOLINT
}
new(&this->_value) _value_type_(o._value); // NOLINT
this->_status = o._status;
return *this;
}
// Should never reach here
make_ub(this->_value);
}
};
#ifdef _MSC_VER
#pragma warning(pop)
#endif
// is_trivially_copyable is true even if type is not copyable, so handle that here
template struct is_storage_trivial
{
static constexpr bool value = std::is_void::value || (std::is_trivially_copy_constructible::value && std::is_trivially_copyable::value);
};
// work around libstdc++ 7 bug
template <> struct is_storage_trivial
{
static constexpr bool value = true;
};
template <> struct is_storage_trivial
{
static constexpr bool value = true;
};
template
using value_storage_select_trivality =
std::conditional_t::value && is_storage_trivial::value, value_storage_trivial, value_storage_nontrivial>;
template
using value_storage_select_move_constructor =
std::conditional_t>::value && std::is_move_constructible>::value, value_storage_select_trivality,
value_storage_delete_move_constructor>>;
template
using value_storage_select_copy_constructor =
std::conditional_t>::value && std::is_copy_constructible>::value, value_storage_select_move_constructor,
value_storage_delete_copy_constructor>>;
template
using value_storage_select_move_assignment =
std::conditional_t>::value && std::is_trivially_move_assignable>::value,
value_storage_select_copy_constructor,
std::conditional_t>::value && std::is_move_assignable>::value,
value_storage_nontrivial_move_assignment>,
value_storage_delete_copy_assignment>>>;
template
using value_storage_select_copy_assignment =
std::conditional_t>::value && std::is_trivially_copy_assignable>::value,
value_storage_select_move_assignment,
std::conditional_t>::value && std::is_copy_assignable>::value,
value_storage_nontrivial_copy_assignment