erased_status_code.h

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#pragma once
 
#include "di/vocab/error/concepts/erased_status_code.h"
#include "di/vocab/error/concepts/status_code_erasable_into.h"
#include "di/vocab/error/erased.h"
#include "di/vocab/error/erasure_cast.h"
#include "di/vocab/error/into_status_code.h"
#include "di/vocab/error/status_code_storage.h"
 
namespace di::vocab {
template<typename T>
class StatusCode<Erased<T>> : public detail::StatusCodeStorage<Erased<T>> {
private:
    using Base = detail::StatusCodeStorage<Erased<T>>;
 
public:
    using Domain = void;
    using Value = T;
 
    StatusCode() = default;
    StatusCode(StatusCode const&) = delete;
    StatusCode(StatusCode&&) = default;
 
    template<typename Domain>
    requires(concepts::StatusCodeErasableInto<Domain, Erased<T>> &&
             !concepts::ErasedStatusCode<StatusCode<meta::Decay<Domain>>>)
    constexpr StatusCode(StatusCode<Domain> const& other)
        : Base(in_place, other.m_domain, detail::erasure_cast<Value>(other.value())) {}
 
    template<typename Domain>
    requires(concepts::StatusCodeErasableInto<Domain, Erased<T>> &&
             !concepts::ErasedStatusCode<StatusCode<meta::Decay<Domain>>>)
    constexpr StatusCode(StatusCode<Domain>&& other)
        : Base(in_place, other.m_domain, detail::erasure_cast<Value>(other.value())) {}
 
    template<typename U, typename... Args>
    requires(!concepts::DecaySameAs<U, StatusCode> && !concepts::DecaySameAs<U, Value> &&
             concepts::ConvertibleToStatusCode<StatusCode, U, Args...>)
    constexpr StatusCode(U&& v, Args&&... args)
        : StatusCode(into_status_code(util::forward<U>(v), util::forward<Args>(args)...)) {}
 
    auto operator=(StatusCode const&) -> StatusCode& = delete;
    auto operator=(StatusCode&&) -> StatusCode& = default;
 
    constexpr ~StatusCode() {
        if (this->m_domain) {
            // FIXME: investigate this sketchy warning generated by GCC on i686, but not x86_64.
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Warray-bounds"
            this->domain().do_erased_destroy(*this, sizeof(*this));
#pragma GCC diagnostic pop
        }
    }
 
    constexpr auto value() const { return this->m_value; }
 
private:
    template<typename Domain>
    friend class StatusCode;
};
}