Rust 自定义结果枚举如何支持```FromResidual`

我想保存实体在数据库中的一些特定错误的情况下，这似乎很好使用自定义结果枚举这应该重新抛出Err和SaveOnErr当使用?.

我试着从Result中复制FromResidual个性状，这似乎是?个使用的原因，但失败了，可以这样做吗？

#[derive(Copy, PartialEq, Eq, Debug, Clone)]
pub enum SavableResult<T, E> {
    Ok(T),
    Err(E),
    SaveOnErr(E),
}

fn test1() {
    let result = test2();

    match result {
        SavableResult::Ok(_) | SavableResult::SaveOnErr(_) => save(),
        SavableResult::Err(_) => {}
    };
}
fn test2() -> SavableResult<(), ApiErr> {
    test3()?; // not working

    SavableResult::Ok(())
}
fn test3() -> SavableResult<(), ApiErr> {
    SavableResult::Ok(())
}
fn save() {
    // save in db
}

我想解决的具体问题:

pub async fn execute(&self) -> Result<JwtTokensPair, ApiErr> {
    let mut auth = AuthRepository::get_by_user_id(user_id, &trx).await?;

    // in case of incorrect password `auth` entity `failed_auth_count`
    // is incremented and I need to save it in database anyway
    // to block any auth after 10 fails for hour
    // but only for one specific error
    let result = auth.login(&self.password, self.hash_service);

    // problem here is that it's easy to forget which
    // entities have this special requirement
    // or use this ugly match everywhere
    match result {
        Ok(_)
        | Err(ApiErr {
            save_on_err: true, ..
        }) => AuthRepository::save(&auth, &trx).await?,
        Err(_) => {}
    };
    trx.commit().await?;

    result
}