make Connection, ToConnection, ToConnectionResult public

[smiera]

I need to create Pool and/or Conn wrapper. Wrapper I use for limit or extend some functionality.
It would be great to be able implement, for example, ToConnection for my wrapper.

Example

impl<'a> ToConnection<'a, 'static> for &'a MyPoolWrapper {
    fn to_connection(self) -> ToConnectionResult<'a, 'static> {
        // ... get conn logic
        ToConnectionResult::Mediate(fut)
    }
}
// ...
#[tokio::test]
async fn test_pool() {
    let pool = MyPoolWrapper::new("mysql://localhost:3306");
    let result: Option<u32> = "SELECT 1".first(&pool).await.unwrap();
    assert_eq!(1, result.unwrap());
}

UPD: After testing my wrapper, I concluded that in addition to the proposed changes, it would be great to implement the DerefMut trait for Transaction.

For example, I create a trait to extend the Conn:

pub trait Administration {
    fn get_connection(&mut self) -> &mut Conn;

    fn create_database<'a>(&'a mut self, db_name: &'a str) -> BoxFuture<'a, Result<()>>
    where
        Self: Send + Sync,
    {
        async move {
            format!("CREATE SCHEMA IF NOT EXISTS `{}`", db_name)
                .ignore(self.get_connection()).await?;
            Ok(())
        }.boxed()
    }
}

impl Administration for Conn {
    fn get_connection(&mut self) -> &mut Conn {
        self
    }
}

But I can't get a &mut Conn from a Transaction instance, as Transaction does not implement the DerefMut trait.

#[tokio::test]
async fn test_transaction() {
    let mut conn = Conn::from_url("mysql://root:@localhost:3306").await.unwrap();
    // Work!
    conn.create_database("db_1").await.unwrap();
    // Not work!
    let mut trx = conn.start_transaction(Default::default()).await.unwrap();
    trx.database_exists("db_2").await.unwrap();
}

   |
77 |         trx.database_exists("db_2").await.unwrap();
   |         ^^^ cannot borrow as mutable
   |
   = help: trait `DerefMut` is required to modify through a dereference, but it is not implemented for `Transaction<'_>`