Trait not implemented for diesel-async pool

[bitgrinder]

I have the following code:

use std::env;
use diesel_async::AsyncPgConnection;
use env_convert::get_default_env_var;
use diesel_async::pooled_connection::AsyncDieselConnectionManager;
use diesel_async::pooled_connection::deadpool::{Pool,BuildError};

async fn get_pool() -> Result<Pool<AsyncDieselConnectionManager<AsyncPgConnection>>, BuildError> {
    let mex_connections: Result<usize,_> = get_default_env_var("MAX_DB_CONNECTIONS", "5").into();
    let db_url = env::var("DATABASE_URL").expect("DATABASE_URL must be set");
    let config = AsyncDieselConnectionManager::<AsyncPgConnection>::new(db_url);
    let pool = Pool::builder(config).build()?;
    Ok(pool)
}

I am getting this error:

error[E0277]: the trait bound `AsyncDieselConnectionManager<AsyncPgConnection>: PoolableConnection` is not satisfied
   --> src/db_pool.rs:11:16
    |
11  |     let pool = Pool::builder(config).build()?;
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `PoolableConnection` is not implemented for `AsyncDieselConnectionManager<AsyncPgConnection>`
    |
    = help: the trait `PoolableConnection` is implemented for `AsyncPgConnection`
    = note: required for `AsyncDieselConnectionManager<AsyncDieselConnectionManager<AsyncPgConnection>>` to implement `deadpool::managed::Manager`
note: required by a bound in `deadpool::managed::Pool`
   --> /home/disguys/.asdf/installs/rust/1.70.0/registry/src/index.crates.io-6f17d22bba15001f/deadpool-0.9.5/src/managed/mod.rs:264:20
    |
264 | pub struct Pool<M: Manager, W: From<Object<M>> = Object<M>> {
    |                    ^^^^^^^ required by this bound in `Pool`

I pulled this almost straight from the docs for diesel-async so I'm a bit confused as to why I am getting this error, and I am not sure how to fix it.

[semicoleon]

The pool types in diesel_async::pooled_connection::deadpool are type aliases with the AsyncDieselConnectionManager part filled in.

If you change the return type to Result<Pool<AsyncPgConnection>, BuildError>, it should work

[bitgrinder]

It was even suggested in the error message, and I didn't believe it. Thank you!