error.log

Checking db v0.1.0 (/home/stephan/Development/mray_server/db)
warning: unused import: `self`
 --> db/src/error.rs:1:16
  |
1 | use std::fmt::{self, Display, Formatter};
  |                ^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

warning: unused import: `bb8`
 --> db/src/error.rs:3:39
  |
3 | use diesel_async::pooled_connection::{bb8, PoolError};
  |                                       ^^^

error[E0223]: ambiguous associated type
  --> db/src/lib.rs:15:9
   |
15 |         AsyncDieselConnectionManager<DbConnection>::Error,
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
help: use fully-qualified syntax
   |
15 |         <AsyncDieselConnectionManager<AsyncPgConnection> as TryFrom>::Error,
   |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
15 |         <AsyncDieselConnectionManager<AsyncPgConnection> as TryInto>::Error,
   |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
15 |         <AsyncDieselConnectionManager<AsyncPgConnection> as bb8::api::ManageConnection>::Error,
   |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
15 |         <AsyncDieselConnectionManager<AsyncPgConnection> as fallible_iterator::IntoFallibleIterator>::Error,
   |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     and 2 other candidates

error[E0277]: the trait bound `AsyncDieselConnectionManager<AsyncPgConnection>: PoolableConnection` is not satisfied
  --> db/src/lib.rs:13:12
   |
13 |       let x: Result<
   |  ____________^
14 | |         Pool<AsyncDieselConnectionManager<DbConnection>>,
15 | |         AsyncDieselConnectionManager<DbConnection>::Error,
16 | |     > = Pool::builder().build(config).await;
   | |_____^ the trait `PoolableConnection` is not implemented for `AsyncDieselConnectionManager<AsyncPgConnection>`, which is required by `AsyncDieselConnectionManager<AsyncDieselConnectionManager<AsyncPgConnection>>: bb8::api::ManageConnection`
   |
   = help: the trait `PoolableConnection` is implemented for `AsyncPgConnection`
   = note: required for `AsyncDieselConnectionManager<AsyncDieselConnectionManager<AsyncPgConnection>>` to implement `bb8::api::ManageConnection`
note: required by a bound in `bb8::api::Pool`
  --> /home/stephan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bb8-0.8.5/src/api.rs:16:8
   |
14 | pub struct Pool<M>
   |            ---- required by a bound in this struct
15 | where
16 |     M: ManageConnection,
   |        ^^^^^^^^^^^^^^^^ required by this bound in `Pool`

error[E0277]: the trait bound `AsyncDieselConnectionManager<AsyncPgConnection>: DerefMut` is not satisfied
  --> db/src/lib.rs:13:12
   |
13 |       let x: Result<
   |  ____________^
14 | |         Pool<AsyncDieselConnectionManager<DbConnection>>,
15 | |         AsyncDieselConnectionManager<DbConnection>::Error,
16 | |     > = Pool::builder().build(config).await;
   | |_____^ the trait `DerefMut` is not implemented for `AsyncDieselConnectionManager<AsyncPgConnection>`, which is required by `AsyncDieselConnectionManager<AsyncDieselConnectionManager<AsyncPgConnection>>: bb8::api::ManageConnection`
   |
   = help: the trait `bb8::api::ManageConnection` is implemented for `AsyncDieselConnectionManager<C>`
   = note: required for `AsyncDieselConnectionManager<AsyncPgConnection>` to implement `AsyncConnection`
   = note: required for `AsyncDieselConnectionManager<AsyncDieselConnectionManager<AsyncPgConnection>>` to implement `bb8::api::ManageConnection`
note: required by a bound in `bb8::api::Pool`
  --> /home/stephan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bb8-0.8.5/src/api.rs:16:8
   |
14 | pub struct Pool<M>
   |            ---- required by a bound in this struct
15 | where
16 |     M: ManageConnection,
   |        ^^^^^^^^^^^^^^^^ required by this bound in `Pool`

Some errors have detailed explanations: E0223, E0277.
For more information about an error, try `rustc --explain E0223`.
warning: `db` (lib) generated 2 warnings
error: could not compile `db` (lib) due to 3 previous errors; 2 warnings emitted

lib.rs

use diesel_async::pooled_connection::bb8::Pool;
use diesel_async::pooled_connection::AsyncDieselConnectionManager;
use diesel_async::AsyncPgConnection;

mod error;
pub use error::DatabaseError;

pub type DbConnection = AsyncPgConnection;
pub type DbPool = Pool<AsyncDieselConnectionManager<DbConnection>>;

pub async fn initialize_db_pool(database_url: &str) -> Result<(), DatabaseError> {
    let config = AsyncDieselConnectionManager::<DbConnection>::new(database_url);
    let x: Result<
        Pool<AsyncDieselConnectionManager<DbConnection>>,
        AsyncDieselConnectionManager<DbConnection>::Error,
    > = Pool::builder().build(config).await;

    Ok(())
}