Rust中DieselConnectionManager<PgConnection>未实现ManageConnection问题求助

在Rust项目中使用bb8-diesel crate的DieselConnectionManager<PgConnection>类型时遇到错误，具体错误提示：

the trait ManageConnection is not implemented for DieselConnectionManager<PgConnection>

使用的版本为Diesel 2.0.3和bb8-diesel 0.2.1，项目的Cargo.toml相关配置如下：

[package]
name = "uchat_query"
version = "0.1.0"
edition = "2021"

[dependencies]
bb8 = "0.8.0"
bb8-diesel = { version = "0.2.1" }
chrono = { version = "0.4.23", features = ["serde"] }
diesel-derive-newtype = "2.0.0-rc.0"
diesel_migrations = { version = "2.0.0", features = ["postgres"] }
password-hash = { version = "0.5.0", features = ["std"] }
r2d2 = "0.8.10"
serde = { version = "1.0.152", features = ["derive"] }
serde_json = "1.0.93"
thiserror = "1.0.38"
tokio = { version = "1.25.0", features = ["full"] }
tracing = { version = "0.1.37", features = ["attributes"] }
url = { version = "2.2.2" }
uuid = { version = "1.3.0", features = ["v4", "serde"] }

[dependencies.diesel]
features = [
  "postgres",
  "uuid",
  "chrono",
  "serde_json",
  "i-implement-a-third-party-backend-and-opt-into-breaking-changes",
  "postgres_backend",
]
version = "2.0.3"
default-features = false

[dev-dependencies]
dotenvy = "0.15.7"
uchat_crypto = { path = "../crypto" }

错误相关的代码定义：

type AsyncConnectionManager = bb8_diesel::DieselConnectionManager;

已尝试更新bb8-diesel到最新版本、将Diesel降级到1.4.5，但问题仍未解决，希望了解这两个crate的交互逻辑是否存在遗漏或兼容性问题，并获取解决建议。

相关完整代码如下：

use diesel::{ConnectionError, PgConnection};
use diesel_migrations::{embed_migrations, EmbeddedMigrations, MigrationHarness};
use std::{error::Error, time::Duration};
use bb8::ManageConnection;
use crate::error::QueryError;
pub const MIGRATIONS: EmbeddedMigrations = embed_migrations!("../migrations");
type AsyncConnectionManager = bb8_diesel::DieselConnectionManager<PgConnection>;
pub type AsyncConnection<'a> = bb8::PooledConnection<'a, AsyncConnectionManager>;
pub type OwnedAsyncConnection = bb8::PooledConnection<'static, AsyncConnectionManager>;
#[derive(Clone, Debug)]
pub struct AsyncConnectionPool(bb8::Pool<AsyncConnectionManager>);
impl AsyncConnectionPool {
    pub async fn new<S: AsRef<str>>(url: S) -> Result<Self, QueryError> {
        let pool = new_async_pool(url).await?;
        {
            // check connection
            let _ = pool
                .0
                .get()
                .await
                .map_err(|e| QueryError::Connection(e.to_string()))?;
        }
        Ok(pool)
    }
    pub async fn get(&self) -> Result<AsyncConnection, QueryError> {
        self.0
            .get()
            .await
            .map_err(|e| QueryError::Connection(e.to_string()))
    }
    pub async fn get_owned(&self) -> Result<OwnedAsyncConnection, QueryError> {
        self.0
            .get_owned()
            .await
            .map_err(|e| QueryError::Connection(e.to_string()))
    }
    pub fn state(&self) -> bb8::State {
        self.0.state()
    }
}
/// Run database migrations
pub fn run_migrations(
    connection: &mut impl MigrationHarness<diesel::pg::Pg>,
) -> Result<(), Box<dyn Error + Send + Sync + 'static>> {
    connection.run_pending_migrations(MIGRATIONS)?;
    Ok(())
}
/// Connect to the database
pub fn connect<S: AsRef<str>>(url: S) -> Result<PgConnection, ConnectionError> {
    use diesel::Connection;
    let url = url.as_ref();
    PgConnection::establish(url)
}
/// Usage:
/// ```
/// let async_pool = new_async_pool("postgres://login@localhost/sample").await;
/// let conn = &mut async_pool.get().await?;
/// ```
pub async fn new_async_pool<S: AsRef<str>>(url: S) -> Result<AsyncConnectionPool, QueryError> {
    let url = url.as_ref();
    let manager = bb8_diesel::DieselConnectionManager::<PgConnection>::new(url);
    bb8::Pool::builder()
        .test_on_check_out(true)
        .connection_timeout(Duration::from_secs(10))
        .build(manager)
        .await
        .map(AsyncConnectionPool)
        .map_err(|e| QueryError::Pool(e.to_string()))
}

核心问题是bb8-diesel 0.2.1基于Diesel 1.x开发，与Diesel 2.x存在兼容性断层；降级Diesel到1.4.5仍出错大概率是依赖树版本冲突导致的。具体解决步骤如下：

1. 切换兼容版本
   使用bb8-diesel 0.3.x版本，它专门适配Diesel 2.x。修改Cargo.toml中的bb8-diesel依赖：

   bb8-diesel = { version = "0.3.0" }
   

   当前使用的Diesel 2.0.3可保持不变，两者兼容。

2. 排查依赖冲突
   运行cargo tree -p diesel查看是否有其他依赖强制引入不兼容的Diesel版本。如果存在，通过patch字段统一版本：

   [patch.crates-io]
   diesel = { version = "2.0.3", features = ["postgres", "uuid", "chrono", "serde_json", "i-implement-a-third-party-backend-and-opt-into-breaking-changes", "postgres_backend"] }
   

3. 调整特征导入
   bb8-diesel 0.3.x实现的是异步特征AsyncManageConnection，而非bb8的同步ManageConnection。在代码顶部添加正确的导入：

   use bb8_diesel::AsyncManageConnection;
   

4. 验证连接池逻辑
   bb8-diesel 0.3.x的DieselConnectionManager已正确实现AsyncManageConnection，因此原代码中bb8::Pool::builder().build(manager)的调用可正常工作，无需额外修改。

内容的提问来源于stack exchange，提问作者Mr Coder