make Connect extend Connection to simplify bounds

sqlx-core/src/connection.rs

@@ -19,11 +19,9 @@ pub trait Connection: Executor + Send + 'static {
 }
 
 /// Represents a type that can directly establish a new connection.
-pub trait Connect {
-    type Connection: Connection;
-
+pub trait Connect: Connection {
     /// Establish a new database connection.
-    fn connect<T>(url: T) -> BoxFuture<'static, crate::Result<Self::Connection>>
+    fn connect<T>(url: T) -> BoxFuture<'static, crate::Result<Self>>
     where
         T: TryInto<Url, Error = crate::Error>,
         Self: Sized;

sqlx-core/src/mysql/connection.rs

@@ -603,8 +603,6 @@ impl MySqlConnection {
 }
 
 impl Connect for MySqlConnection {
-    type Connection = MySqlConnection;
-
     fn connect<T>(url: T) -> BoxFuture<'static, crate::Result<MySqlConnection>>
     where
         T: TryInto<Url, Error = crate::Error>,

sqlx-core/src/pool/conn.rs

@@ -11,7 +11,7 @@ use super::inner::{DecrementSizeGuard, SharedPool};
 /// Will be returned to the pool on-drop.
 pub struct PoolConnection<C>
 where
-    C: Connection + Connect<Connection = C>,
+    C: Connect,
 {
     live: Option<Live<C>>,
     pool: Arc<SharedPool<C>>,
@@ -37,7 +37,7 @@ const DEREF_ERR: &str = "(bug) connection already released to pool";
 
 impl<C> Deref for PoolConnection<C>
 where
-    C: Connection + Connect<Connection = C>,
+    C: Connect,
 {
     type Target = C;
 
@@ -48,7 +48,7 @@ where
 
 impl<C> DerefMut for PoolConnection<C>
 where
-    C: Connection + Connect<Connection = C>,
+    C: Connect,
 {
     fn deref_mut(&mut self) -> &mut Self::Target {
         &mut self.live.as_mut().expect(DEREF_ERR).raw
@@ -57,7 +57,7 @@ where
 
 impl<C> Connection for PoolConnection<C>
 where
-    C: Connection + Connect<Connection = C>,
+    C: Connect,
 {
     /// Detach the connection from the pool and close it nicely.
     fn close(mut self) -> BoxFuture<'static, crate::Result<()>> {
@@ -71,7 +71,7 @@ where
 /// Returns the connection to the [`Pool`][crate::Pool] it was checked-out from.
 impl<C> Drop for PoolConnection<C>
 where
-    C: Connection + Connect<Connection = C>,
+    C: Connect,
 {
     fn drop(&mut self) {
         if let Some(live) = self.live.take() {
@@ -130,7 +130,7 @@ impl<'s, C> Floating<'s, Live<C>> {
 
     pub fn attach(self, pool: &Arc<SharedPool<C>>) -> PoolConnection<C>
     where
-        C: Connection + Connect<Connection = C>,
+        C: Connect,
     {
         let Floating { inner, guard } = self;
 

sqlx-core/src/pool/executor.rs

@@ -3,19 +3,13 @@ use std::ops::DerefMut;
 use futures_core::{future::BoxFuture, stream::BoxStream};
 use futures_util::StreamExt;
 
-use crate::{
-    connection::{Connect, Connection},
-    describe::Describe,
-    executor::Executor,
-    pool::Pool,
-    Database,
-};
+use crate::{connection::Connect, describe::Describe, executor::Executor, pool::Pool, Database};
 
 use super::PoolConnection;
 
 impl<C> Executor for Pool<C>
 where
-    C: Connection + Connect<Connection = C>,
+    C: Connect,
 {
     type Database = <C as Executor>::Database;
 
@@ -66,7 +60,7 @@ where
 
 impl<C> Executor for &'_ Pool<C>
 where
-    C: Connection + Connect<Connection = C>,
+    C: Connect,
 {
     type Database = <C as Executor>::Database;
 
@@ -115,7 +109,7 @@ where
 
 impl<C> Executor for PoolConnection<C>
 where
-    C: Connection + Connect<Connection = C>,
+    C: Connect,
 {
     type Database = <C as Executor>::Database;
 

sqlx-core/src/pool/inner.rs

@@ -130,7 +130,7 @@ where
 
 impl<C> SharedPool<C>
 where
-    C: Connection + Connect<Connection = C>,
+    C: Connect,
 {
     pub(super) async fn new_arc(url: &str, options: Options) -> crate::Result<Arc<Self>> {
         let mut pool = Self {

sqlx-core/src/pool/mod.rs

@@ -6,7 +6,7 @@ use std::{
     time::{Duration, Instant},
 };
 
-use crate::connection::{Connect, Connection};
+use crate::connection::Connect;
 use crate::transaction::Transaction;
 
 use self::inner::SharedPool;
@@ -26,7 +26,7 @@ pub struct Pool<C>(Arc<SharedPool<C>>);
 
 impl<C> Pool<C>
 where
-    C: Connection + Connect<Connection = C>,
+    C: Connect,
 {
     /// Creates a connection pool with the default configuration.
     ///
@@ -127,7 +127,7 @@ impl<C> Clone for Pool<C> {
 
 impl<C> fmt::Debug for Pool<C>
 where
-    C: Connection + Connect<Connection = C>,
+    C: Connect,
 {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         fmt.debug_struct("Pool")
@@ -154,7 +154,7 @@ fn assert_pool_traits() {
     fn assert_send_sync<T: Send + Sync>() {}
     fn assert_clone<T: Clone>() {}
 
-    fn assert_pool<C: Connection + Connect<Connection = C>>() {
+    fn assert_pool<C: Connect>() {
         assert_send_sync::<Pool<C>>();
         assert_clone::<Pool<C>>();
     }

sqlx-core/src/pool/options.rs

@@ -1,7 +1,7 @@
 use std::{marker::PhantomData, time::Duration};
 
 use super::Pool;
-use crate::connection::{Connect, Connection};
+use crate::connection::Connect;
 
 /// Builder for [Pool].
 pub struct Builder<C> {
@@ -102,7 +102,7 @@ impl<C> Builder<C> {
     /// opened and placed into the pool.
     pub async fn build(self, url: &str) -> crate::Result<Pool<C>>
     where
-        C: Connection + Connect<Connection = C>,
+        C: Connect,
     {
         Pool::with_options(url, self.options).await
     }

sqlx-core/src/postgres/connection.rs

@@ -409,8 +409,6 @@ impl PgConnection {
 }
 
 impl Connect for PgConnection {
-    type Connection = PgConnection;
-
     fn connect<T>(url: T) -> BoxFuture<'static, Result<PgConnection>>
     where
         T: TryInto<Url, Error = crate::Error>,