adding an await inside a handler makes the handler invalid

[samuelcolvin]

• I have looked for existing issues (including closed) about this

Bug Report

This fails with he trait Handler<_, _> is not implemented for fn item fn(State<AppState>, axum::Json<Record>) -> impl std::future::Future<Output = &'static str> {post_batch}

async fn post_batch(
    State(state): State<AppState>,
    Json(record): Json<Record>,
) -> &'static str {
    dbg!(&record);
    let mut buffer = state.buffer.lock().expect("buffer lock");
    buffer.insert(vec![record]).await.unwrap();
    "ok"
}

but if I comment out buffer.insert(vec![record]).await.unwrap();, it compiles fine.

If I remote the state parameter, but still do something that requires await inside the handler, it's fine.

Using bytes: Bytes instead of Json, I get the same error.

Version

0.7.5

Platform

MacOS M1