rust-foundation-community-grant VS tokio-diesel

That's a topic where already some work exists. You might want to checkout my collection of bad error messages from such trait heavy crates for example. It's important to notice that most of these errors look complicated, but mostly have a quite simple cause. In some of these cases it's even possible to reword these error messages by removing most of the complicated looking type stuff to something much simpler which then is easier to understand.

As with everything in static type checking, the upfront costs seem high (deciphering type errors can be a bit daunting for both diesel, and to a certain extent dfdx), but I feel like (1) this will get better (especially with the work /u/weiznich is doing), and (2) history has shown the upfront costs are worth it (as evidenced by the takeover of typescript and typed Python).

This change is hopefully only the starting point to a number of future improvements. I've got a project grant as part of the rust foundation community grant program to work on improving the error messages for trait heavy crates like diesel. Hopefully this will result in other improvements as well. I track this work here. If you hit bad error messages with diesel or any other trait heavy crate, please fill an issue there.

axum does basically ]the trick as bevy](https://docs.rs/axum/latest/axum/handler/trait.Handler.html#impl-Handler%3C(T1%2C)%2C%20B%3E) to emulate variadics and someone already filed this https://github.com/weiznich/rust-foundation-community-grant/issues/2

An issue I see is that diesel is already quite usable in async contexts using spawn_blocking or block_in_place (that's what tokio-diesel and async-bb8-diesel does), it's just somewhat inefficient. How much money is worth the extra efficiency of diesel-async?