You need to tell the user that this is an error, otherwise they don’t know if it succeeded or not.

error: --att cannot be used at the same time as --intel

The last line is incomprehensible, just use a full sentence.

I can’t find it on LemmyRS, is it possible that LemmyRS is not federating with kbin.social?

There are executors for more specific use cases.

• For example, bastion is a “Highly-available Distributed Fault-tolerant Runtime”, inspired by Erlang, and including an async executor.
• embassy includes an async executor specifically for embedded systems.
• fuchsia-async is an executor for use in the Fuchsia OS.
• wasm-bindgen-futures converts Rust Futures to JavaScript Promises and schedules them to run to completion. It could also be seen as a (very basic) executor.