Feature Request

Motivation

anyhow provides a formatting of the whole error chain through the alternate selector {:#}: https://docs.rs/anyhow/1.0.38/anyhow/struct.Error.html#display-representations

It would be nice to make use of this within tracing events in a concise way.

Proposal

Add a formatter sigil (possibly #) to tracing that allows to print values using their alternate Display implementation.

For example:

let error = anyhow!("Oh noes!").context("Something went horribly wrong!");

tracing::error!(#error, "What a mess")

Would print as:

ERROR What a mess error=Something went horribly wrong!: Oh noes!

Alternative

One can convert an anyhow error into a std-error. If reporting std-errors were to be made more ergonomic AND tracing provides a way of printing all causes of std-errors, then this feature is not needed. That being said, triggering the alternative Display impl is not specific to anyhow and might be useful in general.