feat: print source for error to make it easier to debug

[PureWhiteWu]

Currently when encounter errors, the Error type only prints a message like this:

error sending request for url (http://xxx)

It doesn't print the underlying cause, so it's hard to debug.

This PR also prints the inner source which makes it easier to debug, such as:

error sending request for url (http://xxx): operation timed out

[seanmonstar]

This was purposefully removed in 0.12, since Rust best practices recommend not doing that. Instead, some reporter that crawls the sources should be used instead.

[PureWhiteWu]

Hi @seanmonstar , thanks very much for your reply!

Rust best practices recommend not doing that

Could you please give me an reference link? I didn't know about this.

Instead, some reporter that crawls the sources should be used instead.

In my case, I'm defining my own error type using thiserror like this:

#[derive(thiserror::Error)]
pub enum Error {
    #[error("reqwest error: {0}")]
    ReqwestError(#[from] reqwest::Error),
}

In this case, I don't know how to add something like Report to print the inner source.

Since thiserror is a famous crate to handle error and the Report is still nightly only, I still think maybe we should add this back now? Maybe we can remove it in the future when the Report is stabilized?

[seanmonstar]

Could you please give me an reference link?

rust-lang/project-error-handling#27 (comment)

You wouldn't use a reporter inside the type you've derived with thiserror. Rather, the reporter is to be used by the application layer, whatever is "reporting" the error in plain text. Things like anyhow and eyre already provide reporters.

[PureWhiteWu]

Thanks very much!

[PureWhiteWu]

I've commented in that issue rust-lang/project-error-handling#27 (comment), and I sincerely look forward to hearing your advice.