Should Display for Error include source?

[stepancheg]

Location (URL)

https://doc.rust-lang.org/std/error/trait.Error.html

Summary

std::error::Error requires Display and has .source().

It is not clear whether Error is supposed to include source in Display.

Libraries like anyhow assume that Display does not print source, the library is popular, so it seems like this is how Display should be done. So would be good to include that in the documentation of Error trait.

This is specification request.

[ChrisDenton]

I think we should be careful with making too strong statements on what people must do. Because maybe someone will have a use case where it makes sense.

But I would agree with saying it is recommended that an error shouldn't print its source in Display.

[Noratrieb]

I think we should at least make recommendations on what to do to play nicely with the ecosystem, which people can always ignore if they have a reason.