Go offers several printing “verbs” designed to format general Go values.
If the value is a struct, the %+v variant will include the struct’s field names.
The %#v variant prints a Go syntax representation of the value, i.e. the source code snippet that would produce that value.
Sorry, but my reading of the code, can you confirm whether the space character is intended? I would think that
"%# v"
should instead be"%#v"
in: https://github.com/cockroachdb/errors/blob/master/errbase/format_error.go#L122