Document #[from] attribute

[jalil-salame]

Document #[from] attribute, it is otherwise not clear that you can use it.

Previous (wrong) issue:

thiserror supports the #[from] attribute (see details) to reduce manually written that code, justerror should support it too:

use thiserror::Error;

#[derive(Error, Debug)]
pub enum DataStoreError {
    #[error("data store disconnected")]
    Disconnect(#[from] io::Error), /// **HERE**
    #[error("the data for key `{0}` is not available")]
    Redaction(String),
    #[error("invalid header (expected {expected:?}, found {found:?})")]
    InvalidHeader {
        expected: String,
        found: String,
    },
    #[error("unknown data store error")]
    Unknown,
}

You otherwise need to manually impl the From trait:

impl From<io::Error> for DataStoreError {
    fn from(value: io::Error) -> Self {
        Self::Disconnect(value)
    }
}

[alex35mil]

It is supported. I use it all the time. What error do you see when you apply it?

[jalil-salame]

It is not detailed anywhere in the documentation so I assumed it didn't exist... I will change the issue title and description.