Releases: dtolnay/thiserror
1.0.3
1.0.2
-
Add a
#[from]
attribute to request an implementation ofstd::convert::From
from your error's source error types, making it easy to build your error via the?
operator.use thiserror::Error; #[derive(Error, Debug)] pub enum Error { Io(#[from] io::Error), Json(#[from] serde_json::Error), Regex(#[from] regex::Error), Other(#[from] anyhow::Error), }
We only permit
From
to be derived from the error's source field, not any arbitrary other field. Notice that this allows#[from]
to imply#[source]
so you don't need to also specify#[source]
explicitly.The variant must not contain any other fields beyond the source error and possibly a backtrace. A backtrace is captured from within the
From
impl if there is a field for it.#[derive(Error, Debug)] pub enum MyError { Io { #[from] source: io::Error, backtrace: Backtrace, }, }
-
Named fields with the name
source
are assumed to be the error source and so no longer require an explicit#[source]
attribute. -
Enum variants now inherit the
#[error(...)]
attribute from atop the enum if there is one.use thiserror::Error; #[derive(Error, Debug)] #[error("{0}")] // applies to every variant without its own attr pub enum Error { Io(io::Error), Json(serde_json::Error), Regex(regex::Error), #[error("unknown error")] Unknown, }