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Support #[from] on an Option field #147

Merged
merged 2 commits into from Aug 28, 2021
Merged

Support #[from] on an Option field #147

merged 2 commits into from Aug 28, 2021

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dtolnay
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@dtolnay dtolnay commented Aug 28, 2021

This allows ? to work with error types that only sometimes have a source (as seen in #1).

use std::io;
use thiserror::Error;

#[derive(Error, Debug)]
#[error("...")]
pub struct Error {
    #[from]
    source: Option<io::Error>,
}

fn main() -> Result<(), Error> {
    io::copy(&mut io::empty(), &mut io::sink())?;
    Ok(())
}

@dtolnay dtolnay merged commit 9af5265 into master Aug 28, 2021
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@dtolnay dtolnay deleted the optionfrom branch Aug 28, 2021
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