miette/eyreish/
into_diagnostic.rs

1use std::{error::Error, fmt::Display};
2
3use crate::{Diagnostic, Report};
4
5/// Convenience [`Diagnostic`] that can be used as an "anonymous" wrapper for
6/// Errors. This is intended to be paired with [`IntoDiagnostic`].
7#[derive(Debug)]
8pub(crate) struct DiagnosticError(pub(crate) Box<dyn std::error::Error + Send + Sync + 'static>);
9
10impl Display for DiagnosticError {
11    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
12        let msg = &self.0;
13        write!(f, "{msg}")
14    }
15}
16impl Error for DiagnosticError {
17    fn source(&self) -> Option<&(dyn Error + 'static)> {
18        self.0.source()
19    }
20}
21
22impl Diagnostic for DiagnosticError {}
23
24/**
25Convenience trait that adds a [`.into_diagnostic()`](IntoDiagnostic::into_diagnostic) method that converts a type implementing
26[`std::error::Error`] to a [`Result<T, Report>`].
27
28## Warning
29
30Calling this on a type implementing [`Diagnostic`] will reduce it to the common denominator of
31[`std::error::Error`]. Meaning all extra information provided by [`Diagnostic`] will be
32inaccessible. If you have a type implementing [`Diagnostic`] consider simply returning it or using
33[`Into`] or the [`Try`](std::ops::Try) operator (`?`).
34*/
35pub trait IntoDiagnostic<T, E> {
36    /// Converts [`Result`] types that return regular [`std::error::Error`]s
37    /// into a [`Result`] that returns a [`Diagnostic`].
38    fn into_diagnostic(self) -> Result<T, Report>;
39}
40
41impl<T, E: std::error::Error + Send + Sync + 'static> IntoDiagnostic<T, E> for Result<T, E> {
42    fn into_diagnostic(self) -> Result<T, Report> {
43        self.map_err(|e| DiagnosticError(Box::new(e)).into())
44    }
45}
46
47#[cfg(test)]
48mod tests {
49    use std::io::{self, ErrorKind};
50
51    use super::*;
52
53    use crate::error::tests::TestError;
54
55    #[test]
56    fn diagnostic_error() {
57        let inner_error = io::Error::new(ErrorKind::Other, "halt and catch fire");
58        let outer_error: Result<(), _> = Err(TestError(inner_error));
59
60        let diagnostic_error = outer_error.into_diagnostic().unwrap_err();
61
62        assert_eq!(diagnostic_error.to_string(), "testing, testing...");
63        assert_eq!(
64            diagnostic_error.source().unwrap().to_string(),
65            "halt and catch fire"
66        );
67    }
68}
miette/eyreish/into_diagnostic.rs

miette/eyreish/
into_diagnostic.rs
