Type Alias Error

pub type Error = Error;

Compilation error.

Aliased Type

struct Error { /* private fields */ }

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 8 bytes

Implementations

impl Report

pub fn new<E>(error: E) -> Report

where E: Error + Send + Sync + 'static,

Create a new error object from any error type.

The error type must be threadsafe and 'static, so that the Report will be as well.

If the error type does not provide a backtrace, a backtrace will be created here to ensure that a backtrace exists.

pub fn msg<M>(message: M) -> Report

where M: Display + Debug + Send + Sync + 'static,

Create a new error object from a printable error message.

If the argument implements std::error::Error, prefer Report::new instead which preserves the underlying error’s cause chain and backtrace. If the argument may or may not implement std::error::Error now or in the future, use eyre!(err) which handles either way correctly.

Report::msg("...") is equivalent to eyre!("...") but occasionally convenient in places where a function is preferable over a macro, such as iterator or stream combinators:

use eyre::{Report, Result};
use futures::stream::{Stream, StreamExt, TryStreamExt};

async fn demo<S>(stream: S) -> Result<Vec<Output>>
where
    S: Stream<Item = Input>,
{
    stream
        .then(ffi::do_some_work) // returns Result<Output, &str>
        .map_err(Report::msg)
        .try_collect()
        .await
}

pub fn wrap_err<D>(self, msg: D) -> Report

where D: Display + Send + Sync + 'static,

Create a new error from an error message to wrap the existing error.

For attaching a higher level error message to a Result as it is propagated, the WrapErr extension trait may be more convenient than this function.

The primary reason to use error.wrap_err(...) instead of result.wrap_err(...) via the WrapErr trait would be if the message needs to depend on some data held by the underlying error:

use eyre::Result;
use std::fs::File;
use std::path::Path;

struct ParseError {
    line: usize,
    column: usize,
}

fn parse_impl(file: File) -> Result<T, ParseError> {
    ...
}

pub fn parse(path: impl AsRef<Path>) -> Result<T> {
    let file = File::open(&path)?;
    parse_impl(file).map_err(|error| {
        let message = format!(
            "only the first {} lines of {} are valid",
            error.line, path.as_ref().display(),
        );
        eyre::Report::new(error).wrap_err(message)
    })
}

pub fn chain(&self) -> Chain<'_>

An iterator of the chain of source errors contained by this Report.

This iterator will visit every error in the cause chain of this error object, beginning with the error that this error object was created from.

Example

use eyre::Report;
use std::io;

pub fn underlying_io_error_kind(error: &Report) -> Option<io::ErrorKind> {
    for cause in error.chain() {
        if let Some(io_error) = cause.downcast_ref::<io::Error>() {
            return Some(io_error.kind());
        }
    }
    None
}

pub fn root_cause(&self) -> &(dyn Error + 'static)

The lowest level cause of this error — this error’s cause’s cause’s cause etc.

The root cause is the last error in the iterator produced by chain().

pub fn is<E>(&self) -> bool

where E: Display + Debug + Send + Sync + 'static,

Returns true if E is the type held by this error object.

For errors constructed from messages, this method returns true if E matches the type of the message D or the type of the error on which the message has been attached. For details about the interaction between message and downcasting, see here.

pub fn downcast<E>(self) -> Result<E, Report>

where E: Display + Debug + Send + Sync + 'static,

Attempt to downcast the error object to a concrete type.

pub fn downcast_ref<E>(&self) -> Option<&E>

where E: Display + Debug + Send + Sync + 'static,

Downcast this error object by reference.

Example

// If the error was caused by redaction, then return a tombstone instead
// of the content.
match root_cause.downcast_ref::<DataStoreError>() {
    Some(DataStoreError::Censored(_)) => Ok(Poll::Ready(REDACTED_CONTENT)),
    None => Err(error),
}

pub fn downcast_mut<E>(&mut self) -> Option<&mut E>

where E: Display + Debug + Send + Sync + 'static,

Downcast this error object by mutable reference.

pub fn handler(&self) -> &(dyn EyreHandler + 'static)

Get a reference to the Handler for this Report.

pub fn handler_mut(&mut self) -> &mut (dyn EyreHandler + 'static)

Get a mutable reference to the Handler for this Report.

Trait Implementations

impl AsRef<dyn Error> for Report

fn as_ref(&self) -> &(dyn Error + 'static)

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<dyn Error + Sync + Send> for Report

fn as_ref(&self) -> &(dyn Error + Sync + Send + 'static)

Converts this type into a shared reference of the (usually inferred) input type.

impl Debug for Report

fn fmt(&self, formatter: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Deref for Report

type Target = dyn Error + Sync + Send

The resulting type after dereferencing.

fn deref(&self) -> &<Report as Deref>::Target

Dereferences the value.

impl DerefMut for Report

fn deref_mut(&mut self) -> &mut <Report as Deref>::Target

Mutably dereferences the value.

impl Display for Report

fn fmt(&self, formatter: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Drop for Report

fn drop(&mut self)

Executes the destructor for this type.

impl<E> From<E> for Report

where E: Error + Send + Sync + 'static,

fn from(error: E) -> Report

Converts to this type from the input type.