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Move error trait into core

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This commit is contained in:
Jane Losare-Lusby
2022-07-29 18:54:47 +00:00
committed by Jane Lusby
parent e0dc8d7801
commit bf7611d55e
25 changed files with 1264 additions and 226 deletions
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307
library/std/src/error.rs
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@@ -1,141 +1,4 @@
//! The `Error` trait provides common functionality for errors.
//!
//! # Error Handling In Rust
//!
//! The Rust language provides two complementary systems for constructing /
//! representing, reporting, propagating, reacting to, and discarding errors.
//! These responsibilities are collectively known as "error handling." The
//! components of the first system, the panic runtime and interfaces, are most
//! commonly used to represent bugs that have been detected in your program. The
//! components of the second system, `Result`, the error traits, and user
//! defined types, are used to represent anticipated runtime failure modes of
//! your program.
//!
//! ## The Panic Interfaces
//!
//! The following are the primary interfaces of the panic system and the
//! responsibilities they cover:
//!
//! * [`panic!`] and [`panic_any`] (Constructing, Propagated automatically)
//! * [`PanicInfo`] (Reporting)
//! * [`set_hook`], [`take_hook`], and [`#[panic_handler]`][panic-handler] (Reporting)
//! * [`catch_unwind`] and [`resume_unwind`] (Discarding, Propagating)
//!
//! The following are the primary interfaces of the error system and the
//! responsibilities they cover:
//!
//! * [`Result`] (Propagating, Reacting)
//! * The [`Error`] trait (Reporting)
//! * User defined types (Constructing / Representing)
//! * [`match`] and [`downcast`] (Reacting)
//! * The question mark operator ([`?`]) (Propagating)
//! * The partially stable [`Try`] traits (Propagating, Constructing)
//! * [`Termination`] (Reporting)
//!
//! ## Converting Errors into Panics
//!
//! The panic and error systems are not entirely distinct. Often times errors
//! that are anticipated runtime failures in an API might instead represent bugs
//! to a caller. For these situations the standard library provides APIs for
//! constructing panics with an `Error` as it's source.
//!
//! * [`Result::unwrap`]
//! * [`Result::expect`]
//!
//! These functions are equivalent, they either return the inner value if the
//! `Result` is `Ok` or panic if the `Result` is `Err` printing the inner error
//! as the source. The only difference between them is that with `expect` you
//! provide a panic error message to be printed alongside the source, whereas
//! `unwrap` has a default message indicating only that you unwraped an `Err`.
//!
//! Of the two, `expect` is generally preferred since its `msg` field allows you
//! to convey your intent and assumptions which makes tracking down the source
//! of a panic easier. `unwrap` on the other hand can still be a good fit in
//! situations where you can trivially show that a piece of code will never
//! panic, such as `"127.0.0.1".parse::<std::net::IpAddr>().unwrap()` or early
//! prototyping.
//!
//! # Common Message Styles
//!
//! There are two common styles for how people word `expect` messages. Using
//! the message to present information to users encountering a panic
//! ("expect as error message") or using the message to present information
//! to developers debugging the panic ("expect as precondition").
//!
//! In the former case the expect message is used to describe the error that
//! has occurred which is considered a bug. Consider the following example:
//!
//! ```should_panic
//! // Read environment variable, panic if it is not present
//! let path = std::env::var("IMPORTANT_PATH").unwrap();
//! ```
//!
//! In the "expect as error message" style we would use expect to describe
//! that the environment variable was not set when it should have been:
//!
//! ```should_panic
//! let path = std::env::var("IMPORTANT_PATH")
//! .expect("env variable `IMPORTANT_PATH` is not set");
//! ```
//!
//! In the "expect as precondition" style, we would instead describe the
//! reason we _expect_ the `Result` should be `Ok`. With this style we would
//! prefer to write:
//!
//! ```should_panic
//! let path = std::env::var("IMPORTANT_PATH")
//! .expect("env variable `IMPORTANT_PATH` should be set by `wrapper_script.sh`");
//! ```
//!
//! The "expect as error message" style does not work as well with the
//! default output of the std panic hooks, and often ends up repeating
//! information that is already communicated by the source error being
//! unwrapped:
//!
//! ```text
//! thread 'main' panicked at 'env variable `IMPORTANT_PATH` is not set: NotPresent', src/main.rs:4:6
//! ```
//!
//! In this example we end up mentioning that an env variable is not set,
//! followed by our source message that says the env is not present, the
//! only additional information we're communicating is the name of the
//! environment variable being checked.
//!
//! The "expect as precondition" style instead focuses on source code
//! readability, making it easier to understand what must have gone wrong in
//! situations where panics are being used to represent bugs exclusively.
//! Also, by framing our expect in terms of what "SHOULD" have happened to
//! prevent the source error, we end up introducing new information that is
//! independent from our source error.
//!
//! ```text
//! thread 'main' panicked at 'env variable `IMPORTANT_PATH` should be set by `wrapper_script.sh`: NotPresent', src/main.rs:4:6
//! ```
//!
//! In this example we are communicating not only the name of the
//! environment variable that should have been set, but also an explanation
//! for why it should have been set, and we let the source error display as
//! a clear contradiction to our expectation.
//!
//! **Hint**: If you're having trouble remembering how to phrase
//! expect-as-precondition style error messages remember to focus on the word
//! "should" as in "env variable should be set by blah" or "the given binary
//! should be available and executable by the current user".
//!
//! [`panic_any`]: crate::panic::panic_any
//! [`PanicInfo`]: crate::panic::PanicInfo
//! [`catch_unwind`]: crate::panic::catch_unwind
//! [`resume_unwind`]: crate::panic::resume_unwind
//! [`downcast`]: crate::error::Error
//! [`Termination`]: crate::process::Termination
//! [`Try`]: crate::ops::Try
//! [panic hook]: crate::panic::set_hook
//! [`set_hook`]: crate::panic::set_hook
//! [`take_hook`]: crate::panic::take_hook
//! [panic-handler]: <https://doc.rust-lang.org/nomicon/panic-handler.html>
//! [`match`]: ../../std/keyword.match.html
//! [`?`]: ../../std/result/index.html#the-question-mark-operator-
#![doc = include_str!("../../core/src/error.md")]
#![stable(feature = "rust1", since = "1.0.0")]
// A note about crates and the facade:
@@ -152,24 +15,48 @@
#[cfg(test)]
mod tests;
#[cfg(bootstrap)]
use core::array;
#[cfg(bootstrap)]
use core::convert::Infallible;
#[cfg(bootstrap)]
use crate::alloc::{AllocError, LayoutError};
use crate::any::{Demand, Provider, TypeId};
#[cfg(bootstrap)]
use crate::any::Demand;
#[cfg(bootstrap)]
use crate::any::{Provider, TypeId};
use crate::backtrace::Backtrace;
#[cfg(bootstrap)]
use crate::borrow::Cow;
#[cfg(bootstrap)]
use crate::cell;
#[cfg(bootstrap)]
use crate::char;
use crate::fmt::{self, Debug, Display, Write};
#[cfg(bootstrap)]
use crate::fmt::Debug;
#[cfg(bootstrap)]
use crate::fmt::Display;
use crate::fmt::{self, Write};
#[cfg(bootstrap)]
use crate::io;
#[cfg(bootstrap)]
use crate::mem::transmute;
#[cfg(bootstrap)]
use crate::num;
#[cfg(bootstrap)]
use crate::str;
#[cfg(bootstrap)]
use crate::string;
#[cfg(bootstrap)]
use crate::sync::Arc;
#[cfg(bootstrap)]
use crate::time;
#[cfg(not(bootstrap))]
#[stable(feature = "rust1", since = "1.0.0")]
pub use core::error::Error;
/// `Error` is a trait representing the basic expectations for error values,
/// i.e., values of type `E` in [`Result<T, E>`].
///
@@ -190,6 +77,7 @@ use crate::time;
/// implementation for debugging via `source` chains.
#[stable(feature = "rust1", since = "1.0.0")]
#[cfg_attr(not(test), rustc_diagnostic_item = "Error")]
#[cfg(bootstrap)]
pub trait Error: Debug + Display {
/// The lower-level source of this error, if any.
///
@@ -355,6 +243,7 @@ pub trait Error: Debug + Display {
fn provide<'a>(&'a self, req: &mut Demand<'a>) {}
}
#[cfg(bootstrap)]
#[unstable(feature = "error_generic_member_access", issue = "99301")]
impl<'b> Provider for dyn Error + 'b {
fn provide<'a>(&'a self, req: &mut Demand<'a>) {
@@ -370,6 +259,7 @@ mod private {
pub struct Internal;
}
#[cfg(bootstrap)]
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, E: Error + 'a> From<E> for Box<dyn Error + 'a> {
/// Converts a type of [`Error`] into a box of dyn [`Error`].
@@ -402,6 +292,7 @@ impl<'a, E: Error + 'a> From<E> for Box<dyn Error + 'a> {
}
}
#[cfg(bootstrap)]
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, E: Error + Send + Sync + 'a> From<E> for Box<dyn Error + Send + Sync + 'a> {
/// Converts a type of [`Error`] + [`Send`] + [`Sync`] into a box of
@@ -440,6 +331,7 @@ impl<'a, E: Error + Send + Sync + 'a> From<E> for Box<dyn Error + Send + Sync +
}
}
#[cfg(bootstrap)]
#[stable(feature = "rust1", since = "1.0.0")]
impl From<String> for Box<dyn Error + Send + Sync> {
/// Converts a [`String`] into a box of dyn [`Error`] + [`Send`] + [`Sync`].
@@ -483,6 +375,7 @@ impl From<String> for Box<dyn Error + Send + Sync> {
}
}
#[cfg(bootstrap)]
#[stable(feature = "string_box_error", since = "1.6.0")]
impl From<String> for Box<dyn Error> {
/// Converts a [`String`] into a box of dyn [`Error`].
@@ -504,6 +397,7 @@ impl From<String> for Box<dyn Error> {
}
}
#[cfg(bootstrap)]
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> From<&str> for Box<dyn Error + Send + Sync + 'a> {
/// Converts a [`str`] into a box of dyn [`Error`] + [`Send`] + [`Sync`].
@@ -527,6 +421,7 @@ impl<'a> From<&str> for Box<dyn Error + Send + Sync + 'a> {
}
}
#[cfg(bootstrap)]
#[stable(feature = "string_box_error", since = "1.6.0")]
impl From<&str> for Box<dyn Error> {
/// Converts a [`str`] into a box of dyn [`Error`].
@@ -548,6 +443,7 @@ impl From<&str> for Box<dyn Error> {
}
}
#[cfg(bootstrap)]
#[stable(feature = "cow_box_error", since = "1.22.0")]
impl<'a, 'b> From<Cow<'b, str>> for Box<dyn Error + Send + Sync + 'a> {
/// Converts a [`Cow`] into a box of dyn [`Error`] + [`Send`] + [`Sync`].
@@ -569,6 +465,7 @@ impl<'a, 'b> From<Cow<'b, str>> for Box<dyn Error + Send + Sync + 'a> {
}
}
#[cfg(bootstrap)]
#[stable(feature = "cow_box_error", since = "1.22.0")]
impl<'a> From<Cow<'a, str>> for Box<dyn Error> {
/// Converts a [`Cow`] into a box of dyn [`Error`].
@@ -589,9 +486,11 @@ impl<'a> From<Cow<'a, str>> for Box<dyn Error> {
}
}
#[cfg(bootstrap)]
#[unstable(feature = "never_type", issue = "35121")]
impl Error for ! {}
#[cfg(bootstrap)]
#[unstable(
feature = "allocator_api",
reason = "the precise API and guarantees it provides may be tweaked.",
@@ -599,9 +498,11 @@ impl Error for ! {}
)]
impl Error for AllocError {}
#[cfg(bootstrap)]
#[stable(feature = "alloc_layout", since = "1.28.0")]
impl Error for LayoutError {}
#[cfg(bootstrap)]
#[stable(feature = "rust1", since = "1.0.0")]
impl Error for str::ParseBoolError {
#[allow(deprecated)]
@@ -610,6 +511,7 @@ impl Error for str::ParseBoolError {
}
}
#[cfg(bootstrap)]
#[stable(feature = "rust1", since = "1.0.0")]
impl Error for str::Utf8Error {
#[allow(deprecated)]
@@ -618,6 +520,7 @@ impl Error for str::Utf8Error {
}
}
#[cfg(bootstrap)]
#[stable(feature = "rust1", since = "1.0.0")]
impl Error for num::ParseIntError {
#[allow(deprecated)]
@@ -626,6 +529,7 @@ impl Error for num::ParseIntError {
}
}
#[cfg(bootstrap)]
#[stable(feature = "try_from", since = "1.34.0")]
impl Error for num::TryFromIntError {
#[allow(deprecated)]
@@ -634,6 +538,7 @@ impl Error for num::TryFromIntError {
}
}
#[cfg(bootstrap)]
#[stable(feature = "try_from", since = "1.34.0")]
impl Error for array::TryFromSliceError {
#[allow(deprecated)]
@@ -642,6 +547,7 @@ impl Error for array::TryFromSliceError {
}
}
#[cfg(bootstrap)]
#[stable(feature = "rust1", since = "1.0.0")]
impl Error for num::ParseFloatError {
#[allow(deprecated)]
@@ -650,6 +556,7 @@ impl Error for num::ParseFloatError {
}
}
#[cfg(bootstrap)]
#[stable(feature = "rust1", since = "1.0.0")]
impl Error for string::FromUtf8Error {
#[allow(deprecated)]
@@ -658,6 +565,7 @@ impl Error for string::FromUtf8Error {
}
}
#[cfg(bootstrap)]
#[stable(feature = "rust1", since = "1.0.0")]
impl Error for string::FromUtf16Error {
#[allow(deprecated)]
@@ -666,6 +574,7 @@ impl Error for string::FromUtf16Error {
}
}
#[cfg(bootstrap)]
#[stable(feature = "str_parse_error2", since = "1.8.0")]
impl Error for Infallible {
fn description(&self) -> &str {
@@ -673,6 +582,7 @@ impl Error for Infallible {
}
}
#[cfg(bootstrap)]
#[stable(feature = "decode_utf16", since = "1.9.0")]
impl Error for char::DecodeUtf16Error {
#[allow(deprecated)]
@@ -681,9 +591,11 @@ impl Error for char::DecodeUtf16Error {
}
}
#[cfg(bootstrap)]
#[stable(feature = "u8_from_char", since = "1.59.0")]
impl Error for char::TryFromCharError {}
#[cfg(bootstrap)]
#[unstable(feature = "map_try_insert", issue = "82766")]
impl<'a, K: Debug + Ord, V: Debug> Error
for crate::collections::btree_map::OccupiedError<'a, K, V>
@@ -694,6 +606,7 @@ impl<'a, K: Debug + Ord, V: Debug> Error
}
}
#[cfg(bootstrap)]
#[unstable(feature = "map_try_insert", issue = "82766")]
impl<'a, K: Debug, V: Debug> Error for crate::collections::hash_map::OccupiedError<'a, K, V> {
#[allow(deprecated)]
@@ -702,6 +615,7 @@ impl<'a, K: Debug, V: Debug> Error for crate::collections::hash_map::OccupiedErr
}
}
#[cfg(bootstrap)]
#[stable(feature = "box_error", since = "1.8.0")]
impl<T: Error> Error for Box<T> {
#[allow(deprecated, deprecated_in_future)]
@@ -719,6 +633,7 @@ impl<T: Error> Error for Box<T> {
}
}
#[cfg(bootstrap)]
#[unstable(feature = "thin_box", issue = "92791")]
impl<T: ?Sized + crate::error::Error> crate::error::Error for crate::boxed::ThinBox<T> {
fn source(&self) -> Option<&(dyn crate::error::Error + 'static)> {
@@ -727,6 +642,7 @@ impl<T: ?Sized + crate::error::Error> crate::error::Error for crate::boxed::Thin
}
}
#[cfg(bootstrap)]
#[stable(feature = "error_by_ref", since = "1.51.0")]
impl<'a, T: Error + ?Sized> Error for &'a T {
#[allow(deprecated, deprecated_in_future)]
@@ -748,6 +664,7 @@ impl<'a, T: Error + ?Sized> Error for &'a T {
}
}
#[cfg(bootstrap)]
#[stable(feature = "arc_error", since = "1.52.0")]
impl<T: Error + ?Sized> Error for Arc<T> {
#[allow(deprecated, deprecated_in_future)]
@@ -769,6 +686,7 @@ impl<T: Error + ?Sized> Error for Arc<T> {
}
}
#[cfg(bootstrap)]
#[stable(feature = "fmt_error", since = "1.11.0")]
impl Error for fmt::Error {
#[allow(deprecated)]
@@ -777,6 +695,7 @@ impl Error for fmt::Error {
}
}
#[cfg(bootstrap)]
#[stable(feature = "try_borrow", since = "1.13.0")]
impl Error for cell::BorrowError {
#[allow(deprecated)]
@@ -785,6 +704,7 @@ impl Error for cell::BorrowError {
}
}
#[cfg(bootstrap)]
#[stable(feature = "try_borrow", since = "1.13.0")]
impl Error for cell::BorrowMutError {
#[allow(deprecated)]
@@ -793,6 +713,7 @@ impl Error for cell::BorrowMutError {
}
}
#[cfg(bootstrap)]
#[stable(feature = "try_from", since = "1.34.0")]
impl Error for char::CharTryFromError {
#[allow(deprecated)]
@@ -801,6 +722,7 @@ impl Error for char::CharTryFromError {
}
}
#[cfg(bootstrap)]
#[stable(feature = "char_from_str", since = "1.20.0")]
impl Error for char::ParseCharError {
#[allow(deprecated)]
@@ -809,12 +731,15 @@ impl Error for char::ParseCharError {
}
}
#[cfg(bootstrap)]
#[stable(feature = "try_reserve", since = "1.57.0")]
impl Error for alloc::collections::TryReserveError {}
#[cfg(bootstrap)]
#[unstable(feature = "duration_checked_float", issue = "83400")]
impl Error for time::FromFloatSecsError {}
#[cfg(bootstrap)]
#[stable(feature = "rust1", since = "1.0.0")]
impl Error for alloc::ffi::NulError {
#[allow(deprecated)]
@@ -823,6 +748,7 @@ impl Error for alloc::ffi::NulError {
}
}
#[cfg(bootstrap)]
#[stable(feature = "rust1", since = "1.0.0")]
impl From<alloc::ffi::NulError> for io::Error {
/// Converts a [`alloc::ffi::NulError`] into a [`io::Error`].
@@ -831,6 +757,7 @@ impl From<alloc::ffi::NulError> for io::Error {
}
}
#[cfg(bootstrap)]
#[stable(feature = "frombyteswithnulerror_impls", since = "1.17.0")]
impl Error for core::ffi::FromBytesWithNulError {
#[allow(deprecated)]
@@ -839,12 +766,15 @@ impl Error for core::ffi::FromBytesWithNulError {
}
}
#[cfg(bootstrap)]
#[unstable(feature = "cstr_from_bytes_until_nul", issue = "95027")]
impl Error for core::ffi::FromBytesUntilNulError {}
#[cfg(bootstrap)]
#[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
impl Error for alloc::ffi::FromVecWithNulError {}
#[cfg(bootstrap)]
#[stable(feature = "cstring_into", since = "1.7.0")]
impl Error for alloc::ffi::IntoStringError {
#[allow(deprecated)]
@@ -857,6 +787,7 @@ impl Error for alloc::ffi::IntoStringError {
}
}
#[cfg(bootstrap)]
impl<'a> dyn Error + 'a {
/// Request a reference of type `T` as context about this error.
#[unstable(feature = "error_generic_member_access", issue = "99301")]
@@ -872,6 +803,7 @@ impl<'a> dyn Error + 'a {
}
// Copied from `any.rs`.
#[cfg(bootstrap)]
impl dyn Error + 'static {
/// Returns `true` if the inner type is the same as `T`.
#[stable(feature = "error_downcast", since = "1.3.0")]
@@ -912,6 +844,7 @@ impl dyn Error + 'static {
}
}
#[cfg(bootstrap)]
impl dyn Error + 'static + Send {
/// Forwards to the method defined on the type `dyn Error`.
#[stable(feature = "error_downcast", since = "1.3.0")]
@@ -947,6 +880,7 @@ impl dyn Error + 'static + Send {
}
}
#[cfg(bootstrap)]
impl dyn Error + 'static + Send + Sync {
/// Forwards to the method defined on the type `dyn Error`.
#[stable(feature = "error_downcast", since = "1.3.0")]
@@ -982,6 +916,7 @@ impl dyn Error + 'static + Send + Sync {
}
}
#[cfg(bootstrap)]
impl dyn Error {
#[inline]
#[stable(feature = "error_downcast", since = "1.3.0")]
@@ -1061,10 +996,12 @@ impl dyn Error {
/// its sources, use `skip(1)`.
#[unstable(feature = "error_iter", issue = "58520")]
#[derive(Clone, Debug)]
#[cfg(bootstrap)]
pub struct Chain<'a> {
current: Option<&'a (dyn Error + 'static)>,
}
#[cfg(bootstrap)]
#[unstable(feature = "error_iter", issue = "58520")]
impl<'a> Iterator for Chain<'a> {
type Item = &'a (dyn Error + 'static);
@@ -1076,6 +1013,7 @@ impl<'a> Iterator for Chain<'a> {
}
}
#[cfg(bootstrap)]
impl dyn Error + Send {
#[inline]
#[stable(feature = "error_downcast", since = "1.3.0")]
@@ -1089,6 +1027,7 @@ impl dyn Error + Send {
}
}
#[cfg(bootstrap)]
impl dyn Error + Send + Sync {
#[inline]
#[stable(feature = "error_downcast", since = "1.3.0")]
@@ -1246,7 +1185,7 @@ impl dyn Error + Send + Sync {
/// # Err(SuperError { source: SuperErrorSideKick })
/// # }
///
/// fn main() -> Result<(), Report> {
/// fn main() -> Result<(), Report<SuperError>> {
/// get_super_error()?;
/// Ok(())
/// }
@@ -1293,7 +1232,7 @@ impl dyn Error + Send + Sync {
/// # Err(SuperError { source: SuperErrorSideKick })
/// # }
///
/// fn main() -> Result<(), Report> {
/// fn main() -> Result<(), Report<SuperError>> {
/// get_super_error()
/// .map_err(Report::from)
/// .map_err(|r| r.pretty(true).show_backtrace(true))?;
@@ -1605,72 +1544,6 @@ where
}
}
impl Report<Box<dyn Error>> {
fn backtrace(&self) -> Option<&Backtrace> {
// have to grab the backtrace on the first error directly since that error may not be
// 'static
let backtrace = self.error.request_ref();
let backtrace = backtrace.or_else(|| {
self.error
.source()
.map(|source| source.chain().find_map(|source| source.request_ref()))
.flatten()
});
backtrace
}
/// Format the report as a single line.
#[unstable(feature = "error_reporter", issue = "90172")]
fn fmt_singleline(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", self.error)?;
let sources = self.error.source().into_iter().flat_map(<dyn Error>::chain);
for cause in sources {
write!(f, ": {cause}")?;
}
Ok(())
}
/// Format the report as multiple lines, with each error cause on its own line.
#[unstable(feature = "error_reporter", issue = "90172")]
fn fmt_multiline(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let error = &self.error;
write!(f, "{error}")?;
if let Some(cause) = error.source() {
write!(f, "\n\nCaused by:")?;
let multiple = cause.source().is_some();
for (ind, error) in cause.chain().enumerate() {
writeln!(f)?;
let mut indented = Indented { inner: f };
if multiple {
write!(indented, "{ind: >4}: {error}")?;
} else {
write!(indented, " {error}")?;
}
}
}
if self.show_backtrace {
let backtrace = self.backtrace();
if let Some(backtrace) = backtrace {
let backtrace = backtrace.to_string();
f.write_str("\n\nStack backtrace:\n")?;
f.write_str(backtrace.trim_end())?;
}
}
Ok(())
}
}
#[unstable(feature = "error_reporter", issue = "90172")]
impl<E> From<E> for Report<E>
where
@@ -1681,17 +1554,6 @@ where
}
}
#[unstable(feature = "error_reporter", issue = "90172")]
impl<'a, E> From<E> for Report<Box<dyn Error + 'a>>
where
E: Error + 'a,
{
fn from(error: E) -> Self {
let error = box error;
Report { error, show_backtrace: false, pretty: false }
}
}
#[unstable(feature = "error_reporter", issue = "90172")]
impl<E> fmt::Display for Report<E>
where
@@ -1702,13 +1564,6 @@ where
}
}
#[unstable(feature = "error_reporter", issue = "90172")]
impl fmt::Display for Report<Box<dyn Error>> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if self.pretty { self.fmt_multiline(f) } else { self.fmt_singleline(f) }
}
}
// This type intentionally outputs the same format for `Display` and `Debug`for
// situations where you unwrap a `Report` or return it from main.
#[unstable(feature = "error_reporter", issue = "90172")]