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Address Review Findings
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‎src/no_std_error.rs‎

Lines changed: 33 additions & 185 deletions
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@@ -1,199 +1,47 @@
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#![allow(missing_docs)]
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use core::fmt::{Debug, Display};
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/// `Error` is a trait representing the basic expectations for error values,
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/// i.e., values of type `E` in `Result<T, E>`. Errors must describe
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/// themselves through the `Display` and `Debug` traits, and may provide
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/// cause chain information:
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///
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/// The [`source`] method is generally used when errors cross "abstraction
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/// boundaries". If one module must report an error that is caused by an error
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/// from a lower-level module, it can allow access to that error via the
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/// [`source`] method. This makes it possible for the high-level module to
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/// provide its own errors while also revealing some of the implementation for
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/// debugging via [`source`] chains.
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///
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/// [`source`]: trait.Error.html#method.source
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pub trait Error: Debug + Display {
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/// **This method is soft-deprecated.**
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///
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/// Although using it won’t cause compilation warning,
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/// new code should use `Display` instead
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/// and new `impl`s can omit it.
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///
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/// To obtain error description as a string, use `to_string()`.
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///
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/// # Examples
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///
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/// ```
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/// match "xc".parse::<u32>() {
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/// Err(e) => {
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/// // Print `e` itself, not `e.description()`.
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/// println!("Error: {}", e);
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/// }
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/// _ => println!("No error"),
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/// }
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/// ```
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fn description(&self) -> &str {
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"description() is deprecated; use Display"
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}
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/// The lower-level cause of this error, if any.
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///
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/// # Examples
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///
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/// ```
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/// use snafu::Error;
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/// use core::fmt;
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///
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/// #[derive(Debug)]
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/// struct SuperError {
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/// side: SuperErrorSideKick,
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/// }
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///
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/// impl fmt::Display for SuperError {
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/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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/// write!(f, "SuperError is here!")
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/// }
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/// }
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///
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/// impl Error for SuperError {
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/// fn description(&self) -> &str {
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/// "I'm the superhero of errors"
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/// }
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///
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/// fn cause(&self) -> Option<&dyn Error> {
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/// Some(&self.side)
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/// }
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/// }
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///
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/// #[derive(Debug)]
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/// struct SuperErrorSideKick;
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///
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/// impl fmt::Display for SuperErrorSideKick {
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/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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/// write!(f, "SuperErrorSideKick is here!")
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/// }
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/// }
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///
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/// impl Error for SuperErrorSideKick {
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/// fn description(&self) -> &str {
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/// "I'm SuperError side kick"
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/// }
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/// }
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///
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/// fn get_super_error() -> Result<(), SuperError> {
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/// Err(SuperError { side: SuperErrorSideKick })
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/// }
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///
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/// fn main() {
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/// match get_super_error() {
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/// Err(e) => {
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/// println!("Error: {}", e.description());
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/// println!("Caused by: {}", e.cause().unwrap());
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/// }
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/// _ => println!("No error"),
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/// }
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/// }
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/// ```
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fn cause(&self) -> Option<&dyn Error> {
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fn cause(&self) -> Option<&Error> {
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self.source()
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}
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/// The lower-level source of this error, if any.
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///
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/// # Examples
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///
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/// ```
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/// use snafu::Error;
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/// use core::fmt;
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///
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/// #[derive(Debug)]
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/// struct SuperError {
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/// side: SuperErrorSideKick,
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/// }
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///
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/// impl fmt::Display for SuperError {
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/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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/// write!(f, "SuperError is here!")
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/// }
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/// }
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///
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/// impl Error for SuperError {
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/// fn description(&self) -> &str {
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/// "I'm the superhero of errors"
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/// }
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///
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/// fn source(&self) -> Option<&(dyn Error + 'static)> {
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/// Some(&self.side)
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/// }
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/// }
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///
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/// #[derive(Debug)]
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/// struct SuperErrorSideKick;
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///
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/// impl fmt::Display for SuperErrorSideKick {
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/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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/// write!(f, "SuperErrorSideKick is here!")
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/// }
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/// }
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///
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/// impl Error for SuperErrorSideKick {
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/// fn description(&self) -> &str {
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/// "I'm SuperError side kick"
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/// }
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/// }
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///
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/// fn get_super_error() -> Result<(), SuperError> {
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/// Err(SuperError { side: SuperErrorSideKick })
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/// }
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///
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/// fn main() {
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/// match get_super_error() {
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/// Err(e) => {
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/// println!("Error: {}", e.description());
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/// println!("Caused by: {}", e.source().unwrap());
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/// }
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/// _ => println!("No error"),
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/// }
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/// }
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/// ```
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fn source(&self) -> Option<&(dyn Error + 'static)> {
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fn source(&self) -> Option<&(Error + 'static)> {
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None
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}
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}
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impl Error for core::str::ParseBoolError {
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fn description(&self) -> &str {
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"failed to parse bool"
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}
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}
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impl Error for core::str::Utf8Error {
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fn description(&self) -> &str {
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"invalid utf-8: corrupt contents"
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}
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}
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impl Error for core::num::ParseIntError {}
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impl Error for core::num::TryFromIntError {}
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impl Error for core::array::TryFromSliceError {}
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impl Error for core::num::ParseFloatError {}
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impl Error for core::fmt::Error {
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fn description(&self) -> &str {
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"an error occurred when formatting an argument"
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}
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}
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impl Error for core::cell::BorrowError {
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fn description(&self) -> &str {
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"already mutably borrowed"
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}
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}
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impl Error for core::cell::BorrowMutError {
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fn description(&self) -> &str {
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"already borrowed"
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macro_rules! impl_error {
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($($e:path),*) => {
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$(
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impl Error for $e {}
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)*
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}
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}
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impl Error for core::char::CharTryFromError {
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fn description(&self) -> &str {
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"converted integer out of range for `char`"
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}
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}
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impl Error for core::char::ParseCharError {}
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// All errors supported by our minimum suported Rust version can be supported by
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// default.
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impl_error![
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core::str::ParseBoolError, // 1.0
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core::str::Utf8Error, // 1.0
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core::num::ParseIntError, // 1.0
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core::num::ParseFloatError, // 1.0
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core::char::DecodeUtf16Error, // 1.9
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core::fmt::Error, // 1.11
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core::cell::BorrowMutError, // 1.13
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core::cell::BorrowError // 1.13
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];
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#[cfg(feature = "rust_1_30")]
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impl_error![core::char::ParseCharError]; // 1.20
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// We can gate these together with std futures.
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#[cfg(feature = "unstable-futures")]
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impl_error![
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core::num::TryFromIntError, // 1.34
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core::array::TryFromSliceError, // 1.34
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core::char::CharTryFromError // 1.34
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];

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