Replace std::error::Error with core_error::Error

Cargo.toml

@@ -17,11 +17,15 @@ path = "./failure_derive"
 optional = true
 version = "0.3.3"
 
+[dependencies.core-error]
+version = "0.0.1-rc3"
+
 [workspace]
 members = [".", "failure_derive"]
 
 [features]
 default = ["std", "derive"]
 #small-error = ["std"]
-std = ["backtrace"]
-derive = ["failure_derive"]
+std = ["backtrace", "core-error/std"]
+alloc = ["core-error/alloc"]
+derive = ["failure_derive"]

README.md

@@ -105,7 +105,9 @@ If either crate fails to compile on any version newer than 1.31.0, please open
 an issue.
 
 failure is **no_std** compatible, though some aspects of it (primarily the
-`Error` type) will not be available in no_std mode.
+`Error` type) will not be available in no_std mode. Additionally, uses of the
+`std::error::Error` trait (such as in the `Compat` struct) are replaced with
+the [core_error] trait to be compatible with other error handling crates.
 
 ## License
 

src/box_std.rs

@@ -1,4 +1,4 @@
-use std::error::Error;
+use core_error::Error;
 use std::fmt;
 use Fail;
 

src/compat.rs

@@ -1,9 +1,12 @@
-use core::fmt::{self, Display};
+use core::fmt::{self, Display, Debug};
+use core_error::Error as StdError;
 
 /// A compatibility wrapper around an error type from this crate.
 ///
 /// `Compat` implements `std::error::Error`, allowing the types from this
 /// crate to be passed to interfaces that expect a type of that trait.
+///
+/// In `no_std`, `Compat` implements `core_error::Error`.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash, Default)]
 pub struct Compat<E> {
  pub(crate) error: E,
@@ -27,18 +30,12 @@ impl<E> Compat<E> {
  }
 }
 
+impl<E: Display + Debug> StdError for Compat<E> {}
+
 with_std! {
- use std::fmt::Debug;
- use std::error::Error as StdError;
 
  use Error;
 
- impl<E: Display + Debug> StdError for Compat<E> {
- fn description(&self) -> &'static str {
- "An error has occurred."
- }
- }
-
  impl From<Error> for Box<dyn StdError> {
  fn from(error: Error) -> Box<dyn StdError> {
  Box::new(Compat { error })

src/error/mod.rs

@@ -12,8 +12,7 @@ use box_std::BoxStd;
 mod error_impl;
 use self::error_impl::ErrorImpl;
 
-#[cfg(feature = "std")]
-use std::error::Error as StdError;
+use core_error::Error as StdError;
 
 
 /// The `Error` type, which can contain any failure.

src/lib.rs

@@ -33,6 +33,8 @@ macro_rules! without_std { ($($i:item)*) => ($(#[cfg(not(feature = "std"))]$i)*)
 #[doc(hidden)]
 pub extern crate core as _core;
 
+extern crate core_error;
+
 mod as_fail;
 mod backtrace;
 #[cfg(feature = "std")]
@@ -59,6 +61,8 @@ extern crate failure_derive;
 #[doc(hidden)]
 pub use failure_derive::*;
 
+use core_error::Error as StdError;
+
 with_std! {
  extern crate core;
 
@@ -67,8 +71,6 @@ with_std! {
 
  mod error;
 
- use std::error::Error as StdError;
-
  pub use error::Error;
 
  /// A common result with an `Error`.
@@ -269,7 +271,6 @@ impl dyn Fail {
  }
 }
 
-#[cfg(feature = "std")]
 impl<E: StdError + Send + Sync + 'static> Fail for E {}
 
 #[cfg(feature = "std")]

src/sync_failure.rs

@@ -1,5 +1,5 @@
 use Fail;
-use std::error::Error;
+use core_error::Error;
 use std::fmt::{self, Debug, Display};
 use std::sync::Mutex;