From 81f906ca30ebe3ff95f4b64612c702b1abdf34eb Mon Sep 17 00:00:00 2001
From: Isis Lovecruft <isis@patternsinthevoid.net>
Date: Sat, 26 Oct 2019 04:16:33 +0000
Subject: [PATCH] Replace failure dependency with impls of std::error::Error.

---
 Cargo.toml    |  1 -
 src/errors.rs | 11 ++++++++---
 src/lib.rs    |  1 -
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 7c582b1..27838cc 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,7 +19,6 @@ travis-ci = { repository = "dalek-cryptography/ed25519-dalek", branch = "master"
 [dependencies]
 clear_on_drop = { version = "0.2" }
 curve25519-dalek = { version = "1", default-features = false }
-failure = { version = "0.1", default-features = false }
 rand = { version = "0.7", default-features = false, optional = true }
 serde = { version = "1.0", optional = true }
 sha2 = { version = "0.8", default-features = false }
diff --git a/src/errors.rs b/src/errors.rs
index 6597f73..ba59180 100644
--- a/src/errors.rs
+++ b/src/errors.rs
@@ -16,6 +16,9 @@
 use core::fmt;
 use core::fmt::Display;
 
+#[cfg(feature = "std")]
+use std::error::Error;
+
 /// Internal errors.  Most application-level developers will likely not
 /// need to pay any attention to these.
 #[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
@@ -50,7 +53,8 @@ impl Display for InternalError {
     }
 }
 
-impl ::failure::Fail for InternalError {}
+#[cfg(feature = "std")]
+impl Error for InternalError { }
 
 /// Errors which may occur while processing signatures and keypairs.
 ///
@@ -75,8 +79,9 @@ impl Display for SignatureError {
     }
 }
 
-impl ::failure::Fail for SignatureError {
-    fn cause(&self) -> Option<&dyn (::failure::Fail)> {
+#[cfg(feature = "std")]
+impl Error for SignatureError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
         Some(&self.0)
     }
 }
diff --git a/src/lib.rs b/src/lib.rs
index e40f4d5..92f1d45 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -241,7 +241,6 @@ extern crate std;
 extern crate alloc;
 extern crate clear_on_drop;
 extern crate curve25519_dalek;
-extern crate failure;
 #[cfg(any(feature = "batch", feature = "std", feature = "alloc", test))]
 extern crate rand;
 #[cfg(feature = "serde")]