Update err-derive.

Cargo.toml

@@ -1,6 +1,7 @@
 [package]
 name = "signifix"
 version = "0.10.0"
+edition = "2018"
 authors = [
 	"Rouven Spreckels <n3vu0r@qu1x.org>",
 ]
@@ -34,4 +35,4 @@ include = [
 travis-ci = { repository = "qu1x/signifix" }
 
 [dependencies]
-err-derive = "0.1"
+err-derive = "0.2"

src/binary.rs

@@ -6,6 +6,8 @@
 //
 // DISCLAIMER: THE WORKS ARE WITHOUT WARRANTY.
 
+use err_derive::Error;
+
 use std::convert::TryFrom;
 
 use std::result;

src/lib.rs

@@ -369,8 +369,7 @@
 
 #![deny(missing_docs)]
 
-#[macro_use]
-extern crate err_derive;
+use err_derive::Error;
 
 use std::result;
 
@@ -451,23 +450,11 @@ pub mod binary;
 pub enum Error {
 	/// A given number is not representable with any metric prefix.
 	#[error(display = "Not representable with any metric prefix")]
-	Metric(#[cause] metric::Error),
+	Metric(#[source] metric::Error),
 
 	/// A given number is not representable with any binary prefix.
 	#[error(display = "Not representable with any binary prefix")]
-	Binary(#[cause] binary::Error),
-}
-
-impl From<metric::Error> for Error {
-	fn from(error: metric::Error) -> Self {
-		Error::Metric(error)
-	}
-}
-
-impl From<binary::Error> for Error {
-	fn from(error: binary::Error) -> Self {
-		Error::Binary(error)
-	}
+	Binary(#[source] binary::Error),
 }
 
 /// The canonical `Result` type using this crate's `Error` type.

src/metric.rs

@@ -6,6 +6,8 @@
 //
 // DISCLAIMER: THE WORKS ARE WITHOUT WARRANTY.
 
+use err_derive::Error;
+
 use std::convert::TryFrom;
 
 use std::result;