Make clippy an optional dependency

Author: carols10cents

Cargo.toml

@@ -7,7 +7,7 @@ authors = ["Pradeep Gowda <[email protected]>"]
 [dependencies]
 glob = "*"
 clap = "*"
-clippy = "*"
+clippy = { version = "*", optional = true }
 
 [dependencies.url]
 version = "1.7.0"

src/lib.rs

@@ -1,5 +1,5 @@
-#![feature(plugin)]
-#![plugin(clippy)]
+#![cfg_attr(feature="clippy", feature(plugin))]
+#![cfg_attr(feature="clippy", plugin(clippy))]
 
 extern crate url;
 

src/main.rs

@@ -1,5 +1,5 @@
-#![feature(plugin)]
-#![plugin(clippy)]
+#![cfg_attr(feature="clippy", feature(plugin))]
+#![cfg_attr(feature="clippy", plugin(clippy))]
 
 extern crate clap;
 extern crate glob;