auto merge of #18467 : japaric/rust/eq, r=alexcrichton

`eq`, `ne`, `cmp`, etc methods now require one less level of indirection when dealing with `&str`/`&[T]`

``` rust
"foo".ne(&"bar") -> "foo".ne("bar")
slice.cmp(&another_slice) -> slice.cmp(another_slice)
// slice and another_slice have type `&[T]`
```

[breaking-change]

src/test/compile-fail/deriving-no-inner-impl-error-message.rs

@@ -12,8 +12,8 @@ struct NoCloneOrEq;
 
 #[deriving(PartialEq)]
 struct E {
-    x: NoCloneOrEq //~ ERROR does not implement any method in scope named `eq`
-         //~^ ERROR does not implement any method in scope named `ne`
+    x: NoCloneOrEq //~ ERROR binary operation `==` cannot be applied to type `NoCloneOrEq`
+         //~^ ERROR binary operation `!=` cannot be applied to type `NoCloneOrEq`
 }
 #[deriving(Clone)]
 struct C {

src/test/run-pass/deriving-eq-ord-boxed-slice.rs

@@ -0,0 +1,24 @@
+// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[deriving(PartialEq, PartialOrd, Eq, Ord)]
+struct Foo(Box<[u8]>);
+
+pub fn main() {
+    let a = Foo(box [0, 1, 2]);
+    let b = Foo(box [0, 1, 2]);
+    assert!(a == b);
+    println!("{}", a != b);
+    println!("{}", a < b);
+    println!("{}", a <= b);
+    println!("{}", a == b);
+    println!("{}", a > b);
+    println!("{}", a >= b);
+}

src/test/run-pass/issue-15689-1.rs

@@ -0,0 +1,18 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[deriving(PartialEq)]
+enum Test<'a> {
+    Slice(&'a int)
+}
+
+fn main() {
+    assert!(Slice(&1) == Slice(&1))
+}