librustc (RFC #34): Implement the new `Index` and `IndexMut` traits.

This will break code that used the old `Index` trait. Change this code
to use the new `Index` traits. For reference, here are their signatures:

    pub trait Index<Index,Result> {
        fn index<'a>(&'a self, index: &Index) -> &'a Result;
    }
    pub trait IndexMut<Index,Result> {
        fn index_mut<'a>(&'a mut self, index: &Index) -> &'a mut Result;
    }

Closes #6515.

[breaking-change]

1 files changed, 64 insertions, 0 deletions

diff --git a/src/test/compile-fail/borrowck-overloaded-index.rs b/src/test/compile-fail/borrowck-overloaded-index.rs
new file mode 100644
index 00000000000..d34aa1cd9cb
--- /dev/null
+++ b/src/test/compile-fail/borrowck-overloaded-index.rs
@@ -0,0 +1,64 @@
+// 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.
+
+struct Foo {
+    x: int,
+    y: int,
+}
+
+impl Index<String,int> for Foo {
+    fn index<'a>(&'a self, z: &String) -> &'a int {
+        if z.as_slice() == "x" {
+            &self.x
+        } else {
+            &self.y
+        }
+    }
+}
+
+impl IndexMut<String,int> for Foo {
+    fn index_mut<'a>(&'a mut self, z: &String) -> &'a mut int {
+        if z.as_slice() == "x" {
+            &mut self.x
+        } else {
+            &mut self.y
+        }
+    }
+}
+
+struct Bar {
+    x: int,
+}
+
+impl Index<int,int> for Bar {
+    fn index<'a>(&'a self, z: &int) -> &'a int {
+        &self.x
+    }
+}
+
+fn main() {
+    let mut f = Foo {
+        x: 1,
+        y: 2,
+    };
+    let mut s = "hello".to_string();
+    let rs = &mut s;
+    println!("{}", f[s]);
+    //~^ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable
+    f[s] = 10;
+    //~^ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable
+    let s = Bar {
+        x: 1,
+    };
+    s[2] = 20;
+    //~^ ERROR cannot assign to immutable indexed content
+}
+
+