Merge pull request #1276 from andymac-2/aliasing-nll

Updated aliasing for nll

Author: marioidival

src/scope/borrow/alias.md

@@ -1,59 +1,58 @@
 # Aliasing
 
 Data can be immutably borrowed any number of times, but while immutably
-borrowed, the original data can't be mutably borrowed. On the other hand,
-only *one* mutable borrow is allowed at a time. The original data can be
-borrowed again only *after* the mutable reference goes out of scope.
+borrowed, the original data can't be mutably borrowed. On the other hand, only
+*one* mutable borrow is allowed at a time. The original data can be borrowed
+again only *after* the mutable reference has been used for the last time.
 
 ```rust,editable
 struct Point { x: i32, y: i32, z: i32 }
 
 fn main() {
     let mut point = Point { x: 0, y: 0, z: 0 };
 
-    {
-        let borrowed_point = &point;
-        let another_borrow = &point;
-
-        // Data can be accessed via the references and the original owner
-        println!("Point has coordinates: ({}, {}, {})",
-                 borrowed_point.x, another_borrow.y, point.z);
-
-        // Error! Can't borrow `point` as mutable because it's currently
-        // borrowed as immutable.
-        //let mutable_borrow = &mut point;
-        // TODO ^ Try uncommenting this line
-
-        // Immutable references go out of scope
-    }
-
-    {
-        let mutable_borrow = &mut point;
-
-        // Change data via mutable reference
-        mutable_borrow.x = 5;
-        mutable_borrow.y = 2;
-        mutable_borrow.z = 1;
-
-        // Error! Can't borrow `point` as immutable because it's currently
-        // borrowed as mutable.
-        //let y = &point.y;
-        // TODO ^ Try uncommenting this line
-
-        // Error! Can't print because `println!` takes an immutable reference.
-        //println!("Point Z coordinate is {}", point.z);
-        // TODO ^ Try uncommenting this line
-
-        // Ok! Mutable references can be passed as immutable to `println!`
-        println!("Point has coordinates: ({}, {}, {})",
-                 mutable_borrow.x, mutable_borrow.y, mutable_borrow.z);
-
-        // Mutable reference goes out of scope
-    }
-
-    // Immutable references to `point` are allowed again
     let borrowed_point = &point;
+    let another_borrow = &point;
+
+    // Data can be accessed via the references and the original owner
+    println!("Point has coordinates: ({}, {}, {})",
+                borrowed_point.x, another_borrow.y, point.z);
+
+    // Error! Can't borrow `point` as mutable because it's currently
+    // borrowed as immutable.
+    // let mutable_borrow = &mut point;
+    // TODO ^ Try uncommenting this line
+
+    // The borrowed values are used again here
+    println!("Point has coordinates: ({}, {}, {})",
+                borrowed_point.x, another_borrow.y, point.z);
+
+    // The immutable references are no longer used for the rest of the code so
+    // it is possible to reborrow with a mutable reference.
+    let mutable_borrow = &mut point;
+
+    // Change data via mutable reference
+    mutable_borrow.x = 5;
+    mutable_borrow.y = 2;
+    mutable_borrow.z = 1;
+
+    // Error! Can't borrow `point` as immutable because it's currently
+    // borrowed as mutable.
+    // let y = &point.y;
+    // TODO ^ Try uncommenting this line
+
+    // Error! Can't print because `println!` takes an immutable reference.
+    // println!("Point Z coordinate is {}", point.z);
+    // TODO ^ Try uncommenting this line
+
+    // Ok! Mutable references can be passed as immutable to `println!`
+    println!("Point has coordinates: ({}, {}, {})",
+                mutable_borrow.x, mutable_borrow.y, mutable_borrow.z);
+
+    // The mutable reference is no longer used for the rest of the code so it
+    // is possible to reborrow
+    let new_borrowed_point = &point;
     println!("Point now has coordinates: ({}, {}, {})",
-             borrowed_point.x, borrowed_point.y, borrowed_point.z);
+             new_borrowed_point.x, new_borrowed_point.y, new_borrowed_point.z);
 }
 ```