---

yaml
---
r: 105148
b: refs/heads/snap-stage3
c: 4b224af
h: refs/heads/master
v: v3

Author: noam

[refs]

@@ -1,7 +1,7 @@
 ---
 refs/heads/master: 62f1d68439dcfd509eaca29887afa97f22938373
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
-refs/heads/snap-stage3: 7dfa4b298262fde037b5fbbb8fe20468d7306cbb
+refs/heads/snap-stage3: 4b224af72a76770694dc0998b356d9ce4d77529b
 refs/heads/try: db814977d07bd798feb24f6b74c00800ef458a13
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b

branches/snap-stage3/src/doc/guide-lifetimes.md

@@ -559,13 +559,13 @@ points at a static constant).
 
 # Named lifetimes
 
-Lifetimes can be named and referenced. For example, the special lifetime 
+Lifetimes can be named and referenced. For example, the special lifetime
 `'static`, which does not go out of scope, can be used to create global
 variables and communicate between tasks (see the manual for usecases).
 
 ## Parameter Lifetimes
 
-Named lifetimes allow for grouping of parameters by lifetime. 
+Named lifetimes allow for grouping of parameters by lifetime.
 For example, consider this function:
 
 ~~~
@@ -674,6 +674,11 @@ Named lifetime notation can also be used to control the flow of execution:
 }
 ~~~
 
+> ***Note:*** Labelled breaks are not currently supported within `while` loops.
+
+Named labels are hygienic and can be used safely within macros.
+See the macros guide section on hygiene for more details.
+
 # Conclusion
 
 So there you have it: a (relatively) brief tour of the lifetime

branches/snap-stage3/src/doc/guide-macros.md

@@ -398,6 +398,38 @@ position (in particular, not as an argument to yet another macro invocation),
 the expander will then proceed to evaluate `m2!()` (along with any other macro
 invocations `m1!(m2!())` produced).
 
+# Hygiene
+
+To prevent clashes, rust implements
+[hygienic macros](http://en.wikipedia.org/wiki/Hygienic_macro).
+
+As an example, `loop` and `for-loop` labels (discussed in the lifetimes guide)
+will not clash. The following code will print "Hello!" only once:
+
+~~~
+#[feature(macro_rules)];
+
+macro_rules! loop_x (
+    ($e: expr) => (
+        // $e will not interact with this 'x
+        'x: loop {
+            println!("Hello!");
+            $e
+        }
+    );
+)
+
+fn main() {
+    'x: loop {
+        loop_x!(break 'x);
+        println!("I am never printed.");
+    }
+}
+~~~
+
+The two `'x` names did not clash, which would have caused the loop
+to print "I am never printed" and to run forever.
+
 # A final note
 
 Macros, as currently implemented, are not for the faint of heart. Even