---

yaml
---
r: 179198
b: refs/heads/auto
c: 310ada0
h: refs/heads/master
v: v3

Author: Junseok Lee

[refs]

@@ -10,7 +10,7 @@ refs/tags/release-0.3: b5f0d0f648d9a6153664837026ba1be43d3e2503
 refs/tags/release-0.3.1: 495bae036dfe5ec6ceafd3312b4dca48741e845b
 refs/tags/release-0.4: e828ea2080499553b97dfe33b3f4d472b4562ad7
 refs/tags/release-0.5: 7e3bcfbf21278251ee936ad53e92e9b719702d73
-refs/heads/auto: b6544fd3520d5eed05aafeb6b78737e32bf2c435
+refs/heads/auto: 310ada06f2d632340845ccd4d7e68a1b54d2f28a
 refs/heads/servo: af82457af293e2a842ba6b7759b70288da276167
 refs/tags/release-0.6: b4ebcfa1812664df5e142f0134a5faea3918544c
 refs/tags/0.1: b19db808c2793fe2976759b85a355c3ad8c8b336

branches/auto/src/libcore/marker.rs

@@ -308,6 +308,20 @@ impl<T: ?Sized> Clone for ContravariantType<T> {
 ///
 /// For more information about variance, refer to this Uncyclopedia
 /// article <http://en.wikipedia.org/wiki/Variance_%28computer_science%29>.
+///
+/// # Example
+///
+/// The Cell type is an example of an `InvariantType` which uses unsafe
+/// code to achieve "interior" mutability:
+///
+/// ```
+/// struct Cell<T> { value: T }
+/// ```
+///
+/// The type system would infer that `value` is only read here
+/// and never written, but in fact `Cell` uses unsafe code to achieve
+/// interior mutability. In order to get correct behavior, the
+/// `InvariantType` marker must be applied.
 #[unstable(feature = "core",
            reason = "likely to change with new variance strategy")]
 #[lang="invariant_type"]