---

yaml
---
r: 33216
b: refs/heads/snap-stage3
c: 860573e
h: refs/heads/master
v: v3

Author: graydon

[refs]

@@ -1,7 +1,7 @@
 ---
 refs/heads/master: cd6f24f9d14ac90d167386a56e7a6ac1f0318195
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
-refs/heads/snap-stage3: 012bb7de5ba65bfd7b3483595e65a4cda1d1f682
+refs/heads/snap-stage3: 860573e3e00b5a807021b8c7a94a9672de4fa687
 refs/heads/try: d324a424d8f84b1eb049b12cf34182bda91b0024
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b

branches/snap-stage3/doc/rust.md

@@ -936,11 +936,13 @@ fn f(i: int) -> int {
 }
 ~~~~
 
-The typechecker would complain that `f` doesn't return a value in the
-`else` branch. Adding the `!` annotation on `my_err` would
-express that `f` requires no explicit `return`, as if it returns
-control to the caller, it returns a value (true because it never returns
-control).
+This will not compile without the `!` annotation on `my_err`,
+since the `else` branch of the conditional in `f` does not return an `int`,
+as required by the signature of `f`.
+Adding the `!` annotation to `my_err` informs the typechecker that,
+should control ever enter `my_err`, no further type judgments about `f` need to hold,
+since control will never resume in any context that relies on those judgments.
+Thus the return type on `f` only needs to reflect the `if` branch of the conditional.
 
 #### Pure functions