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catamorphism · catamorphism · commit 0433927f5376 · 2012-08-18T13:45:18.000-07:00
yaml --- r: 23326 b: refs/heads/master c: 1d3abf1 h: refs/heads/master v: v3
diff --git a/[refs] b/[refs]
@@ -1,5 +1,5 @@
 ---
-refs/heads/master: 3e52a0acdec93357806771eb04f0f479873a637b
+refs/heads/master: 1d3abf15f149036cfd0fa939f6393136ffcd1d7f
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: cd6f24f9d14ac90d167386a56e7a6ac1f0318195
 refs/heads/try: ffbe0e0e00374358b789b0037bcb3a577cd218be
diff --git a/trunk/doc/tutorial.md b/trunk/doc/tutorial.md
@@ -1859,6 +1859,13 @@ match my_rec {
 }
 ~~~~
 
+It's unsafe to dereference `b` in the second `log` expression, because `b` is
+a _pointer_ to the inside of `my_rec`, and the assignment statement has
+allocated a new record and assigned `my_rec` to point to it. Thus, the old
+contents of `my_rec` are no longer live, and `b` is dangling at this point.
+The borrow-checking analysis inside the compiler recognizes this situation
+and rejects the program.
+
 ## Argument passing styles
 
 The fact that arguments are conceptually passed by safe reference does
