AA's and mutating keys

[Steven Schveighoffer]

There isn't any documentation that I can tell on the Arrays page that 
determines whether a mutating key can be used for an AA.  For example, if I 
use char[] as a key:

char[][char[]] map;

char[] keyvalue = "hello";

map[keyvalue] = "world";
keyvalue[] = "cello";

char[] *val = "hello" in map;

So does val get set to non-null?

-Steve