From digitalmars.D.learn newsgroup:
http://forum.dlang.org/thread/mailman.911.1337336339.24740.digitalmars-d-learn@puremagic.com

struct S { }

struct AS
{
    alias S Alias;
}

struct Wrapper
{
    AS as;
}

void main()
{
    Wrapper w;
    static assert(is(typeof(w.as).Alias == S));         // fail
    static assert(is(AS.Alias == S));                   // ok
    static assert(is(typeof(w.as) == AS));              // ok
    static assert(is(typeof(w.as).Alias == AS.Alias));  // fail
}