I'm revising this to make it more readable.  The following example illustrates my results using the v0.136 D compiler.  NOTE: The error condition shown here is opposite that shown in the similar example from the documentation, class.html, under "Field Properties".

class Foo
{
   int x;
}
...
void test(Foo foo)
{
   size_t o;

   o = Foo.x.offsetof; // error,
.offsetof an int type
   o = foo.x.offsetof; // yields 8
}