Why callers should explicitly document storage classes

[Mehrdad]

Consider this example:

     // In module foo.d:
     void baz(bool condition, lazy int value)
     {
         if (condition)
             writeln(value);
     }

     // In module bar.d:
     import foo;
     bool someCondition() { return false; }
     void main()
     {
         auto vals = [1, 2, 3, 4];
         while (!vals.empty)
             baz(someCondition(), items.moveFront());
     }

There is **absolutely NO WAY** to figure out what's wrong at the calling 
site. You need to check /every/ method call and make sure nothing weird 
is happening (e.g. lazy), and it's pretty much impossible to figure it 
out unless you're intimately familiar with the entire library you're 
calling -- something which (obviously) doesn't scale.

I don't know of a similar example off the top of my head for out/ref, 
but the same idea applies.

Is this convincing enough that we need to document storage classes at 
the CALLING site, rather than just the CALLEE site?