Theory question

[BCS]

Are there any cases where the following cases both compile but are not identical?

A a;
B b;

a = b;
a.Foo();

//// and

A a;
B b;

a = b;
b.Foo();

The reason I ask is I'm wondering if making the type (and value) of an assignment 
expression the right hand side rather than the left hand side would silently 
break code. It would be handy for cases like this because it avoids the need 
for a temp variable:

class C { }
class D : C { int i();}

D newD();

C c;

void main()
{
   (c = newD()).i();
}