So why is i = ++i + 1 well-defined in C++11?

I've seen the other similar questions and read the defect about it. But I still don't get it. Why is `i = ++i + 1` well-defined in C++11 when `i = i++ + 1` is not? How does the standard make this well defined? By my working out, I have the following sequenced before graph (where an arrow represents the sequenced before relationship and everything is a value computation unless otherwise specified): ``` i = ++i + 1 ^ | assignment (side effect on i) ^ ^ | | ☆i ++i + 1 || ^ i+=1 | ^ 1 | ★assignment (side effect on i) ^ ^ | | i 1 ``` I've marked a side effect on `i` with a black star and value computation of `i` with a white star. These appear to be unsequenced with respect to each other (according to my logic). And the standard says: If a side effect on a scalar object is unsequenced relative to either another side effect on the same scalar object or a value computation using the value of the same scalar object, the behavior is undefined. The explanation in the defect report didn't help me understand. What does the lvalue-to-rvalue conversion have to do with anything? What have I gotten wrong?