[jbert]

Is there a significant benefit to this over using a new name for the result?

    y = (x + 1) / atan(x) - x;
    x = y; // If you're in a loop and updating some value

If would hope/imagine that a compiler could reduce the two to the same code - and I don't think it reads any worse. Is there a downside beyond the extra line of code?

[JoeAltmaier]

To be clear: the assignment isn't the optimization; its the use of a symbol for 'x' on the rhs so that the compiler can recognize it. To illustrate that

    X &x = { complex reference expression for x }
    y = (x + 1) / atan(x) - x;

Now the compiler has the clues it needs to write good code. And with language support I don't have to introduce new names for each occurrence; just one name like <LHS> that readers can quickly learn.

[jbert]

> And with language support I don't have to introduce new names for each occurrence;

Having <LHS> as a name is only useful I think if you don't want to give it another name? I was asking what's the downside of giving it a name.