es6 loop variable bindings

gistfile1.js

// will this example
let arr = [];
for (let x = 0; x < 5; x++) {
    x++;
    arr.push(function() { return x; });
}


// ..be semantically equivalent to this?
let arr = [];
for (let x_ = 0; x_ < 5; x_++) {
    let x = x_;
    {
        x++;
        arr.push(function() { return x; });
    }
    x_ = x;
}

yes, that is a valid equivalence for this simple case. but there are some complicaiton. See the thread that starts with https://mail.mozilla.org/pipermail/es-discuss/2012-February/020272.html

Thanks for commenting @allenwb. I guess I wondered whether this transformation was valid for any loop body and it seems that may or may not be the case. Looking forward to seeing the semantics nailed down! cc @Benvie