let-var renaming can break things

[chocolateboy]

Is it possible to turn off the name -> _name renaming used for let vars?

This works in Firefox (and Traceur) but doesn't work with 6to5:

function foo (n) {
    let bar = n;
    eval('console.log(bar)');
}

foo(42);

6to5 produces:

"use strict";
function foo (n) {
    var _bar = n;
    eval('console.log(bar)');
}

foo(42);

Function parameters are affected as well in some circumstances, which could break Function.toString hacks (e.g. DI in AngularJS):

let n = 42;

function square(n) {
    return n * n;
}

6to5:

"use strict";
var _n = 42;

function square(_n) {
    return _n * _n;
}

[sebmck]

The let scoping transformer is definently very funky at the moment and needs a rewrite.

[chocolateboy]

Another test case for the rewrite:

let n = 42;

function add(n, _n) {
    return n + _n;
}

6to5:

"use strict";
var _n = 42;

function add(_n, _n) {
    return _n + _n;
}

6to5-node:

function add(_n, _n) {
                 ^^
SyntaxError: Strict mode function may not have duplicate parameter names

P.S. This isn't a dealbreaker for me at the moment, and I'm loving the quick fixes/responses!

[sebmck]

Yeah, generateUid which we use to generate unique ids needs to check if there are any variables with the same name. I'm currently rewriting the let scoping transformer as it's long over due and there are a variety of issues with it.

Thanks for the feedback!

[sebmck]

Fixed when 287cbbb is merged.

[sebmck]

Fixed as of 1.11.0