for (let x of x) doesn't work in next+1 branch

[andy-hanson]

This code:

let x = [ 1, 2, 3 ]
for (let x of x)
    console.log(x)

works in iojs 2.4.0, but not in the branch next+1 (commit a6b6295).
Now it fails with:

ReferenceError: x is not defined
    at Object.<anonymous> (/home/andy/programming/mason3/TEST/class.js:4:15)
    at Module._compile (module.js:432:26)
    at Object.Module._extensions..js (module.js:450:10)
    at Module.load (module.js:353:32)
    at Function.Module._load (module.js:308:12)
    at Function.Module.runMain (module.js:473:10)
    at startup (node.js:117:18)
    at node.js:947:3

[ChALkeR]

I suppose that's v8, and that looks like a fixed version of let implementation, not a bug.

http://www.ecma-international.org/ecma-262/6.0/#sec-let-and-const-declarations
http://jsrocks.org/2015/01/temporal-dead-zone-tdz-demystified/

[ChALkeR]

It was wrong before (in iojs 2.4.0, due to v8), now it's good (was fixed in the new v8 version that got into next+1).

[ChALkeR]

Btw, it's nice that that was finally fixed in v8 =).
Relevant mozilla bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1069480

[ChALkeR]

As a note: this is technically a backwards-incompatible change on the v8 side.
But evertything is perfectly fine as long as the update to v8 4.5 happens in a major release of node.