971712 - Fix scope of let-bound loop variables in for loops

Status: RESOLVED DUPLICATE of bug 854037

(Core :: JavaScript Engine, defect)

Description

[Andy Wingo [:wingo]]

SM's implementation of for (let x = 0; x < 10; x++); is obsolete.  The current desugaring is:

 {
   let x;
   for (x = 0; x < 10; x++);
 }

whereas it should create a new binding for "x" on each iteration.

Here's one spec link: http://people.mozilla.org/~jorendorff/es6-draft.html#sec-for-statement-runtime-semantics-labelledevaluation

Comment 1

[Andy Wingo [:wingo]]

See also https://mail.mozilla.org/pipermail/es-discuss/2014-February/036278.html.

Comment 2

[André Bargull [:anba]]

dup of bug 854037?

Comment 3

[Andy Wingo [:wingo]]

Indeed; I knew there was one somewhere.  (I searched for "scope", not "binding" :)  Thanks André.