1157774 - Set.prototype.forEach default "this" should be undefined, not global object

Status: RESOLVED INVALID

(Core :: JavaScript Engine, defect)

Description

[Rick Waldron [:rwaldron]]

Replicate with: 

  var s = new Set([1]);

  s.forEach(function() {
    console.log(this === undefined);
  });


Actual: false

Expect: true



The value of `this` is incorrectly the global object: 

23.2.3.6 Set.prototype.forEach ( callbackfn [ , thisArg ] ) https://people.mozilla.org/~jorendorff/es6-draft.html#sec-set.prototype.foreach


...
5. If thisArg was supplied, let T be thisArg; else let T be undefined.
...

Comment 1

[Tom S [:evilpie]]

Well boxing happens on the callee site, and this is not a strict function.

Comment 2

[Tom S [:evilpie]]

*side!!!!!

Comment 3

[Rick Waldron [:rwaldron]]

For reference, the rationale for filing the bug was a result of reading: 

9.3.1 [[Call]] ( thisArgument, argumentsList) https://people.mozilla.org/~jorendorff/es6-draft.html#sec-built-in-function-objects-call-thisargument-argumentslist


When I should've been reading: 

9.2.1 [[Call]] ( thisArgument, argumentsList) https://people.mozilla.org/~jorendorff/es6-draft.html#sec-ecmascript-function-objects-call-thisargument-argumentslist