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#3779 — B.3.1 __proto__ : Directly set [[Prototype]] instead calling [[SetPrototypeOf]] ?

• bug_id: 3779
• creation_ts: 2015-02-05 14:24:00 -0800
• short_desc: B.3.1 __proto__ : Directly set [[Prototype]] instead calling [[SetPrototypeOf]] ?
• delta_ts: 2015-02-12 12:17:39 -0800
• product: Draft for 6th Edition
• component: technical issue
• version: Rev 32: February 2, 2015 Draft
• rep_platform: All
• op_sys: All
• bug_status: RESOLVED
• resolution: FIXED
• priority: Normal
• bug_severity: enhancement
• everconfirmed: true
• reporter: André Bargull
• assigned_to: Allen Wirfs-Brock

---

• commentid: 12150
• comment_count: 0
• who: André Bargull
• bug_when: 2015-02-05 14:24:45 -0800

B.3.1 __proto__ Property Names in Object Initializers

PropertyDefinition : PropertyName : AssignmentExpression

Step 6.a.i

If `propValue` is a Proxy its [[GetPrototypeOf]] method will be called when the default ordinary [[SetPrototypeOf]] is invoked. And that means user code may get executed.


I wonder if it makes sense to change this step to make a direct assignment to [[Prototype]]. The proto cycle chain check from [[SetPrototypeOf]] is not needed at this point and less intervening user code is always preferable ;-)

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• commentid: 12178
• comment_count: 1
• who: Allen Wirfs-Brock
• bug_when: 2015-02-05 20:37:54 -0800

see Bug 2437

Evaluation routines at this level shouldn't be bypassing the MOP.

On the other hand, 9.1.2 probably shouldn't bother to call non-ordinary [[GetPrototypeOf]]

---

• commentid: 12197
• comment_count: 2
• who: Allen Wirfs-Brock
• bug_when: 2015-02-06 13:24:35 -0800

Fixed in rev33 editor's draft

I changed ordinary [[SetPrototypeOf]] so it so longer calls [[GetPrototypeOf]] to on the new __proto__ value.

See Bug 2437

That eliminates the user code concern.

---

• commentid: 12437
• comment_count: 3
• who: Allen Wirfs-Brock
• bug_when: 2015-02-12 12:17:39 -0800

fixed in rev33