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#3577 — 7.3.19 SpeciesConstructor, 9.4.2.3 ArraySpeciesCreate: inconsistency in the handling of originalObj.constructor === null

• bug_id: 3577
• creation_ts: 2015-01-20 04:35:00 -0800
• short_desc: 7.3.19 SpeciesConstructor, 9.4.2.3 ArraySpeciesCreate: inconsistency in the handling of originalObj.constructor === null
• delta_ts: 2015-02-12 12:17:39 -0800
• product: Draft for 6th Edition
• component: technical issue
• version: Rev 31: January 15, 2015 Draft
• rep_platform: All
• op_sys: All
• bug_status: RESOLVED
• resolution: FIXED
• priority: Normal
• bug_severity: normal
• everconfirmed: true
• reporter: Claude Pache
• assigned_to: Allen Wirfs-Brock

---

• commentid: 11559
• comment_count: 0
• who: Claude Pache
• bug_when: 2015-01-20 04:35:43 -0800

7.3.19 SpeciesConstructor
Returns the default constructor in the following cases:
(a) originalObj.constructor is undefined,
(c) originalObj.constructor[@@species] is undefined or null.

9.4.2.3 ArraySpeciesCreate
Uses the default constructor in the following cases:
(a) originalObj.constructor is undefined or null,
(b) originalObj.constructor is a constructor from a different realm,
(c) originalObj.constructor[@@species] is undefined or null.

There is an inconsistency between the two abstract operations in item (a) above.

According to Bug 3524, the editor didn't want to add `null` in the case of SpeciesConstructor. In that case, we should consider removing `null` in the case of ArraySpeciesCreate.

Proposed patch: In the algorithm of ArraySpeciesCreate:
* Add step 4.d.iii: If C is null, let C be undefined.
* Change step 5: If C is undefined, return ArrayCreate(length).

---

• commentid: 11562
• comment_count: 1
• who: Allen Wirfs-Brock
• bug_when: 2015-01-20 10:07:25 -0800

fixed in rev32 editor's draft

---

• commentid: 11974
• comment_count: 2
• who: Allen Wirfs-Brock
• bug_when: 2015-02-02 18:38:55 -0800

fixed in rev32 draft

---

• commentid: 12087
• comment_count: 3
• who: Claude Pache
• bug_when: 2015-02-03 23:19:58 -0800

Only partially fixed: Now, in 9.4.2.3 ArraySpeciesCreate, when originalObj.constructor[@@species] is null, a TypeError will be thrown (contrarily to 7.3.19 SpeciesConstructor). [I guess I should've made explicit the implicit "and" between the two bullets at the end of Comment 0.]

* In 9.4.2.3 ArraySpeciesCreate, add step 4.d.iii: If C is null, let C be undefined.

(Alternatively, see Bug 3725 for the opposite change in 7.3.19 SpeciesConstructor.)

---

• commentid: 12291
• comment_count: 4
• who: Allen Wirfs-Brock
• bug_when: 2015-02-10 13:22:54 -0800

fixed in rev33 editor's draft

---

• commentid: 12434
• comment_count: 5
• who: Allen Wirfs-Brock
• bug_when: 2015-02-12 12:17:39 -0800

fixed in rev33