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#1869 — Implicit ToObject() conversion in destructuring still present for some productions

• bug_id: 1869
• creation_ts: 2013-08-30 11:15:00 -0700
• short_desc: Implicit ToObject() conversion in destructuring still present for some productions
• delta_ts: 2013-10-29 09:46:41 -0700
• product: Draft for 6th Edition
• component: technical issue
• version: Rev 17: August 23, 2013 Draft
• rep_platform: All
• op_sys: All
• bug_status: RESOLVED
• resolution: FIXED
• priority: Normal
• bug_severity: normal
• everconfirmed: true
• reporter: André Bargull
• assigned_to: Allen Wirfs-Brock

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• commentid: 5280
• comment_count: 0
• who: André Bargull
• bug_when: 2013-08-30 11:15:41 -0700

For consistency with destructuring assignment, the following algorithms should be changed to throw a TypeError instead of performing ToObject():

11.1.4.2 Array Comprehension
Runtime Semantics: Binding Initialisation
- step 1 uses ToObject()

12.6.4.2 Runtime Semantics
Runtime Semantics: For In/Of Expression Evaluation Abstract Operation
- step 3.h.iii.2 uses ToObject()

12.14.2 Runtime Semantics
Runtime Semantics: Binding Initialisation
- step 1 uses ToObject()


For example `for (var [head, ...tail] of ["123"]) {print(tail)}` currently prints "2,3" whereas the similar assignment `var [head, ...tail] = "123"` throws a TypeError.

---

• commentid: 5770
• comment_count: 1
• who: André Bargull
• bug_when: 2013-10-01 09:27:12 -0700

rev19 update: ToObject() removed from

- 13.6.4.7 Runtime Semantics: ForIn/OfBodyEvaluation
- 13.14.3 Runtime Semantics: BindingInitialisation

That means only "12.1.4.2.2 Runtime Semantics: BindingInitialisation" still calls ToObject() in a destructuring context.

---

• commentid: 5974
• comment_count: 2
• who: Allen Wirfs-Brock
• bug_when: 2013-10-24 15:52:20 -0700

fixed in rev20 editor's draft

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• commentid: 6155
• comment_count: 3
• who: Allen Wirfs-Brock
• bug_when: 2013-10-29 09:46:41 -0700

fixed in rev20 draft, Oct. 28, 2013