clarify what are the "circumstances" for refining the interpretation of LeftHandSideExpression

[ltcmelo]

In 13.15.5 Destructuring Assignment, we have:

"In certain circumstances when processing an instance of the production AssignmentExpression : LeftHandSideExpression = AssignmentExpression the interpretation of LeftHandSideExpression is refined using the following grammar: ..."

But I couldn't find where these circumstances are explained. Have I missed it?

If my understand is correct, then in a context like the one below, the refinement should apply:

let o = { x: "s", y: 0 };
({x: v, y: w} = o);

In one case or another, the spec should clarify — if isn't yet doing so — what the circumstances in question are; if this is already clarified and I've missed it, it might be worth to link the clarification in section 13.15.5.

[jmdyck]

See 13.15.1 Static Semantics: Early Errors.

The circumstance is when the LeftHandSideExpression (of the AssignmentExpression) is either an ObjectLiteral or an ArrayLiteral.

And the 'refinement' is that the LeftHandSideExpression must cover an AssignmentPattern.

[jmdyck]

If my understand is correct, then in a context like the one below, the refinement should apply:

let o = { x: "s", y: 0 };
({x: v, y: w} = o);

Yes, I think so. {x: v, y: w} is initially parsed as a LeftHandSideExpression (consisting of an ObjectLiteral), and then as an AssignmentPattern (consisting of an ObjectAssignmentPattern).

[ltcmelo]

Thanks for clarifying @jmdyck! I'm leaving this open nevertheless in case the editors would consider an explicit pointer for the explanation of the circumstances.