1771690 - Nested array make misleading error message

Status: NEW

(Core :: JavaScript Engine, defect, P3)

Description

[845043157]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:100.0) Gecko/20100101 Firefox/100.0

Steps to reproduce:

Run the program:
[i,[j]]=[123,456];

Actual results:

TypeError:[123,456]Symbol.iterator.next().value is not iterable

Expected results:

In V8, it throws "TypeError:number 456 is not iterable (cannot read property Symbol(Symbol.iterator))".
I think it is 456 instead of [123,456] need to be iterable,the error message in V8 may be better.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::JavaScript Engine' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Tooru Fujisawa [:arai]]

The expression decompiler tries to provide the code, but the Symbol.iterator access and next access/call are generated internally, and not in the user-code.
Might be better abort the decompiler when it sees Symbol.iterator access and fallback to actual value on the stack.