Array binding pattern with only OmittedExpressions does not check RHS of for-of loop

[Fireboltofdeath]

Bug Report

🔎 Search Terms

array binding patterns for-of loop omittedexpression binding elements

🕗 Version & Regression Information

• This is the behavior in every version I tried

⏯ Playground Link

Playground link with relevant code

💻 Code

// doesn't error
for (const [,] of doesntExist() /= 2) {

}

// does error
for (const [_,,,] of doesntExist() /= 2) {

}

🙁 Actual behavior

The right hand side of the for-of loop is not checked at all.

This appears to be because OmittedExpression is not actually a BindingElement and the right hand side's type is only checked whenever encountering a BindingElement in checkVariableLikeDeclaration or when there are no elements in the pattern.

🙂 Expected behavior

The right hand side of the for-of loop to be checked.

[wannieman98]

Can I give this issue a try?

[Fireboltofdeath]

Can I give this issue a try?

Yes, feel free.

[wannieman98]

Can I get some help on where I should begin looking to tackle this issue? Thanks!

[Fireboltofdeath]

You should take a look in checkVariableLikeDeclaration which is where the right side of the for-of loop gets checked, when encountering a binding element or pattern.

[wannieman98]

Hi, sorry for another question, but I had been trying to fix the problem but I am not sure whether the [,] counts as a variable declaration or array literal. Could I get a clarification on that?

[bentongxyz]

Hi there, if this is not being actively worked on right now, may I give this a try?
Thanks!

[bentongxyz]

Hi @RyanCavanaugh @Fireboltofdeath, I made a PR for this issue, please check at your latest convenience!

Much thanks.