Selector `Property > .key` can't match key in `const {a = 1} = b;`

Tell us about your environment

• ESLint Version: v7.30.0
• Node Version: v16.4.2
• npm Version: v7.9.0
• Operating System: win32 10.0.19043

What parser (default, @babel/eslint-parser, @typescript-eslint/parser, etc.) are you using?

The default parser.

The issue template doesn’t fit, so I removed these sections.

I was making an eslint plugin, for this code

const {a = 1} = b;

I should be able to use Property > .key to select the key, but ESLint won’t match.

I think this happens because we use the same reference for key and value.left, so they both have the AssignmentPattern as parent. For this reason, I don’t think this is an issue by espree or acorn.

This happens to assignment too.

({a = 1} = b);

[nzakas]

@fisker thanks for the followup. The Espree upgrade will happen with the ESLint v8.0.0 release, which we hope we will have a preview release of in a couple weeks.

We can’t upgrade Espree in ESLint v7.x line due to breaking changes.

[fisker]

This is a bug in Acorn 7 / Espree 7, nodes in a tree shouldn’t have multiple parents. The bug is fixed in Acorn 8 / Espree 8 (relevant test is here).

Thank you, I didn’t know that.

Can you try by using Espree 8 locally and let us know the result?

Confirmed, updating to Espree 8 fixes this.

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Question: ETA for switch to Espree 8.0.0? Do we need workaround in ESLint before that?