id-length does not check identifier in array pattern

[yeonjuan]

Tell us about your environment

• ESLint Version: 6.8.0
• Node Version: 12.13.0
• npm Version: 6.12.0

What parser (default, Babel-ESLint, etc.) are you using?

default

Please show your full configuration:

Configuration

What did you do? Please include the actual source code causing the issue, as well as the command that you used to run ESLint.

Online demo

/*eslint id-length: "error"*/     // default is minimum 2-chars ({ "min": 2 })
/*eslint-env es6*/
const [a] = foo;

What did you expect to happen?

Warn about short named identifier a;

What actually happened? Please include the actual, raw output from ESLint.

No error.

Are you willing to submit a pull request to fix this bug?

Yes. I already finished the implementation.(locally)

But, I have a question before pull request.

Examples of correct code for this rule with the default options:
...
var { prop: [x] } = {};
...

By the docs in id-length, there is an example in the correct example section showing the array pattern with the short identifier x.
In my understanding, the x is an identifier created by array destructuring so it should be checked by this rule.

Am I missing something? Is it intended behavior?

[kaicataldo]

Thanks for reporting this! Agreed that this is a bug. The rule already warns for this alternative equivalent:

const a = foo[0];

See demo here.

[yeonjuan]

To note

After #12881 merged, there are false negative examples in the id-length.md:

At Examples of correct code...

/*eslint id-length: "error"*/     // default is minimum 2-chars ({ "min": 2 })
/*eslint-env es6*/
// ...
var { prop: [x] } = {}; // false negative, It should be placed in an incorrect example
// ...

This will be fixed in #12839.