Trying to upgrade from eslint 8 to eslint 9 on a exsting SF project mainly LWC

[thesunlover]

Trace:

Oops! Something went wrong! :(

ESLint: 9.28.0

TypeError: Converting circular structure to JSON
    --> starting at object with constructor 'Object'
    |     property 'configs' -> object with constructor 'Object'   
    |     property 'flat/all' -> object with constructor 'Object'  
    |     property 'plugins' -> object with constructor 'Object'   
    --- property 'jest' closes the circle
Referenced from:
    at JSON.stringify (<anonymous>)
    at node_modules\@eslint\eslintrc\dist\eslintrc.cjs:2255:45  
    at Array.map (<anonymous>)
    at ConfigValidator.formatErrors (node_modules\@eslint\eslintrc\dist\eslintrc.cjs:2246:23)
    at ConfigValidator.validateConfigSchema (node_modules\@eslint\eslintrc\dist\eslintrc.cjs:2277:84)
    at ConfigArrayFactory._normalizeConfigData (node_modules\@eslint\eslintrc\dist\eslintrc.cjs:3123:19)
    at ConfigArrayFactory._loadConfigData (node_modules\@eslint\eslintrc\dist\eslintrc.cjs:3088:21)
    at ConfigArrayFactory._loadExtendedShareableConfig (node_modules\@eslint\eslintrc\dist\eslintrc.cjs:3393:21)
    at ConfigArrayFactory._loadExtends (node_modules\@eslint\eslintrc\dist\eslintrc.cjs:3261:25)
    at ConfigArrayFactory._normalizeObjectConfigDataBody (node_modules\@eslint\eslintrc\dist\eslintrc.cjs:3199:25)

config starts:

const { FlatCompat } = require("@eslint/eslintrc");
const js = require("@eslint/js");

const compat = new FlatCompat({
    baseDirectory: __dirname,                  // optional; default: process.cwd()
    resolvePluginsRelativeTo: __dirname,       // optional
    recommendedConfig: js.configs.recommended, // optional unless using "eslint:recommended"
    allConfig: js.configs.all,                 // optional unless using "eslint:all"
});
const LWC = compat.config({
    extends: [
      "@salesforce/eslint-config-lwc/recommended",
    //   "@locker/eslint-config-locker",
    ],
});

If I try to use

const LWC = compat.config({
    extends: [
      "@salesforce/eslint-config-lwc/recommended",
    //   "@locker/eslint-config-locker",
    ],
    plugins:[],
});

It is the same error.

If I try to use

const LWC = compat.config({
    extends: [
      "@salesforce/eslint-config-lwc/base",
    //   "@locker/eslint-config-locker",
    ],
});

It's not working saying "message":"Please do not import from @salesforce/lds, these modules are ephemeral and could change at any time."

[wjhsf]

What version of eslint-config-lwc are you using? v4.0.0 has support for flat configs, so the compat adapter is not needed.

[thesunlover]

Yes, I use 4.0.0, but haven't found yet what's the expected form of it.
I need to have two separate configurations one for LWC and another for react, so I need a solution with files property.

[wjhsf]

This package is just a standard flat config. You can use it the same way that you would use any other eslint config. The minimal setup to use only the recommended LWC config is this:

// eslint.config.mjs
import lwc from '@salesforce/eslint-config-lwc';
export default lwc.configs.recommended;

[thesunlover]

I understand. Thaks you for the clarification.
I have one last question.
If have to combine with specific paths, file extensions and rules how do I do that? I'm new to the eslint 9.0 specific configuration flows. Currently, I have multiple .eslintrc files?