Bug: [no-invalid-void-type] false positive on this: X | void annotation

[jedwards1211]

Before You File a Bug Report Please Confirm You Have Done The Following...

• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I have searched for related issues and found none that matched my issue.
• I have read the FAQ and my problem is not listed.

Playground Link

https://typescript-eslint.io/play/#ts=5.7.2&fileType=.tsx&code=KYDwDg9gTgLgBDAnmYcAKUIFsCWBnYAdRxgAsAlYPCAGwDdgo8AeAFQD44BeOAbwCg4cAPTC4AOkn8Avv37CAVAsEK4AVQJQaAQwB2AEzg4sYGsCzBdMbTBwRdcCADM4AbQzZ8wcQHcSFKloGJgBdXgABGhxdAGs4UhgYMDwALlF9YAYaCBQocSwIAC8cGh1xaABzYUsAWjUAZWF9CABjPGFCYAAjYQApbTptepaoHDAYYUonRksW4GEAcWyu7RoAfQB5LoArYBaYdo9cAmE-MkpqekY8aXEVOA3dObgfVABXMAqobQyECDgAHIQX4AJhBABoXqgWno4Hgzi1SH8EKRUF03iVbLo7nAFMJ%2BKBILA4E43k9bPYXv4LkFrmx2AAKQQo-ApdCYY7AADC9jwMCgb320DgAB84HQIDh9PwAJRso5eYjnQJXJj0vjMqDAGBvKAOARCISiCRSISyWRAA&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6Jge1uYDcBDRgBNaPDpWFFS6KImjQO0SODABfECqA&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eAcgK6qoDCAFutAGsylBm3TgwAXxCSgA&tokens=false

Repro Code

export type PromiseWithResolvers<T> = {
  // ...
}

/**
 * Userland implementation of [Promise.withResolvers]{@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/withResolvers}.
 * Once we upgrade to Node 22, we can switch to the builtin.
 */
export function withResolvers<T>(
  this: PromiseConstructor | void
): PromiseWithResolvers<T> {
  return {
    // ...
  }
}

ESLint Config

module.exports = {
  parser: "@typescript-eslint/parser",
  rules: {
    "@typescript-eslint/no-invalid-void-type": "error",
  },
};

tsconfig

{
  "compilerOptions": {
    // ...
  }
}

Expected Result

No error

Actual Result

void is not valid as a constituent in a union type 10:30 - 10:34

Additional Info

This is the only possible way to type an optional this binding other than function overloads, but function overloads trigger @typescript-eslint/unified-signatures.

[JoshuaKGoldberg]

🤔 Interesting, I've seen ponyfills and wrappers for withResolvers before but never with a union type for this. Could you please explain why you went with this type? Also, why not PromiseConstructor | undefined?

[jedwards1211]

I don't remember where I got it from, but probably the idea was you could call withResolvers() (TS only accepts this: void in that case, not this: undefined) or withResolvers.call(thirdPartyPromiseConstructor). It may be unusual but it's never fun when it's impossible to satisfy both TS and typescript-eslint, I hope it's always your goal to avoid that