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=5.9.2&fileType=.tsx&code=FAEwpgxgNghgTmABAcygewEYyog3sRRASwDsAXMOAMxgiQAU40BbIgZzAB4AVAPjwKFEVNGgAUASgBciNmTilkAbkEBfYOuBgAHgAc0cMnkSqlQA&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6Jge1tidmUQAmtAG4BDaKgyRE0aB2iRwYAL4hlQA&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eAcgK6qoDCAFutAGsylBm3QAacDUjxYAEw7oASuhKxUbAsQpQi89EXQAPPJEk0oshRh2RVhk5CkBfEM6A&tokens=false

Repro Code

declare global {
  interface Promise<T> {
    foo(): string;
  }
}

export { };

ESLint Config

module.exports = {
  "rules": {
    "@typescript-eslint/no-unused-vars": "error"
  }
}

tsconfig

{
  "compilerOptions": {
    "strictNullChecks": true,
  }
}

Expected Result

No warnings

Actual Result

Warning 'T' is defined but never used. 3:21 - 3:22. But when I remove the <T> get an error from typescript: 2428: All declarations of 'Promise' must have identical type parameters. 3:13 - 3:20. Typescript also won't allow you to rename the type parameters to _T.

Additional Info

See also microsoft/TypeScript#62881 and TanStack/table#5222