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=4.7.2&sourceType=module&code=CYUwxgNghgTiAEYD2A7AzgF3gMyUgXPADwAqANPAKoB8AFAG5QQCuIhlAlPALzXwkBYAFDCA9KIDmIFCBgBLMGniwEKJAHd4clNllxgypURTMAtgCNZFTPJQS6jFm3g3tErr3gmLs4cnRY5rA8OHi0AEThXFBK3pYw8OJ6SDCEagC0zCgyYCBoaLAAnukYhQAOIOkxaLIYcqhAA&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6Jge1tiacTJTIAhtEK0ipWkOTJE0fJQ5N0UOdA7RI4MAF8QOoA&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eAcgK6qoDCAFutAGsylBm3TgwAXxCSgA

Repro Code

declare const foo: <T, U>(value: U) => T

//generics are now inferred as <number, string>(value: string) => number
const bar = foo("") as number //error: no-unnecessary-type-assertion

ESLint Config

module.exports = {
  "rules": {
    "@typescript-eslint/no-unnecessary-type-assertion": "error"
  }
};

tsconfig

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

Expected Result

no error

Actual Result

error: no-unnecessary-type-assertion

Additional Info

sometimes it's useful to use a cast instead of specifying the generic, in case you only want to have to specify one type while still having the other types inferred.

Versions