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=5.6.3&fileType=.tsx&code=LAKAJgpgxgNghgJwgAgGYFcB2UAuBLAe0zQIIAoBKALmU3QFsAjCBZAH2S0lT0wjFCRYiFBmz4iyRoko06TFoOjwkaLLkLFpALzKY5DZgmrIAbgTxgA3KFBiNk%2BnF4BGSsgDeoZMhgQcyAAeNiA%2BgcgAvFIyFCFhkSTksd7RuoEAhMkgAL62IPYSxE68AEzuXqG%2B-kFxQQnSCJS14VGopE0pOmSBWbkgQA&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6Jge1tiacTJTIAhtEK0ipWkOTJE0fJQ5N0UOdA7RI4MAF8QOoA&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eFYDArugDTg10NM8AOXapUAYQAW6aAGsylDul4BfECqA&tokens=false

Repro Code

declare function foo(): number | undefined
declare function bar(): number
declare function baz(n: number): void;

function main1() {
  let x;
  x = bar();
  x = foo();
  baz(x!);
}

function main2() {
  let x;
  x = bar();
  x = foo();
  baz(x);
}

ESLint Config

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

tsconfig

{
  "compilerOptions": {
    "strict": true
  }
}

Expected Result

The linter should not treat baz(x!) as an unnecessary type assertion

Actual Result

@typescript-eslint/no-unnecessary-type-assertion rule warns about the assertion baz(x!) as unnecessary, suggesting it could be removed. Removing the assertion causes TypeScript to raise an error.

Additional Info

No response