Return value with unknown key is not restricted

[loynoir]

Bug Report

🔎 Search Terms

return value unknown key

🕗 Version & Regression Information

• This is a crash
• This changed between versions Version 4.7.4__ and _______
• This is the behavior in every version I tried, and I reviewed the FAQ for entries about _________
• I was unable to test this on prior versions because _______

⏯ Playground Link

Playground link with relevant code

💻 Code

type FooEnv = {
  FOO: string;
};

type BarEnv = {
  BAR: string;
};

type EnvMap = {
  foo: FooEnv;
  bar: BarEnv;
};

function createFoobar<T extends keyof EnvMap>(
  _name: T,
  fn: (ctx: {}) => { env: EnvMap[T] }
) {
  return fn({});
}

createFoobar("foo", () => {
  return {
    env: {
      FOO: "",
      UNKNOWN: 42,
    },
  };
});

Config

{
  "exclude": ["dist"],
  "extends": "@tsconfig/node16-strictest-esm/tsconfig.json",
  "compilerOptions": {
    "noEmit": true
  }
}

🙁 Actual behavior

No error

🙂 Expected behavior

createFoobar("foo", () => {
  return {
    env: {
      FOO: "",
      // @ts-expect-error
      UNKNOWN: 42,
    },
  };
});

Type '{ FOO: string; UNKNOWN: number; }' is not assignable to type 'FooEnv'. 
Object literal may only specify known properties, 
and 'UNKNOWN' does not exist in type 'FooEnv'.

[jcalz]

Duplicate of #241, most recent duplicate at #50064

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.