Callable types are not validated properly

[karlismelderis]

TypeScript Version: 4.0.2

Search Terms:
callable

Code

type Retrieve = () => {
  extracted?: string
  raw: string
}

const retrieve: Retrieve = () => {
  return {
    raw: 'mhm',
    extracted: 'aha',
    a: 1, // no error for this extra prop
  }
}

interface RetrieveInterface {
  (): {
  extracted?: string
  raw: string
}
}

const retrieveInterface: RetrieveInterface = () => {
  return {
    raw: 'mhm',
    extracted: 'aha',
    a: 1, // no error for this extra prop
  }
}

Expected behavior:
get same error as setting return type to arrow function

const retrieve = (): {
  extracted?: string
  raw: string
} => {
  return {
    raw: 'mhm',
    extracted: 'aha',
    a: 1,
  }
}

Actual behavior:
no error

Playground Link:
https://www.typescriptlang.org/play?#code/C4TwDgpgBAShwCcCWEBu0C8UAUBKKGAfFAN4BQUUEAHogIYDGwEAJgPwBcUAzokgHYBzClAR0A7l17IhZAL5kyDAPb9eo+MjQQucPtoI5cXAsXKUE8AK4J+pERYlcA5AFsAFq+cAaB1VpiTKwudO50Pn50XACMvpQKCmQCzAgAZozQelroAJL8KekM0OZGXCU09EHsUnyyjpI8tcIJiipqwBr6ufkQaRm6mijdBRmGeKb2Fta2k5SiTlBunhFz-pXMLCFhK3NRULEiLUqq6pZdEACiCAjKCGPGsxWBG5yNMsL1Ne-yEyVnNnYSp9Fh4vHE5k9GBstuFwZQ9gd4vIgA

Related Issues:
Maybe I hit same as on going discussion here -> #241

[DanielRosenwasser]

Duplicate of #241, but I have a potential fix. Check out #40311 (comment)

[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.