Extra properties does not trigger error when spreading object

[hansott]

Bug Report

function inferType(value: string) {
    const asBoolean: boolean | null = null;
    const asDate: Date | null = null;
    const asDouble: number | null = null;
    const asLong: number | null = null;
    const asURL: URL | null = null;

    return {
        value_as_string: value,
        value_as_boolean: asBoolean,
        value_as_date: asDate,
        value_as_double: asDouble,
        value_as_long: asLong,
        value_as_url: asURL,
  };
}

type EventMetaData = {
  key: string;
  value_as_string: string;
  value_as_boolean: boolean | null;
  value_as_date: string | null;
  value_as_long: number | null;
  value_as_double: number | null;
};

function convert(key: string, value: string): EventMetaData {
    const types = inferType(value);

    return {
        key: key,
        ...types // Expect error here because `value_as_url` is not allowed
    };
}

Would expect the following error (or something like that):

Type '{ value_as_url: URL; value_as_string: string; value_as_boolean: null; value_as_date: null; value_as_double: null; value_as_long: null; key: string; }' is not assignable to type 'EventMetaData'.
  Object literal may only specify known properties, and 'value_as_url' does not exist in type 'EventMetaData'.(2322)

🔎 Search Terms

object spread extra properties expected error

🕗 Version & Regression Information

Using TypeScript 4.1.5

⏯ Playground Link

No error playground

Expected error

[MartinJohns]

This is intentional: #19775

[hansott]

@MartinJohns I see, thanks!

Subscribing to #12936 ;)