Type checker fails to report when combining Omit with & {[key: string]: unknown}

[kdeberk]

Bug Report

🔎 Search Terms

omit type checker

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about Omit

⏯ Playground Link

Playground link with relevant code

💻 Code

type Status = "created" | "canceled"

type StructA = {} & {[key: string]: unknown}

interface StructB extends StructA {
    status: Status
    version: number
    bar: string
}

interface StructC extends Omit<StructB, "bar"> {}

const x: StructC = {
    status: "cancelled",  // <- mistyped canceled
    version: "string"     // <- wrong type
}

🙁 Actual behavior

TS playground is not complaining about the two issues at the bottom. cancelled should be canceled and version should only accept numbers, not strings.

🙂 Expected behavior

TS playground should report about the two issues. In case of the cancelled<->canceled issue we're really relying on TS to catch these easy mistakes.

[jcalz]

Duplicate of #50638

[MartinJohns]

Also, be aware that indexer types with properties are never really type safe. Your type says any property has the type unknown, so you can assign any type to any property, including status and version.

[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.