"Omit" type using "keyof any" instead of "keyof T"

[gins3000]

TypeScript Version: 3.6.0

Search Terms:
Omit
Omit any

Code

interface Foo {
  a: string;
  b: number;
  c: boolean
}

// Omit has the issue
type FooWithoutC = Omit<Foo, "c">; // no intellisense for second generic parameter
type FooWithoutD = Omit<Foo, "d">; // no type error

// Counter example with Pick
type FooWithA = Pick<Foo, "a">; // provides intellisense for filling out second generic parameter
type FooWithD = Pick<Foo, "d">; // type error

Expected behavior:
In the above example, I would expect

• to get auto-completion for keys of Foo when filling out the second generic parameter
• to get a type error when putting in a key that does not exist on Foo

similar to how it works in all the other similar helpers, e.g. Pick.

Actual behavior:
Since the definition of the second generic parameter is keyof any instead of keyof T, I can put whatever I want into the second generic parameter, and I also get no Intellisense.

Related line:

TypeScript/src/lib/es5.d.ts

Line 1449 in ea73093

type Omit<T, K extends keyof any> = Pick<T, Exclude<keyof T, K>>;

Playground Link: http://www.typescriptlang.org/play/#code/JYOwLgpgTgZghgYwgAgGIHt3IN4ChnJwBcyAzmFKAOYDc+yARiSAK4C2D0dBCJDmAGwhwQuAL65cAeinIA8m2BhkACzilkYFSmClSLCLjABPAA4oM6AOpKV6FmADCyALzzFYADyWANMgBECP4AfDTIMsggWKCQAgK6ECCkKDDoUGQQCOggACbIVInQwAjIpnBQcGwQkFBGZhaYNlr2YAAiru5K3ph+-jkhYRFRmvXI0FBpkhGO9uDQYwAelaZCyADutsgACsUA1nXmaI22AIIdOwi73ei9cAPhsqYTAG7AORAaMRBxCUkpacgYMAfiAqMgWhksrl8oVKCUyhUqjUDg1rLZ2m4LldfAF+qEHiNDuM0kA

Is there a reason why this has been implemented like this with keyof any instead of keyof T?

[gins3000]

Never mind, apparently there is already an issue about this: #30825