Looking into this, it looks like a bug (or a feature?) in typescript.

It is inferring that the function call uses HTMLInputElement as a generic:

The type checker we consume will therefore always report to us that the function's return type is the same as the type cast.

I'm going to close this, as there's nothing we can do about this from our side without adding a large amount of extra code to check if the value being cast comes from a function and that function has a generic etc.

As a workaround you can either delete the generic (I doubt you can, it's probably a library function, right?):

declare function foo(): Element;
const a = (foo() as HTMLInputElement).value;

Or use the generic.

declare function foo<T extends Element = Element>(): T;
const a = foo<HTMLInputElement>().value;

Both of these workarounds do not flag the lint rule, and type check okay.

If you feel strongly about it, I would suggest raising an issue in the typescript repo.

Thank you for the investigation.

Yes, it is the library function and I do no want to use the generic parameter because I think that it is the anti-pattern:

getMeAT(): T: If a type parameter does not appear in the types of any parameters, you don't really have a generic function, you just have a disguised type assertion. Prefer to use a real type assertion, e.g. getMeAT() as number. Example where a type parameter is acceptable: function id(value: T): T;. Example where it is not acceptable: function parseJson(json: string): T;. Exception: new Map<string, number>() is OK.

https://github.com/DefinitelyTyped/DefinitelyTyped#common-mistakes

I need to think a little more about it.