callback inside generated object type doesn't allow implicit arguments types

[cevek]

TypeScript Version: 3.4.0-dev.20190223

Search Terms:

Code

declare function x<T>(obj: T, args: {[P in keyof T]: (arg: number) => void}): void;
x({get: 1}, {get: arg => arg + 1});
// Parameter 'arg' implicitly has an 'any' type.

Expected behavior:

Actual behavior:

Playground Link:

Related Issues:

[dragomirtitian]

Just as a workaround you can do the following:

declare function x<T>(obj: T, args: Record<keyof T, (arg: number) => void> & Record<string, (arg: number) => void>): void;
x({ get: 1 }, { get: arg => arg + 1 });

arg would be correctly inferred but you will still get errors if the key was not in T.

[cevek]

Yeah, but I want something more complex, this example just a repro
for example arg should be ReturnType<T[P]>

[yortus]

Duplicate of #24694? There's a PR to fix it, to be discussed 'next week' on the Design Meeting Docket - but I think it's been on 'next week' for quite a few weeks now.

[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.