Can't assign to partial of intersection with mapped type over generic

🔎 Search Terms

"mapped type", "mapped generic type", "intersection", "partial"

🕗 Version & Regression Information

Current version of Typescript, not sure if it's a regression

⏯ Playground Link

No response

💻 Code

Simple to reproduce:

type X = 'a' | 'b' | 'c'
const foo = <T extends X>() => {
    const result: Partial<{d:number} & {[P in T]: boolean}> = {
       // error: Type '{ d: number; }' is not assignable to type 'Partial<{ d: number; } & { [P in T]: boolean; }>'
        d: 1
    }
}

🙁 Actual behavior

I get an error

🙂 Expected behavior

I am able to use this type in general; I expect to be able to use a partial of it as well. The only thing I've found that satisfies the type is an empty object

Additional information about the issue

No response

Inizia con l’esempio generico minimo in TypeScript presente nell’issue e riproduci l’errore usando il compilatore attuale. Analizza come il type checker gestisce Partial su un’intersezione contenente un mapped type e considera completata l’issue quando l’esempio accetta d: 1 mantenendo il vincolo generico.