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// regression test from https://github.com/Microsoft/TypeScript/issues/29692
interface DeepObject {
[k1: string]: {
[k2: string]: any;
};
}
type keys2broken<
O extends DeepObject,
K1 extends keyof O
> = O[K1] extends object ? Extract<keyof O[K1], string> : never;
type keys2working<
O extends DeepObject,
K1 extends keyof O
> = O[K1] extends object ? keyof O[K1] : never;
type keys2workaround<O extends DeepObject, K1 extends keyof O> = Extract<
O[K1] extends object ? keyof O[K1] : never,
string
>;
interface Foo extends DeepObject {
a: {
"1": 123;
"2": string;
"3": boolean;
};
}
class Bar<O extends DeepObject> {
broken<
K1 extends keyof O,
K2 extends keys2broken<O, K1>,
V extends O[K1][K2]
>(k1: K1, k2: K2, value: V) {}
working<
K1 extends keyof O,
K2 extends keys2working<O, K1>,
V extends O[K1][K2]
>(k1: K1, k2: K2, value: V) {}
workaround<
K1 extends keyof O,
K2 extends keys2workaround<O, K1>,
V extends O[K1][K2]
>(k1: K1, k2: K2, value: V) {}
}
const bar = new Bar<Foo>();
// all 3 of the below should error on passing `true` for `"1"`
bar.broken("a", "1", true); // was broken in the past - with 2nd argument incorrectly of type "1" | "2" | "3".
bar.working("a", "1", true); // ok - true is not allowed
bar.workaround("a", "1", true); // ok - true is not allowed
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