TypeScript/tests/cases/conformance/types/mapped/recursiveMappedTypes.ts
Anders Hejlsberg cd37a327a7
Fix non-homomorphic mapped type constraint issues (#41807)
* Less aggressive wildcard check, 'keyof any' constraint for 'infer T' in mapped type constraint position

* Accept new baselines

* Add regression tests
2020-12-03 16:36:45 -10:00

93 lines
2.3 KiB
TypeScript

// @declaration: true
// Recursive mapped types simply appear empty
type Recurse = {
[K in keyof Recurse]: Recurse[K]
}
type Recurse1 = {
[K in keyof Recurse2]: Recurse2[K]
}
type Recurse2 = {
[K in keyof Recurse1]: Recurse1[K]
}
// Repro from #27881
export type Circular<T> = {[P in keyof T]: Circular<T>};
type tup = [number, number, number, number];
function foo(arg: Circular<tup>): tup {
return arg;
}
// Repro from #29442
type DeepMap<T extends unknown[], R> = {
[K in keyof T]: T[K] extends unknown[] ? DeepMap<T[K], R> : R;
};
type tpl = [string, [string, [string]]];
type arr = string[][];
type t1 = DeepMap<tpl, number>; // [number, [number, [number]]]
type t2 = DeepMap<arr, number>; // number[][]
// Repro from #29577
type Transform<T> = { [K in keyof T]: Transform<T[K]> };
interface User {
avatar: string;
}
interface Guest {
displayName: string;
}
interface Product {
users: (User | Guest)[];
}
declare var product: Transform<Product>;
product.users; // (Transform<User> | Transform<Guest>)[]
// Repro from #29702
type Remap1<T> = { [P in keyof T]: Remap1<T[P]>; };
type Remap2<T> = T extends object ? { [P in keyof T]: Remap2<T[P]>; } : T;
type a = Remap1<string[]>; // string[]
type b = Remap2<string[]>; // string[]
// Repro from #29992
type NonOptionalKeys<T> = { [P in keyof T]: undefined extends T[P] ? never : P }[keyof T];
type Child<T> = { [P in NonOptionalKeys<T>]: T[P] }
export interface ListWidget {
"type": "list",
"minimum_count": number,
"maximum_count": number,
"collapsable"?: boolean, //default to false, means all expanded
"each": Child<ListWidget>;
}
type ListChild = Child<ListWidget>
declare let x: ListChild;
x.type;
// Repros from #41790
export type TV<T, K extends keyof T> = T[K] extends Record<infer E, any> ? E : never;
export type ObjectOrArray<T, K extends keyof any = keyof any> = T[] | Record<K, T | Record<K, T> | T[]>;
export type ThemeValue<K extends keyof ThemeType, ThemeType, TVal = any> =
ThemeType[K] extends TVal[] ? number :
ThemeType[K] extends Record<infer E, TVal> ? E :
ThemeType[K] extends ObjectOrArray<infer F> ? F : never;
export type Foo<T> = T extends { [P in infer E]: any } ? E : never;