198 lines
4.9 KiB
TypeScript
198 lines
4.9 KiB
TypeScript
// @strict: true
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// @declaration: true
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interface Covariant<T> {
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foo: T extends string ? T : number;
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}
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interface Contravariant<T> {
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foo: T extends string ? keyof T : number;
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}
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interface Invariant<T> {
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foo: T extends string ? keyof T : T;
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}
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function f1<A, B extends A>(a: Covariant<A>, b: Covariant<B>) {
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a = b;
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b = a; // Error
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}
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function f2<A, B extends A>(a: Contravariant<A>, b: Contravariant<B>) {
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a = b; // Error
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b = a;
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}
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function f3<A, B extends A>(a: Invariant<A>, b: Invariant<B>) {
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a = b; // Error
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b = a; // Error
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}
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// Extract<T, Function> is a T that is known to be a Function
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function isFunction<T>(value: T): value is Extract<T, Function> {
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return typeof value === "function";
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}
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function getFunction<T>(item: T) {
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if (isFunction(item)) {
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return item;
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}
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throw new Error();
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}
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function f10<T>(x: T) {
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if (isFunction(x)) {
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const f: Function = x;
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const t: T = x;
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}
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}
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function f11(x: string | (() => string) | undefined) {
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if (isFunction(x)) {
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x();
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}
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}
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function f12(x: string | (() => string) | undefined) {
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const f = getFunction(x); // () => string
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f();
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}
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type Foo = { foo: string };
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type Bar = { bar: string };
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declare function fooBar(x: { foo: string, bar: string }): void;
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declare function fooBat(x: { foo: string, bat: string }): void;
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type Extract2<T, U, V> = T extends U ? T extends V ? T : never : never;
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function f20<T>(x: Extract<Extract<T, Foo>, Bar>, y: Extract<T, Foo & Bar>, z: Extract2<T, Foo, Bar>) {
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fooBar(x);
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fooBar(y);
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fooBar(z);
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}
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function f21<T>(x: Extract<Extract<T, Foo>, Bar>, y: Extract<T, Foo & Bar>, z: Extract2<T, Foo, Bar>) {
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fooBat(x); // Error
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fooBat(y); // Error
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fooBat(z); // Error
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}
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// Repros from #22860
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class Opt<T> {
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toVector(): Vector<T> {
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return <any>undefined;
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}
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}
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interface Seq<T> {
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tail(): Opt<Seq<T>>;
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}
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class Vector<T> implements Seq<T> {
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tail(): Opt<Vector<T>> {
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return <any>undefined;
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}
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partition2<U extends T>(predicate:(v:T)=>v is U): [Vector<U>,Vector<Exclude<T, U>>];
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partition2(predicate:(x:T)=>boolean): [Vector<T>,Vector<T>];
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partition2<U extends T>(predicate:(v:T)=>boolean): [Vector<U>,Vector<any>] {
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return <any>undefined;
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}
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}
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interface A1<T> {
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bat: B1<A1<T>>;
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}
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interface B1<T> extends A1<T> {
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bat: B1<B1<T>>;
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boom: T extends any ? true : true
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}
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// Repro from #22899
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declare function toString1(value: object | Function): string ;
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declare function toString2(value: Function): string ;
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function foo<T>(value: T) {
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if (isFunction(value)) {
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toString1(value);
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toString2(value);
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}
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}
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// Repro from #23052
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type A<T, V, E> =
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T extends object
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? { [Q in { [P in keyof T]: T[P] extends V ? P : P; }[keyof T]]: A<T[Q], V, E>; }
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: T extends V ? T : never;
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type B<T, V> =
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T extends object
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? { [Q in { [P in keyof T]: T[P] extends V ? P : P; }[keyof T]]: B<T[Q], V>; }
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: T extends V ? T : never;
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type C<T, V, E> =
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{ [Q in { [P in keyof T]: T[P] extends V ? P : P; }[keyof T]]: C<T[Q], V, E>; };
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// Repro from #23100
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type A2<T, V, E> =
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T extends object ? T extends any[] ? T : { [Q in keyof T]: A2<T[Q], V, E>; } : T;
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type B2<T, V> =
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T extends object ? T extends any[] ? T : { [Q in keyof T]: B2<T[Q], V>; } : T;
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type C2<T, V, E> =
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T extends object ? { [Q in keyof T]: C2<T[Q], V, E>; } : T;
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// Repro from #28654
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type MaybeTrue<T extends { b: boolean }> = true extends T["b"] ? "yes" : "no";
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type T0 = MaybeTrue<{ b: never }> // "no"
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type T1 = MaybeTrue<{ b: false }>; // "no"
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type T2 = MaybeTrue<{ b: true }>; // "yes"
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type T3 = MaybeTrue<{ b: boolean }>; // "yes"
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// Repro from #28824
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type Union = 'a' | 'b';
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type Product<A extends Union, B> = { f1: A, f2: B};
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type ProductUnion = Product<'a', 0> | Product<'b', 1>;
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// {a: "b"; b: "a"}
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type UnionComplement = {
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[K in Union]: Exclude<Union, K>
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};
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type UCA = UnionComplement['a'];
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type UCB = UnionComplement['b'];
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// {a: "a"; b: "b"}
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type UnionComplementComplement = {
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[K in Union]: Exclude<Union, Exclude<Union, K>>
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};
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type UCCA = UnionComplementComplement['a'];
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type UCCB = UnionComplementComplement['b'];
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// {a: Product<'b', 1>; b: Product<'a', 0>}
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type ProductComplement = {
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[K in Union]: Exclude<ProductUnion, { f1: K }>
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};
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type PCA = ProductComplement['a'];
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type PCB = ProductComplement['b'];
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// {a: Product<'a', 0>; b: Product<'b', 1>}
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type ProductComplementComplement = {
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[K in Union]: Exclude<ProductUnion, Exclude<ProductUnion, { f1: K }>>
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};
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type PCCA = ProductComplementComplement['a'];
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type PCCB = ProductComplementComplement['b'];
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// Repro from #31326
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type Hmm<T, U extends T> = U extends T ? { [K in keyof U]: number } : never;
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type What = Hmm<{}, { a: string }>
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const w: What = { a: 4 };
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