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Merge pull request microsoft#22869 from Microsoft/fixConditionalTypeVariance
Fix conditional type variance
2 parents d7df84d + 9acdb75 commit fe8f239

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6 files changed

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6 files changed

+709
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‎src/compiler/checker.ts

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@@ -10200,8 +10200,11 @@ namespace ts {
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}
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else if (source.flags & TypeFlags.Conditional) {
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if (target.flags & TypeFlags.Conditional) {
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if (isTypeIdenticalTo((<ConditionalType>source).checkType, (<ConditionalType>target).checkType) &&
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isTypeIdenticalTo((<ConditionalType>source).extendsType, (<ConditionalType>target).extendsType)) {
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// Two conditional types 'T1 extends U1 ? X1 : Y1' and 'T2 extends U2 ? X2 : Y2' are related if
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// one of T1 and T2 is related to the other, U1 and U2 are identical types, X1 is related to X2,
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// and Y1 is related to Y2.
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if (isTypeIdenticalTo((<ConditionalType>source).extendsType, (<ConditionalType>target).extendsType) &&
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(isRelatedTo((<ConditionalType>source).checkType, (<ConditionalType>target).checkType) || isRelatedTo((<ConditionalType>target).checkType, (<ConditionalType>source).checkType))) {
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if (result = isRelatedTo(getTrueTypeFromConditionalType(<ConditionalType>source), getTrueTypeFromConditionalType(<ConditionalType>target), reportErrors)) {
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result &= isRelatedTo(getFalseTypeFromConditionalType(<ConditionalType>source), getFalseTypeFromConditionalType(<ConditionalType>target), reportErrors);
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}

‎tests/baselines/reference/conditionalTypes2.errors.txt

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tests/cases/conformance/types/conditional/conditionalTypes2.ts(15,5): error TS2322: Type 'Covariant<A>' is not assignable to type 'Covariant<B>'.
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Type 'A' is not assignable to type 'B'.
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tests/cases/conformance/types/conditional/conditionalTypes2.ts(19,5): error TS2322: Type 'Contravariant<B>' is not assignable to type 'Contravariant<A>'.
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Type 'A' is not assignable to type 'B'.
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tests/cases/conformance/types/conditional/conditionalTypes2.ts(24,5): error TS2322: Type 'Invariant<B>' is not assignable to type 'Invariant<A>'.
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Types of property 'foo' are incompatible.
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Type 'B extends string ? keyof B : B' is not assignable to type 'A extends string ? keyof A : A'.
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Type 'keyof B' is not assignable to type 'keyof A'.
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tests/cases/conformance/types/conditional/conditionalTypes2.ts(25,5): error TS2322: Type 'Invariant<A>' is not assignable to type 'Invariant<B>'.
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Types of property 'foo' are incompatible.
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Type 'A extends string ? keyof A : A' is not assignable to type 'B extends string ? keyof B : B'.
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Type 'A' is not assignable to type 'B'.
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==== tests/cases/conformance/types/conditional/conditionalTypes2.ts (4 errors) ====
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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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!!! error TS2322: Type 'Covariant<A>' is not assignable to type 'Covariant<B>'.
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!!! error TS2322: Type 'A' is not assignable to type 'B'.
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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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~
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!!! error TS2322: Type 'Contravariant<B>' is not assignable to type 'Contravariant<A>'.
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!!! error TS2322: Type 'A' is not assignable to type 'B'.
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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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~
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!!! error TS2322: Type 'Invariant<B>' is not assignable to type 'Invariant<A>'.
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!!! error TS2322: Types of property 'foo' are incompatible.
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!!! error TS2322: Type 'B extends string ? keyof B : B' is not assignable to type 'A extends string ? keyof A : A'.
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!!! error TS2322: Type 'keyof B' is not assignable to type 'keyof A'.
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b = a; // Error
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~
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!!! error TS2322: Type 'Invariant<A>' is not assignable to type 'Invariant<B>'.
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!!! error TS2322: Types of property 'foo' are incompatible.
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!!! error TS2322: Type 'A extends string ? keyof A : A' is not assignable to type 'B extends string ? keyof B : B'.
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!!! error TS2322: Type 'A' is not assignable to type 'B'.
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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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‎tests/baselines/reference/conditionalTypes2.js

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//// [conditionalTypes2.ts]
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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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// 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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//// [conditionalTypes2.js]
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"use strict";
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function f1(a, 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) {
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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) {
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a = b; // Error
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b = a; // Error
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}
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// Repros from #22860
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var Opt = /** @class */ (function () {
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function Opt() {
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}
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Opt.prototype.toVector = function () {
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return undefined;
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};
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return Opt;
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}());
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var Vector = /** @class */ (function () {
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function Vector() {
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}
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Vector.prototype.tail = function () {
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return undefined;
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};
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Vector.prototype.partition2 = function (predicate) {
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return undefined;
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};
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return Vector;
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}());
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//// [conditionalTypes2.d.ts]
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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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declare function f1<A, B extends A>(a: Covariant<A>, b: Covariant<B>): void;
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declare function f2<A, B extends A>(a: Contravariant<A>, b: Contravariant<B>): void;
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declare function f3<A, B extends A>(a: Invariant<A>, b: Invariant<B>): void;
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declare class Opt<T> {
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toVector(): Vector<T>;
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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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declare class Vector<T> implements Seq<T> {
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tail(): Opt<Vector<T>>;
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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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}
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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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