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interface Base {
foo: string|number;
optional?: number;
}
// Derived1 is assignable to, but not a subtype of, Base
class Derived1 implements Base {
foo: string;
}
// Derived2 is a subtype of Base that is not assignable to Derived1
class Derived2 implements Base {
foo: number;
optional: number;
}
class Animal {
move;
}
class Mammal extends Animal { milk; }
class Giraffe extends Mammal { neck; }
function fn1(x: Array<number>|Array<string>|boolean) {
if(x instanceof Array) {
// 1.5: y: Array<number>|Array<string>
// Want: y: Array<number>|Array<string>
let y = x;
}
}
function fn2(x: Base) {
if(x instanceof Derived1) {
// 1.5: y: Base
// Want: y: Derived1
let y = x;
}
}
function fn3(x: Base|Derived1) {
if(x instanceof Derived2) {
// 1.5: y: Derived2
// Want: Derived2
let y = x;
}
}
function fn4(x: Base|Derived2) {
if(x instanceof Derived1) {
// 1.5: y: {}
// Want: Derived1
let y = x;
}
}
function fn5(x: Derived1) {
if(x instanceof Derived2) {
// 1.5: y: Derived1
// Want: ???
let y = x;
}
}
function fn6(x: Animal|Mammal) {
if(x instanceof Giraffe) {
// 1.5: y: Derived1
// Want: ???
let y = x;
}
}
function fn7(x: Array<number>|Array<string>) {
if(x instanceof Array) {
// 1.5: y: Array<number>|Array<string>
// Want: y: Array<number>|Array<string>
let y = x;
}
}
interface Alpha { a }
interface Beta { b }
interface Gamma { c }
class ABC { a; b; c; }
function fn8(x: Alpha|Beta|Gamma) {
if(x instanceof ABC) {
let y = x;
}
}
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