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export {}
// @strict: true
declare let f1: (x: Object) => Object;
declare let f2: (x: Object) => string;
declare let f3: (x: string) => Object;
declare let f4: (x: string) => string;
f1 = f2; // Ok
f1 = f3; // Error
f1 = f4; // Error
f2 = f1; // Error
f2 = f3; // Error
f2 = f4; // Error
f3 = f1; // Ok
f3 = f2; // Ok
f3 = f4; // Ok
f4 = f1; // Error
f4 = f2; // Ok
f4 = f3; // Error
type Func<T, U> = (x: T) => U;
declare let g1: Func<Object, Object>;
declare let g2: Func<Object, string>;
declare let g3: Func<string, Object>;
declare let g4: Func<string, string>;
g1 = g2; // Ok
g1 = g3; // Error
g1 = g4; // Error
g2 = g1; // Error
g2 = g3; // Error
g2 = g4; // Error
g3 = g1; // Ok
g3 = g2; // Ok
g3 = g4; // Ok
g4 = g1; // Error
g4 = g2; // Ok
g4 = g3; // Error
declare let h1: Func<Func<Object, void>, Object>;
declare let h2: Func<Func<Object, void>, string>;
declare let h3: Func<Func<string, void>, Object>;
declare let h4: Func<Func<string, void>, string>;
h1 = h2; // Ok
h1 = h3; // Ok
h1 = h4; // Ok
h2 = h1; // Error
h2 = h3; // Error
h2 = h4; // Ok
h3 = h1; // Error
h3 = h2; // Error
h3 = h4; // Ok
h4 = h1; // Error
h4 = h2; // Error
h4 = h3; // Error
declare let i1: Func<Object, Func<Object, void>>;
declare let i2: Func<Object, Func<string, void>>;
declare let i3: Func<string, Func<Object, void>>;
declare let i4: Func<string, Func<string, void>>;
i1 = i2; // Error
i1 = i3; // Error
i1 = i4; // Error
i2 = i1; // Ok
i2 = i3; // Error
i2 = i4; // Error
i3 = i1; // Ok
i3 = i2; // Error
i3 = i4; // Error
i4 = i1; // Ok
i4 = i2; // Ok
i4 = i3; // Ok
interface Animal { animal: void }
interface Dog extends Animal { dog: void }
interface Cat extends Animal { cat: void }
interface Comparer1<T> {
compare(a: T, b: T): number;
}
declare let animalComparer1: Comparer1<Animal>;
declare let dogComparer1: Comparer1<Dog>;
animalComparer1 = dogComparer1; // Ok
dogComparer1 = animalComparer1; // Ok
interface Comparer2<T> {
compare: (a: T, b: T) => number;
}
declare let animalComparer2: Comparer2<Animal>;
declare let dogComparer2: Comparer2<Dog>;
animalComparer2 = dogComparer2; // Error
dogComparer2 = animalComparer2; // Ok
// Crate<T> is invariant in --strictFunctionTypes mode
interface Crate<T> {
item: T;
onSetItem: (item: T) => void;
}
declare let animalCrate: Crate<Animal>;
declare let dogCrate: Crate<Dog>;
// Errors below should elaborate the reason for invariance
animalCrate = dogCrate; // Error
dogCrate = animalCrate; // Error
// Verify that callback parameters are strictly checked
declare let fc1: (f: (x: Animal) => Animal) => void;
declare let fc2: (f: (x: Dog) => Dog) => void;
fc1 = fc2; // Error
fc2 = fc1; // Error
// Verify that callback parameters aren't loosely checked when types
// originate in method declarations
namespace n1 {
class Foo {
static f1(x: Animal): Animal { throw "wat"; }
static f2(x: Dog): Animal { throw "wat"; };
}
declare let f1: (cb: typeof Foo.f1) => void;
declare let f2: (cb: typeof Foo.f2) => void;
f1 = f2;
f2 = f1; // Error
}
namespace n2 {
type BivariantHack<Input, Output> = { foo(x: Input): Output }["foo"];
declare let f1: (cb: BivariantHack<Animal, Animal>) => void;
declare let f2: (cb: BivariantHack<Dog, Animal>) => void;
f1 = f2;
f2 = f1; // Error
}
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