File: contextualSignatureInstatiationContravariance.ts

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interface Animal { x }
interface Giraffe extends Animal { y }
interface Elephant extends Animal { y2 }

var f2: <T extends Animal>(x: T, y: T) => void;

var g2: (g: Giraffe, e: Elephant) => void;
g2 = f2; // error because Giraffe and Elephant are disjoint types

var h2: (g1: Giraffe, g2: Giraffe) => void;
h2 = f2; // valid because Giraffe satisfies the constraint. It is safe in the traditional contravariant fashion.