Extend Array.prototype only if Array type extends a specific interface

Question

I'm trying to add an extension function to the Array.prototype but only for Arrays of a generic type extending an interface:

const a: MyTypeExtendingInterface[] = [];
a.myFunc(); // Works
const b: number[] = [];
b.myFunc(); // Compiler error

This is what I tried so far, but it doesn't compile. Any hints?

interface MyInterface {
    v: number;
}

declare interface Array<T extends MyInterface> {
    myFunc(this: Array<T extends MyInterface>): Array<T extends MyInterface>;
}

Object.defineProperty(Array.prototype, 'myFunc', {
    value: function(this: Array<T extends MyInterface>): Array<T extends MyInterface> {
        return this;
    },
});