how to access both child event param and parent param in vue

1<template>
2    <ul>
3        <product v-for="product in products"
4                 :product="product"
5                 @add="addToChart" />
6    </ul>
7</template>
8
9<script>
10const Product = {
11    props: ["product"],
12    render(h) {
13        return h("li", { on: { click: this.click } }, this.product);
14    },
15    methods: {
16        click() {
17            this.$emit("add", { product: this.product, quantity: 42 });
18        }
19    }
20};
21
22export default {
23    data() {
24        return {
25            products: ["Foo", "Bar"]
26        };
27    },
28    components: {
29        Product
30    },
31    methods: {
32        addToChart({ product, quantity }) {
33            console.log(product, quantity);
34        }
35    }
36}
37</script>
38