Slot forwarding and render functions

[diachedelic]

It seems that there is no reliable way for a component written using render functions to forward a slot. As best I can tell, forwarding can only be made to work by rewriting the component with an SFC-style template, or (in some special cases) by exploiting Vue internals. The problem is described, with reproductions, in discussion vuejs/core#10847.

My proposal is that Vue could infer forwarded slots by comparing function references. For example, consider the following trivial component. All it does is wrap its default slot in a <div> element.

export default {
    setup(props, {slots}) {
        return function render() {
            return h("div", slots.default);
        };
    }
};

The render function returns a vnode containing the slot function, unaltered:

{
    type: "div",
    children: {
        default: slots.default,
    },
    ...
}

Notice that the slot function in this vnode is identical to the slot function passed in to setup. It seems possible, then, that Vue could detect the equality of the two functions during rendering (i.e. vnode.children.default === slots.default) and thus provide the same optimisation available to template components.

I am aware that I may be asking the impossible, and if so I apologise in advance. I am willing to do more research if somebody wants to point me in the right direction.