Array of classes in cloneVNode are joined with ',' instead of mimicking class prop

[adamwathan]

Version

3.0.0-rc.8

Reproduction link

https://codesandbox.io/s/weathered-bush-fd9mf?file=/src/LabeledIcon.vue

Steps to reproduce

Creating a render function component that looks something like this:

import { h, cloneVNode } from "vue";

export default {
  setup(props, { slots }) {
    const [span] = slots.default();

    return () => cloneVNode(span, { class: ["foo", "bar"] });
  }
};

...will ultimately render something like instead of .

What is expected?

Should treat the class property like the class prop, and support array syntax, object syntax, etc.

What is actually happening?

Classes appear to just be joined with ",", looks like Array.toString() sort of behavior.