Function convertLegacyRenderFn

packages/runtime-core/src/compat/renderFn.ts:42–70

(
  instance: ComponentInternalInstance,
)

import { compatModelEventPrefix } from './componentVModel'

export function convertLegacyRenderFn(
  instance: ComponentInternalInstance,
): void {
  const Component = instance.type as ComponentOptions
  const render = Component.render as InternalRenderFunction | undefined

  // v3 runtime compiled, or already checked / wrapped
  if (!render || render._rc || render._compatChecked || render._compatWrapped) {
    return
  }

  if (render.length >= 2) {
    // v3 pre-compiled function, since v2 render functions never need more than
    // 2 arguments, and v2 functional render functions would have already been
    // normalized into v3 functional components
    render._compatChecked = true
    return
  }

  // v2 render function, try to provide compat
  if (checkCompatEnabled(DeprecationTypes.RENDER_FUNCTION, instance)) {
    const wrapped = (Component.render = function compatRender() {
      // @ts-expect-error
      return render.call(this, compatH)
    })
    // @ts-expect-error
    wrapped._compatWrapped = true
  }
}

interface LegacyVNodeProps {
  key?: string | number