wip: vdom slot interop

Author: edison1105

packages/runtime-core/src/helpers/renderSlot.ts

@@ -81,6 +81,10 @@ export function renderSlot(
   }
   openBlock()
   const validSlotContent = slot && ensureValidVNode(slot(props))
+
+  // handle forwarded vapor slot fallback
+  ensureVaporSlotFallback(validSlotContent, fallback)
+
   const slotKey =
     props.key ||
     // slot content array of a dynamic conditional slot may have a branch
@@ -124,3 +128,20 @@ export function ensureValidVNode(
     ? vnodes
     : null
 }
+
+export function ensureVaporSlotFallback(
+  vnodes: VNodeArrayChildren | null | undefined,
+  fallback?: () => VNodeArrayChildren,
+): void {
+  let vaporSlot: any
+  if (
+    vnodes &&
+    vnodes.length === 1 &&
+    isVNode(vnodes[0]) &&
+    (vaporSlot = vnodes[0].vs)
+  ) {
+    if (!vaporSlot.fallback && fallback) {
+      vaporSlot.fallback = fallback
+    }
+  }
+}

packages/runtime-core/src/index.ts

@@ -557,3 +557,7 @@ export { startMeasure, endMeasure } from './profiling'
  * @internal
  */
 export { initFeatureFlags } from './featureFlags'
+/**
+ * @internal
+ */
+export { ensureVaporSlotFallback } from './helpers/renderSlot'

packages/runtime-core/src/renderer.ts

@@ -2622,7 +2622,7 @@ export function traverseStaticChildren(
 function locateNonHydratedAsyncRoot(
   instance: ComponentInternalInstance,
 ): ComponentInternalInstance | undefined {
-  const subComponent = instance.subTree.component
+  const subComponent = instance.vapor ? null : instance.subTree.component
   if (subComponent) {
     if (subComponent.asyncDep && !subComponent.asyncResolved) {
       return subComponent