fix(ssr): fix ssr scopeId on component root

packages/server-renderer/src/helpers/ssrRenderSlot.ts

@@ -1,4 +1,4 @@
-import { ComponentInternalInstance, Slot, Slots } from 'vue'
+import { ComponentInternalInstance, Slots } from 'vue'
 import { Props, PushFn, renderVNodeChildren } from '../render'
 
 export type SSRSlots = Record<string, SSRSlot>
@@ -21,13 +21,16 @@ export function ssrRenderSlot(
   push(`<!--[-->`)
   const slotFn = slots[slotName]
   if (slotFn) {
-    if (slotFn.length > 1) {
-      // only ssr-optimized slot fns accept more than 1 arguments
-      const scopeId = parentComponent && parentComponent.type.__scopeId
-      slotFn(slotProps, push, parentComponent, scopeId ? ` ${scopeId}-s` : ``)
-    } else {
+    const scopeId = parentComponent && parentComponent.type.__scopeId
+    const ret = slotFn(
+      slotProps,
+      push,
+      parentComponent,
+      scopeId ? ` ${scopeId}-s` : ``
+    )
+    if (Array.isArray(ret)) {
       // normal slot
-      renderVNodeChildren(push, (slotFn as Slot)(slotProps), parentComponent)
+      renderVNodeChildren(push, ret, parentComponent)
     }
   } else if (fallbackRenderFn) {
     fallbackRenderFn()

packages/server-renderer/src/render.ts

@@ -109,11 +109,23 @@ function renderComponentSubTree(
 
     if (comp.ssrRender) {
       // optimized
+      // resolve fallthrough attrs
+      let attrs =
+        instance.type.inheritAttrs !== false ? instance.attrs : undefined
+
+      // inherited scopeId
+      const scopeId = instance.vnode.scopeId
+      const treeOwnerId = instance.parent && instance.parent.type.__scopeId
+      const slotScopeId =
+        treeOwnerId && treeOwnerId !== scopeId ? treeOwnerId + '-s' : null
+      if (scopeId || slotScopeId) {
+        attrs = { ...attrs }
+        if (scopeId) attrs[scopeId] = ''
+        if (slotScopeId) attrs[slotScopeId] = ''
+      }
+
       // set current rendering instance for asset resolution
       setCurrentRenderingInstance(instance)
-      // fallthrough attrs
-      const attrs =
-        instance.type.inheritAttrs !== false ? instance.attrs : undefined
       comp.ssrRender(instance.proxy, push, instance, attrs)
       setCurrentRenderingInstance(null)
     } else if (instance.render) {