fix(runtime-core): avoid scopeId as attr for slot nodes with same sco…

…peId (#1561)

fix vitejs/vite#536

packages/runtime-core/src/componentRenderUtils.ts

@@ -166,12 +166,16 @@ export function renderComponentRoot(
 
  // inherit scopeId
  const scopeId = vnode.scopeId
+ // vite#536: if subtree root is created from parent slot if would already
+ // have the correct scopeId, in this case adding the scopeId will cause
+ // it to be removed if the original slot vnode is reused.
+ const needScopeId = scopeId && root.scopeId !== scopeId
  const treeOwnerId = parent && parent.type.__scopeId
  const slotScopeId =
  treeOwnerId && treeOwnerId !== scopeId ? treeOwnerId + '-s' : null
- if (scopeId || slotScopeId) {
+ if (needScopeId || slotScopeId) {
  const extras: Data = {}
- if (scopeId) extras[scopeId] = ''
+ if (needScopeId) extras[scopeId] = ''
  if (slotScopeId) extras[slotScopeId] = ''
  root = cloneVNode(root, extras)
  }