fix(runtime-core): enable block tracking when normalizing plain element with slot children (#1987)

fix #1980

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

@@ -11,6 +11,8 @@ import { PatchFlags, SlotFlags } from '@vue/shared'
 import { warn } from '../warning'
 
 export let isRenderingCompiledSlot = 0
+export const setCompiledSlotRendering = (n: number) =>
+  (isRenderingCompiledSlot += n)
 
 /**
  * Compiler runtime helper for rendering `<slot/>`

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

@@ -16,7 +16,7 @@ export function withCtx(
   ctx: ComponentInternalInstance | null = currentRenderingInstance
 ) {
   if (!ctx) return fn
-  return function renderFnWithContext() {
+  const renderFnWithContext = (...args: any[]) => {
     // If a user calls a compiled slot inside a template expression (#1745), it
     // can mess up block tracking, so by default we need to push a null block to
     // avoid that. This isn't necessary if rendering a compiled `<slot>`.
@@ -25,11 +25,13 @@ export function withCtx(
     }
     const owner = currentRenderingInstance
     setCurrentRenderingInstance(ctx)
-    const res = fn.apply(null, arguments as any)
+    const res = fn(...args)
     setCurrentRenderingInstance(owner)
     if (!isRenderingCompiledSlot) {
       closeBlock()
     }
     return res
   }
+  renderFnWithContext._c = true
+  return renderFnWithContext
 }