fix(runtime-core): should not warn out-of-render slot fn usage when mounting another app in setup (#10125)

close #10124

packages/runtime-core/__tests__/componentSlots.spec.ts

@@ -1,4 +1,5 @@
 import {
+  createApp,
   getCurrentInstance,
   h,
   nextTick,
@@ -240,4 +241,32 @@ describe('component: slots', () => {
     await nextTick()
     expect(spy).toHaveBeenCalledTimes(2)
   })
+
+  test('should not warn when mounting another app in setup', () => {
+    const Comp = {
+      setup(_: any, { slots }: any) {
+        return () => slots.default?.()
+      },
+    }
+
+    const mountComp = () => {
+      createApp({
+        setup() {
+          return () => h(Comp, () => 'msg')
+        },
+      }).mount(nodeOps.createElement('div'))
+    }
+
+    const App = {
+      setup() {
+        mountComp()
+        return () => null
+      },
+    }
+
+    createApp(App).mount(nodeOps.createElement('div'))
+    expect(
+      'Slot "default" invoked outside of the render function',
+    ).not.toHaveBeenWarned()
+  })
 })

packages/runtime-core/src/componentSlots.ts

@@ -97,7 +97,11 @@ const normalizeSlot = (
     return rawSlot as Slot
   }
   const normalized = withCtx((...args: any[]) => {
-    if (__DEV__ && currentInstance) {
+    if (
+      __DEV__ &&
+      currentInstance &&
+      (!ctx || ctx.root === currentInstance.root)
+    ) {
       warn(
         `Slot "${key}" invoked outside of the render function: ` +
           `this will not track dependencies used in the slot. ` +