fix(runtime-core): avoid double-setting props when casting

fix #3371, close #3384

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

@@ -12,7 +12,8 @@ import {
   provide,
   inject,
   watch,
-  toRefs
+  toRefs,
+  SetupContext
 } from '@vue/runtime-test'
 import { render as domRender, nextTick } from 'vue'
 
@@ -508,4 +509,51 @@ describe('component props', () => {
     await nextTick()
     expect(changeSpy).toHaveBeenCalledTimes(1)
   })
+
+  // #3371
+  test(`avoid double-setting props when casting`, async () => {
+    const Parent = {
+      setup(props: any, { slots }: SetupContext) {
+        const childProps = ref()
+        const registerChildProps = (props: any) => {
+          childProps.value = props
+        }
+        provide('register', registerChildProps)
+
+        return () => {
+          // access the child component's props
+          childProps.value && childProps.value.foo
+          return slots.default!()
+        }
+      }
+    }
+
+    const Child = {
+      props: {
+        foo: {
+          type: Boolean,
+          required: false
+        }
+      },
+      setup(props: { foo: boolean }) {
+        const register = inject('register') as any
+        // 1. change the reactivity data of the parent component
+        // 2. register its own props to the parent component
+        register(props)
+
+        return () => 'foo'
+      }
+    }
+
+    const App = {
+      setup() {
+        return () => h(Parent, () => h(Child as any, { foo: '' }, () => null))
+      }
+    }
+
+    const root = nodeOps.createElement('div')
+    render(h(App), root)
+    await nextTick()
+    expect(serializeInner(root)).toBe(`foo`)
+  })
 })