fix(runtime-core): prevent self-injection (vuejs#2400)

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

@@ -303,4 +303,19 @@ describe('api: provide/inject', () => {
  render(h(Provider), root)
  expect(`injection "foo" not found.`).not.toHaveBeenWarned()
  })
+
+ // #2400
+ it('should not self-inject', () => {
+ const Comp = {
+ setup() {
+ provide('foo', 'foo')
+ const injection = inject('foo', null)
+ return () => injection
+ }
+ }
+
+ const root = nodeOps.createElement('div')
+ render(h(Comp), root)
+ expect(serialize(root)).toBe(`<div><!----></div>`)
+ })
 })

packages/runtime-core/src/apiInject.ts

@@ -47,8 +47,15 @@ export function inject(
  // a functional component
  const instance = currentInstance || currentRenderingInstance
  if (instance) {
- const provides = instance.provides
- if ((key as string | symbol) in provides) {
+ // #2400
+ // to support `app.use` plugins,
+ // fallback to appContext's `provides` if the intance is at root
+ const provides =
+ instance.parent == null
+ ? instance.vnode.appContext && instance.vnode.appContext.provides
+ : instance.parent.provides
+
+ if (provides && (key as string | symbol) in provides) {
  // TS doesn't allow symbol as index type
  return provides[key as string]
  } else if (arguments.length > 1) {