opened
Dominator008
username_0
<!-- BUGS: Please use this template. -->
<!-- QUESTIONS: This is not a general support forum! Ask Qs at http://stackoverflow.com/questions/tagged/typescript -->
<!-- SUGGESTIONS: See https://github.com/Microsoft/TypeScript-wiki/blob/master/Writing-Good-Design-Proposals.md -->

**TypeScript Version:**  2.2.1 / nightly (2.2.0-dev.201xxxxx)

**Code**

```ts
(function ({ x = false } = { x }){})()
```

**Expected behavior:**
Give an error on trying to refer to `x` before it's defined. This is a temporal dead zone violation and throws in the browsers.
**Actual behavior:**
No error
Early reference to parameters defined via object destructuring should trigger an error
issue