Why Babel parses IIFE of arrow function

Question

As I may see from grammar of ES2015 this expression is not a valid one:

() => { console.log("hello"); } ();

You need at least put parentheses:

(() => { console.log("hello"); }) ();

Chrome fails on first sample with Uncaught SyntaxError: Unexpected token (

But Babel is ok with that. Why?

Answer 1

But Babel is ok with that. Why?

Because Babel is buggy :-) See https://phabricator.babeljs.io/T2118 and https://phabricator.babeljs.io/T2027 . If I understand correctly, it was fixed with Babel 6 - it was a quite breaking change.