{"action":"closed","issue":{"url":"https://api.github.com/repos/ternjs/acorn/issues/361","labels_url":"https://api.github.com/repos/ternjs/acorn/issues/361/labels{/name}","comments_url":"https://api.github.com/repos/ternjs/acorn/issues/361/comments","events_url":"https://api.github.com/repos/ternjs/acorn/issues/361/events","html_url":"https://github.com/ternjs/acorn/issues/361","id":120128762,"number":361,"title":"'undefined' is reserved word if ecmaVerison>=6 ?","user":{"login":"matAtWork","id":9590115,"avatar_url":"https://avatars.githubusercontent.com/u/9590115?v=3","gravatar_id":"","url":"https://api.github.com/users/matAtWork","html_url":"https://github.com/matAtWork","followers_url":"https://api.github.com/users/matAtWork/followers","following_url":"https://api.github.com/users/matAtWork/following{/other_user}","gists_url":"https://api.github.com/users/matAtWork/gists{/gist_id}","starred_url":"https://api.github.com/users/matAtWork/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/matAtWork/subscriptions","organizations_url":"https://api.github.com/users/matAtWork/orgs","repos_url":"https://api.github.com/users/matAtWork/repos","events_url":"https://api.github.com/users/matAtWork/events{/privacy}","received_events_url":"https://api.github.com/users/matAtWork/received_events","type":"User","site_admin":false},"labels":[],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":1,"created_at":"2015-12-03T09:41:06Z","updated_at":"2015-12-03T09:54:52Z","closed_at":"2015-12-03T09:54:52Z","body":"The following fails to parse with acorn 2.6.4, but I'm unsure as to why:\r\n```\r\n$ echo 'function x() { return undefined }' | ./acorn --ecma7\r\nThe keyword 'undefined' is reserved (1:22)\r\n```\r\nIt works with --ecma6 - am I missing some subtle understanding of reserved words in ES7? "}}