{"action":"created","issue":{"url":"https://api.github.com/repos/tc39/proposal-class-fields/issues/25","repository_url":"https://api.github.com/repos/tc39/proposal-class-fields","labels_url":"https://api.github.com/repos/tc39/proposal-class-fields/issues/25/labels{/name}","comments_url":"https://api.github.com/repos/tc39/proposal-class-fields/issues/25/comments","events_url":"https://api.github.com/repos/tc39/proposal-class-fields/issues/25/events","html_url":"https://github.com/tc39/proposal-class-fields/issues/25","id":244772383,"number":25,"title":"Initializer Containing arrow containing `arguments`","user":{"login":"bakkot","id":1653598,"avatar_url":"https://avatars2.githubusercontent.com/u/1653598?v=4","gravatar_id":"","url":"https://api.github.com/users/bakkot","html_url":"https://github.com/bakkot","followers_url":"https://api.github.com/users/bakkot/followers","following_url":"https://api.github.com/users/bakkot/following{/other_user}","gists_url":"https://api.github.com/users/bakkot/gists{/gist_id}","starred_url":"https://api.github.com/users/bakkot/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/bakkot/subscriptions","organizations_url":"https://api.github.com/users/bakkot/orgs","repos_url":"https://api.github.com/users/bakkot/repos","events_url":"https://api.github.com/users/bakkot/events{/privacy}","received_events_url":"https://api.github.com/users/bakkot/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":0,"created_at":"2017-07-21T20:16:01Z","updated_at":"2017-07-21T20:27:02Z","closed_at":null,"body":"[The rule](https://tc39.github.io/proposal-class-fields/#sec-static-semantics-early-errors) which prevents initializers from referring to `arguments` uses `Contains`, which [does not](https://tc39.github.io/ecma262/#sec-arrow-function-definitions-static-semantics-contains) descend into arrow functions except for `new.target`, `super`, and `this`.\r\n\r\nIt should be an early error, I think. Including recursively - we should disallow\r\n\r\n```js\r\nclass A {\r\n  a = b => c => { return arguments; };\r\n}\r\n```\r\n\r\nNot entirely sure how to spec it though."},"comment":{"url":"https://api.github.com/repos/tc39/proposal-class-fields/issues/comments/317104350","html_url":"https://github.com/tc39/proposal-class-fields/issues/25#issuecomment-317104350","issue_url":"https://api.github.com/repos/tc39/proposal-class-fields/issues/25","id":317104350,"user":{"login":"bakkot","id":1653598,"avatar_url":"https://avatars2.githubusercontent.com/u/1653598?v=4","gravatar_id":"","url":"https://api.github.com/users/bakkot","html_url":"https://github.com/bakkot","followers_url":"https://api.github.com/users/bakkot/followers","following_url":"https://api.github.com/users/bakkot/following{/other_user}","gists_url":"https://api.github.com/users/bakkot/gists{/gist_id}","starred_url":"https://api.github.com/users/bakkot/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/bakkot/subscriptions","organizations_url":"https://api.github.com/users/bakkot/orgs","repos_url":"https://api.github.com/users/bakkot/repos","events_url":"https://api.github.com/users/bakkot/events{/privacy}","received_events_url":"https://api.github.com/users/bakkot/received_events","type":"User","site_admin":false},"created_at":"2017-07-21T20:27:02Z","updated_at":"2017-07-21T20:27:02Z","body":"As a strawman, we could add a new algorithm `ContainsArguments` which descends into everything except `FunctionDeclaration/Expression` and `ClassBody` (taking advantage of chain productions to minimize the amount of spec text necessary). I'll try to spec that to see how it looks."}}
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