{"action":"created","issue":{"url":"https://api.github.com/repos/tc39/ecma262/issues/299","labels_url":"https://api.github.com/repos/tc39/ecma262/issues/299/labels{/name}","comments_url":"https://api.github.com/repos/tc39/ecma262/issues/299/comments","events_url":"https://api.github.com/repos/tc39/ecma262/issues/299/events","html_url":"https://github.com/tc39/ecma262/issues/299","id":127508500,"number":299,"title":"Possibly-unreachable specification text","user":{"login":"jugglinmike","id":677252,"avatar_url":"https://avatars.githubusercontent.com/u/677252?v=3","gravatar_id":"","url":"https://api.github.com/users/jugglinmike","html_url":"https://github.com/jugglinmike","followers_url":"https://api.github.com/users/jugglinmike/followers","following_url":"https://api.github.com/users/jugglinmike/following{/other_user}","gists_url":"https://api.github.com/users/jugglinmike/gists{/gist_id}","starred_url":"https://api.github.com/users/jugglinmike/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jugglinmike/subscriptions","organizations_url":"https://api.github.com/users/jugglinmike/orgs","repos_url":"https://api.github.com/users/jugglinmike/repos","events_url":"https://api.github.com/users/jugglinmike/events{/privacy}","received_events_url":"https://api.github.com/users/jugglinmike/received_events","type":"User","site_admin":false},"labels":[],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":2,"created_at":"2016-01-19T18:27:55Z","updated_at":"2016-01-19T18:42:41Z","closed_at":"2016-01-19T18:42:41Z","body":"I'm having trouble verifying step 4.a.ii.1 in section 13.12.9 (\"Runtime Semantics: CaseBlockEvaluation\"):\r\n\r\n>     CaseBlock : { CaseClauses }\r\n>\r\n>     1. Let V = undefined.\r\n>     2. Let A be the List of CaseClause items in CaseClauses, in source text order.\r\n>     3. Let found be false.\r\n>     4. Repeat for each CaseClause C in A,\r\n>        a. If found is false, then\r\n>           i. Let clauseSelector be the result of CaseSelectorEvaluation of C.\r\n>           ii. If clauseSelector is an abrupt completion, then\r\n>               1. If clauseSelector.[[value]] is empty, return\r\n>                  Completion{[[type]]: clauseSelector.[[type]], [[value]]:\r\n>                  undefined, [[target]]: clauseSelector.[[target]]}.\r\n\r\nsource: http://www.ecma-international.org/ecma-262/6.0/#sec-runtime-semantics-caseblockevaluation\r\n\r\n(The algorithm for blocks containing the `default` case have an equivalent step.)\r\n\r\nBecause CaseSelectorEvaluation is defined as follows:\r\n\r\n>     CaseClause : case Expression : StatementListopt\r\n>\r\n>     1. Let exprRef be the result of evaluating Expression.\r\n>     2. Return GetValue(exprRef).\r\n\r\n...the question I'm having trouble answering is: which Expression will return an empty abrupt completion?"},"comment":{"url":"https://api.github.com/repos/tc39/ecma262/issues/comments/172946466","html_url":"https://github.com/tc39/ecma262/issues/299#issuecomment-172946466","issue_url":"https://api.github.com/repos/tc39/ecma262/issues/299","id":172946466,"user":{"login":"jugglinmike","id":677252,"avatar_url":"https://avatars.githubusercontent.com/u/677252?v=3","gravatar_id":"","url":"https://api.github.com/users/jugglinmike","html_url":"https://github.com/jugglinmike","followers_url":"https://api.github.com/users/jugglinmike/followers","following_url":"https://api.github.com/users/jugglinmike/following{/other_user}","gists_url":"https://api.github.com/users/jugglinmike/gists{/gist_id}","starred_url":"https://api.github.com/users/jugglinmike/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jugglinmike/subscriptions","organizations_url":"https://api.github.com/users/jugglinmike/orgs","repos_url":"https://api.github.com/users/jugglinmike/repos","events_url":"https://api.github.com/users/jugglinmike/events{/privacy}","received_events_url":"https://api.github.com/users/jugglinmike/received_events","type":"User","site_admin":false},"created_at":"2016-01-19T18:42:41Z","updated_at":"2016-01-19T18:42:41Z","body":"@anba Thank you!"}}