{"action":"created","issue":{"url":"https://api.github.com/repos/rust-lang/rust/issues/26465","labels_url":"https://api.github.com/repos/rust-lang/rust/issues/26465/labels{/name}","comments_url":"https://api.github.com/repos/rust-lang/rust/issues/26465/comments","events_url":"https://api.github.com/repos/rust-lang/rust/issues/26465/events","html_url":"https://github.com/rust-lang/rust/issues/26465","id":89866937,"number":26465,"title":"Type inference breakage around extend()","user":{"login":"Tobba","id":1667853,"avatar_url":"https://avatars.githubusercontent.com/u/1667853?v=3","gravatar_id":"","url":"https://api.github.com/users/Tobba","html_url":"https://github.com/Tobba","followers_url":"https://api.github.com/users/Tobba/followers","following_url":"https://api.github.com/users/Tobba/following{/other_user}","gists_url":"https://api.github.com/users/Tobba/gists{/gist_id}","starred_url":"https://api.github.com/users/Tobba/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Tobba/subscriptions","organizations_url":"https://api.github.com/users/Tobba/orgs","repos_url":"https://api.github.com/users/Tobba/repos","events_url":"https://api.github.com/users/Tobba/events{/privacy}","received_events_url":"https://api.github.com/users/Tobba/received_events","type":"User","site_admin":false},"labels":[],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":1,"created_at":"2015-06-21T05:23:27Z","updated_at":"2015-06-21T06:56:20Z","closed_at":"2015-06-21T06:56:20Z","body":"```\r\nuse std::mem::uninitialized;\r\n\r\nfn main() {\r\n    let mut foo = Vec::<u32>::new();\r\n    unsafe {\r\n    \tfoo.extend((0..0).map(|_| uninitialized()));\r\n    }\r\n}\r\n```\r\n\r\nThis builds on stable, but not on nightly."},"comment":{"url":"https://api.github.com/repos/rust-lang/rust/issues/comments/113870148","html_url":"https://github.com/rust-lang/rust/issues/26465#issuecomment-113870148","issue_url":"https://api.github.com/repos/rust-lang/rust/issues/26465","id":113870148,"user":{"login":"Gankro","id":1136864,"avatar_url":"https://avatars.githubusercontent.com/u/1136864?v=3","gravatar_id":"","url":"https://api.github.com/users/Gankro","html_url":"https://github.com/Gankro","followers_url":"https://api.github.com/users/Gankro/followers","following_url":"https://api.github.com/users/Gankro/following{/other_user}","gists_url":"https://api.github.com/users/Gankro/gists{/gist_id}","starred_url":"https://api.github.com/users/Gankro/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Gankro/subscriptions","organizations_url":"https://api.github.com/users/Gankro/orgs","repos_url":"https://api.github.com/users/Gankro/repos","events_url":"https://api.github.com/users/Gankro/events{/privacy}","received_events_url":"https://api.github.com/users/Gankro/received_events","type":"User","site_admin":false},"created_at":"2015-06-21T06:56:20Z","updated_at":"2015-06-21T06:56:20Z","body":"This is expected behaviour due to the addition of `extend<Item=&T> where T: Clone` (and indeed picking the wrong default would cause UB here). "}}