{"action":"created","issue":{"url":"https://api.github.com/repos/rust-lang/rfcs/issues/1410","labels_url":"https://api.github.com/repos/rust-lang/rfcs/issues/1410/labels{/name}","comments_url":"https://api.github.com/repos/rust-lang/rfcs/issues/1410/comments","events_url":"https://api.github.com/repos/rust-lang/rfcs/issues/1410/events","html_url":"https://github.com/rust-lang/rfcs/pull/1410","id":122385336,"number":1410,"title":"Add a `noalias` language item","user":{"login":"mahkoh","id":1882250,"avatar_url":"https://avatars.githubusercontent.com/u/1882250?v=3","gravatar_id":"","url":"https://api.github.com/users/mahkoh","html_url":"https://github.com/mahkoh","followers_url":"https://api.github.com/users/mahkoh/followers","following_url":"https://api.github.com/users/mahkoh/following{/other_user}","gists_url":"https://api.github.com/users/mahkoh/gists{/gist_id}","starred_url":"https://api.github.com/users/mahkoh/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/mahkoh/subscriptions","organizations_url":"https://api.github.com/users/mahkoh/orgs","repos_url":"https://api.github.com/users/mahkoh/repos","events_url":"https://api.github.com/users/mahkoh/events{/privacy}","received_events_url":"https://api.github.com/users/mahkoh/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/rust-lang/rfcs/labels/T-lang","name":"T-lang","color":"bfd4f2"}],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":16,"created_at":"2015-12-15T22:48:16Z","updated_at":"2015-12-19T08:03:40Z","closed_at":null,"pull_request":{"url":"https://api.github.com/repos/rust-lang/rfcs/pulls/1410","html_url":"https://github.com/rust-lang/rfcs/pull/1410","diff_url":"https://github.com/rust-lang/rfcs/pull/1410.diff","patch_url":"https://github.com/rust-lang/rfcs/pull/1410.patch"},"body":"Add a `noalias` language item and wrapper struct (similar to `non_zero`) to\r\nmark raw pointers as `noalias`."},"comment":{"url":"https://api.github.com/repos/rust-lang/rfcs/issues/comments/165959706","html_url":"https://github.com/rust-lang/rfcs/pull/1410#issuecomment-165959706","issue_url":"https://api.github.com/repos/rust-lang/rfcs/issues/1410","id":165959706,"user":{"login":"Ericson2314","id":1055245,"avatar_url":"https://avatars.githubusercontent.com/u/1055245?v=3","gravatar_id":"","url":"https://api.github.com/users/Ericson2314","html_url":"https://github.com/Ericson2314","followers_url":"https://api.github.com/users/Ericson2314/followers","following_url":"https://api.github.com/users/Ericson2314/following{/other_user}","gists_url":"https://api.github.com/users/Ericson2314/gists{/gist_id}","starred_url":"https://api.github.com/users/Ericson2314/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Ericson2314/subscriptions","organizations_url":"https://api.github.com/users/Ericson2314/orgs","repos_url":"https://api.github.com/users/Ericson2314/repos","events_url":"https://api.github.com/users/Ericson2314/events{/privacy}","received_events_url":"https://api.github.com/users/Ericson2314/received_events","type":"User","site_admin":false},"created_at":"2015-12-19T08:03:39Z","updated_at":"2015-12-19T08:03:39Z","body":"> ```rust\r\nunsafe fn f(x: *mut u8, y: *mut u8) -> u8 {\r\n    {\r\n        let x = &mut *x;\r\n        *x = 11;\r\n    }\r\n    {\r\n        let y = &mut *y;\r\n        *y = 22;\r\n    }\r\n    {\r\n        let x = &mut *x;\r\n        *x\r\n    }\r\n}\r\n```\r\n\r\nI rather have a notion of \"disjoint lifetimes\": it is OK to `&mut-borrow` multiple times as long they are never \"used simultaneously\". I am not sure of the exact semantics of LLVM's `noalias`, but I hope that if re-borrowing doesn't violate any rules, this won't either."}}