{"action":"created","issue":{"url":"https://api.github.com/repos/Microsoft/TypeScript/issues/2224","labels_url":"https://api.github.com/repos/Microsoft/TypeScript/issues/2224/labels{/name}","comments_url":"https://api.github.com/repos/Microsoft/TypeScript/issues/2224/comments","events_url":"https://api.github.com/repos/Microsoft/TypeScript/issues/2224/events","html_url":"https://github.com/Microsoft/TypeScript/issues/2224","id":60076288,"number":2224,"title":"Two interface with same identifier misbehavior","user":{"login":"tinganho","id":1324476,"avatar_url":"https://avatars.githubusercontent.com/u/1324476?v=3","gravatar_id":"","url":"https://api.github.com/users/tinganho","html_url":"https://github.com/tinganho","followers_url":"https://api.github.com/users/tinganho/followers","following_url":"https://api.github.com/users/tinganho/following{/other_user}","gists_url":"https://api.github.com/users/tinganho/gists{/gist_id}","starred_url":"https://api.github.com/users/tinganho/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/tinganho/subscriptions","organizations_url":"https://api.github.com/users/tinganho/orgs","repos_url":"https://api.github.com/users/tinganho/repos","events_url":"https://api.github.com/users/tinganho/events{/privacy}","received_events_url":"https://api.github.com/users/tinganho/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":5,"created_at":"2015-03-06T09:05:53Z","updated_at":"2015-03-06T10:40:38Z","closed_at":null,"body":"I just noticed that the compiler complains about this:\r\n```typescript\r\n\r\ninterface Car {\r\n\tengine: string;\r\n}\r\n\r\ninterface Car {\r\n\twheels: string;\r\n}\r\n\r\nvar myCar: Car = {\r\n\twheels: 'Hej'\r\n};\r\n\r\nconsole.log(myCar);\r\n\r\n```\r\n\r\n```\r\nProperty 'engine' is missing in type '{ wheels: string; }'.\r\n```\r\nWhen I change to  :\r\n```typescript\r\nvar myCar: Car = {\r\n\tengine: 'Hej'\r\n};\r\n```\r\nIt still complains\r\n```\r\nProperty 'wheels' is missing in type '{ engine: string; }'.\r\n```\r\nHere is playground link:\r\nhttp://www.typescriptlang.org/Playground#src=%0D%0Ainterface%20Car%20%7B%0D%0A%09engine%3A%20string%3B%0D%0A%7D%0D%0A%0D%0Ainterface%20Car%20%7B%0D%0A%09wheels%3A%20string%3B%0D%0A%7D%0D%0A%0D%0Avar%20myCar%3A%20Car%20%3D%20%7B%0D%0A%09wheels%3A%20'Hej'%0D%0A%7D%3B%0D%0A%0D%0Aconsole.log(myCar)%3B%0D%0A\r\n\r\nI think it should complain that two interfaces can't use the same identifier in same scope/module?"},"comment":{"url":"https://api.github.com/repos/Microsoft/TypeScript/issues/comments/77539494","html_url":"https://github.com/Microsoft/TypeScript/issues/2224#issuecomment-77539494","issue_url":"https://api.github.com/repos/Microsoft/TypeScript/issues/2224","id":77539494,"user":{"login":"NoelAbrahams","id":1106823,"avatar_url":"https://avatars.githubusercontent.com/u/1106823?v=3","gravatar_id":"","url":"https://api.github.com/users/NoelAbrahams","html_url":"https://github.com/NoelAbrahams","followers_url":"https://api.github.com/users/NoelAbrahams/followers","following_url":"https://api.github.com/users/NoelAbrahams/following{/other_user}","gists_url":"https://api.github.com/users/NoelAbrahams/gists{/gist_id}","starred_url":"https://api.github.com/users/NoelAbrahams/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/NoelAbrahams/subscriptions","organizations_url":"https://api.github.com/users/NoelAbrahams/orgs","repos_url":"https://api.github.com/users/NoelAbrahams/repos","events_url":"https://api.github.com/users/NoelAbrahams/events{/privacy}","received_events_url":"https://api.github.com/users/NoelAbrahams/received_events","type":"User","site_admin":false},"created_at":"2015-03-06T10:40:38Z","updated_at":"2015-03-06T10:40:38Z","body":"This is called [declaration merging](https://github.com/Microsoft/TypeScript/wiki/Declaration%20Merging)\r\n\r\n> But I can define two props \r\n\r\nWhat if you want to extend an existing interface provided by a library?"}}