René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Generic not inferred from contextual types","articleBody":"\u003c!-- 🚨 STOP 🚨 𝗦𝗧𝗢𝗣 🚨 𝑺𝑻𝑶𝑷 🚨\r\n\r\nHalf of all issues filed here are duplicates, answered in the FAQ, or not appropriate for the bug tracker. Even if you think you've found a *bug*, please read the FAQ first, especially the Common \"Bugs\" That Aren't Bugs section!\r\n\r\nPlease help us by doing the following steps before logging an issue:\r\n  * Search: https://github.com/Microsoft/TypeScript/search?type=Issues\r\n  * Read the FAQ: https://github.com/Microsoft/TypeScript/wiki/FAQ\r\n\r\nPlease fill in the *entire* template below.\r\n--\u003e\r\n\r\n\u003c!-- Please try to reproduce the issue with `typescript@next`. It may have already been fixed. --\u003e\r\n**TypeScript Version:**  2.9.2\r\n\r\n\u003c!-- Search terms you tried before logging this (so others can find this issue more easily) --\u003e\r\n**Search Terms:** generic infer contextual type\r\n\r\n**Code**\r\n\r\n```ts\r\nconst baz: (n: number) =\u003e number = (\r\n    // param `n` is correctly inferred to be `number` :-)\r\n    n =\u003e n\r\n);\r\n\r\nconst identity = \u003cT\u003e(t: T) =\u003e t;\r\n\r\nconst bar: (n: number) =\u003e number = identity(\r\n    // param `n` is inferred as `any`, expected `number` :-(\r\n    x =\u003e x\r\n);\r\n```\r\n\r\n**Expected behavior:** TypeScript should infer the generic `T` in `identity` from the contextual type.\r\n\r\n**Actual behavior:** TypeScript infers the generic `T` in `identity` as `any`!\r\n\r\n**Playground Link:** \u003c!-- A link to a TypeScript Playground \"Share\" link which demonstrates this behavior --\u003e \r\n\r\n**Related Issues:** \u003c!-- Did you find other bugs that looked similar? --\u003e\r\n","author":{"url":"https://github.com/OliverJAsh","@type":"Person","name":"OliverJAsh"},"datePublished":"2018-06-28T13:20:29.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":12},"url":"https://github.com/25293/TypeScript/issues/25293"}