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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Unexpected error when using generic with Pick and Exclude","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:**  3.2.1\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 pick exclude\r\n\r\n**Code**\r\n\r\n``` ts\r\n//\r\n// Example 1\r\n//\r\n\r\nconst fn = \u003cParams extends {}\u003e(\r\n    params: Pick\u003cParams, Exclude\u003ckeyof Params, never\u003e\u003e,\r\n): Params =\u003e\r\n    // Unexpected error\r\n    /* Type 'Pick\u003cParams, Exclude\u003ckeyof Params, never\u003e\u003e' is not assignable to type 'Params'. */\r\n    params;\r\n\r\n//\r\n// Example 2\r\n//\r\n\r\nimport * as React from 'react';\r\nimport { ComponentType, FunctionComponent } from 'react';\r\n\r\ntype User = { name: string };\r\ntype UserProp = { user: User };\r\n\r\nexport const myHoc = function\u003cComposedComponentProps extends UserProp\u003e(\r\n    ComposedComponent: ComponentType\u003cComposedComponentProps\u003e,\r\n) {\r\n    // These two should be equivalent, but they're not?\r\n    // Doesn't work:\r\n    type Props = Pick\u003c\r\n        ComposedComponentProps,\r\n        Exclude\u003ckeyof ComposedComponentProps, never\u003e\r\n    \u003e;\r\n    // Works:\r\n    // type Props = ComposedComponentProps;\r\n\r\n    const Component: FunctionComponent\u003cProps\u003e = props =\u003e (\r\n        // Unexpected error\r\n        /* Type 'PropsWithChildren\u003cPick\u003cComposedComponentProps, Exclude\u003ckeyof ComposedComponentProps, never\u003e\u003e\u003e' is not assignable to type 'IntrinsicAttributes \u0026 ComposedComponentProps \u0026 { children?: ReactNode; }'.\r\n            Type 'PropsWithChildren\u003cPick\u003cComposedComponentProps, Exclude\u003ckeyof ComposedComponentProps, never\u003e\u003e\u003e' is not assignable to type 'ComposedComponentProps'. */\r\n        \u003cComposedComponent {...props} /\u003e\r\n    );\r\n\r\n    return Component;\r\n};\r\n```","author":{"url":"https://github.com/OliverJAsh","@type":"Person","name":"OliverJAsh"},"datePublished":"2018-11-29T22:48:20.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":21},"url":"https://github.com/28748/TypeScript/issues/28748"}