Description

Serhii Pomaraiko (Pomar81)

opened on Jun 28, 2019

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TypeScript Version: 3.5.1-3.5.2

Search Terms:
infer type from generic function

Code

type genericProps<T> = {
  abcId: string
  count: number
  flag: boolean
  className?: string
  as?: T
}


declare function genericFC<T>(props: genericProps<T>): any 

type test<T> = typeof genericFC extends <T>(props: infer P) => any ? P : never

Expected behavior:

 {
    abcId: string
    count: number
    flag: boolean
    className?: string
    as?: T
  }

Actual behavior:

{
   abcId: string
   count: number
   flag: boolean
   className?: string
   as?: unknown
 }

Playground Link: link

Related Issues:

Activity

1. RyanCavanaugh commented on Jul 2, 2019

   

   Ryan Cavanaugh (RyanCavanaugh)

   on Jul 2, 2019

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   This is working as expected. There's no relation between the two Ts in test's declaration; i.e. you could equally have written

   type test<T> = typeof genericFC extends <U>(props: infer P) => any ? P : never

   I expect what you're trying to do is refer to a specific call instantiation of a generic function, which isn't currently possible.

   Reacted by owl from hogvarts
2. Ryan Cavanaugh (RyanCavanaugh)

   added

   QuestionAn issue which isn't directly actionable in codeAn issue which isn't directly actionable in code

   on Jul 2, 2019
3. Pomar81 commented on Jul 4, 2019

   

   Serhii Pomaraiko (Pomar81)

   on Jul 4, 2019

   Author

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   Yes, I wanted to refer to specific call instantiation of a generic function
   e.g
   genericFC<'div'>
4. TypeScript Bot (typescript-bot)

   closed this as completedon Jul 13, 2019
5. ahejlsberg commented on Jan 27, 2022

   

   Anders Hejlsberg (ahejlsberg)

   on Jan 27, 2022

   Member

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   With #47607 it is possible to refer to specific instantiations of generic functions.
6. microsoft

   locked as resolved and limited conversation to collaborators on Oct 21, 2025

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