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Inference failure in <T>(f: (get: () => T) => T) => TΒ #60929
Description
π Search Terms
Similar/duplicate of #49618, #47599 & #30134. Sorry couldn't come up with a better title.
π Version & Regression Information
Tested with TypeScript 5.7.2
β― Playground Link
π» Code
declare const create: <T>(f: (get: () => T) => T) => T
let t0 = create(() => "")
// ^? string
let t1 = create(_ => "")
// ^? unknownπ Actual behavior
t1 is inferred as unknown
π Expected behavior
t1 should be inferred as string
Additional information about the issue
This is a minimal reproduction of zustand's create...
import { create } from "zustand"
let t0 = create(() => "")
// ^? UseBoundStore<StoreApi<string>>
let t1 = create(_ => "")
// ^? UseBoundStore<StoreApi<unknown>>I'm certain this is a duplicate of one of the above mentioned issue I just want to know it's duplicate of which issue exactly
Activity
Andarist commentedon Jan 7, 2025
It looks to me like a duplicate of #49618 . There were also 2 other issues, similar to this one, reported recently: #60922 , #60544 . Despite those 2 mentioning
NoInfer, the root cause of the issue is quite the same as here: resolving contextual parameter type that references a type parameter "fixes" its inference, it can't be changed afterward and the return type is not known at all before this point because it can only be computed after analyzing the function's body and that requires resolving the parameter's typetypescript-bot commentedon Jan 11, 2025
This issue has been marked as "Duplicate" and has seen no recent activity. It has been automatically closed for house-keeping purposes.