Microsoft/TypeScript
Voir sur GitHubType inference behaves unexpectedly when dealing with functions that have type parameters
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#54 251 ouverte le 15 mai 2023
Domain: check: Type InferenceHelp WantedPossible Improvement
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Description
Bug Report
When a function definition a with type parameters is passed as an argument to another function b, b is unable to destructure the parameters of the passed a function.
🔎 Search Terms
type parameter function argument destructure
🕗 Version & Regression Information
- This is the behavior in every version I tried, and I reviewed the FAQ for entries about generics
⏯ Playground Link
Playground link with relevant code
💻 Code
type DefaultVariantProps = {
tabsClassName?: string
}
function fn<P extends {}>(arg1?: (props: P) => void): P {
return null as any
}
const a = fn(null as any as (props: DefaultVariantProps) => void)
const b = fn(null as any as <T>(props: DefaultVariantProps) => void)
// no problem
a.tabsClassName
// Property 'tabsClassName' does not exist on type '{}'.(2339)
b.tabsClassName
type T1 = (props: DefaultVariantProps) => void
type T2 = <T>(props: DefaultVariantProps) => void
// no problem
type T3 = Parameters<T1>[0]['tabsClassName']
// no problem
type T4 = Parameters<T2>[0]['tabsClassName']
🙁 Actual behavior
When a function definition a with type parameters is passed as an argument to another function b, b is unable to destructure the parameters of the passed a function. It seems that generics should not cause type inference failures.
🙂 Expected behavior
No error.