This is the narrowed down code from my actual use case.
function wrapMe<F extends (...args: any) => any>(
f: F,
): (...args: Parameters<F>) => ReturnType<F> {
return function(...args: Parameters<F>): ReturnType<F> {
return f(...args);
// ^^^^
// Type 'Parameters<F>' must have a '[Symbol.iterator]()' method that returns an iterator. [2488]
}
}
Why is this a typescript error?
This is a known bug in TypeScript, as described in microsoft/TypeScript#36874. Until and unless it's resolved, you can work around it either by changing the constraint to make the parameter any[] instead of any:
function wrapMe<F extends (...args: any[]) => any>(
// -----------------------------> ^^^^^
f: F,
): (...args: Parameters<F>) => ReturnType<F> {
return function (...args: Parameters<F>): ReturnType<F> {
return f(...args);
}
}
or by wrapping Parameters<T> in a variadic tuple:
function wrapMe<F extends (...args: any) => any>(
f: F,
): (...args: Parameters<F>) => ReturnType<F> {
return function (...args: [...Parameters<F>]): ReturnType<F> {
// ---------------------> ^^^^^^^^^^^^^^^^^^
return f(...args);
}
}
