ReadonlyDeep does not work for objects with call signatures

[marekdedic]

Hi,
I have recently stumbled upon an issue with the ReadonlyDeep<> type. I have a type which has both members as well as call signatures (in my case the JQueryStatic type from @types/jquery). When I tried to create ReadonlyDeep<JQueryStatic>, what I got back was just JQueryStatic - no change in type...

Eventually, I tracked it down to the definition:

type-fest/source/readonly-deep.d.ts

Lines 37 to 45 in f45033c

	export type ReadonlyDeep<T> = T extends Primitive | ((...arguments: any[]) => unknown)
	? T
	: T extends ReadonlyMap<infer KeyType, infer ValueType>
	? ReadonlyMapDeep<KeyType, ValueType>
	: T extends ReadonlySet<infer ItemType>
	? ReadonlySetDeep<ItemType>
	: T extends object
	? ReadonlyObjectDeep<T>
	: unknown;

In this case, because the type has a call signature, T extends Primitive | ((...arguments: any[]) => unknown) evaluates to true and therefore what you get back is the original type...

Trying to fix the issue

I tried to fix the issue by changing the first check to be just T extends Primitive, but then the type would lose all of its call signatures, as it would return ReadonlyObjectDeep<>...

So I tried changing ReadonlyObjectDeep from

type-fest/source/readonly-deep.d.ts

Lines 62 to 64 in f45033c

	type ReadonlyObjectDeep<ObjectType extends object> = {
	readonly [KeyType in keyof ObjectType]: ReadonlyDeep<ObjectType[KeyType]>
	};

to

type ReadonlyObjectDeep<ObjectType extends object> = {
    readonly [KeyType in keyof ObjectType]: ReadonlyDeep<ObjectType[KeyType]>
    (...parameters: Parameters<ObjectType>): ReturnType<ObjectType>
};

but that just got me TS7061: A mapped type may not declare properties or methods.

Is there any way to fix this? Also, as far as I know TS objects have members, call signatures, construct signatures and index infos - the current ReadonlyObjectDeep does only members and index infos, I stumbled here upon call signatures, but construct signatures should probably be solved as well...

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[skarab42]

Seems to be fixed with #359 (Playground)

[marekdedic]

Thanks, trying it out!