Typescript issue with 5.0.2

[ZebraFlesh]

Bug Description

I think #2875 created a Typescript issue. With 5.0.1, this code is perfectly fine:

export const createStore = <TStore extends Record<string, unknown>>(
  getStore: (set: NamedSet<TStore>) => TStore,
) => create<TStore>()(devtools(getStore, { enabled: process.env.NODE_ENV === 'development' }));

But with 5.0.2, I get the following error:

error TS2345: Argument of type 'StateCreator<TStore | Partial<TStore>, [], [["zustand/devtools", never]]>' is not assignable to parameter of type 'StateCreator<TStore, [], [["zustand/devtools", never]]>'.
  Type 'StateCreator<TStore | Partial<TStore>, [], [["zustand/devtools", never]]>' is not assignable to type '(setState: { (partial: TStore | Partial<TStore> | ((state: TStore) => TStore | Partial<TStore>), replace?: false | undefined): void; (state: TStore | ((state: TStore) => TStore), replace: true): void; }, getState: () => TStore, store: StoreApi<...>) => TStore'.
    Type 'TStore | Partial<TStore>' is not assignable to type 'TStore'.
      'TStore | Partial<TStore>' is assignable to the constraint of type 'TStore', but 'TStore' could be instantiated with a different subtype of constraint 'Record<string, unknown>'.
        Type 'Partial<TStore>' is not assignable to type 'TStore'.
          'Partial<TStore>' is assignable to the constraint of type 'TStore', but 'TStore' could be instantiated with a different subtype of constraint 'Record<string, unknown>'.

   9 | export const createStore = <TStore extends Record<string, unknown>>(
  10 |   getStore: (set: NamedSet<TStore>) => TStore,
> 11 | ) => create<TStore>()(devtools(getStore, { enabled: process.env.NODE_ENV === 'development' }));
     |                       ^
  12 | 

(I would create a reproduction, but I've inherited this project and am not proficient enough with Zustand to do this without a stackblitz template or similar.)

For now, downgrading to 5.0.1 is the answer.

Reproduction Link

see above

[dai-shi]

@AndyRightNow Can you help this?

[AndyRightNow]

@AndyRightNow Can you help this?

@dai-shi Sure, let me check

[AndyRightNow]

I just created a minimal reproduction here https://stackblitz.com/edit/vitejs-vite-b4fksmbb?file=src%2Fstore.ts

However it's weird that I can't seem to be able to reproduce it locally in unit tests. I will look into it and find a fix when I can.

[dai-shi]

just curious if it can be reproduced with typescript playground.

[AndyRightNow]

@dai-shi I tried and it's the same as reproducing in unit tests. No errors 🤔

TS Playground

[AndyRightNow]

@ZebraFlesh

Could you upgrade to 5.0.2 and use the following workaround for now?

export const createStore = <TStore extends Record<string, unknown>>(
-  getStore: (set: NamedSet<TStore>) => TStore,
+  getStore: StateCreator<TStore>,
) => create<TStore>()(devtools(getStore, { enabled: process.env.NODE_ENV === 'development' }));

Not sure why the relatively low-level type NamedSet is used in your implementation but after #2875, the return type has been factored in so it'd be better to use the complete type as well.

I also added this workaround to the demo https://stackblitz.com/edit/vitejs-vite-b4fksmbb?file=src%2Fstore.ts

[dai-shi]

Oh, yeah, I think we may want to consider NamedSet as an internal type.

[ZebraFlesh]

Thanks, that works for me!