Persist middleware causing typescript error with boolean values

[johnslemmer]

Summary

This is certainly related to #2068 and #2163 which point to the merged PR #2170 suggesting that this should be fixed. But it isn't. There was also some mention of tsconfig.moduleResolution being set to bundler causing issues. But both on my linked codesandbox and my local project that is not the case. So I'm starting a new discussion.

Here is an example of the code that errors. This seems unexpected.

import { create } from "zustand";
import { persist } from "zustand/middleware";

type FooStore = {
  foo: string;
};

type BarStore = {
  bar: boolean;
};

// NOTE: typescript does not error on these
const useFooStore = create<FooStore>()(() => ({
  foo: "asdf"
}));
const useFooStorePersist = create<FooStore>()(
  persist(
    () => ({
      foo: "asdf"
    }),
    { name: "foo" }
  )
);
const useBarStore = create<BarStore>()(() => ({
  bar: false
}));

// NOTE: typescript does error here
const useBarStorePersist = create<BarStore>()(
  persist(
    () => ({
      bar: false
    }),
    {
      name: "bar"
    }
  )
);

Error being generated: Type 'boolean' is not assignable to type 'false'.ts(2345)

Certainly there is a workaround: loading: false as boolean but that seems like that shouldn't be needed. And per the documentation "You do not have to do anything special to use middlewares in TypeScript."

Tried this on versions 4.3.9, 4.4.6, 4.4.7. Typescript 5.3.2 and 5.3.3. Node 20.10.0.

Any ideas?

Link to reproduction

https://codesandbox.io/s/romantic-williamson-3hz8vl

(try the old editor on codesandbox, the new editor is being real buggy today)

[dai-shi]

#2068 (reply in thread)

TS Playground: https://tsplay.dev/Wo1O8N

I don't think there's anything we can do. Would anyone like to create a reproduction without Zustand and report it to https://github.com/microsoft/TypeScript/issues?

[johnslemmer]

Ok, thanks for changing the answer on #2068 that makes things more clear.

I'll let my brain stew on what is happening underneath the hood of zustand type-wise to see if a simpler typescript only reproduction comes to mind.