solidjs-community / solidjs-community/solid-primitives

`makePersisted()` cannot correctly infer types under Typescript 7

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#1,000 3 comments 5 reactions 0 assignees View on GitHub

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bug
Dominant language
TypeScript
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Merged PRs (30d)
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Description

Describe the bug
const [thing, setThing] = makePersisted(createSignal("hello"), {
    name: "thing",
    storage: localStorage,
});
> tsc --noEmit

src/App.tsx(8,43): error TS2769: No overload matches this call.
  The last overload gave the following error.
    Argument of type 'Signal<string>' is not assignable to parameter of type 'Signal<unknown> | [unknown, SetStoreFunction<unknown>]'.
      Type '[get: Accessor<string>, set: Setter<string>]' is not assignable to type 'Signal<unknown>'.
        Type at position 1 in source is not compatible with type at position 1 in target.
          Type 'Setter<string>' is not assignable to type 'Setter<unknown>'.
            Target signature provides too few arguments. Expected 1 or more, but got 0.

Currently, the only way to fix it seems to be to provide full, explicit types:

const [thing, setThing] = makePersisted<string, Signal<string>>(createSignal("hello"), {
    name: "thing",
    storage: localStorage,
});
Minimal Reproduction Link

https://stackblitz.com/edit/github-ojctyhmm

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start at the makePersisted entry point and reproduce the inferred-type failure from src/App.tsx using the linked StackBlitz example. Run tsc --noEmit with the createSignal("hello") call and compare it with the explicit generic version. Done means the inferred call type-checks without requiring explicit types.

Written by the indexing model from the issue text.

Assessment

Tech stack
typescript
Domain
developer-experience
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
55/100

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