Using a `$derived` value with `setContext` emits warning

[Stadly]

Describe the bug

When putting a $derived inside setContext, a state_referenced_locally warning is shown. I think the warning is wrong.

let foo = $derived(...);

// Warning: This reference only captures the initial value of `foo`.
// Did you mean to reference it inside a closure instead?
setContext("derived-context", foo);

Reproduction

https://svelte.dev/playground/1cdbccb4b0be48aba01cd0d27e74aa35?version=5.38.1

Logs

System Info

System:
    OS: Linux 5.15 Debian GNU/Linux 12 (bookworm) 12 (bookworm)
    CPU: (16) x64 Intel(R) Xeon(R) W-11955M CPU @ 2.60GHz
    Memory: 3.03 GB / 15.23 GB
    Container: Yes
    Shell: 5.2.15 - /bin/bash
  Binaries:
    Node: 20.19.3 - /usr/local/bin/node
    npm: 10.8.2 - /usr/local/bin/npm
    pnpm: 10.11.1 - /usr/local/bin/pnpm
  npmPackages:
    svelte: ^5.37.3 => 5.37.3

Severity

annoyance

[brunnerh]

The warning is correct in that when the $derived variable changes (i.e. points to another object), the context will still point to the previous one. That the properties of the object are reactive is separate from that.

(In the example, the $derived does not really serve any purpose since it never changes.)

Example showing how it never changes

You will also get a warning on using $state in a context, if the $state variable is reassigned somewhere since this will also desynchronize the context.

[Stadly]

Thanks for explaining! I was struggling to understand why there should be any difference between using $state and $derived, but with your last comment it finally made sense to me :)

You will also get a warning on using $state in a context, if the $state variable is reassigned somewhere since this will also desynchronize the context.