SSR: writable store set in component does not update $store variable

[btakita]

Here is the repro. https://svelte.dev/repl/e8ab45ee0a1e44ff8da3d09a427e201d?version=3.12.1

You have to look at the SSR output to see the issue, since the repl does not render SSR.

Notice that $name is defined before name.set('Joe') & is not updated afterwards. This causes the SSR to render the state from the previous request.

/* App.svelte generated by Svelte v3.12.1 */
import {
	create_ssr_component,
	escape,
	get_store_value
} from "svelte/internal";
import { writable, get } from "svelte/store"

const App = create_ssr_component(($$result, $$props, $$bindings, $$slots) => {
	let $name;

	const name = writable('Peter'); $name = get_store_value(name)

	$name = get_store_value(name);

	name.set('Joe')
	console.debug($name)
	console.debug(get(name))

	return `<h1>Hello ${escape($name)}!</h1>`;
});

export default App;

[btakita]

It looks like $name is hoisted in SSR, causing the issue. Not sure when this was introduced.

<script>
	import { writable, get } from 'svelte/store'
	const name = writable('Peter')
	$: name.set('Joe')
	$: console.debug($name)
	$: console.debug(get(name))
</script>

<h1>Hello {$name}!</h1>

[Conduitry]

This looks like a similar issue to #3582 but I'm not sure whether they're the same.

[btakita]

They look similar but the behavior is different. #3582 is an undeclared variable while this issue is the store convenience variable ($name) is not updated after name.set.

[Conduitry]

This is finally fixed in 3.31.2 as part of a more sweeping change to how store autosubscriptions are handled in SSR code. See the generated code for https://svelte.dev/repl/e8ab45ee0a1e44ff8da3d09a427e201d?version=3.31.2