fix: better handling of derived signals that have no dependencies (#10558)

* fix: better handling of derived signals that have no dependencies

* fix: better handling of derived signals that have no dependencies

.changeset/witty-tomatoes-care.md

@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+fix: better handling of derived signals that have no dependencies

packages/svelte/src/internal/client/runtime.js

@@ -824,7 +824,8 @@ function update_derived(signal, force_schedule) {
 	destroy_references(signal);
 	const value = execute_signal_fn(signal);
 	updating_derived = previous_updating_derived;
-	const status = current_skip_consumer || (signal.f & UNOWNED) !== 0 ? DIRTY : CLEAN;
+	const status =
+		(current_skip_consumer || (signal.f & UNOWNED) !== 0) && signal.d !== null ? DIRTY : CLEAN;
 	set_signal_status(signal, status);
 	const equals = /** @type {import('./types.js').EqualsFunctions} */ (signal.e);
 	if (!equals(value, signal.v)) {

packages/svelte/tests/signals/test.ts

@@ -263,6 +263,27 @@ describe('signals', () => {
 		};
 	});
 
+	let no_deps = $.derived(() => {
+		return [];
+	});
+
+	test('two effects with an unowned derived that has no depedencies', () => {
+		const log: Array<Array<any>> = [];
+
+		$.render_effect(() => {
+			log.push($.get(no_deps));
+		});
+
+		$.render_effect(() => {
+			log.push($.get(no_deps));
+		});
+
+		return () => {
+			$.flushSync();
+			assert.deepEqual(log, [[], []]);
+		};
+	});
+
 	test('schedules rerun when writing to signal before reading it', (runes) => {
 		if (!runes) return () => {};