fix: don't transform references of function declarations in legacy mode (#17431)

.changeset/better-games-invite.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: don't transform references of function declarations in legacy mode

packages/svelte/src/compiler/phases/2-analyze/index.js

@@ -657,7 +657,8 @@ export function analyze_component(root, source, options) {
 									if (
 										binding &&
 										binding.kind === 'normal' &&
-										binding.declaration_kind !== 'import'
+										binding.declaration_kind !== 'import' &&
+										binding.declaration_kind !== 'function'
 									) {
 										binding.kind = 'state';
 										binding.mutated = true;

packages/svelte/src/compiler/phases/2-analyze/visitors/EachBlock.js

@@ -54,8 +54,10 @@ export function EachBlock(node, context) {
 
 		// collect transitive dependencies...
 		for (const binding of node.metadata.expression.dependencies) {
+			if (binding.declaration_kind !== 'function') {
 				collect_transitive_dependencies(binding, node.metadata.transitive_deps);
 			}
+		}
 
 		// ...and ensure they are marked as state, so they can be turned
 		// into mutable sources and invalidated

packages/svelte/tests/runtime-legacy/samples/binding-indirect-fn/_config.js

@@ -0,0 +1,7 @@
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		assert.htmlEqual(target.innerHTML, `<input>`);
+	}
+});

packages/svelte/tests/runtime-legacy/samples/binding-indirect-fn/main.svelte

@@ -0,0 +1,11 @@
+<script>
+  $: items = [{ value: 'hello' }];
+
+  function fn(value) {
+		return true;
+	}
+</script>
+
+{#each items.filter(fn) as item}
+  <input bind:value={item.value} />
+{/each}