From d3fe49548ab832045ab208399c42dd59c8ebe7a8 Mon Sep 17 00:00:00 2001
From: raythurnvoid <53383860+raythurnvoid@users.noreply.github.com>
Date: Sun, 15 Jun 2025 00:09:39 +0100
Subject: [PATCH] Improve compiler output on legacy components to prevent
 infinite loops from <select> bind:value on $: derived variables

---
 .../3-transform/client/visitors/RegularElement.js      | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
index e823792993..c6afdf67d3 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
@@ -414,6 +414,16 @@ function setup_select_synchronization(value_binding, context) {
 		bound = /** @type {Identifier | MemberExpression} */ (bound.object);
 	}
 
+	// guard against reactively-derived bindings to prevent circular dependencies
+	if (bound.type === 'Identifier') {
+		const binding = context.state.scope.get(bound.name);
+		if (binding && binding.kind === 'legacy_reactive') {
+			// skip synchronization for reactive-derived bindings,
+			// the reactive statement already handles updates properly
+			return;
+		}
+	}
+
 	/** @type {string[]} */
 	const names = [];