better fix

Author: trueadm

packages/svelte/src/compiler/migrate/index.js

@@ -549,27 +549,28 @@ const instance_script = {
 				let labeled_statement;
 
 				// Analyze declaration bindings to see if they're exclusively updated within a single reactive statement
-				const possible_derived = bindings.every(
-					(binding) =>
-						binding.initial !== null &&
-						binding.references.every((reference) => {
-							const declaration = reference.path.find((el) => el.type === 'VariableDeclaration');
-							const assignment = reference.path.find((el) => el.type === 'AssignmentExpression');
-							const update = reference.path.find((el) => el.type === 'UpdateExpression');
-							const labeled = reference.path.find(
-								(el) => el.type === 'LabeledStatement' && el.label.name === '$'
-							);
+				const possible_derived = bindings.every((binding) =>
+					binding.references.every((reference) => {
+						const declaration = reference.path.find((el) => el.type === 'VariableDeclaration');
+						const assignment = reference.path.find((el) => el.type === 'AssignmentExpression');
+						const update = reference.path.find((el) => el.type === 'UpdateExpression');
+						const labeled = reference.path.find(
+							(el) => el.type === 'LabeledStatement' && el.label.name === '$'
+						);
 
-							if (assignment && labeled) {
-								if (assignment_in_labeled) return false;
-								assignment_in_labeled = /** @type {AssignmentExpression} */ (assignment);
-								labeled_statement = /** @type {LabeledStatement} */ (labeled);
-							}
+						if (assignment && labeled) {
+							if (assignment_in_labeled) return false;
+							assignment_in_labeled = /** @type {AssignmentExpression} */ (assignment);
+							labeled_statement = /** @type {LabeledStatement} */ (labeled);
+						}
 
-							return (
-								!update && (declaration || (labeled && assignment) || (!labeled && !assignment))
-							);
-						})
+						return (
+							!update &&
+							((declaration && binding.initial) ||
+								(labeled && assignment) ||
+								(!labeled && !assignment))
+						);
+					})
 				);
 
 				const labeled_has_single_assignment =

packages/svelte/tests/migrate/samples/reactive-statements-reorder-with-comments/output.svelte

@@ -6,7 +6,10 @@
 
 
 	// triple
-	let triple = $state();
+	//  update triple
+	let triple = $derived(count * 3)
+	//  trailing comment
+	//  in triple;
 
 	function increment() {
 		count += 1;
@@ -16,12 +19,7 @@
 	run(() => {
 		console.log({ count, double });
 	});
-	run(() => {
-		// update triple
-		triple = count * 3;
-		// trailing comment
-		// in triple
-	});
+	
 </script>
 
 <button onclick={increment}>

packages/svelte/tests/migrate/samples/single-assignment-labeled/output.svelte

@@ -2,10 +2,8 @@
 	import { run } from 'svelte/legacy';
 
 	let count = $state(0);
-	let double = $state();
-	run(() => {
-		double = count * 2;
-	});
+	let double = $derived(count * 2);
+	
 	
 	let quadruple = $state();
 	run(() => {
@@ -43,13 +41,10 @@
 		evenmore_doubled = evenmore * 2;
 	});
 
-	let almost_infinity = $state();
-	run(() => {
-		almost_infinity = count * 128;
-	});
+	let almost_infinity = $derived(count * 128);
+	
 
-	let should_be_state = $state();
-	let should_be_state = $state();
+	let should_be_state = $state(42);
 	
 	let should_be_state_too = $state(42);