do not remove defaults if they are in spreads

Author: 7nik

packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js

@@ -172,7 +172,16 @@ export function RegularElement(node, context) {
 				bindings.has('group') ||
 				(!bindings.has('group') && has_value_attribute))
 		) {
-			context.state.init.push(b.stmt(b.call('$.remove_input_defaults', context.state.node)));
+			const spreads = has_spread
+				? b.object(
+						attributes
+							.filter((attr) => attr.type === 'SpreadAttribute')
+							.map((attr) => b.spread(attr.expression))
+					)
+				: null;
+			context.state.init.push(
+				b.stmt(b.call('$.remove_input_defaults', context.state.node, spreads))
+			);
 		}
 	}
 

packages/svelte/src/internal/client/dom/elements/attributes.js

@@ -31,14 +31,20 @@ const IS_CUSTOM_ELEMENT = Symbol('is custom element');
 const IS_HTML = Symbol('is html');
 
 /**
- * The value/checked attribute in the template actually corresponds to the defaultValue property, so we need
- * to remove it upon hydration to avoid a bug when someone resets the form value.
+ * The value/checked attribute in the template actually corresponds to the defaultValue property,
+ * so we need to remove it upon hydration to avoid a bug when someone resets the form value,
+ * unless the property is presented in the spreaded objects and is handled by `set_attributes()`
  * @param {HTMLInputElement} input
+ * @param {Record<string, any>} [spread]
  * @returns {void}
  */
-export function remove_input_defaults(input) {
+export function remove_input_defaults(input, spread) {
 	if (!hydrating) return;
 
+	if (spread && (input.type === 'checkbox' ? 'defaultChecked' : 'defaultValue') in spread) {
+		return;
+	}
+
 	var already_removed = false;
 
 	// We try and remove the default attributes later, rather than sync during hydration.