fix one-way <select> bind with spread (#6512)

src/compiler/compile/render_dom/wrappers/Element/index.ts

@@ -669,10 +669,10 @@ export default class ElementWrapper extends Wrapper {
 			}
 
 			block.chunks.mount.push(b`
-				if (${data}.multiple) @select_options(${this.var}, ${data}.value);
+				(${data}.multiple ? @select_options : @select_option)(${this.var}, ${data}.value);
 			`);
 			block.chunks.update.push(b`
-				if (${block.renderer.dirty(Array.from(dependencies))} && ${data}.multiple) @select_options(${this.var}, ${data}.value);
+				if (${block.renderer.dirty(Array.from(dependencies))}) (${data}.multiple ? @select_options : @select_option)(${this.var}, ${data}.value);;
 			`);
 		} else if (this.node.name === 'input' && this.attributes.find(attr => attr.node.name === 'value')) {
 			const type = this.node.get_static_attribute_value('type');

test/runtime/samples/spread-element-input-select/_config.js

@@ -0,0 +1,25 @@
+export default {
+	async test({ assert, component, target, window }) {
+		const select = target.querySelector('select');
+		const [option1, option2] = select.childNodes;
+
+		let selections = Array.from(select.selectedOptions);
+		assert.equal(selections.length, 1);
+		assert.ok(!selections.includes(option1));
+		assert.ok(selections.includes(option2));
+
+		component.value = 'Hello';
+
+		selections = Array.from(select.selectedOptions);
+		assert.equal(selections.length, 1);
+		assert.ok(selections.includes(option1));
+		assert.ok(!selections.includes(option2));
+
+		component.spread = { value: 'World' };
+
+		selections = Array.from(select.selectedOptions);
+		assert.equal(selections.length, 1);
+		assert.ok(!selections.includes(option1));
+		assert.ok(selections.includes(option2));
+	}
+};

test/runtime/samples/spread-element-input-select/main.svelte

@@ -0,0 +1,9 @@
+<script>
+  export let value = 'World';
+  export let spread = {};
+</script>
+
+<select {value} {...spread}>
+  <option>Hello</option>
+  <option>World</option>
+</select>