Fix #4803 by changing setAttributes to set value as well as __value

src/runtime/internal/dom.ts

@@ -98,7 +98,11 @@ export function set_attributes(node: Element & ElementCSSInlineStyle, attributes
 			node.removeAttribute(key);
 		} else if (key === 'style') {
 			node.style.cssText = attributes[key];
-		} else if (key === '__value' || descriptors[key] && descriptors[key].set) {
+		} else if (key === '__value') {
+			const value = attributes[key];
+			(node as any).__value = value;
+			(node as any).value = value;
+		} else if (descriptors[key] && descriptors[key].set) {
 			node[key] = attributes[key];
 		} else {
 			attr(node, key, attributes[key]);

test/runtime/samples/spread-element-input-bind-group-with-value-attr/_config.js

@@ -0,0 +1,15 @@
+export default {
+	props: {
+		props: {
+			'data-foo': 'bar'
+		}
+	},
+
+	html: `<input data-foo="bar" type="radio" value="abc">`,
+
+	async test({ assert, component, target, window }) {
+		const input = target.querySelector('input');
+		assert.equal(input.value, 'abc');
+		assert.equal(input.__value, 'abc');
+	}
+};

test/runtime/samples/spread-element-input-bind-group-with-value-attr/main.svelte

@@ -0,0 +1,6 @@
+<script>
+	export let props;
+	let radioValue;
+</script>
+
+<input type="radio" value="abc" {...props} bind:group={radioValue} />

test/runtime/samples/spread-element-input-bind-group-with-value-in-spread/_config.js

@@ -0,0 +1,22 @@
+export default {
+	// This fails because the test checks for __value being set on the node, which
+	// bind:group requires to work, but when a spread is used to set `value` on the
+	// element, the code that also sets `__value` on the node is not triggered.
+	// This is issue #4808.
+	skip: true,
+
+	props: {
+		props: {
+			'data-foo': 'bar',
+			value: 'abc'
+		}
+	},
+
+	html: `<input data-foo="bar" type="radio" value="abc">`,
+
+	async test({ assert, component, target, window }) {
+		const input = target.querySelector('input');
+		assert.equal(input.value, 'abc');
+		assert.equal(input.__value, 'abc');
+	}
+};

test/runtime/samples/spread-element-input-bind-group-with-value-in-spread/main.svelte

@@ -0,0 +1,6 @@
+<script>
+	export let props;
+	let radioValue;
+</script>
+
+<input type="radio" {...props} bind:group={radioValue} />