Check for duplicate slot attributes on components

Author: dimfeld

packages/svelte/src/compiler/phases/2-analyze/validation.js

@@ -37,6 +37,10 @@ function validate_component(node, context) {
 		) {
 			error(attribute, 'invalid-event-modifier');
 		}
+
+		if (attribute.type === 'Attribute' && attribute.name === 'slot') {
+			validate_slot_attribute(context, attribute);
+		}
 	}
 
 	context.next({

packages/svelte/tests/compiler-errors/samples/component-slot-duplicate-error-5/_config.js

@@ -0,0 +1,8 @@
+import { test } from '../../test';
+
+export default test({
+	error: {
+		code: 'duplicate-slot-name',
+		message: "Duplicate slot name 'foo' in <Nested>"
+	}
+});

packages/svelte/tests/compiler-errors/samples/component-slot-duplicate-error-5/main.svelte

@@ -0,0 +1,9 @@
+<script>
+	import Nested from './irrelevant';
+	import Inner from './irrelevant';
+</script>
+
+<Nested>
+	<Inner slot="foo">{value}</Inner>
+	<Inner slot="foo">{value}</Inner>
+</Nested>

packages/svelte/tests/compiler-errors/samples/component-slot-duplicate-error-6/_config.js

@@ -0,0 +1,8 @@
+import { test } from '../../test';
+
+export default test({
+	error: {
+		code: 'duplicate-slot-name',
+		message: "Duplicate slot name 'foo' in <Nested>"
+	}
+});

packages/svelte/tests/compiler-errors/samples/component-slot-duplicate-error-6/main.svelte

@@ -0,0 +1,9 @@
+<script>
+	import Nested from './irrelevant';
+	import Inner from './irrelevant';
+</script>
+
+<Nested>
+	<p slot="foo">{value}</p>
+	<Inner slot="foo">{value}</Inner>
+</Nested>