From 14e739379b0503327aa5574cdb6e978a011a8935 Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Mon, 24 Jun 2019 13:51:14 -0400
Subject: [PATCH] handle member expressions in destructuring assignments -
 fixes #3092

---
 src/compiler/compile/utils/scope.ts           |  5 ++++
 .../destructuring-assignment-array/_config.js | 23 +++++++++++++++++++
 .../main.svelte                               | 18 +++++++++++++++
 3 files changed, 46 insertions(+)
 create mode 100644 test/runtime/samples/destructuring-assignment-array/_config.js
 create mode 100644 test/runtime/samples/destructuring-assignment-array/main.svelte

diff --git a/src/compiler/compile/utils/scope.ts b/src/compiler/compile/utils/scope.ts
index 6bf3f9eaf4..75e44f0adf 100644
--- a/src/compiler/compile/utils/scope.ts
+++ b/src/compiler/compile/utils/scope.ts
@@ -2,6 +2,7 @@ import { walk } from 'estree-walker';
 import is_reference from 'is-reference';
 import { Node } from '../../interfaces';
 import { Node as ESTreeNode } from 'estree';
+import get_object from './get_object';
 
 export function create_scopes(expression: Node) {
 	const map = new WeakMap();
@@ -114,6 +115,10 @@ const extractors = {
 		nodes.push(param);
 	},
 
+	MemberExpression(nodes: Node[], param: Node) {
+		nodes.push(get_object(param));
+	},
+
 	ObjectPattern(nodes: Node[], param: Node) {
 		param.properties.forEach((prop: Node) => {
 			if (prop.type === 'RestElement') {
diff --git a/test/runtime/samples/destructuring-assignment-array/_config.js b/test/runtime/samples/destructuring-assignment-array/_config.js
new file mode 100644
index 0000000000..ede4552803
--- /dev/null
+++ b/test/runtime/samples/destructuring-assignment-array/_config.js
@@ -0,0 +1,23 @@
+export default {
+	html: `
+		<ul>
+			<li>Gruyere</li>
+			<li>Compté</li>
+			<li>Beaufort</li>
+			<li>Abondance</li>
+		</ul>
+	`,
+
+	async test({ assert, component, target }) {
+		await component.swap(0, 1);
+
+		assert.htmlEqual(target.innerHTML, `
+			<ul>
+				<li>Compté</li>
+				<li>Gruyere</li>
+				<li>Beaufort</li>
+				<li>Abondance</li>
+			</ul>
+		`);
+	}
+};
\ No newline at end of file
diff --git a/test/runtime/samples/destructuring-assignment-array/main.svelte b/test/runtime/samples/destructuring-assignment-array/main.svelte
new file mode 100644
index 0000000000..aebbfe204c
--- /dev/null
+++ b/test/runtime/samples/destructuring-assignment-array/main.svelte
@@ -0,0 +1,18 @@
+<script>
+	let cheese = [
+		'Gruyere',
+		'Compté',
+		'Beaufort',
+		'Abondance',
+	];
+
+	export function swap(a, b) {
+		[cheese[a], cheese[b]] = [cheese[b], cheese[a]];
+	}
+</script>
+
+<ul>
+	{#each cheese as cheese}
+		<li>{cheese}</li>
+	{/each}
+</ul>
\ No newline at end of file