feat: Reactive delete statements

src/compiler/compile/Component.ts

@@ -844,7 +844,7 @@ export default class Component {
 					scope = map.get(node);
 				}
 
-				if (node.type === 'AssignmentExpression' || node.type === 'UpdateExpression') {
+				if (node.type === 'AssignmentExpression' || node.type === 'UpdateExpression' || (node.type === 'UnaryExpression' && node.operator === 'delete')) {
 					const assignee = node.type === 'AssignmentExpression' ? node.left : node.argument;
 					const names = extract_names(assignee as Node);
 
@@ -1303,7 +1303,7 @@ export default class Component {
 							if (node.operator !== '=') {
 								dependencies.add(left.name);
 							}
-						} else if (node.type === 'UpdateExpression') {
+						} else if (node.type === 'UpdateExpression' || (node.type === 'UnaryExpression' && node.operator === 'delete')) {
 							const identifier = get_object(node.argument);
 							assignees.add(identifier.name);
 						} else if (is_reference(node as NodeWithPropertyDefinition, parent as NodeWithPropertyDefinition)) {

src/compiler/compile/nodes/shared/Expression.ts

@@ -125,7 +125,7 @@ export default class Expression {
 					if (node.type === 'AssignmentExpression') {
 						deep = node.left.type === 'MemberExpression';
 						names = extract_names(deep ? get_object(node.left) : node.left);
-					} else if (node.type === 'UpdateExpression') {
+					} else if (node.type === 'UpdateExpression' || (node.type === 'UnaryExpression' && node.operator === 'delete')) {
 						names = extract_names(get_object(node.argument));
 					}
 				}
@@ -343,7 +343,7 @@ export default class Expression {
 					}
 				}
 
-				if (node.type === 'AssignmentExpression' || node.type === 'UpdateExpression') {
+				if (node.type === 'AssignmentExpression' || node.type === 'UpdateExpression' || (node.type === 'UnaryExpression' && node.operator === 'delete')) {
 					const assignee = node.type === 'AssignmentExpression' ? node.left : node.argument;
 
 					const object_name = get_object(assignee).name;

src/compiler/compile/render_dom/index.ts

@@ -283,7 +283,7 @@ export default function dom(
 					execution_context = null;
 				}
 
-				if (node.type === 'AssignmentExpression' || node.type === 'UpdateExpression') {
+				if (node.type === 'AssignmentExpression' || node.type === 'UpdateExpression' || (node.type === 'UnaryExpression' && node.operator === 'delete')) {
 					const assignee = node.type === 'AssignmentExpression' ? node.left : node.argument;
 
 					// normally (`a = 1`, `b.c = 2`), there'll be a single name

src/compiler/compile/render_dom/invalidate.ts

@@ -58,7 +58,8 @@ export function invalidate(renderer: Renderer, scope: Scope, node: Node, names:
 		const pass_value = (
 			extra_args.length > 0 ||
 			(node.type === 'AssignmentExpression' && node.left.type !== 'Identifier') ||
-			(node.type === 'UpdateExpression' && (!node.prefix || node.argument.type !== 'Identifier'))
+			(node.type === 'UpdateExpression' && (!node.prefix || node.argument.type !== 'Identifier')) ||
+			(node.type === 'UnaryExpression' && node.operator === 'delete' && (!node.prefix || node.argument.type !== 'Identifier'))
 		);
 		if (pass_value) {
 			extra_args.unshift({

test/js/samples/reactive-delete/expected.js

@@ -0,0 +1,31 @@
+/* generated by Svelte vX.Y.Z */
+import { SvelteComponent, init, safe_not_equal } from "svelte/internal";
+
+function instance($$self, $$props, $$invalidate) {
+	const a = { b: true };
+
+	function removeB() {
+		$$invalidate(1, delete a.b, a);
+	}
+
+	$$self.$$.update = () => {
+		if ($$self.$$.dirty & /*a*/ 2) {
+			$: console.log(a.b);
+		}
+	};
+
+	return [removeB, a];
+}
+
+class Component extends SvelteComponent {
+	constructor(options) {
+		super();
+		init(this, options, instance, null, safe_not_equal, { removeB: 0 });
+	}
+
+	get removeB() {
+		return this.$$.ctx[0];
+	}
+}
+
+export default Component;

test/js/samples/reactive-delete/input.svelte

@@ -0,0 +1,9 @@
+<script>
+	const a = { b: true };
+
+	export function removeB() {
+		delete a.b;
+	}
+
+	$: console.log(a.b);
+</script>