fix invalidation in ++foo.bar (#4395)

CHANGELOG.md

@@ -9,6 +9,7 @@
 * Permit reserved keywords as destructuring keys in `{#each}` ([#4372](https://github.com/sveltejs/svelte/issues/4372))
 * Disallow reserved keywords in `{expressions}` ([#4372](https://github.com/sveltejs/svelte/issues/4372))
 * Fix code generation error with precedence of arrow functions ([#4384](https://github.com/sveltejs/svelte/issues/4384))
+* Fix invalidation in expressions like `++foo.bar` ([#4393](https://github.com/sveltejs/svelte/issues/4393))
 
 ## 3.18.1
 

src/compiler/compile/render_dom/invalidate.ts

@@ -49,7 +49,7 @@ 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.type === 'UpdateExpression' && (!node.prefix || node.argument.type !== 'Identifier'))
 			);
 
 			if (pass_value) {

test/runtime/samples/instrumentation-update-expression/_config.js

@@ -0,0 +1,31 @@
+export default {
+	html: `
+		<p>0</p>
+		<button>foo++</button>
+		<button>++foo</button>
+		<p>0</p>
+		<button>bar.bar++</button>
+		<button>++bar.bar</button>
+	`,
+	async test({ assert, target, window }) {
+		const [foo, bar] = target.querySelectorAll('p');
+		const [button1, button2, button3, button4] = target.querySelectorAll('button');
+		const event = new window.MouseEvent('click');
+
+		await button1.dispatchEvent(event);
+		assert.equal(foo.innerHTML, '1');
+		assert.equal(bar.innerHTML, '0');
+
+		await button2.dispatchEvent(event);
+		assert.equal(foo.innerHTML, '2');
+		assert.equal(bar.innerHTML, '0');
+
+		await button3.dispatchEvent(event);
+		assert.equal(foo.innerHTML, '2');
+		assert.equal(bar.innerHTML, '1');
+
+		await button4.dispatchEvent(event);
+		assert.equal(foo.innerHTML, '2');
+		assert.equal(bar.innerHTML, '2');
+	}
+};

test/runtime/samples/instrumentation-update-expression/main.svelte

@@ -0,0 +1,14 @@
+<script>
+	let foo = 0;
+	let bar = { bar: 0 };
+</script>
+
+<p>{foo}</p>
+
+<button on:click={() => foo++}>foo++</button>
+<button on:click={() => ++foo}>++foo</button>
+
+<p>{bar.bar}</p>
+
+<button on:click={() => bar.bar++}>bar.bar++</button>
+<button on:click={() => ++bar.bar}>++bar.bar</button>