From 10148c6356e16997db220c41799c0bb23a73f517 Mon Sep 17 00:00:00 2001
From: Lukas Taegert-Atkinson <lukas.taegert-atkinson@tngtech.com>
Date: Wed, 2 Jun 2021 06:54:56 +0200
Subject: [PATCH] Respect propertyReadSideEffects in spread elements

---
 src/ast/nodes/SpreadElement.ts                |  8 ++++++-
 .../main.js                                   | 24 ++++++++++++++++---
 .../_expected.js                              | 18 ++++++++++++++
 .../keep-property-access-side-effects/main.js | 18 ++++++++++++++
 4 files changed, 64 insertions(+), 4 deletions(-)

diff --git a/src/ast/nodes/SpreadElement.ts b/src/ast/nodes/SpreadElement.ts
index 742eaa848a4..794436ee8a4 100644
--- a/src/ast/nodes/SpreadElement.ts
+++ b/src/ast/nodes/SpreadElement.ts
@@ -1,3 +1,4 @@
+import { NormalizedTreeshakingOptions } from '../../rollup/types';
 import { HasEffectsContext } from '../ExecutionContext';
 import { NodeEvent } from '../NodeEvents';
 import { ObjectPath, PathTracker, UNKNOWN_PATH, UnknownKey } from '../utils/PathTracker';
@@ -27,9 +28,14 @@ export default class SpreadElement extends NodeBase {
 	}
 
 	hasEffects(context: HasEffectsContext): boolean {
+		if (!this.deoptimized) this.applyDeoptimizations();
+		const { propertyReadSideEffects } = this.context.options
+			.treeshake as NormalizedTreeshakingOptions;
 		return (
 			this.argument.hasEffects(context) ||
-			this.argument.hasEffectsWhenAccessedAtPath(UNKNOWN_PATH, context)
+			(propertyReadSideEffects &&
+				(propertyReadSideEffects === 'always' ||
+					this.argument.hasEffectsWhenAccessedAtPath(UNKNOWN_PATH, context)))
 		);
 	}
 
diff --git a/test/form/samples/ignore-property-access-side-effects/main.js b/test/form/samples/ignore-property-access-side-effects/main.js
index a501b27ef3f..de7558b2ef0 100644
--- a/test/form/samples/ignore-property-access-side-effects/main.js
+++ b/test/form/samples/ignore-property-access-side-effects/main.js
@@ -1,6 +1,6 @@
 const getter = {
-	get foo () {
-		console.log( 'effect' );
+	get foo() {
+		console.log('effect');
 	}
 };
 const foo1 = getter.foo;
@@ -13,4 +13,22 @@ function accessArg(arg) {
 }
 accessArg(null);
 
-const foo4 = globalThis.globalThis.unknown.unknownProperty;
+const foo4 = globalThis.unknown.unknownProperty;
+
+const foo5 = {
+	...{
+		get prop() {
+			console.log('effect');
+		}
+	}
+};
+
+const foo6 = (async function () {
+	await {
+		get then() {
+			console.log('effect');
+			return () => {};
+		}
+	};
+	return { then() {} };
+})();
diff --git a/test/form/samples/keep-property-access-side-effects/_expected.js b/test/form/samples/keep-property-access-side-effects/_expected.js
index cf72b049414..79d250893d1 100644
--- a/test/form/samples/keep-property-access-side-effects/_expected.js
+++ b/test/form/samples/keep-property-access-side-effects/_expected.js
@@ -14,3 +14,21 @@ function accessArg(arg) {
 accessArg(null);
 
 globalThis.unknown.unknownProperty;
+
+({
+	...{
+		get prop() {
+			console.log('effect');
+		}
+	}
+});
+
+((async function () {
+	await {
+		get then() {
+			console.log('effect');
+			return () => {};
+		}
+	};
+	return { then() {} };
+}))();
diff --git a/test/form/samples/keep-property-access-side-effects/main.js b/test/form/samples/keep-property-access-side-effects/main.js
index 79c0b9bf78d..6125631a94d 100644
--- a/test/form/samples/keep-property-access-side-effects/main.js
+++ b/test/form/samples/keep-property-access-side-effects/main.js
@@ -14,3 +14,21 @@ function accessArg(arg) {
 accessArg(null);
 
 const foo4 = globalThis.unknown.unknownProperty;
+
+const foo5 = {
+	...{
+		get prop() {
+			console.log('effect');
+		}
+	}
+};
+
+const foo6 = (async function () {
+	await {
+		get then() {
+			console.log('effect');
+			return () => {};
+		}
+	};
+	return { then() {} };
+})();