From 4eeef6ec8ac65c6cf144db13152cdfdd3ea89738 Mon Sep 17 00:00:00 2001
From: Lukas Taegert-Atkinson <lukastaegert@users.noreply.github.com>
Date: Sat, 29 May 2021 06:36:11 +0200
Subject: [PATCH] Track access side effects when using object spread operator
 (#4113)

* Check for access side effects when using the object spread operator

* Make test a little more robust
---
 src/ast/nodes/SpreadElement.ts                         | 10 +++++++++-
 .../samples/watch/watch-config-early-update/_config.js |  2 +-
 .../samples/object-spread-side-effect/_config.js       |  3 +++
 .../function/samples/object-spread-side-effect/main.js |  9 +++++++++
 4 files changed, 22 insertions(+), 2 deletions(-)
 create mode 100644 test/function/samples/object-spread-side-effect/_config.js
 create mode 100644 test/function/samples/object-spread-side-effect/main.js

diff --git a/src/ast/nodes/SpreadElement.ts b/src/ast/nodes/SpreadElement.ts
index 4e5bee8874c..742eaa848a4 100644
--- a/src/ast/nodes/SpreadElement.ts
+++ b/src/ast/nodes/SpreadElement.ts
@@ -1,5 +1,6 @@
+import { HasEffectsContext } from '../ExecutionContext';
 import { NodeEvent } from '../NodeEvents';
-import { ObjectPath, PathTracker, UnknownKey } from '../utils/PathTracker';
+import { ObjectPath, PathTracker, UNKNOWN_PATH, UnknownKey } from '../utils/PathTracker';
 import * as NodeType from './NodeType';
 import { ExpressionEntity } from './shared/Expression';
 import { ExpressionNode, NodeBase } from './shared/Node';
@@ -25,6 +26,13 @@ export default class SpreadElement extends NodeBase {
 		}
 	}
 
+	hasEffects(context: HasEffectsContext): boolean {
+		return (
+			this.argument.hasEffects(context) ||
+			this.argument.hasEffectsWhenAccessedAtPath(UNKNOWN_PATH, context)
+		);
+	}
+
 	protected applyDeoptimizations(): void {
 		this.deoptimized = true;
 		// Only properties of properties of the argument could become subject to reassignment
diff --git a/test/cli/samples/watch/watch-config-early-update/_config.js b/test/cli/samples/watch/watch-config-early-update/_config.js
index 93e7190886d..c13c2690ab6 100644
--- a/test/cli/samples/watch/watch-config-early-update/_config.js
+++ b/test/cli/samples/watch/watch-config-early-update/_config.js
@@ -23,7 +23,7 @@ module.exports = {
                 format: 'es'
               }
             }),
-          500
+          1000
         );
       });
   		`
diff --git a/test/function/samples/object-spread-side-effect/_config.js b/test/function/samples/object-spread-side-effect/_config.js
new file mode 100644
index 00000000000..bf01828fab0
--- /dev/null
+++ b/test/function/samples/object-spread-side-effect/_config.js
@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'triggers getter side effects when spreading objects'
+};
diff --git a/test/function/samples/object-spread-side-effect/main.js b/test/function/samples/object-spread-side-effect/main.js
new file mode 100644
index 00000000000..ae997485f8b
--- /dev/null
+++ b/test/function/samples/object-spread-side-effect/main.js
@@ -0,0 +1,9 @@
+let result = 'FAIL';
+const unused = {
+	...{
+		get prop() {
+			result = 'PASS';
+		}
+	}
+};
+assert.strictEqual(result, 'PASS');