From 9418822b625b37da3c5d08db3ad5e86f5cd9fd93 Mon Sep 17 00:00:00 2001
From: Lukas Taegert-Atkinson <lukastaegert@users.noreply.github.com>
Date: Tue, 11 Jun 2019 09:32:03 +0200
Subject: [PATCH] Do not tree-shake arguments with side-effects (#2924)

---
 src/ast/scopes/ParameterScope.ts                       |  3 ++-
 .../argument-side-effects/_config.js                   |  3 +++
 .../argument-side-effects/_expected.js                 | 10 ++++++++++
 .../argument-side-effects/main.js                      | 10 ++++++++++
 4 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 test/form/samples/treeshake-excess-arguments/argument-side-effects/_config.js
 create mode 100644 test/form/samples/treeshake-excess-arguments/argument-side-effects/_expected.js
 create mode 100644 test/form/samples/treeshake-excess-arguments/argument-side-effects/main.js

diff --git a/src/ast/scopes/ParameterScope.ts b/src/ast/scopes/ParameterScope.ts
index 4e29d59f6b8..c5823008da7 100644
--- a/src/ast/scopes/ParameterScope.ts
+++ b/src/ast/scopes/ParameterScope.ts
@@ -58,7 +58,8 @@ export default class ParameterScope extends ChildScope {
 						calledFromTryStatement = true;
 					}
 				}
-			} else if (!argIncluded && arg.shouldBeIncluded()) {
+			}
+			if (!argIncluded && arg.shouldBeIncluded()) {
 				argIncluded = true;
 			}
 			if (argIncluded) {
diff --git a/test/form/samples/treeshake-excess-arguments/argument-side-effects/_config.js b/test/form/samples/treeshake-excess-arguments/argument-side-effects/_config.js
new file mode 100644
index 00000000000..d2acef03025
--- /dev/null
+++ b/test/form/samples/treeshake-excess-arguments/argument-side-effects/_config.js
@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'retains arguments that have side-effects'
+};
diff --git a/test/form/samples/treeshake-excess-arguments/argument-side-effects/_expected.js b/test/form/samples/treeshake-excess-arguments/argument-side-effects/_expected.js
new file mode 100644
index 00000000000..b92aab28bbc
--- /dev/null
+++ b/test/form/samples/treeshake-excess-arguments/argument-side-effects/_expected.js
@@ -0,0 +1,10 @@
+function sideEffects() {
+	console.log('print message');
+	return true;
+}
+
+function hola(a, b) {
+	console.log(a);
+}
+
+hola(1, sideEffects());
diff --git a/test/form/samples/treeshake-excess-arguments/argument-side-effects/main.js b/test/form/samples/treeshake-excess-arguments/argument-side-effects/main.js
new file mode 100644
index 00000000000..b92aab28bbc
--- /dev/null
+++ b/test/form/samples/treeshake-excess-arguments/argument-side-effects/main.js
@@ -0,0 +1,10 @@
+function sideEffects() {
+	console.log('print message');
+	return true;
+}
+
+function hola(a, b) {
+	console.log(a);
+}
+
+hola(1, sideEffects());