Do not create invalid code if a function argument is an empty object …

…pattern (#3998)
rollup · Mar 16, 2021 · 9cae40d · 9cae40d
1 parent 770da18
commit 9cae40d
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Showing 3 changed files with 23 additions and 6 deletions.
diff --git a/src/ast/scopes/ParameterScope.ts b/src/ast/scopes/ParameterScope.ts
@@ -64,12 +64,17 @@ export default class ParameterScope extends ChildScope {
 			const arg = args[index];
 			if (paramVars) {
 				calledFromTryStatement = false;
-				for (const variable of paramVars) {
-					if (variable.included) {
-						argIncluded = true;
-					}
-					if (variable.calledFromTryStatement) {
-						calledFromTryStatement = true;
+				if (paramVars.length === 0) {
+					// handle empty destructuring
+					argIncluded = true;
+				} else {
+					for (const variable of paramVars) {
+						if (variable.included) {
+							argIncluded = true;
+						}
+						if (variable.calledFromTryStatement) {
+							calledFromTryStatement = true;
+						}
 					}
 				}
 			}

diff --git a/test/function/samples/unused-parameter-side-effects/_config.js b/test/function/samples/unused-parameter-side-effects/_config.js
@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'does not tree-shake arguments where the corresponding parameters have side-effects'
+};
diff --git a/test/function/samples/unused-parameter-side-effects/main.js b/test/function/samples/unused-parameter-side-effects/main.js
@@ -0,0 +1,9 @@
+let sideEffects = 0;
+
+function destructured({}) {
+	sideEffects++;
+}
+
+destructured({});
+
+assert.strictEqual(sideEffects, 1);