Do not tree-shake arguments that contain a spread element (#3654)

src/ast/scopes/ParameterScope.ts

@@ -51,6 +51,14 @@ export default class ParameterScope extends ChildScope {
 		let calledFromTryStatement = false;
 		let argIncluded = false;
 		const restParam = this.hasRest && this.parameters[this.parameters.length - 1];
+		for (const checkedArg of args) {
+			if (checkedArg instanceof SpreadElement) {
+				for (const arg of args) {
+					arg.include(context, false);
+				}
+				break;
+			}
+		}
 		for (let index = args.length - 1; index >= 0; index--) {
 			const paramVars = this.parameters[index] || restParam;
 			const arg = args[index];

test/function/samples/spread-arguments-unused/_config.js

@@ -0,0 +1,4 @@
+module.exports = {
+	description:
+		'handles using the spread operator to add arguments when the first argument is unused (#3652)'
+};

test/function/samples/spread-arguments-unused/main.js

@@ -0,0 +1,5 @@
+function test(unused, used) {
+	assert.strictEqual(used, 'used');
+}
+
+test(...['unused', 'used']);