Deconflict unused parameters (#2972)

src/ast/scopes/ChildScope.ts

@@ -67,7 +67,7 @@ export default class ChildScope extends Scope {
 			}
 		}
 		for (const [name, variable] of this.variables) {
-			if (variable.included) {
+			if (variable.included || variable.alwaysRendered) {
 				variable.setSafeName(getSafeName(name, usedNames));
 			}
 		}

src/ast/scopes/ParameterScope.ts

@@ -38,6 +38,11 @@ export default class ParameterScope extends ChildScope {
 
 	addParameterVariables(parameters: LocalVariable[][], hasRest: boolean) {
 		this.parameters = parameters;
+		for (const parameterList of parameters) {
+			for (const parameter of parameterList) {
+				parameter.alwaysRendered = true;
+			}
+		}
 		this.hasRest = hasRest;
 	}
 

src/ast/variables/Variable.ts

@@ -11,6 +11,7 @@ import { ImmutableEntityPathTracker } from '../utils/ImmutableEntityPathTracker'
 import { LiteralValueOrUnknown, ObjectPath, UNKNOWN_EXPRESSION, UNKNOWN_VALUE } from '../values';
 
 export default class Variable implements ExpressionEntity {
+	alwaysRendered = false;
 	exportName: string | null = null;
 	included = false;
 	isId = false;

test/function/samples/argument-treeshaking-parameter-conflict/_config.js

@@ -0,0 +1,4 @@
+module.exports = {
+	solo: true,
+	description: 'does not cause conflicts when deconflicting non-included parameters'
+};

test/function/samples/argument-treeshaking-parameter-conflict/dep.js

@@ -0,0 +1,2 @@
+export let value = 0;
+export const mutate = () => value++;

test/function/samples/argument-treeshaking-parameter-conflict/main.js

@@ -0,0 +1,9 @@
+import * as dep from './dep';
+
+function test(mutate) {
+	dep.mutate('hello');
+}
+
+test();
+
+assert.strictEqual(dep.value, 1);