Correctly include functions with side effects from side-effect-free modules

src/Module.ts

@@ -1061,14 +1061,16 @@ export default class Module {
 			variable.include();
 			this.graph.needsTreeshakingPass = true;
 			const variableModule = variable.module;
-			if (variableModule && variableModule !== this && variableModule instanceof Module) {
+			if (variableModule && variableModule instanceof Module) {
 				if (!variableModule.isExecuted) {
 					markModuleAndImpureDependenciesAsExecuted(variableModule);
 				}
-				const sideEffectModules = getAndExtendSideEffectModules(variable, this);
-				for (const module of sideEffectModules) {
-					if (!module.isExecuted) {
-						markModuleAndImpureDependenciesAsExecuted(module);
+				if (variableModule !== this) {
+					const sideEffectModules = getAndExtendSideEffectModules(variable, this);
+					for (const module of sideEffectModules) {
+						if (!module.isExecuted) {
+							markModuleAndImpureDependenciesAsExecuted(module);
+						}
 					}
 				}
 			}

src/ast/nodes/shared/Node.ts

@@ -286,5 +286,5 @@ export function locateNode(node: Node) {
 }
 
 export function logNode(node: Node) {
-	console.log(node.context.code.slice(node.start, node.end));
+	return node.context.code.slice(node.start, node.end);
 }

test/function/samples/side-effect-free-module-function/_config.js

@@ -0,0 +1,11 @@
+module.exports = {
+	description:
+		'correctly include functions with side effects from side-effect-free modules (#3942)',
+	options: {
+		plugins: {
+			transform() {
+				return { moduleSideEffects: false };
+			}
+		}
+	}
+};

test/function/samples/side-effect-free-module-function/curry.js

@@ -0,0 +1,4 @@
+export function curry(fn, args = []) {
+	return (..._args) =>
+		(rest => (rest.length >= fn.length ? fn(...rest) : curry(fn, rest)))([...args, ..._args]);
+}

test/function/samples/side-effect-free-module-function/main.js

@@ -0,0 +1,11 @@
+import { curry } from './curry';
+let result;
+
+function foo() {
+	result = 'foo';
+}
+
+var fooc = curry(foo);
+fooc();
+
+assert.strictEqual(result, 'foo');