also generate a new identifier for interop name

fixes #5481

lib/optimize/ConcatenatedModule.js

@@ -32,17 +32,16 @@ function ensureNsObjSource(info, moduleToInfoMap, requestShortener) {
 	}
 }
 
-function getExternalImport(importedModule, importedVar, exportName, asCall) {
+function getExternalImport(importedModule, info, exportName, asCall) {
-	const isHarmonyModule = importedModule && (!importedModule.meta || importedModule.meta.harmonyModule);
+	if(exportName === true) return info.name;
-	if(exportName === true) return importedVar;
 	const used = importedModule.isUsed(exportName);
 	if(!used) return "/* unused reexport */undefined";
-	if(!isHarmonyModule && exportName === "default") {
+	if(info.interop && exportName === "default") {
-		return asCall ? `${importedVar}_default()` : `${importedVar}_default.a`;
+		return asCall ? `${info.interopName}()` : `${info.interopName}.a`;
 	}
 	// TODO use Template.toNormalComment when merging with pure-module
 	const comment = used !== exportName ? ` /* ${exportName} */` : "";
-	const reference = `${importedVar}[${JSON.stringify(used)}${comment}]`;
+	const reference = `${info.name}[${JSON.stringify(used)}${comment}]`;
 	if(asCall)
 		return `Object(${reference})`;
 	return reference;
@@ -67,12 +66,6 @@ function getFinalName(info, exportName, moduleToInfoMap, requestShortener, asCal
 					if(refInfo) {
 						// module is in the concatenation
 						return getFinalName(refInfo, reexport.exportName, moduleToInfoMap, requestShortener, asCall);
-					} else {
-						const dep = reexport.dependency;
-						const importedModule = reexport.module;
-						const exportName = reexport.exportName;
-						const importedVar = dep.importedVar;
-						return getExternalImport(importedModule, importedVar, exportName, asCall);
 					}
 				}
 				const problem = `Cannot get final name for export "${exportName}" in "${info.module.readableIdentifier(requestShortener)}"` +
@@ -84,7 +77,7 @@ function getFinalName(info, exportName, moduleToInfoMap, requestShortener, asCal
 		case "external":
 			{
 				const importedModule = info.module;
-				return getExternalImport(importedModule, info.name, exportName, asCall);
+				return getExternalImport(importedModule, info, exportName, asCall);
 			}
 	}
 }
@@ -363,7 +356,9 @@ class ConcatenatedModule extends Module {
 						type: "external",
 						module: info.module,
 						index: idx,
-						name: undefined
+						name: undefined,
+						interopName: undefined,
+						interop: undefined
 					};
 				default:
 					throw new Error(`Unsupported concatenation entry type ${info.type}`);
@@ -458,6 +453,8 @@ class ConcatenatedModule extends Module {
 			"switch", "synchronized", "this", "throw", "throws", "transient", "true", "try", "typeof",
 			"var", "void", "volatile", "while", "with", "yield",
 
+			"module", "__dirname", "__filename", "exports",
+
 			"Array", "Date", "eval", "function", "hasOwnProperty", "Infinity", "isFinite", "isNaN",
 			"isPrototypeOf", "length", "Math", "NaN", "name", "Number", "Object", "prototype", "String",
 			"toString", "undefined", "valueOf",
@@ -531,9 +528,15 @@ class ConcatenatedModule extends Module {
 					}
 				case "external":
 					{
+						info.interop = info.module.meta && !info.module.meta.harmonyModule;
 						const externalName = this.findNewName("", allUsedNames, null, info.module.readableIdentifier(requestShortener));
 						allUsedNames.add(externalName);
 						info.name = externalName;
+						if(info.interop) {
+							const externalNameInterop = this.findNewName("default", allUsedNames, null, info.module.readableIdentifier(requestShortener));
+							allUsedNames.add(externalNameInterop);
+							info.interopName = externalNameInterop;
+						}
 						break;
 					}
 			}
@@ -588,8 +591,8 @@ class ConcatenatedModule extends Module {
 				case "external":
 					result.add(`\n// EXTERNAL MODULE: ${info.module.readableIdentifier(requestShortener)}\n`);
 					result.add(`var ${info.name} = __webpack_require__(${JSON.stringify(info.module.id)});\n`);
-					if(info.module.meta && !info.module.meta.harmonyModule) {
+					if(info.interop) {
-						result.add(`var ${info.name}_default = /*#__PURE__*/__webpack_require__.n(${info.name});\n`);
+						result.add(`var ${info.interopName} = /*#__PURE__*/__webpack_require__.n(${info.name});\n`);
 					}
 					break;
 				default:

test/cases/scope-hoisting/issue-5481/cjs.js

@@ -0,0 +1 @@
+module.exports = "ok";

test/cases/scope-hoisting/issue-5481/index.js

@@ -0,0 +1,5 @@
+import value from "./module";
+
+it("should not cause name conflicts", function() {
+	(typeof value).should.be.eql("undefined");
+});

test/cases/scope-hoisting/issue-5481/module.js

@@ -0,0 +1,5 @@
+import a from "./cjs";
+
+var cjs_default;
+
+export default cjs_default;