Fixed default names.

src/Bundle.js

@@ -65,6 +65,16 @@ export default class Bundle {
 
 				// As a last step, deconflict all identifier names, once.
 				this.scope.deconflict();
+
+				// Alias the default import to the external module named
+				// for external modules that don't need named imports.
+				this.externalModules.forEach( module => {
+					const externalDefault = module.exports.lookup( 'default' );
+
+					if ( externalDefault && !module.needsNamed ) {
+						externalDefault.name = module.name;
+					}
+				});
 			});
 	}
 

src/Module.js

@@ -601,7 +601,9 @@ export default class Module {
 
 						if ( id.module && id.module.isExternal ) {
 							replacements[ name ] = id.originalName === 'default' ?
-								`${id.module.name}['default']` :
+								// default names are always directly accessed
+								id.name :
+								// other names are indirectly accessed
 								`${id.module.name}.${id.originalName}`;
 						}
 					});

src/finalisers/cjs.js

@@ -1,3 +1,4 @@
+import getInteropBlock from './shared/getInteropBlock';
 import getExportBlock from './shared/getExportBlock';
 
 export default function cjs ( bundle, magicString, { exportMode }, options ) {
@@ -5,16 +6,8 @@ export default function cjs ( bundle, magicString, { exportMode }, options ) {
 
 	// TODO handle empty imports, once they're supported
 	const importBlock = bundle.externalModules
-		.map( module => {
-			let requireStatement = `var ${module.name} = require('${module.id}');`;
-
-			if ( module.needsDefault ) {
-				requireStatement += '\n' + ( module.needsNamed ? `var ${module.name}__default = ` : `${module.name} = ` ) +
-					`'default' in ${module.name} ? ${module.name}['default'] : ${module.name};`;
-			}
-
-			return requireStatement;
-		})
+		.map( module => `var ${module.name} = require('${module.id}');`)
+		.concat( getInteropBlock( bundle ) )
 		.join( '\n' );
 
 	if ( importBlock ) {

src/finalisers/shared/getInteropBlock.js

@@ -1,13 +1,12 @@
 export default function getInteropBlock ( bundle ) {
 	return bundle.externalModules
 		.map( module => {
-			if ( !module.exports.inScope( 'default' ) ) return;
+			const def = module.exports.lookup( 'default' );
 
-			if ( module.needsNamed ) {
-				return `var ${module.name}__default = 'default' in ${module.name} ? ${module.name}['default'] : ${module.name};`;
-			} else {
-				return `${module.name} = 'default' in ${module.name} ? ${module.name}['default'] : ${module.name};`;
-			}
+			if ( !def ) return;
+
+			return ( module.needsNamed ? 'var ' : '' ) +
+				`${def.name} = 'default' in ${module.name} ? ${module.name}['default'] : ${module.name};`;
 		})
 		.filter( Boolean )
 		.join( '\n' );