prevent conflicts with globals (assumed or otherwise) - fixes #20

src/Bundle.js

@@ -43,6 +43,7 @@ export default class Bundle {
 		this.statements = [];
 		this.externalModules = [];
 		this.internalNamespaceModules = [];
+		this.assumedGlobals = blank();
 	}
 
 	fetchModule ( importee, importer ) {
@@ -169,11 +170,23 @@ export default class Bundle {
 			module.name = name;
 		});
 
+		// Ensure we don't conflict with globals
+		keys( this.assumedGlobals ).forEach( name => {
+			if ( definers[ name ] ) {
+				conflicts[ name ] = true;
+			}
+		});
+
 		// Rename conflicting identifiers so they can live in the same scope
 		keys( conflicts ).forEach( name => {
 			const modules = definers[ name ];
 
-			modules.pop(); // the module closest to the entryModule gets away with keeping things as they are
+			if ( !this.assumedGlobals[ name ] ) {
+				// the module closest to the entryModule gets away with
+				// keeping things as they are, unless we have a conflict
+				// with a global name
+				modules.pop();
+			}
 
 			modules.forEach( module => {
 				const replacement = getSafeName( name );

src/Module.js

@@ -181,6 +181,14 @@ export default class Module {
 				this.modifications[ name ].push( statement );
 			});
 		});
+
+		this.statements.forEach( statement => {
+			keys( statement.dependsOn ).forEach( name => {
+				if ( !this.definitions[ name ] && !this.imports[ name ] ) {
+					this.bundle.assumedGlobals[ name ] = true;
+				}
+			});
+		});
 	}
 
 	findDeclaration ( localName ) {

test/function/deconflicts-globals/_config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'deconflicts names that are assumed to be global'
+};

test/function/deconflicts-globals/bar.js

@@ -0,0 +1,6 @@
+import foo from './foo';
+
+export default function() {
+	assert.equal( foo(), 'foo' );
+	return Number;
+};

test/function/deconflicts-globals/foo.js

@@ -0,0 +1,5 @@
+export var Number = 42;
+
+export default function() {
+	return 'foo';
+};

test/function/deconflicts-globals/main.js

@@ -0,0 +1,5 @@
+import { Number } from './foo';
+import bar from './bar';
+
+assert.equal( Number, 42 );
+assert.notEqual( bar(), Number );