fix DDC ES6 module export names, part of #32272

We use renamable variables for Dart libraries, this ensures we still
export it with the correct name.

Change-Id: I96dc161e33d265c0ffbd07f8d642629504dffe62
Reviewed-on: https://dart-review.googlesource.com/42892
Commit-Queue: Jenny Messerly <[email protected]>
Reviewed-by: Vijay Menon <[email protected]>

Author: Jenny Messerly

pkg/dev_compiler/lib/src/analyzer/code_generator.dart

@@ -329,8 +329,9 @@ class CodeGenerator extends Object
     var root = new JS.Identifier('_root');
     items.add(js.statement('const # = Object.create(null)', [root]));
 
-    if (compilationUnits.any((u) => isSdkInternalRuntime(
-        resolutionMap.elementDeclaredByCompilationUnit(u).library))) {
+    var isBuildingSdk =
+        compilationUnits.any((u) => isSdkInternalRuntime(u.element.library));
+    if (isBuildingSdk) {
       // Don't allow these to be renamed when we're building the SDK.
       // There is JS code in dart:* that depends on their names.
       _runtimeModule = new JS.Identifier('dart');
@@ -343,28 +344,29 @@ class CodeGenerator extends Object
     _typeTable = new TypeTable(_runtimeModule);
 
     // Initialize our library variables.
-    var isBuildingSdk = false;
+    var exports = <JS.NameSpecifier>[];
+    void emitLibrary(JS.Identifier id) {
+      items.add(js.statement('const # = Object.create(#)', [id, root]));
+      exports.add(new JS.NameSpecifier(id));
+    }
+
     for (var unit in compilationUnits) {
-      var library =
-          resolutionMap.elementDeclaredByCompilationUnit(unit).library;
+      var library = unit.element.library;
       if (unit.element != library.definingCompilationUnit) continue;
 
       var libraryTemp = isSdkInternalRuntime(library)
           ? _runtimeModule
           : new JS.TemporaryId(jsLibraryName(_libraryRoot, library));
       _libraries[library] = libraryTemp;
-      items.add(new JS.ExportDeclaration(
-          js.call('const # = Object.create(#)', [libraryTemp, root])));
-
-      // dart:_runtime has a magic module that holds extension method symbols.
-      // TODO(jmesserly): find a cleaner design for this.
-      if (isSdkInternalRuntime(library)) {
-        isBuildingSdk = true;
-        items.add(new JS.ExportDeclaration(js.call(
-            'const # = Object.create(#)', [_extensionSymbolsModule, root])));
-      }
+      emitLibrary(libraryTemp);
     }
 
+    // dart:_runtime has a magic module that holds extension method symbols.
+    // TODO(jmesserly): find a cleaner design for this.
+    if (isBuildingSdk) emitLibrary(_extensionSymbolsModule);
+
+    items.add(new JS.ExportDeclaration(new JS.ExportClause(exports)));
+
     // Collect all class/type Element -> Node mappings
     // in case we need to forward declare any classes.
     _declarationNodes = new HashMap<TypeDefiningElement, AstNode>.identity();

pkg/dev_compiler/lib/src/compiler/module_builder.dart

@@ -134,7 +134,10 @@ abstract class _ModuleBuilder {
 
   visitExportDeclaration(ExportDeclaration node) {
     exports.add(node);
-    statements.add(node.exported.toStatement());
+    var exported = node.exported;
+    if (exported is! ExportClause) {
+      statements.add(exported.toStatement());
+    }
   }
 
   visitStatement(Statement node) {

pkg/dev_compiler/lib/src/js_ast/printer.dart

@@ -1233,7 +1233,7 @@ class Printer extends TypeScriptTypePrinter implements NodeVisitor {
         spaceOut();
       }
     }
-    nameSpecifierListOut(node.namedImports);
+    nameSpecifierListOut(node.namedImports, false);
     fromClauseOut(node.from);
     outSemicolonLn();
   }
@@ -1248,15 +1248,15 @@ class Printer extends TypeScriptTypePrinter implements NodeVisitor {
   }
 
   visitExportClause(ExportClause node) {
-    nameSpecifierListOut(node.exports);
+    nameSpecifierListOut(node.exports, true);
     fromClauseOut(node.from);
   }
 
-  nameSpecifierListOut(List<NameSpecifier> names) {
+  nameSpecifierListOut(List<NameSpecifier> names, bool export) {
     if (names == null) return;
 
     if (names.length == 1 && names[0].name == '*') {
-      visit(names[0]);
+      nameSpecifierOut(names[0], export);
       return;
     }
 
@@ -1267,7 +1267,7 @@ class Printer extends TypeScriptTypePrinter implements NodeVisitor {
         out(',');
         spaceOut();
       }
-      visit(names[i]);
+      nameSpecifierOut(names[i], export);
     }
     spaceOut();
     out('}');
@@ -1281,22 +1281,28 @@ class Printer extends TypeScriptTypePrinter implements NodeVisitor {
     }
   }
 
+  /// This is unused, see [nameSpecifierOut].
   visitNameSpecifier(NameSpecifier node) {
+    throw new UnsupportedError('visitNameSpecifier');
+  }
+
+  nameSpecifierOut(NameSpecifier node, bool export) {
     if (node.isStar) {
       out('*');
     } else {
-      var importName = node.name.name;
-      out(importName);
-
+      var name = node.name.name;
       if (node.asName == null) {
         // If our local was renamed, generate an implicit "as".
-        // This is a convenience feature so imports can be renamed.
+        // This is a convenience feature so imports and exports can be renamed.
         var localName = localNamer.getName(node.name);
-        if (localName != importName) {
+        if (localName != name) {
+          out(export ? localName : name);
           out(' as ');
-          out(localName);
+          out(export ? name : localName);
+          return;
         }
       }
+      out(name);
     }
     if (node.asName != null) {
       out(' as ');

pkg/dev_compiler/lib/src/kernel/compiler.dart

@@ -280,22 +280,29 @@ class ProgramCompiler
 
     // Initialize our library variables.
     var items = <JS.ModuleItem>[];
+    var exports = <JS.NameSpecifier>[];
+    var root = new JS.Identifier('_root');
+    items.add(js.statement('const # = Object.create(null)', [root]));
+
+    void emitLibrary(JS.Identifier id) {
+      items.add(js.statement('const # = Object.create(#)', [id, root]));
+      exports.add(new JS.NameSpecifier(id));
+    }
+
     for (var library in libraries) {
       var libraryTemp = library == ddcRuntime
           ? _runtimeModule
           : new JS.TemporaryId(jsLibraryName(library));
       _libraries[library] = libraryTemp;
-      items.add(new JS.ExportDeclaration(
-          js.call('const # = Object.create(null)', [libraryTemp])));
-
-      // dart:_runtime has a magic module that holds extension method symbols.
-      // TODO(jmesserly): find a cleaner design for this.
-      if (library == ddcRuntime) {
-        items.add(new JS.ExportDeclaration(js
-            .call('const # = Object.create(null)', [_extensionSymbolsModule])));
-      }
+      emitLibrary(libraryTemp);
     }
 
+    // dart:_runtime has a magic module that holds extension method symbols.
+    // TODO(jmesserly): find a cleaner design for this.
+    if (ddcRuntime != null) emitLibrary(_extensionSymbolsModule);
+
+    items.add(new JS.ExportDeclaration(new JS.ExportClause(exports)));
+
     // Collect all class/type Element -> Node mappings
     // in case we need to forward declare any classes.
     _pendingClasses = new HashSet.identity();