Reify type params on map literals

lib/src/compiler/code_generator.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:collection' show HashMap, HashSet;
 import 'dart:math' show min, max;
 
 import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart' show Token, TokenType;
@@ skipping 4926 matching lines @@
     if (isConst) return _cacheConst(emitList);
     return emitList();
   }
 
   @override
   visitMapLiteral(MapLiteral node) {
     // TODO(jmesserly): we can likely make these faster.
     JS.Expression emitMap() {
       var entries = node.entries;
       var mapArguments = null;
-      var typeArgs = node.typeArguments;
-      if (entries.isEmpty && typeArgs == null) {
+      var type = node.staticType as InterfaceType;
+      var typeArgs = type.typeArguments;
+      var reifyTypeArgs = typeArgs != null && typeArgs.any((t) => !t.isDynamic);

[Jennifer Messerly, 2016/08/05 13:48:32]

typeArguments should never be null on an InterfaceType, so you shouldn't need a
check for it here.

[vsm, 2016/08/05 14:15:03]

Removed - thanks!

+      if (entries.isEmpty && !reifyTypeArgs) {
         mapArguments = [];
       } else if (entries.every((e) => e.key is StringLiteral)) {
         // Use JS object literal notation if possible, otherwise use an array.
         // We could do this any time all keys are non-nullable String type.
         // For now, support StringLiteral as the common non-nullable String case.
         var props = <JS.Property>[];
         for (var e in entries) {
           props.add(new JS.Property(_visit(e.key), _visit(e.value)));
         }
         mapArguments = new JS.ObjectInitializer(props);
       } else {
         var values = <JS.Expression>[];
         for (var e in entries) {
           values.add(_visit(e.key));
           values.add(_visit(e.value));
         }
         mapArguments = new JS.ArrayInitializer(values);
       }
       var types = <JS.Expression>[];
-      if (typeArgs != null) {
-        types.addAll(typeArgs.arguments.map((e) => _emitType(e.type)));
+      if (reifyTypeArgs) {
+        types.addAll(typeArgs.map((e) => _emitType(e)));
       }
       return js.call('dart.map(#, #)', [mapArguments, types]);
     }
     if (node.constKeyword != null) return _emitConst(emitMap);
     return emitMap();
   }
 
   @override
   JS.LiteralString visitSimpleStringLiteral(SimpleStringLiteral node) =>
       js.escapedString(node.value, node.isSingleQuoted ? "'" : '"');
@@ skipping 385 matching lines @@
 }
 
 bool isLibraryPrefix(Expression node) =>
     node is SimpleIdentifier && node.staticElement is PrefixElement;
 
 LibraryElement _getLibrary(AnalysisContext c, String uri) =>
     c.computeLibraryElement(c.sourceFactory.forUri(uri));
 
 bool _isDartRuntime(LibraryElement l) =>
     l.isInSdk && l.source.uri.toString() == 'dart:_runtime';