Remove AST-hack for multi-field declarations.

R=sigmund@google.com

Review URL: https://codereview.chromium.org/2244333003 .

pkg/compiler/lib/src/elements/modelx.dart

@@ -1473,6 +1473,7 @@ abstract class VariableElementX extends ElementX
   final Token token;
   final VariableList variables;
   VariableDefinitions definitionsCache;
+  Expression definitionCache;
   Expression initializerCache;
 
   Modifiers get modifiers => variables.modifiers;
@@ -1505,6 +1506,16 @@ abstract class VariableElementX extends ElementX
     return definitionsCache;
   }
 
+  /// Returns the node that defines this field.
+  ///
+  /// For instance in `var a, b = true`, the definitions nodes for fields 'a'
+  /// and 'b' are the nodes for `a` and `b = true`, respectively.
+  Expression get definition {
+    assert(invariant(this, definitionCache != null,
+        message: "Definition node has not been computed for $this."));
+    return definitionCache;
+  }
+
   Expression get initializer {
     assert(invariant(this, definitionsCache != null,
         message: "Initializer has not been computed for $this."));
@@ -1522,8 +1533,6 @@ abstract class VariableElementX extends ElementX
   void createDefinitions(VariableDefinitions definitions) {
     assert(invariant(this, definitionsCache == null,
         message: "VariableDefinitions has already been computed for $this."));
-    Expression node;
-    int count = 0;
     for (Link<Node> link = definitions.definitions.nodes;
         !link.isEmpty;
         link = link.tail) {
@@ -1533,28 +1542,16 @@ abstract class VariableElementX extends ElementX
         SendSet sendSet = initializedIdentifier.asSendSet();
         identifier = sendSet.selector.asIdentifier();
         if (identical(name, identifier.source)) {
-          node = initializedIdentifier;
+          definitionCache = initializedIdentifier;
           initializerCache = sendSet.arguments.first;
         }
       } else if (identical(name, identifier.source)) {
-        node = initializedIdentifier;
+        definitionCache = initializedIdentifier;
       }
-      count++;
-    }
-    invariant(definitions, node != null, message: "Could not find '$name'.");
-    if (count == 1) {
-      definitionsCache = definitions;
-    } else {
-      // Create a [VariableDefinitions] node for the single definition of
-      // [node].
-      definitionsCache = new VariableDefinitions(
-          definitions.type,
-          definitions.modifiers,
-          new NodeList(
-              definitions.definitions.beginToken,
-              const Link<Node>().prepend(node),
-              definitions.definitions.endToken));
     }
+    invariant(definitions, definitionCache != null,
+        message: "Could not find '$name'.");
+    definitionsCache = definitions;
   }
 
   DartType computeType(Resolution resolution) {
@@ -1659,6 +1656,14 @@ class ErroneousFieldElementX extends ElementX
 
   Token get token => node.getBeginToken();
 
+  get definitionCache {
+    throw new UnsupportedError("definitionCache");
+  }
+
+  set definitionCache(_) {
+    throw new UnsupportedError("definitionCache=");
+  }
+
   get initializerCache {
     throw new UnsupportedError("initializerCache");
   }
@@ -1673,6 +1678,8 @@ class ErroneousFieldElementX extends ElementX
 
   get initializer => null;
 
+  get definition => null;
+
   bool get isMalformed => true;
 
   get nestedClosures {
@@ -3016,6 +3023,7 @@ class EnumFieldElementX extends FieldElementX {
     definitionsCache = new VariableDefinitions(
         null, variableList.modifiers, new NodeList.singleton(definition));
     initializerCache = initializer;
+    definitionCache = definition;
   }
 
   @override

pkg/compiler/lib/src/resolution/resolution.dart

@@ -361,7 +361,7 @@ class ResolverTask extends CompilerTask {
       ResolutionRegistry registry = visitor.registry;
       // TODO(johnniwinther): Maybe remove this when placeholderCollector migrates
       // to the backend ast.
-      registry.defineElement(tree.definitions.nodes.head, element);
+      registry.defineElement(element.definition, element);
       // TODO(johnniwinther): Share the resolved type between all variables
       // declared in the same declaration.
       if (tree.type != null) {

tests/compiler/dart2js/semantic_visitor_test_decl_data.dart

@@ -661,6 +661,8 @@ const Map<String, List<Test>> DECL_TESTS = const {
         const [
           const Visit(VisitKind.VISIT_INSTANCE_FIELD_DECL,
               element: 'field(C#m)'),
+          const Visit(VisitKind.VISIT_INSTANCE_FIELD_DECL,
+              element: 'field(C#n)'),
         ]),
     const Test.clazz(
         '''
@@ -787,7 +789,9 @@ const Map<String, List<Test>> DECL_TESTS = const {
         ''',
         const [
           const Visit(VisitKind.VISIT_STATIC_FIELD_DECL,
-                element: 'field(C#m)'),
+              element: 'field(C#m)'),
+          const Visit(VisitKind.VISIT_STATIC_FIELD_DECL,
+              element: 'field(C#n)'),
         ]),
     const Test.clazz(
         '''
@@ -797,7 +801,13 @@ const Map<String, List<Test>> DECL_TESTS = const {
         ''',
         const [
           const Visit(VisitKind.VISIT_STATIC_FIELD_DECL,
-                element: 'field(C#m)'),
+              element: 'field(C#k)'),
+          const Visit(VisitKind.VISIT_STATIC_FIELD_DECL,
+              element: 'field(C#l)'),
+          const Visit(VisitKind.VISIT_STATIC_FIELD_DECL,
+              element: 'field(C#m)'),
+          const Visit(VisitKind.VISIT_STATIC_FIELD_DECL,
+              element: 'field(C#n)'),
         ]),
     const Test.clazz(
         '''
@@ -820,6 +830,9 @@ const Map<String, List<Test>> DECL_TESTS = const {
           const Visit(VisitKind.VISIT_STATIC_FIELD_DECL,
                 element: 'field(C#m)',
                 rhs: 42),
+          const Visit(VisitKind.VISIT_STATIC_FIELD_DECL,
+              element: 'field(C#n)',
+              rhs: true),
         ]),
     const Test.clazz(
         '''
@@ -846,7 +859,9 @@ const Map<String, List<Test>> DECL_TESTS = const {
         ''',
         const [
           const Visit(VisitKind.VISIT_TOP_LEVEL_FIELD_DECL,
-                element: 'field(m)'),
+              element: 'field(m)'),
+          const Visit(VisitKind.VISIT_TOP_LEVEL_FIELD_DECL,
+              element: 'field(n)'),
         ]),
     const Test(
         '''

tests/compiler/dart2js/serialization/test_data.dart

@@ -671,6 +671,18 @@ class ConstClass {
   final x;
   const ConstClass(this.x);
 }
+''',
+  }),
+
+  const Test('Multi variable declaration', const {
+    'main.dart': '''
+import 'a.dart';
+
+main() => y;
+''',
+  }, preserializedSourceFiles: const {
+    'a.dart': '''
+var x, y = 2;
 ''',
   }),
 ];