Fix for issue 4921: ad the generic type info to a List when we create it.

lib/compiler/implementation/ssa/builder.dart

Index: lib/compiler/implementation/ssa/builder.dart
===================================================================
--- lib/compiler/implementation/ssa/builder.dart	(revision 12240)
+++ lib/compiler/implementation/ssa/builder.dart	(working copy)
@@ -1239,16 +1239,7 @@
         typeVariables.add("'$typeVariable': #");
         rtiInputs.add(localsHandler.directLocals[typeVariable.element]);
       });
-      String jsCode = '{ ${Strings.join(typeVariables, ', ')} }';
-      HInstruction typeInfo = new HForeign(new LiteralDartString(jsCode),
-                                           new LiteralDartString('Object'),
-                                           rtiInputs);
-      add(typeInfo);
-      Element typeInfoSetterElement = interceptors.getSetRuntimeTypeInfo();
-      HInstruction typeInfoSetter = new HStatic(typeInfoSetterElement);
-      add(typeInfoSetter);
-      add(new HInvokeStatic(
-          <HInstruction>[typeInfoSetter, newObject, typeInfo]));
+      callSetRuntimeTypeInfo(typeVariables, rtiInputs, newObject);
     }
 
     // Generate calls to the constructor bodies.
@@ -2627,10 +2618,43 @@
     }
   }
 
+  void handleListConstructor(InterfaceType type,
+                             Node currentNode,
+                             HInstruction newObject) {
+    if (type.arguments.isEmpty()) return;
+    List<HInstruction> inputs = <HInstruction>[];
+    type.arguments.forEach((DartType argument) {
+      inputs.add(analyzeTypeArgument(argument, currentNode));
+    });
+
+    List<String> typeVariables = <String>[];
+    type.element.typeVariables.forEach((TypeVariableType typeVariable) {
+      typeVariables.add("'$typeVariable': #");
+    });
+
+    callSetRuntimeTypeInfo(typeVariables, inputs, newObject);
+  }
+
+  void callSetRuntimeTypeInfo(List<String> typeVariables,
+                              List<HInstruction> inputs,
+                              HInstruction newObject) {
+    String jsCode = '{ ${Strings.join(typeVariables, ', ')} }';

[kasperl, 2012/09/12 12:19:04]

Somehow the decoupling of the way you turn the type variables into an object
(split between callSetRuntimeTypeInfo and the callers of it) seems complicated.
Would it be terrible to pass in the list of TypeVariableTypes and convert them
to an object literal in a string inside callSetRuntimeTypeInfo?

[ngeoffray, 2012/09/12 12:30:39]

Done.

+    HInstruction typeInfo = new HForeign(new LiteralDartString(jsCode),
+                                         new LiteralDartString('Object'),
+                                         inputs);
+    add(typeInfo);
+    Element typeInfoSetterElement = interceptors.getSetRuntimeTypeInfo();
+    HInstruction typeInfoSetter = new HStatic(typeInfoSetterElement);
+    add(typeInfoSetter);
+    add(new HInvokeStatic(<HInstruction>[typeInfoSetter, newObject, typeInfo]));
+  }
+
   visitNewSend(Send node) {
+    bool isListConstructor = false;
     computeType(element) {
       Element originalElement = elements[node];
       if (originalElement.getEnclosingClass() === compiler.listClass) {
+        isListConstructor = true;
         if (node.arguments.isEmpty()) {
           return HType.EXTENDABLE_ARRAY;
         } else {
@@ -2675,6 +2699,14 @@
     HType elementType = computeType(constructor);
     HInstruction newInstance = new HInvokeStatic(inputs, elementType);
     pushWithPosition(newInstance, node);
+
+    // The List constructor forwards to a Dart static method that does
+    // not know about the type argument. Therefore we special case
+    // this constructor to have the setRuntimeTypeInfo called where
+    // the 'new' is done.
+    if (isListConstructor) {
+      handleListConstructor(type, node, newInstance);
+    }
   }
 
   visitStaticSend(Send node) {