Fix bug in our SSA optimizations: by giving an empty type to a box, we were assuming that anything …

sdk/lib/_internal/compiler/implementation/ssa/builder.dart

 // Copyright (c) 2012, 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.
 
 part of ssa;
 
 /**
  * A special element for the extra parameter taken by intercepted
  * methods. We need to override [Element.computeType] because our
  * optimizers may look at its declared type.
@@ skipping 351 matching lines @@
         } else {
           builder.compiler.internalError(
               "Cannot find value $element",
               element: element);
         }
       }
       return directLocals[element];
     } else if (isStoredInClosureField(element)) {
       Element redirect = redirectionMapping[element];
       HInstruction receiver = readLocal(closureData.closureElement);
-      HInstruction fieldGet = new HFieldGet(
-          redirect, receiver, builder.getTypeOfCapturedVariable(redirect));
+      HType type = (element.kind == ElementKind.VARIABLE_LIST)
+          ? builder.backend.nonNullType
+          : builder.getTypeOfCapturedVariable(redirect);
+      assert(element.kind != ElementKind.VARIABLE_LIST
+             || element is BoxElement);
+      HInstruction fieldGet = new HFieldGet(redirect, receiver, type);
       builder.add(fieldGet);
       return fieldGet;
     } else if (isBoxed(element)) {
       Element redirect = redirectionMapping[element];
       // In the function that declares the captured variable the box is
       // accessed as direct local. Inside the nested closure the box is
       // accessed through a closure-field.
       // Calling [readLocal] makes sure we generate the correct code to get
       // the box.
-      assert(redirect.enclosingElement.isVariable());
+      assert(redirect.enclosingElement is BoxElement);
       HInstruction box = readLocal(redirect.enclosingElement);
       HInstruction lookup = new HFieldGet(
           redirect, box, builder.getTypeOfCapturedVariable(redirect));
       builder.add(lookup);
       return lookup;
     } else {
       assert(isUsedInTry(element));
       HLocalValue local = getLocal(element);
       HInstruction variable = new HLocalGet(
           element, local, builder.backend.dynamicType);
@@ skipping 33 matching lines @@
   void updateLocal(Element element, HInstruction value) {
     assert(!isStoredInClosureField(element));
     if (isAccessedDirectly(element)) {
       directLocals[element] = value;
     } else if (isBoxed(element)) {
       Element redirect = redirectionMapping[element];
       // The box itself could be captured, or be local. A local variable that
       // is captured will be boxed, but the box itself will be a local.
       // Inside the closure the box is stored in a closure-field and cannot
       // be accessed directly.
-      assert(redirect.enclosingElement.isVariable());
+      assert(redirect.enclosingElement is BoxElement);
       HInstruction box = readLocal(redirect.enclosingElement);
       builder.add(new HFieldSet(redirect, box, value));
     } else {
       assert(isUsedInTry(element));
       HLocalValue local = getLocal(element);
       builder.add(new HLocalSet(element, local, value));
     }
   }
 
   /**
@@ skipping 5274 matching lines @@
           new HSubGraphBlockInformation(elseBranch.graph));
 
     HBasicBlock conditionStartBlock = conditionBranch.block;
     conditionStartBlock.setBlockFlow(info, joinBlock);
     SubGraph conditionGraph = conditionBranch.graph;
     HIf branch = conditionGraph.end.last;
     assert(branch is HIf);
     branch.blockInformation = conditionStartBlock.blockFlow;
   }
 }