Fix type variables in closures.

sdk/lib/_internal/compiler/implementation/closure.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.
 
 library closureToClassMapper;
 
 import "elements/elements.dart";
 import "dart2jslib.dart";
 import "dart_types.dart";
 import "scanner/scannerlib.dart" show Token;
@@ skipping 451 matching lines @@
       }
     }
   }
 
   visitTypeAnnotation(TypeAnnotation node) {
     Element member = currentElement.getEnclosingMember();
     DartType type = elements.getType(node);
     // TODO(karlklose,johnniwinther): if the type is null, the annotation is
     // from a parameter which has been analyzed before the method has been
     // resolved and the result has been thrown away.
-    if (compiler.enableTypeAssertions && type != null &&
-        type.containsTypeVariables) {
-      if (insideClosure && member.isFactoryConstructor()) {
+    if (type != null && type.containsTypeVariables) {
+      // TODO(karlklose): try to get rid of the isField check; there is a bug
+      // with type variable use in field initializer (in both modes).

[ngeoffray, 2013/06/18 11:14:51]

use -> used

Could you file a bug? Do you have a failing test case?

[karlklose, 2013/06/19 12:17:27]

In fact it is not really a bug, we have to special case field initializers
because of the way they are generated.  This comment is obsolete because I
reverted the change, but I changed the comment at the place I copied this from.

+      if (!member.isField()) {
+        // In checked mode, using a type variable in a type annotation may lead
+        // to a runtime type check that needs to access the type argument and
+        // therefore the closure needs a this-element.
+        registerNeedsThis();

[ngeoffray, 2013/06/18 11:14:51]

Thinking more about it, it looks my previous comment was wrong: how do you
differentiate between an is check and a type annotation here? A type annotation
only needs to register this in checked mode. It looks like you're
unconditionally registering it here.

[karlklose, 2013/06/19 12:17:27]

Reverted it back.

+      }
+      if (compiler.enableTypeAssertions && insideClosure &&
+          member.isFactoryConstructor()) {
         // This is a closure in a factory constructor.  Since there is no
         // [:this:], we have to mark the type arguments as free variables to
         // capture them in the closure.
         type.forEachTypeVariable((variable) => useLocal(variable.element));
       }
-      // TODO(karlklose): try to get rid of the isField check; there is a bug
-      // with type variable use in field initializer (in both modes).
-      if (member.isInstanceMember() && !member.isField()) {
-        // In checked mode, using a type variable in a type annotation may lead
-        // to a runtime type check that needs to access the type argument and
-        // therefore the closure needs a this-element.
-        registerNeedsThis();
-      }
     }
   }
 
   visitIdentifier(Identifier node) {
     if (node.isThis()) {
       registerNeedsThis();
     } else {
       Element element = elements[node];
       if (element != null && element.kind == ElementKind.TYPE_VARIABLE) {
         registerNeedsThis();
@@ skipping 37 matching lines @@
     if (Elements.isLocal(element) &&
         element.computeType(compiler).containsTypeVariables) {
       registerNeedsThis();
     }
     super.visitSendSet(node);
   }
 
   visitNewExpression(NewExpression node) {
     DartType type = elements.getType(node);
 
-    bool hasTypeVariable(DartType type) {
-      if (type is TypeVariableType) {
-        return true;
-      } else if (type is InterfaceType) {
-        InterfaceType ifcType = type;
-        for (DartType argument in ifcType.typeArguments) {
-          if (hasTypeVariable(argument)) {
-            return true;
-          }
-        }
-      }
-      return false;
-    }
-
     void analyzeTypeVariables(DartType type) {
       if (type is TypeVariableType) {
         useLocal(type.element);
+        // Field initializers are inlined and access the type variable as
+        // normal parameters.
+        if (!outermostElement.isField()) {
+          registerNeedsThis();
+        }
       } else if (type is InterfaceType) {
         InterfaceType ifcType = type;
         for (DartType argument in ifcType.typeArguments) {
           analyzeTypeVariables(argument);
         }
       }
     }
 
     if (outermostElement.isMember() &&
         compiler.backend.needsRti(outermostElement.getEnclosingClass())) {
       if (outermostElement.isConstructor() || outermostElement.isField()) {
         analyzeTypeVariables(type);
       } else if (outermostElement.isInstanceMember()) {
-        if (hasTypeVariable(type)) {
+        if (type.containsTypeVariables) {
           registerNeedsThis();
         }
       }
     }
 
     node.visitChildren(this);
   }
 
   // If variables that are declared in the [node] scope are captured and need
   // to be boxed create a box-element and update the [capturingScopes] in the
@@ skipping 216 matching lines @@
   }
 
   visitTryStatement(TryStatement node) {
     // TODO(ngeoffray): implement finer grain state.
     bool oldInTryStatement = inTryStatement;
     inTryStatement = true;
     node.visitChildren(this);
     inTryStatement = oldInTryStatement;
   }
 }