Reapply "Enable full type-checks in checked mode."

sdk/lib/_internal/compiler/implementation/closure.dart

Index: sdk/lib/_internal/compiler/implementation/closure.dart
diff --git a/sdk/lib/_internal/compiler/implementation/closure.dart b/sdk/lib/_internal/compiler/implementation/closure.dart
index b9b83e2bb716db19122e95b3bf1800e4a6cf4a11..fff0b379a9f566126ad8960642af2cf25550bdb5 100644
--- a/sdk/lib/_internal/compiler/implementation/closure.dart
+++ b/sdk/lib/_internal/compiler/implementation/closure.dart
@@ -390,11 +390,20 @@ class ClosureTranslator extends Visitor {
     scopeVariables.add(element);
   }
 
+  void registerNeedsThis() {
+    if (closureData.thisElement != null) {
+      useLocal(closureData.thisElement);
+    }
+  }
+
   visit(Node node) => node.accept(this);
 
   visitNode(Node node) => node.visitChildren(this);
 
   visitVariableDefinitions(VariableDefinitions node) {
+    if (node.type != null) {
+      visit(node.type);
+    }
     for (Link<Node> link = node.definitions.nodes;
          !link.isEmpty;
          link = link.tail) {
@@ -417,13 +426,38 @@ class ClosureTranslator extends Visitor {
     }
   }
 
+  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()) {
+        // 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()) {
-      useLocal(closureData.thisElement);
+      registerNeedsThis();
     } else {
       Element element = elements[node];
       if (element != null && element.kind == ElementKind.TYPE_VARIABLE) {
-        useLocal(closureData.thisElement);
+        registerNeedsThis();
       }
     }
     node.visitChildren(this);
@@ -435,9 +469,9 @@ class ClosureTranslator extends Visitor {
       useLocal(element);
     } else if (node.receiver == null &&
                Elements.isInstanceSend(node, elements)) {
-      useLocal(closureData.thisElement);
+      registerNeedsThis();
     } else if (node.isSuperCall) {
-      useLocal(closureData.thisElement);
+      registerNeedsThis();
     } else if (node.isParameterCheck) {
       Element parameter = elements[node.receiver];
       FunctionElement enclosing = parameter.enclosingElement;
@@ -461,6 +495,10 @@ class ClosureTranslator extends Visitor {
     if (Elements.isLocal(element)) {
       mutatedVariables.add(element);
     }
+    if (Elements.isLocal(element) &&
+        element.computeType(compiler).containsTypeVariables) {
+      registerNeedsThis();
+    }
     super.visitSendSet(node);
   }
 
@@ -497,7 +535,9 @@ class ClosureTranslator extends Visitor {
       if (outermostElement.isConstructor() || outermostElement.isField()) {
         analyzeTypeVariables(type);
       } else if (outermostElement.isInstanceMember()) {
-        if (hasTypeVariable(type)) useLocal(closureData.thisElement);
+        if (hasTypeVariable(type)) {
+          registerNeedsThis();
+        }
       }
     }
 
@@ -669,6 +709,12 @@ class ClosureTranslator extends Visitor {
         });
       }
 
+      // Compute the function type and check for type variables in return or
+      // parameter types.
+      if (element.computeType(compiler).containsTypeVariables) {
+        registerNeedsThis();
+      }
+
       visitChildren();
     });