'as?' works on types with generics

idea/src/org/jetbrains/jet/codegen/ExpressionCodegen.java

@@ -1268,9 +1268,6 @@ public class ExpressionCodegen extends JetVisitor {
         else {
             JetTypeReference typeReference = expression.getRight();
             JetType jetType = bindingContext.resolveTypeReference(typeReference);
-            if (jetType.getArguments().size() > 0) {
-                throw new UnsupportedOperationException("don't know how to handle type arguments in as/as?");
-            }
             DeclarationDescriptor descriptor = jetType.getConstructor().getDeclarationDescriptor();
             if (!(descriptor instanceof ClassDescriptor)) {
                 throw new UnsupportedOperationException("don't know how to handle non-class types in as/as?");
@@ -1278,8 +1275,7 @@ public class ExpressionCodegen extends JetVisitor {
             Type type = typeMapper.jvmType((ClassDescriptor) descriptor, OwnerKind.INTERFACE);
             gen(expression.getLeft(), OBJECT_TYPE);
             if (opToken == JetTokens.AS_SAFE) {
-                v.dup();
-                v.instanceOf(type);
+                generateInstanceOf(expression.getLeft(), jetType, true);
                 Label isInstance = new Label();
                 v.ifne(isInstance);
                 v.pop();
@@ -1288,7 +1284,7 @@ public class ExpressionCodegen extends JetVisitor {
                 myStack.push(StackValue.onStack(type));
             }
             else {
-                throw new UnsupportedOperationException("as not yet implemented");
+                throw new UnsupportedOperationException("'as' not yet implemented");
             }
         }
     }
@@ -1307,22 +1303,32 @@ public class ExpressionCodegen extends JetVisitor {
         }
         JetTypeReference typeReference = ((JetTypePattern) pattern).getTypeReference();
         JetType jetType = bindingContext.resolveTypeReference(typeReference);
+        generateInstanceOf(expression.getLeftHandSide(), jetType, false);
+        StackValue value = StackValue.onStack(Type.BOOLEAN_TYPE);
+        myStack.push(expression.isNot() ? StackValue.not(value) : value);
+    }
+
+    private void generateInstanceOf(JetExpression expression, JetType jetType, boolean leaveExpressionOnStack) {
         DeclarationDescriptor descriptor = jetType.getConstructor().getDeclarationDescriptor();
         if (!(descriptor instanceof ClassDescriptor)) {
-            throw new UnsupportedOperationException("don't know how to handle non-class types in is");
+            throw new UnsupportedOperationException("don't know how to handle non-class types");
         }
         if (jetType.getArguments().size() > 0) {
             generateTypeInfo(jetType);
-            gen(expression.getLeftHandSide(), OBJECT_TYPE);
+            gen(expression, OBJECT_TYPE);
+            if (leaveExpressionOnStack) {
+                v.dupX1();
+            }
             v.invokevirtual("jet/typeinfo/TypeInfo", "isInstance", "(Ljava/lang/Object;)Z");
         }
         else {
-            gen(expression.getLeftHandSide(), OBJECT_TYPE);
+            gen(expression, OBJECT_TYPE);
+            if (leaveExpressionOnStack) {
+                v.dup();
+            }
             Type type = typeMapper.jvmType((ClassDescriptor) descriptor, OwnerKind.INTERFACE);
             v.instanceOf(type);
         }
-        StackValue value = StackValue.onStack(Type.BOOLEAN_TYPE);
-        myStack.push(expression.isNot() ? StackValue.not(value) : value);
     }
 
     private void generateTypeInfo(JetType jetType) {

idea/testData/codegen/typeInfo/asSafeWithGenerics.jet

@@ -0,0 +1,8 @@
+class Wrapper<T>() {
+  fun castToSelf(wrapper: Any) = wrapper as? Wrapper<T>
+}
+
+fun foo() {
+  val wrapper = new Wrapper<Int>()
+  return wrapper.castToSelf(new Wrapper<String>())
+}

idea/tests/org/jetbrains/jet/codegen/TypeInfoTest.java

@@ -65,6 +65,12 @@ public class TypeInfoTest extends CodegenTestCase {
         assertFalse((Boolean) foo.invoke(null));
     }
 
+    public void testAsSafeWithGenerics() throws Exception {
+        loadFile();
+        Method foo = generateFunction();
+        assertNull(foo.invoke(null));
+    }
+
     private Runnable newRunnable() {
         return new Runnable() {
             @Override