'is' works on class type parameters

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

@@ -1688,10 +1688,7 @@ public class ExpressionCodegen extends JetVisitor {
 
     private void generateInstanceOf(Runnable expressionGen, 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");
-        }
-        if (jetType.getArguments().size() > 0) {
+        if (jetType.getArguments().size() > 0 || !(descriptor instanceof ClassDescriptor)) {
             generateTypeInfo(jetType);
             expressionGen.run();
             if (leaveExpressionOnStack) {
@@ -1712,14 +1709,8 @@ public class ExpressionCodegen extends JetVisitor {
     private void generateTypeInfo(JetType jetType) {
         DeclarationDescriptor declarationDescriptor = jetType.getConstructor().getDeclarationDescriptor();
         if (declarationDescriptor instanceof TypeParameterDescriptor) {
-            DeclarationDescriptor containingDeclaration = declarationDescriptor.getContainingDeclaration();
-            if (containingDeclaration == contextType && contextType instanceof ClassDescriptor) {
-                loadTypeInfo(typeMapper, (ClassDescriptor) contextType, v);
-                v.iconst(((TypeParameterDescriptor) declarationDescriptor).getIndex());
-                v.invokevirtual("jet/typeinfo/TypeInfo", "getTypeParameter", "(I)Ljet/typeinfo/TypeInfo;");
-                return;
-            }
-            throw new UnsupportedOperationException("don't know what this type parameter resolves to");
+            loadTypeParameterTypeInfo(declarationDescriptor);
+            return;
         }
 
         final Type jvmType = typeMapper.mapType(jetType, OwnerKind.INTERFACE);
@@ -1751,6 +1742,17 @@ public class ExpressionCodegen extends JetVisitor {
         }
     }
 
+    private void loadTypeParameterTypeInfo(DeclarationDescriptor declarationDescriptor) {
+        DeclarationDescriptor containingDeclaration = declarationDescriptor.getContainingDeclaration();
+        if (containingDeclaration == contextType && contextType instanceof ClassDescriptor) {
+            loadTypeInfo(typeMapper, (ClassDescriptor) contextType, v);
+            v.iconst(((TypeParameterDescriptor) declarationDescriptor).getIndex());
+            v.invokevirtual("jet/typeinfo/TypeInfo", "getTypeParameter", "(I)Ljet/typeinfo/TypeInfo;");
+            return;
+        }
+        throw new UnsupportedOperationException("don't know what this type parameter resolves to");
+    }
+
     @Override
     public void visitWhenExpression(JetWhenExpression expression) {
         JetExpression expr = expression.getSubjectExpression();

idea/testData/codegen/typeInfo/isTypeParameter.jet

@@ -0,0 +1,13 @@
+class Foo() {}
+class Bar() {}
+
+class InstanceChecker<T>() {
+  fun check(obj: Any?) = obj is T
+}
+
+fun box(): String {
+  val checker = InstanceChecker<Foo>()
+  if (!checker.check(Foo())) return "fail 1"
+  if (checker.check(Bar())) return "fail 2"
+  return "OK"
+}

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

@@ -73,6 +73,10 @@ public class TypeInfoTest extends CodegenTestCase {
         assertFalse((Boolean) foo.invoke(null));
     }
 
+    public void testIsTypeParameter() throws Exception {
+        blackBoxFile("typeInfo/isTypeParameter.jet");
+    }
+
     public void testAsSafeWithGenerics() throws Exception {
         loadFile();
         Method foo = generateFunction();