honor abstract modifier for classes

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

@@ -5,6 +5,7 @@ import com.intellij.psi.PsiElement;
 import org.jetbrains.jet.lang.descriptors.*;
 import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.types.JetType;
+import org.jetbrains.jet.lexer.JetTokens;
 import org.objectweb.asm.ClassVisitor;
 import org.objectweb.asm.MethodVisitor;
 import org.objectweb.asm.Opcodes;
@@ -32,8 +33,11 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
         if (!(myClass instanceof JetObjectDeclaration)) {
             interfaces.add(JetTypeMapper.jvmNameForInterface(descriptor));
         }
+
+        boolean isAbstract = myClass instanceof JetClass && ((JetClass) myClass).hasModifier(JetTokens.ABSTRACT_KEYWORD);
+
         v.visit(Opcodes.V1_6,
-                Opcodes.ACC_PUBLIC,
+                Opcodes.ACC_PUBLIC | (isAbstract ? Opcodes.ACC_ABSTRACT : 0),
                 jvmName(),
                 null,
                 superClass,

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

@@ -1,6 +1,7 @@
 package org.jetbrains.jet.codegen;
 
 import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
 import java.util.List;
 
 /**
@@ -107,4 +108,11 @@ public class ClassGenTest extends CodegenTestCase {
     public void testSimpleBox() throws Exception {
         blackBoxFile("classes/simpleBox.jet");
     }
+
+    public void testAbstractClass() throws Exception {
+        loadText("abstract class SimpleClass() { }");
+
+        final Class aClass = loadAllClasses(generateClassesInFile()).get("SimpleClass$$Impl");
+        assertTrue((aClass.getModifiers() & Modifier.ABSTRACT) != 0);
+    }
 }