fix for KT-152

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

@@ -1202,6 +1202,14 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> {
     private StackValue generateEquals(JetExpression left, JetExpression right, IElementType opToken) {
         Type leftType = expressionType(left);
         Type rightType = expressionType(right);
+        if(leftType == JetTypeMapper.TYPE_NOTHING) {
+            return genCmpWithNull(right, rightType, opToken);
+        }
+
+        if(rightType == JetTypeMapper.TYPE_NOTHING) {
+            return genCmpWithNull(left, leftType, opToken);
+        }
+
         if(JetTypeMapper.isPrimitive(leftType) != JetTypeMapper.isPrimitive(rightType)) {
             gen(left, leftType);
             v.valueOf(leftType);
@@ -1217,6 +1225,28 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> {
         return generateEqualsForExpressionsOnStack(opToken, leftType, rightType);
     }
 
+    private StackValue genCmpWithNull(JetExpression exp, Type expType, IElementType opToken) {
+        gen(exp, typeMapper.boxType(expType));
+        Label fail = new Label(), end = new Label();
+        if(JetTokens.EQEQ == opToken || JetTokens.EQEQEQ == opToken) {
+            v.ifnonnull(fail);
+            v.iconst(1);
+            v.goTo(end);
+            v.mark(fail);
+            v.iconst(0);
+            v.mark(end);
+        }
+        else {
+            v.ifnull(fail);
+            v.iconst(1);
+            v.goTo(end);
+            v.mark(fail);
+            v.iconst(0);
+            v.mark(end);
+        }
+        return StackValue.onStack(Type.BOOLEAN_TYPE);
+    }
+
     private StackValue generateEqualsForExpressionsOnStack(IElementType opToken, Type leftType, Type rightType) {
         if (isNumberPrimitive(leftType) && leftType == rightType) {
             return compareExpressionsOnStack(opToken, leftType);

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

@@ -25,6 +25,7 @@ public class JetTypeMapper {
     public static final Type TYPE_TYPEINFO = Type.getType(TypeInfo.class);
     public static final Type TYPE_JET_OBJECT = Type.getType(JetObject.class);
     public static final Type TYPE_CLASS = Type.getType(Class.class);
+    public static final Type TYPE_NOTHING = Type.getObjectType("jet/Nothing");
 
     private final JetStandardLibrary standardLibrary;
     private final BindingContext bindingContext;
@@ -289,6 +290,9 @@ public class JetTypeMapper {
     }
 
     public Type mapType(@NotNull final JetType jetType, OwnerKind kind) {
+        if (jetType.equals(JetStandardClasses.getNothingType()) || jetType.equals(JetStandardClasses.getNullableNothingType())) {
+            return TYPE_NOTHING;
+        }
         if (jetType.equals(standardLibrary.getIntType())) {
             return Type.INT_TYPE;
         }

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

@@ -282,7 +282,7 @@ public abstract class StackValue {
         @Override
         public void condJump(Label label, boolean jumpIfFalse, InstructionAdapter v) {
             if (value instanceof Boolean) {
-                boolean boolValue = ((Boolean) value).booleanValue();
+                boolean boolValue = (Boolean) value;
                 if (boolValue ^ jumpIfFalse) {
                     v.goTo(label);
                 }

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

@@ -148,4 +148,14 @@ public class ControlStructuresTest extends CodegenTestCase {
     public void testKt237() throws Exception {
         blackBoxFile("regressions/kt237.jet");
     }
+
+    public void testCompareToNull() throws Exception {
+        loadText("fun foo(a: String?, b: String?): Boolean = a == null && b !== null");
+        String text = generateToText();
+        assertTrue(!text.contains("java/lang/Object.equals"));
+        System.out.println(text);
+        final Method main = generateFunction();
+        assertEquals(true, main.invoke(null, null, "lala"));
+        assertEquals(false, main.invoke(null, null, null));
+    }
 }