Merge pull request #99 from udalov/kt2382

KT-2382 Placing final modifier to overriden method in trait produces runtime exception

compiler/backend/src/org/jetbrains/jet/codegen/FunctionCodegen.java

@@ -101,7 +101,10 @@ public class FunctionCodegen {
 
         Modality modality = functionDescriptor.getModality();
         if (modality == Modality.FINAL) {
-            flags |= ACC_FINAL;
+            DeclarationDescriptor containingDeclaration = functionDescriptor.getContainingDeclaration();
+            if (!(containingDeclaration instanceof ClassDescriptor) || ((ClassDescriptor)containingDeclaration).getKind() != ClassKind.TRAIT) {
+                flags |= ACC_FINAL;
+            }
         }
 
         OwnerKind kind = context.getContextKind();

compiler/testData/codegen/traits/finalMethod.jet

@@ -0,0 +1,9 @@
+//KT-2382
+
+trait T {
+    final fun foo() = "OK"
+}
+
+class S : T { }
+
+fun box(): String = S().foo()

compiler/tests/org/jetbrains/jet/codegen/TraitsTest.java

@@ -68,4 +68,8 @@ public class TraitsTest extends CodegenTestCase {
     public void testKt2541() {
         blackBoxFile("regressions/kt2541.kt");
     }
+
+    public void testFinalMethod() throws Exception {
+        blackBoxFile("traits/finalMethod.jet");
+    }
 }