Generate INVOKESPECIAL instruction for private method with default argument

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

@@ -687,7 +687,7 @@ public class FunctionCodegen extends GenerationStateAware {
                 iv.invokeinterface(internalName, jvmSignatureName, jvmSignatureDescriptor);
             }
             else {
-                if (!constructor) {
+                if (!constructor && functionDescriptor.getVisibility() != Visibilities.PRIVATE) {
                     iv.invokevirtual(internalName, jvmSignatureName, jvmSignatureDescriptor);
                 }
                 else {

compiler/testData/codegen/functions/privateDefaultArgs.kt

@@ -0,0 +1,13 @@
+// Check that this code doesn't contains INVOKEVIRTUAL instruction
+class B {
+    private fun foo(i: Int = 1) {
+    }
+
+    fun f() {
+       foo(2)
+    }
+}
+
+fun box(): String {
+    return "OK"
+}

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

@@ -195,4 +195,11 @@ public class FunctionGenTest extends CodegenTestCase {
     public void testKt2929() {
         blackBoxFile("regressions/kt2929.kt");
     }
+
+    public void testPrivateDefaultArgs() throws Exception {
+        loadFile("functions/privateDefaultArgs.kt");
+        String text = generateToText();
+        assertFalse(text.contains("INVOKEVIRTUAL"));
+        assertTrue(text.contains("INVOKESPECIAL"));
+    }
 }