Fixed #2459 (False positive with unused private function and friend)

lib/checkclass.cpp

@@ -583,6 +583,11 @@ void CheckClass::privateFunctions()
     if (Token::findmatch(_tokenizer->tokens(), "; __property ;"))
         return;
 
+    // skip checking if there are friends
+    // Todo: check if each class has friends
+    if (Token::findmatch(_tokenizer->tokens(), "friend"))
+        return;
+
     // #2407 calls from operator() is not detected
     // TODO: Don't bailout. Detect the call.
     if (Token::findmatch(_tokenizer->tokens(), "operator ( )"))

test/testunusedprivfunc.cpp

@@ -53,6 +53,8 @@ private:
 
         TEST_CASE(derivedClass);   // skip warning for derived classes. It might be a virtual function.
 
+        TEST_CASE(friendClass);
+
         TEST_CASE(borland);     // skip FP when using __property
 
         // No false positives when there are "unused" templates that are removed in the simplified token list
@@ -387,6 +389,17 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void friendClass()
+    {
+        // ticket #2459 - friend class
+        check("class Foo {\n"
+              "private:\n"
+              "    friend Bar;\n"
+              "    void f() { }\n"
+              "};");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void borland()
     {
         // ticket #2034 - Borland C++ __property