Fixed #1881 (false positive: The function '...' can be const (nonconst code is hidden inside #if))

lib/checkclass.cpp

@@ -1849,7 +1849,7 @@ bool CheckClass::isVirtual(const std::vector<std::string> &derivedFrom, const To
 // Can a function be const?
 void CheckClass::checkConst()
 {
-    if (!_settings->_checkCodingStyle)
+    if (!_settings->_checkCodingStyle || _settings->ifcfg)
         return;
 
     createSymbolDatabase();

lib/cppcheck.cpp

@@ -711,6 +711,8 @@ unsigned int CppCheck::check()
                 preprocessor.preprocess(fin, filedata, configurations, fname, _settings._includePaths);
             }
 
+            _settings.ifcfg = bool(configurations.size() > 1);
+
             if (!_settings.userDefines.empty())
             {
                 configurations.clear();

lib/settings.cpp

@@ -42,6 +42,7 @@ Settings::Settings()
     _terminate = false;
     inconclusive = false;
     test_2_pass = false;
+    ifcfg = false;
 }
 
 std::string Settings::Suppressions::parseFile(std::istream &istr)

lib/settings.h

@@ -170,6 +170,12 @@ public:
 
     /** @brief Experimentat 2 pass checking of files */
     bool test_2_pass;
+
+    /**
+     * @brief Is there any #if configurations in the source code?
+     * As usual, include guards are not counted.
+     */
+    bool ifcfg;
 };
 
 /// @}

test/testclass.cpp

@@ -140,6 +140,7 @@ private:
         TEST_CASE(constLPVOID);     // a function that returns LPVOID can't be const
         TEST_CASE(constFunc); // a function that calls const functions can be const
         TEST_CASE(constVirtualFunc);
+        TEST_CASE(constIfCfg);  // ticket #1881 - fp when there are #if
     }
 
     // Check the operator Equal
@@ -2349,7 +2350,7 @@ private:
                       "[test.cpp:3]: (style) Suspicious pointer subtraction\n", errout.str());
     }
 
-    void checkConst(const char code[])
+    void checkConst(const char code[], const Settings *s = 0)
     {
         // Tokenize..
         Tokenizer tokenizer;
@@ -2362,7 +2363,10 @@ private:
 
         // Check..
         Settings settings;
-        settings._checkCodingStyle = true;
+        if (s)
+            settings = *s;
+        else
+            settings._checkCodingStyle = true;
         CheckClass checkClass(&tokenizer, &settings, this);
         checkClass.checkConst();
     }
@@ -3848,6 +3852,24 @@ private:
                       "[test.cpp:11]: (style) The function 'Y::getY' can be const\n"
                       "[test.cpp:17]: (style) The function 'Z::getZ' can be const\n", errout.str());
     }
+
+    void constIfCfg()
+    {
+        const char code[] = "class foo {\n"
+                            "    void f() { }\n"
+                            "};";
+
+        Settings settings;
+        settings._checkCodingStyle = true;
+
+        settings.ifcfg = false;
+        checkConst(code, &settings);
+        ASSERT_EQUALS("[test.cpp:2]: (style) The function 'foo::f' can be const\n", errout.str());
+
+        settings.ifcfg = true;
+        checkConst(code, &settings);
+        ASSERT_EQUALS("", errout.str());
+    }
 };
 
 REGISTER_TEST(TestClass)