const: fixed false positive when using increment/decrement

lib/checkclass.cpp

@@ -1470,6 +1470,13 @@ void CheckClass::checkConst()
                                 break;
                             }
 
+                            // increment/decrement (member variable?)..
+                            else if (Token::Match(tok3, "++|--"))
+                            {
+                                isconst = false;
+                                break;
+                            }
+
                             // function call..
                             else if (tok3->str() != "return" && Token::Match(tok3, "%var% ("))
                             {

test/testclass.cpp

@@ -81,7 +81,8 @@ private:
 
         // can member function be made const
         TEST_CASE(const1);
-        TEST_CASE(const2);
+        TEST_CASE(constoperator);   // operator< can often be const
+        TEST_CASE(constincdec);     // increment/decrement => non-const
     }
 
     // Check the operator Equal
@@ -1558,7 +1559,7 @@ private:
     }
 
     // operator< can often be const
-    void const2()
+    void constoperator()
     {
         checkConst("struct Fred {\n"
                    "    int a;\n"
@@ -1566,6 +1567,16 @@ private:
                    "};\n");
         ASSERT_EQUALS("[test.cpp:3]: (style) The function 'Fred::operator<' can be const\n", errout.str());
     }
+
+    // increment/decrement => not const
+    void constincdec()
+    {
+        checkConst("class Fred {\n"
+                   "    int a;\n"
+                   "    void nextA() { return ++a; }\n"
+                   "};\n");
+        ASSERT_EQUALS("", errout.str());
+    }
 };
 
 REGISTER_TEST(TestClass)