fix #3052 (False Positive - Technically the member function 'Example::Clear' can be const.)

lib/checkclass.cpp

@@ -1413,6 +1413,10 @@ bool CheckClass::isMemberVar(const Scope *scope, const Token *tok)
         {
             return true;
         }
+        else if (Token::Match(tok->tokAt(-3), "( * this )"))
+        {
+            return true;
+        }
         else if (Token::Match(tok->tokAt(-2), "%var% . %var%"))
         {
             tok = tok->tokAt(-2);

test/testclass.cpp

@@ -181,6 +181,7 @@ private:
         TEST_CASE(const50); // ticket #2943
         TEST_CASE(const51); // ticket #3040
         TEST_CASE(const52); // ticket #3049
+        TEST_CASE(const53); // ticket #3052
         TEST_CASE(assigningPointerToPointerIsNotAConstOperation);
         TEST_CASE(assigningArrayElementIsNotAConstOperation);
         TEST_CASE(constoperator1);  // operator< can often be const
@@ -5711,6 +5712,15 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void const53() // ticket 3052
+    {
+        checkConst("class Example {\n"
+                   "  public:\n"
+                   "    void Clear(void) { Example tmp; (*this) = tmp; }\n"
+                   "};\n");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void assigningPointerToPointerIsNotAConstOperation()
     {
         checkConst("struct s\n"