memset: using memset on struct/class that has std::string member variable. ticket: #1655

lib/checkclass.cpp

@@ -712,6 +712,18 @@ void CheckClass::noMemset()
             type = tok->strAt(10);
         else if (Token::Match(tok, "%type% ( %var% , %var% , sizeof ( %type% ) )"))
             type = tok->strAt(8);
+        else if (Token::Match(tok, "memset ( & %var% , %num% , sizeof ( %var% ) )"))
+        {
+            unsigned int varid = tok->tokAt(3)->varId();
+            for (const Token *lookback = tok->previous(); lookback; lookback = lookback->previous())
+            {
+                if (Token::Match(lookback, "%type% %varid%",varid))
+                {
+                    type = lookback->str();
+                    break;
+                }
+            }
+        }
 
         // No type defined => The tokens didn't match
         if (type.empty())

test/testclass.cpp

@@ -2966,7 +2966,7 @@ private:
                       "    Fred fred;\n"
                       "    memset(&fred, 0, sizeof(fred));\n"
                       "}\n");
-        TODO_ASSERT_EQUALS("error", "", errout.str());
+        ASSERT_EQUALS("[test.cpp:8]: (error) Using 'memset' on struct that contains a 'std::string'\n", errout.str());
     }
 
     void memsetVector()