Fix #12662 FP unreadVariable with QMap iterator (#6354)

Author: chrchr-github

lib/fwdanalysis.cpp

@@ -498,6 +498,8 @@ bool FwdAnalysis::possiblyAliased(const Token *expr, const Token *startToken) co
         return true;
     if (Token::simpleMatch(expr, ". *"))
         return true;
+    if (expr->str() == "(" && Token::simpleMatch(expr->astOperand1(), "."))
+        return true;
 
     const bool macro = false;
     const bool pure = false;

test/cfg/qt.cpp

@@ -775,3 +775,13 @@ void unusedVariable_qtContainers() // #10689
     QLatin1String ql1s;
 }
 
+void unreadVariable_QMapIterator(QMap<QString, QObject*>& m)
+{
+    auto it = m.find("abc"); // #12662
+    if (it != m.end()) {
+        // cppcheck-suppress checkLibraryFunction // TODO
+        delete it.value();
+        // cppcheck-suppress checkLibraryFunction
+        it.value() = new QObject();
+    }
+}