Fix #10710 FN passedByValue with QString (#3696)

gui/mainwindow.cpp

@@ -1918,7 +1918,7 @@ void MainWindow::editVariableContract(QString var)
     updateVariableContractsTab();
 }
 
-void MainWindow::deleteFunctionContract(QString function)
+void MainWindow::deleteFunctionContract(const QString& function)
 {
     if (mProjectFile) {
         mProjectFile->deleteFunctionContract(function);
@@ -1926,7 +1926,7 @@ void MainWindow::deleteFunctionContract(QString function)
     }
 }
 
-void MainWindow::deleteVariableContract(QString var)
+void MainWindow::deleteVariableContract(const QString& var)
 {
     if (mProjectFile) {
         mProjectFile->deleteVariableContract(var);

gui/mainwindow.h

@@ -234,10 +234,10 @@ protected slots:
     void editVariableContract(QString var);
 
     /** Delete contract for function */
-    void deleteFunctionContract(QString function);
+    void deleteFunctionContract(const QString& function);
 
     /** Edit constraints for variable */
-    void deleteVariableContract(QString var);
+    void deleteVariableContract(const QString& var);
 
 private:
 

gui/projectfile.cpp

@@ -788,7 +788,7 @@ void ProjectFile::setLibraries(const QStringList &libraries)
     mLibraries = libraries;
 }
 
-void ProjectFile::setFunctionContract(QString function, QString expects)
+void ProjectFile::setFunctionContract(const QString& function, const QString& expects)
 {
     mFunctionContracts[function.toStdString()] = expects.toStdString();
 }
@@ -818,7 +818,7 @@ void ProjectFile::setVSConfigurations(const QStringList &vsConfigs)
     mVsConfigurations = vsConfigs;
 }
 
-void ProjectFile::setWarningTags(std::size_t hash, QString tags)
+void ProjectFile::setWarningTags(std::size_t hash, const QString& tags)
 {
     if (tags.isEmpty())
         mWarningTags.erase(hash);

gui/projectfile.h

@@ -236,15 +236,15 @@ public:
         return mVariableContracts;
     }
 
-    void setVariableContracts(QString var, QString min, QString max) {
+    void setVariableContracts(QString var, const QString& min, const QString& max) {
         mVariableContracts[var] = Settings::VariableContracts{min.toStdString(), max.toStdString()};
     }
 
-    void deleteFunctionContract(QString function) {
+    void deleteFunctionContract(const QString& function) {
         mFunctionContracts.erase(function.toStdString());
     }
 
-    void deleteVariableContract(QString var) {
+    void deleteVariableContract(const QString& var) {
         mVariableContracts.erase(var);
     }
 
@@ -313,7 +313,7 @@ public:
     void setLibraries(const QStringList &libraries);
 
     /** Set contract for a function */
-    void setFunctionContract(QString function, QString expects);
+    void setFunctionContract(const QString& function, const QString& expects);
 
     /**
      * @brief Set platform.
@@ -350,7 +350,7 @@ public:
     }
 
     /** Set tags for a warning */
-    void setWarningTags(std::size_t hash, QString tags);
+    void setWarningTags(std::size_t hash, const QString& tags);
 
     /** Get tags for a warning */
     QString getWarningTags(std::size_t hash) const;

gui/variablecontractsdialog.cpp

@@ -13,7 +13,7 @@ VariableContractsDialog::VariableContractsDialog(QWidget *parent, QString var) :
 
     this->setWindowTitle(mVarName);
 
-    auto getMinMax = [](QString var, QString minmax) {
+    auto getMinMax = [](const QString& var, const QString& minmax) {
         if (var.indexOf(" " + minmax + ":") < 0)
             return QString();
         int pos1 = var.indexOf(" " + minmax + ":") + 2 + minmax.length();

lib/checkother.cpp

@@ -1170,7 +1170,7 @@ static int estimateSize(const Type* type, const Settings* settings, const Symbol
     return cumulatedSize;
 }
 
-static bool canBeConst(const Variable *var)
+static bool canBeConst(const Variable *var, const Settings* settings)
 {
     {
         // check initializer list. If variable is moved from it can't be const.
@@ -1214,17 +1214,26 @@ static bool canBeConst(const Variable *var)
                     argNr++;
                 tok3 = tok3->previous();
             }
-            if (!tok3 || tok3->str() != "(" || !tok3->astOperand1() || !tok3->astOperand1()->function())
+            if (!tok3 || tok3->str() != "(")
                 return false;
-            else {
+            const Token* functionTok = tok3->astOperand1();
-                const Variable* argVar = tok3->astOperand1()->function()->getArgumentVar(argNr);
+            if (!functionTok)
+                return false;
+            const Function* tokFunction = functionTok->function();
+            if (!tokFunction && functionTok->str() == "." && (functionTok = functionTok->astOperand2()))
+                tokFunction = functionTok->function();
+            if (tokFunction) {
+                const Variable* argVar = tokFunction->getArgumentVar(argNr);
                 if (!argVar || (!argVar->isConst() && argVar->isReference()))
                     return false;
             }
+            else if (!settings->library.isFunctionConst(functionTok))
+                return false;
         } else if (parent->isUnaryOp("&")) {
             // TODO: check how pointer is used
             return false;
-        } else if (parent->isConstOp())
+        } else if (parent->isConstOp() ||
+                   (parent->astOperand2() && settings->library.isFunctionConst(parent->astOperand2())))
             continue;
         else if (parent->isAssignmentOp()) {
             if (parent->astOperand1() == tok2)
@@ -1290,7 +1299,7 @@ void CheckOther::checkPassByReference()
         if (!var->scope() || var->scope()->function->hasVirtualSpecifier())
             continue;
 
-        if (canBeConst(var)) {
+        if (canBeConst(var, mSettings)) {
             passedByValueError(var->nameToken(), var->name(), inconclusive);
         }
     }

test/cfg/qt.cpp

@@ -55,6 +55,21 @@ void QString4()
     QString qs;
 }
 
+// cppcheck-suppress passedByValue
+bool QString5(QString s) { // #10710
+    return s.isEmpty();
+}
+
+// cppcheck-suppress passedByValue
+QStringList QString6(QString s) {
+    return QStringList{ "*" + s + "*" };
+}
+
+// cppcheck-suppress passedByValue
+bool QString7(QString s, const QString& l) {
+    return l.startsWith(s);
+}
+
 void QByteArray1(QByteArray byteArrayArg)
 {
     for (int i = 0; i <= byteArrayArg.size(); ++i) {
@@ -297,6 +312,7 @@ QVector<int>::iterator QVector2()
     return it;
 }
 
+// cppcheck-suppress passedByValue
 void duplicateExpression_QString_Compare(QString style) //#8723
 {
     // cppcheck-suppress duplicateExpression

test/cfg/std.cpp

@@ -3261,6 +3261,7 @@ void uninitvar_setbase(void)
     std::cout << std::setbase(p);
 }
 
+// cppcheck-suppress passedByValue
 void uninitvar_find(std::string s)
 {
     // testing of size_t find (const string& str, size_t pos = 0)
@@ -3341,6 +3342,7 @@ void ignoredReturnValue_abs(int i)
     std::abs(-199);
 }
 
+// cppcheck-suppress passedByValue
 void ignoredReturnValue_string_compare(std::string teststr, std::wstring testwstr)
 {
     // cppcheck-suppress ignoredReturnValue