CppEditor: Make value vs const ref return type configurable

... in the quickfix settings.
Also change the default: With mandatory RVO and move semantics, value
return types are the right choice most of the time.

Fixes: QTCREATORBUG-25790
Change-Id: I68fc6c616358478ba893101b3e04aa6bbbe79348
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>

src/plugins/cppeditor/cppeditorconstants.h

@@ -49,6 +49,7 @@ const char QUICK_FIX_SETTING_SETTER_PARAMETER_NAME[] = "SetterParameterName";
 const char QUICK_FIX_SETTING_CPP_FILE_NAMESPACE_HANDLING[] = "CppFileNamespaceHandling";
 const char QUICK_FIX_SETTING_MEMBER_VARIABEL_NAME_TEMPLATE[] = "MemberVariableNameTemplate";
 const char QUICK_FIX_SETTING_VALUE_TYPES[] = "ValueTypes";
+const char QUICK_FIX_SETTING_RETURN_BY_CONST_REF[] = "ReturnNonValueTypesByConstRef";
 const char QUICK_FIX_SETTING_CUSTOM_TEMPLATES[] = "CustomTemplate";
 const char QUICK_FIX_SETTING_CUSTOM_TEMPLATE_TYPES[] = "Types";
 const char QUICK_FIX_SETTING_CUSTOM_TEMPLATE_COMPARISON[] = "Comparison";

src/plugins/cppeditor/cppquickfix_test.cpp

@@ -2722,6 +2722,7 @@ void QuickfixTest::testGenerateGetterSetterValueTypes()
     s->getterInCppFileFrom = 0;
     s->getterNameTemplate = "get<Name>";
     s->valueTypes << "Value";
+    s->returnByConstRef = true;
 
     GenerateGetterSetter factory;
     QuickFixOperationTest(testDocuments, &factory, ProjectExplorer::HeaderPaths(), operation);
@@ -3434,6 +3435,7 @@ public:
     s->getterOutsideClassFrom = 0;
     s->getterInCppFileFrom = 0;
     s->getterNameTemplate = "get<Name>";
+    s->returnByConstRef = true;
 
     GenerateGetterSetter factory;
     QuickFixOperationTest(testDocuments, &factory, ProjectExplorer::HeaderPaths(), 1);
@@ -3615,6 +3617,7 @@ void QuickfixTest::testGenerateGettersSetters()
     s->setterParameterNameTemplate = "value";
     s->setterOutsideClassFrom = 1;
     s->getterOutsideClassFrom = 1;
+    s->returnByConstRef = true;
 
     TestFactory factory;
     QuickFixOperationTest({CppTestDocument::create("file.h", original, expected)}, &factory);

src/plugins/cppeditor/cppquickfixes.cpp

@@ -3881,7 +3881,7 @@ void GetterSetterRefactoringHelper::performGeneration(ExistingGetterSetterData d
     }
     const FullySpecifiedType returnTypeHeader = [&] {
         if (!getSetTemplate.returnTypeTemplate.has_value())
-            return parameterType;
+            return m_settings->returnByConstRef ? parameterType : memberVariableType;
         QString typeTemplate = getSetTemplate.returnTypeTemplate.value();
         if (returnTypeTemplateParameter.has_value())
             typeTemplate.replace(Pattern::TEMPLATE_PARAMETER_PATTERN,
@@ -3947,7 +3947,7 @@ void GetterSetterRefactoringHelper::performGeneration(ExistingGetterSetterData d
                                                            data.clazz,
                                                            targetFile,
                                                            targetLoc);
-                    if (!isValueType)
+                    if (m_settings->returnByConstRef && !isValueType)
                         return makeConstRef(returnType);
                     return returnType;
                 }

src/plugins/cppeditor/cppquickfixsettings.cpp

@@ -79,6 +79,8 @@ void CppQuickFixSettings::loadSettingsFrom(QSettings *s)
                                           def.memberVariableNameTemplate)
                                      .toString();
     valueTypes = s->value(Constants::QUICK_FIX_SETTING_VALUE_TYPES, def.valueTypes).toStringList();
+    returnByConstRef = s->value(Constants::QUICK_FIX_SETTING_RETURN_BY_CONST_REF,
+                                def.returnByConstRef).toBool();
     customTemplates = def.customTemplates;
     int size = s->beginReadArray(Constants::QUICK_FIX_SETTING_CUSTOM_TEMPLATES);
     if (size > 0)
@@ -171,6 +173,10 @@ void CppQuickFixSettings::saveSettingsTo(QSettings *s)
                                      Constants::QUICK_FIX_SETTING_VALUE_TYPES,
                                      valueTypes,
                                      def.valueTypes);
+    QtcSettings::setValueWithDefault(s,
+                                     Constants::QUICK_FIX_SETTING_RETURN_BY_CONST_REF,
+                                     returnByConstRef,
+                                     def.returnByConstRef);
     if (customTemplates == def.customTemplates) {
         s->remove(Constants::QUICK_FIX_SETTING_CUSTOM_TEMPLATES);
     } else {

src/plugins/cppeditor/cppquickfixsettings.h

@@ -129,6 +129,7 @@ public:
     MissingNamespaceHandling cppFileNamespaceHandling = MissingNamespaceHandling::CreateMissing;
     QString memberVariableNameTemplate = "m_<name>";
     QStringList valueTypes; // if contains use value. Ignores namespaces and template parameters
+    bool returnByConstRef = false;
     std::vector<CustomTemplate> customTemplates;
 };
 } // namespace CppEditor

src/plugins/cppeditor/cppquickfixsettingswidget.cpp

@@ -79,6 +79,7 @@ e.g. name = "m_test_foo_":
     QObject::connect(this->ui->pushButton_addValueType, &QPushButton::clicked, then);
     QObject::connect(this->ui->pushButton_removeValueType, &QPushButton::clicked, then);
     QObject::connect(this->ui->valueTypes, &QListWidget::itemChanged, then);
+    QObject::connect(this->ui->returnByConstRefCheckBox, &QCheckBox::clicked, then);
     QObject::connect(this->ui->lineEdit_customTemplateAssignment, &QLineEdit::textEdited, then);
     QObject::connect(this->ui->lineEdit_customTemplateComparison, &QLineEdit::textEdited, then);
     QObject::connect(this->ui->lineEdit_customTemplateReturnExpression, &QLineEdit::textEdited, then);
@@ -142,6 +143,7 @@ void CppQuickFixSettingsWidget::loadSettings(CppQuickFixSettings *settings)
         item->setFlags(Qt::ItemIsSelectable | Qt::ItemIsEditable | Qt::ItemIsEnabled
                        | Qt::ItemNeverHasChildren);
     }
+    ui->returnByConstRefCheckBox->setChecked(settings->returnByConstRef);
     ui->listWidget_customTemplates->clear();
     for (const auto &customTemplate : settings->customTemplates) {
         auto item = new QListWidgetItem(customTemplate.types.join(", "),
@@ -201,6 +203,7 @@ void CppQuickFixSettingsWidget::saveSettings(CppQuickFixSettings *settings)
     for (int i = 0; i < ui->valueTypes->count(); ++i) {
         settings->valueTypes << ui->valueTypes->item(i)->text();
     }
+    settings->returnByConstRef = ui->returnByConstRefCheckBox->isChecked();
     settings->customTemplates.clear();
     for (int i = 0; i < ui->listWidget_customTemplates->count(); ++i) {
         auto item = ui->listWidget_customTemplates->item(i);

src/plugins/cppeditor/cppquickfixsettingswidget.ui

@@ -7,7 +7,7 @@
     <x>0</x>
     <y>0</y>
     <width>641</width>
-    <height>1074</height>
+    <height>1141</height>
    </rect>
   </property>
   <layout class="QVBoxLayout" name="verticalLayout_3">
@@ -25,9 +25,6 @@
         <property name="text">
          <string>Default</string>
         </property>
-        <property name="alignment">
-         <set>Qt::AlignCenter</set>
-        </property>
        </widget>
       </item>
       <item row="4" column="1" alignment="Qt::AlignHCenter">
@@ -329,9 +326,6 @@
         <property name="text">
          <string>Default</string>
         </property>
-        <property name="alignment">
-         <set>Qt::AlignCenter</set>
-        </property>
        </widget>
       </item>
       <item row="0" column="2">
@@ -350,9 +344,6 @@
         <property name="text">
          <string>Generate Getters</string>
         </property>
-        <property name="alignment">
-         <set>Qt::AlignCenter</set>
-        </property>
        </widget>
       </item>
       <item row="0" column="1">
@@ -371,9 +362,6 @@
         <property name="text">
          <string>Generate Setters</string>
         </property>
-        <property name="alignment">
-         <set>Qt::AlignCenter</set>
-        </property>
        </widget>
       </item>
       <item row="5" column="0">
@@ -886,6 +874,16 @@
      </item>
     </layout>
    </item>
+   <item>
+    <widget class="QCheckBox" name="returnByConstRefCheckBox">
+     <property name="text">
+      <string>Return non-value types by const reference</string>
+     </property>
+     <property name="checked">
+      <bool>false</bool>
+     </property>
+    </widget>
+   </item>
   </layout>
  </widget>
  <resources/>