"New Class" wizard: Check custom base class for QObject parent

That is, if the user specifies a custom base class, we check whether its
constructor takes a "QObject *parent" parameter, and if it does, we give
the derived class one as well.
This is technically a heuristic, but the pattern is pretty stable in the
Qt world.

Fixes: QTCREATORBUG-25156
Change-Id: Ie64440929df61cca7258d6d692c5de62970f9a65
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

share/qtcreator/templates/wizards/classes/cpp/file.cpp

@@ -13,6 +13,8 @@ public:
 %{CN}::%{CN}(QObject *parent) : QObject(parent)%{JS: ('%{SharedDataInit}') ? ', %{SharedDataInit}' : ''}
 @elsif '%{Base}' === 'QWidget' || '%{Base}' === 'QMainWindow'
 %{CN}::%{CN}(QWidget *parent) : %{Base}(parent)%{JS: ('%{SharedDataInit}') ? ', %{SharedDataInit}' : ''}
+@elsif %{JS: Cpp.hasQObjectParent('%{Base}')}
+%{CN}::%{CN}(QObject *parent) : %{Base}(parent)%{JS: ('%{SharedDataInit}') ? ', %{SharedDataInit}' : ''}
 @else
 %{CN}::%{CN}()%{JS: ('%{SharedDataInit}') ? ' : %{SharedDataInit}' : ''}
 @endif

share/qtcreator/templates/wizards/classes/cpp/file.h

@@ -33,7 +33,7 @@ class %{CN}
      Q_OBJECT
 @endif
 public:
-@if '%{Base}' === 'QObject'
+@if '%{Base}' === 'QObject' || %{JS: Cpp.hasQObjectParent('%{Base}')}
     explicit %{CN}(QObject *parent = nullptr);
 @elsif '%{Base}' === 'QWidget' || '%{Base}' === 'QMainWindow'
     explicit %{CN}(QWidget *parent = nullptr);

src/plugins/cpptools/cppmodelmanager.cpp

@@ -42,6 +42,7 @@
 #include "cpprefactoringchanges.h"
 #include "cpprefactoringengine.h"
 #include "cppsourceprocessor.h"
+#include "cpptoolsjsextension.h"
 #include "cpptoolsplugin.h"
 #include "cpptoolsconstants.h"
 #include "cpptoolsreuse.h"
@@ -54,6 +55,7 @@
 #include <coreplugin/documentmanager.h>
 #include <coreplugin/editormanager/editormanager.h>
 #include <coreplugin/icore.h>
+#include <coreplugin/jsexpander.h>
 #include <coreplugin/progressmanager/progressmanager.h>
 #include <coreplugin/vcsmanager.h>
 #include <cplusplus/ASTPath.h>
@@ -575,6 +577,13 @@ CppModelManager *CppModelManager::instance()
     return m_instance;
 }
 
+void CppModelManager::registerJsExtension()
+{
+    Core::JsExpander::registerGlobalObject("Cpp", [this] {
+        return new CppToolsJsExtension(&d->m_locatorData);
+    });
+}
+
 void CppModelManager::initCppTools()
 {
     // Objects

src/plugins/cpptools/cppmodelmanager.h

@@ -98,6 +98,8 @@ public:
 
     static CppModelManager *instance();
 
+    void registerJsExtension();
+
      // Documented in source file.
      enum ProgressNotificationMode {
         ForcedProgressNotification,

src/plugins/cpptools/cpptoolsjsextension.cpp

@@ -26,6 +26,8 @@
 #include "cpptoolsjsextension.h"
 
 #include "cppfilesettingspage.h"
+#include "cpplocatordata.h"
+#include "cppworkingcopy.h"
 
 #include <coreplugin/icore.h>
 
@@ -33,9 +35,13 @@
 #include <projectexplorer/projectnodes.h>
 #include <projectexplorer/session.h>
 
+#include <cplusplus/AST.h>
+#include <cplusplus/ASTPath.h>
+#include <cplusplus/Overview.h>
 #include <utils/codegeneration.h>
 #include <utils/fileutils.h>
 
+#include <QElapsedTimer>
 #include <QFileInfo>
 #include <QStringList>
 #include <QTextStream>
@@ -118,6 +124,90 @@ QString CppToolsJsExtension::closeNamespaces(const QString &klass) const
     return result;
 }
 
+bool CppToolsJsExtension::hasQObjectParent(const QString &klassName) const
+{
+    // This is a synchronous function, but the look-up is potentially expensive.
+    // Since it's not crucial information, we just abort if retrieving it takes too long,
+    // in order not to freeze the UI.
+    // TODO: Any chance to at least cache between successive invocations for the same dialog?
+    //       I don't see it atm...
+    QElapsedTimer timer;
+    timer.start();
+    static const int timeout = 5000;
+
+    // Find symbol.
+    QList<IndexItem::Ptr> candidates;
+    m_locatorData->filterAllFiles([&](const IndexItem::Ptr &item) {
+        if (timer.elapsed() > timeout)
+            return IndexItem::VisitorResult::Break;
+        if (item->scopedSymbolName() == klassName) {
+            candidates = {item};
+            return IndexItem::VisitorResult::Break;
+        }
+        if (item->symbolName() == klassName)
+            candidates << item;
+        return IndexItem::VisitorResult::Recurse;
+    });
+    if (timer.elapsed() > timeout)
+        return false;
+    if (candidates.isEmpty())
+        return false;
+    const IndexItem::Ptr item = candidates.first();
+
+    // Find class in AST.
+    const CPlusPlus::Snapshot snapshot = CppModelManager::instance()->snapshot();
+    const WorkingCopy workingCopy = CppModelManager::instance()->workingCopy();
+    QByteArray source = workingCopy.source(item->fileName());
+    if (source.isEmpty()) {
+        QFile file(item->fileName());
+        if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
+            return false;
+        source = file.readAll();
+    }
+    const auto doc = snapshot.preprocessedDocument(source, item->fileName());
+    if (!doc)
+        return false;
+    doc->check();
+    if (!doc->translationUnit())
+        return false;
+    if (timer.elapsed() > timeout)
+        return false;
+    CPlusPlus::ClassSpecifierAST *classSpec = nullptr;
+    const QList<CPlusPlus::AST *> astPath = CPlusPlus::ASTPath(doc)(item->line(), item->column());
+    for (auto it = astPath.rbegin(); it != astPath.rend(); ++it) {
+        if ((classSpec = (*it)->asClassSpecifier()))
+            break;
+    }
+    if (!classSpec)
+        return false;
+
+    // Check whether constructor has a QObject parent parameter.
+    CPlusPlus::Overview overview;
+    const CPlusPlus::Class * const klass = classSpec->symbol;
+    if (!klass)
+        return false;
+    for (auto it = klass->memberBegin(); it != klass->memberEnd(); ++it) {
+        const CPlusPlus::Symbol * const member = *it;
+        if (overview.prettyName(member->name()) != item->symbolName())
+            continue;
+        const CPlusPlus::Function *function = (*it)->asFunction();
+        if (!function)
+            function = member->type().type()->asFunctionType();
+        if (!function)
+            continue;
+        for (int i = 0; i < function->argumentCount(); ++i) {
+            const CPlusPlus::Symbol * const arg = function->argumentAt(i);
+            const QString argName = overview.prettyName(arg->name());
+            const QString argType = overview.prettyType(arg->type())
+                    .split("::", Qt::SkipEmptyParts).last();
+            if (argName == "parent" && argType == "QObject *")
+                return true;
+        }
+    }
+
+    return false;
+}
+
 QString CppToolsJsExtension::includeStatement(
         const QString &fullyQualifiedClassName,
         const QString &suffix,

src/plugins/cpptools/cpptoolsjsextension.h

@@ -30,6 +30,8 @@
 #include <QStringList>
 
 namespace CppTools {
+class CppLocatorData; // FIXME: Belongs in namespace Internal
+
 namespace Internal {
 
 /**
@@ -40,7 +42,8 @@ class CppToolsJsExtension : public QObject
     Q_OBJECT
 
 public:
-    explicit CppToolsJsExtension(QObject *parent = nullptr) : QObject(parent) { }
+    explicit CppToolsJsExtension(CppLocatorData *locatorData, QObject *parent = nullptr)
+        : QObject(parent), m_locatorData(locatorData) { }
 
     // Generate header guard:
     Q_INVOKABLE QString headerGuard(const QString &in) const;
@@ -55,6 +58,7 @@ public:
     Q_INVOKABLE QString classToHeaderGuard(const QString &klass, const QString &extension) const;
     Q_INVOKABLE QString openNamespaces(const QString &klass) const;
     Q_INVOKABLE QString closeNamespaces(const QString &klass) const;
+    Q_INVOKABLE bool hasQObjectParent(const QString &klassName) const;
 
     // Find header file for class.
     Q_INVOKABLE QString includeStatement(
@@ -63,6 +67,9 @@ public:
             const QStringList &specialClasses,
             const QString &pathOfIncludingFile
             );
+
+private:
+    CppLocatorData * const m_locatorData;
 };
 
 } // namespace Internal

src/plugins/cpptools/cpptoolsplugin.cpp

@@ -33,7 +33,6 @@
 #include "cpptoolsbridge.h"
 #include "cpptoolsbridgeqtcreatorimplementation.h"
 #include "cpptoolsconstants.h"
-#include "cpptoolsjsextension.h"
 #include "cpptoolsreuse.h"
 #include "cpptoolssettings.h"
 #include "projectinfo.h"
@@ -46,7 +45,6 @@
 #include <coreplugin/editormanager/editormanager.h>
 #include <coreplugin/icore.h>
 #include <coreplugin/idocument.h>
-#include <coreplugin/jsexpander.h>
 #include <coreplugin/vcsmanager.h>
 #include <cppeditor/cppeditorconstants.h>
 #include <extensionsystem/pluginmanager.h>
@@ -167,7 +165,7 @@ bool CppToolsPlugin::initialize(const QStringList &arguments, QString *error)
     d = new CppToolsPluginPrivate;
     d->initialize();
 
-    JsExpander::registerGlobalObject<CppToolsJsExtension>("Cpp");
+    CppModelManager::instance()->registerJsExtension();
     ExtensionSystem::PluginManager::addObject(&d->m_cppProjectUpdaterFactory);
 
     // Menus