Implement code navigation for QObjects.

Allows for QObjects to navigate to the code location, where they were
created. Not (only) the header file or the class's constructor, but
where the constructor was called from.

This is done by generating a backtrace from
Probe::objectAdded, which is called from the QObject constructor. From
there we can step up to the frame above the object's constructor and
get the source location of that frame.

The stacktrace generation is based on backward-cpp.

CMakeLists.txt

@@ -83,6 +83,7 @@ include(FeatureSummary)
 include(ECMGeneratePriFile)
 include(ECMEnableSanitizers)
 include(GenerateExportHeader)
+include("3rdparty/backward-cpp/BackwardMacros.cmake")
 
 # Exit for blacklisted compilers (those that don't support C++11 very well)
 #  MSVC++ < 2010 aka 10.0 aka 1600

core/CMakeLists.txt

@@ -134,6 +134,8 @@ else()
   )
 endif()
 
+add_backward(gammaray_core)
+
 if(NOT GAMMARAY_PROBE_ONLY_BUILD)
   install(TARGETS gammaray_core EXPORT GammaRayTargets ${INSTALL_TARGETS_DEFAULT_ARGS})
 

core/objectdataprovider.cpp

@@ -27,6 +27,7 @@
 */
 
 #include "objectdataprovider.h"
+#include "probe.h"
 
 #include <common/sourcelocation.h>
 
@@ -91,6 +92,7 @@ SourceLocation ObjectDataProvider::creationLocation(QObject *obj)
             return loc;
     }
 
+    loc = Probe::instance()->objectCreationSourceLocation(obj);
     return loc;
 }
 

core/probe.cpp

@@ -53,6 +53,8 @@
 #include <common/streamoperators.h>
 #include <common/paths.h>
 
+#include <3rdparty/backward-cpp/backward.hpp>
+
 #if QT_VERSION < QT_VERSION_CHECK(5, 0, 0)
 #include <QApplication>
 #else
@@ -194,6 +196,7 @@ struct Listener
 
     bool trackDestroyed;
     QVector<QObject *> addedBeforeProbeInstance;
+    QHash<QObject *, backward::StackTrace> constructionBacktracesForObjects;
 };
 
 Q_GLOBAL_STATIC(Listener, s_listener)
@@ -209,6 +212,7 @@ Probe::Probe(QObject *parent)
     , m_window(nullptr)
     , m_queueTimer(new QTimer(this))
     , m_server(nullptr)
+    , m_traceResolver(new backward::TraceResolver())
 {
     Q_ASSERT(thread() == qApp->thread());
     IF_DEBUG(cout << "attaching GammaRay probe" << endl;)
@@ -538,6 +542,9 @@ void Probe::objectAdded(QObject *obj, bool fromCtor)
 
 #endif
 
+    if (fromCtor) {
+        s_listener()->constructionBacktracesForObjects[obj].load_here(32);
+    }
     if (!isInitialized()) {
         IF_DEBUG(cout
                  << "objectAdded Before: "
@@ -993,3 +1000,41 @@ void Probe::executeSignalCallback(const Func &func)
                   instance()->m_signalSpyCallbacks.constEnd(),
                   func);
 }
+
+SourceLocation Probe::objectCreationSourceLocation(QObject* object)
+{
+  if (!s_listener()->constructionBacktracesForObjects.contains(object)) {
+    IF_DEBUG(std::cout << "No backtrace for object available for object" << object << "." << std::endl;)
+    return SourceLocation();
+  }
+
+  backward::StackTrace &st = s_listener()->constructionBacktracesForObjects[object];
+  int distanceToQObject = 0;
+  m_traceResolver->load_stacktrace(st);
+
+  const QMetaObject *metaObject = object->metaObject();
+  while (metaObject && metaObject != &QObject::staticMetaObject) {
+    distanceToQObject++;
+    metaObject = metaObject->superClass();
+  }
+
+  IF_DEBUG(std::cout << " - Distance: " << distanceToQObject << std::endl;
+    for (size_t i = 4; i < (uint)6 + distanceToQObject; ++i) {
+        backward::ResolvedTrace trace = m_traceResolver->resolve(st[i]);
+        std::cout << "#" << i
+            << " " << trace.object_function
+            << " " << trace.source.filename
+            << ":" << trace.source.line
+            << ":" << trace.source.col
+        << std::endl;
+    })
+
+  backward::ResolvedTrace trace = m_traceResolver->resolve(st[4 + distanceToQObject + 1]);
+
+  SourceLocation loc;
+  loc.setUrl(QUrl::fromLocalFile(QString::fromStdString(trace.source.filename)));
+  loc.setLine(trace.source.line);
+  loc.setColumn(trace.source.col);
+
+  return loc;
+}

core/probe.h

@@ -33,10 +33,13 @@
 #include "probeinterface.h"
 #include "signalspycallbackset.h"
 
+#include <common/sourcelocation.h>
+
 #include <QObject>
 #include <QList>
 #include <QSet>
 #include <QVector>
+#include <memory>
 
 QT_BEGIN_NAMESPACE
 class QItemSelectionModel;
@@ -47,6 +50,10 @@ class QTimer;
 class QMutex;
 QT_END_NAMESPACE
 
+namespace backward {
+    class TraceResolver;
+}
+
 namespace GammaRay {
 class ProbeCreator;
 class ObjectListModel;
@@ -87,6 +94,8 @@ class GAMMARAY_CORE_EXPORT Probe : public QObject, public ProbeInterface
     void selectObject(void *object, const QString &typeName) override;
     void registerSignalSpyCallbackSet(const SignalSpyCallbackSet &callbacks) override;
 
+    SourceLocation objectCreationSourceLocation(QObject *object);
+
     QObject *window() const;
     void setWindow(QObject *window);
 
@@ -216,6 +225,7 @@ private slots:
     QVector<SignalSpyCallbackSet> m_signalSpyCallbacks;
     SignalSpyCallbackSet m_previousSignalSpyCallbackSet;
     Server *m_server;
+    std::unique_ptr<backward::TraceResolver> m_traceResolver;
 };
 }