libshiboken: Refactor type discovery graph handling

Replace BindingManager::.resolveType() by
a new function BindingManager::findDerivedType()
which does exactly that and returns a pair of type/cptr
instead of modifying the in-parameter.

As a drive-by, remove a unused variable in BindingManagerPrivate.

Task-number: PYSIDE-2404
Task-number: PYSIDE-2675
Pick-to: 6.7
Change-Id: I5b39ea8370b0fc1a196feb6934306f1f1dfeb8b3
Reviewed-by: Shyamnath Premnadh <Shyamnath.Premnadh@qt.io>

3 files changed, 51 insertions, 34 deletions

diff --git a/sources/shiboken6/libshiboken/basewrapper.cpp b/sources/shiboken6/libshiboken/basewrapper.cpp
index 3cd8a5c2b..f34e053ca 100644
--- a/sources/shiboken6/libshiboken/basewrapper.cpp
+++ b/sources/shiboken6/libshiboken/basewrapper.cpp
@@ -1460,10 +1460,15 @@ PyObject *newObject(PyTypeObject *instanceType,
 {
     // Try to find the exact type of cptr.
     if (!isExactType) {
-        if (PyTypeObject *exactType = ObjectType::typeForTypeName(typeName))
+        if (PyTypeObject *exactType = ObjectType::typeForTypeName(typeName)) {
             instanceType = exactType;
-        else
-            instanceType = BindingManager::instance().resolveType(&cptr, instanceType);
+        } else {
+            auto resolved = BindingManager::instance().findDerivedType(cptr, instanceType);
+            if (resolved.first != nullptr) {
+                instanceType = resolved.first;
+                cptr = resolved.second;
+            }
+        }
     }
 
     bool shouldCreate = true;
diff --git a/sources/shiboken6/libshiboken/bindingmanager.cpp b/sources/shiboken6/libshiboken/bindingmanager.cpp
index 7542e60b8..84424a78a 100644
--- a/sources/shiboken6/libshiboken/bindingmanager.cpp
+++ b/sources/shiboken6/libshiboken/bindingmanager.cpp
@@ -43,35 +43,32 @@ public:
         m_edges[from].push_back(to);
     }
 
+    BindingManager::TypeCptrPair identifyType(void *cptr, PyTypeObject *type, PyTypeObject *baseType) const;
+
     bool dumpTypeGraph(const char *fileName) const;
     NodeSet nodeSet() const;
 
-    PyTypeObject *identifyType(void **cptr, PyTypeObject *type, PyTypeObject *baseType) const
-    {
-        auto edgesIt = m_edges.find(type);
-        if (edgesIt != m_edges.end()) {
-            const NodeList &adjNodes = m_edges.find(type)->second;
-            for (PyTypeObject *node : adjNodes) {
-                PyTypeObject *newType = identifyType(cptr, node, baseType);
-                if (newType)
-                    return newType;
-            }
-        }
-        void *typeFound = nullptr;
-        auto *sotp = PepType_SOTP(type);
-        if (sotp->type_discovery)
-            typeFound = sotp->type_discovery(*cptr, baseType);
-        if (typeFound) {
-            // This "typeFound != type" is needed for backwards compatibility with old modules using a newer version of
-            // libshiboken because old versions of type_discovery function used to return a PyTypeObject *instead of
-            // a possible variation of the C++ instance pointer (*cptr).
-            if (typeFound != type)
-                *cptr = typeFound;
-            return type;
+};
+
+BindingManager::TypeCptrPair Graph::identifyType(void *cptr, PyTypeObject *type, PyTypeObject *baseType) const
+{
+    auto edgesIt = m_edges.find(type);
+    if (edgesIt != m_edges.end()) {
+        const NodeList &adjNodes = edgesIt->second;
+        for (PyTypeObject *node : adjNodes) {
+            auto newType = identifyType(cptr, node, baseType);
+            if (newType.first != nullptr)
+                return newType;
         }
-        return nullptr;
     }
-};
+
+    auto *sotp = PepType_SOTP(type);
+    if (sotp->type_discovery != nullptr) {
+        if (void *derivedCPtr = sotp->type_discovery(cptr, baseType))
+            return {type, derivedCPtr};
+    }
+    return {nullptr, nullptr};
+}
 
 static void formatDotNode(const char *nameC, std::ostream &file)
 {
@@ -132,9 +129,6 @@ struct BindingManager::BindingManagerPrivate {
     std::recursive_mutex wrapperMapLock;
     Graph classHierarchy;
     DestructorEntries deleteInMainThread;
-    bool destroying;
-
-    BindingManagerPrivate() : destroying(false) {}
 
     bool releaseWrapper(void *cptr, SbkObject *wrapper, const int *bases = nullptr);
     bool releaseWrapperHelper(void *cptr, SbkObject *wrapper);
@@ -386,10 +380,18 @@ void BindingManager::addClassInheritance(PyTypeObject *parent, PyTypeObject *chi
     m_d->classHierarchy.addEdge(parent, child);
 }
 
+BindingManager::TypeCptrPair BindingManager::findDerivedType(void *cptr, PyTypeObject *type) const
+{
+    return m_d->classHierarchy.identifyType(cptr, type, type);
+}
+
+// FIXME PYSIDE7: remove, just for compatibility
 PyTypeObject *BindingManager::resolveType(void **cptr, PyTypeObject *type)
 {
-    PyTypeObject *identifiedType = m_d->classHierarchy.identifyType(cptr, type, type);
-    return identifiedType ? identifiedType : type;
+    auto result = findDerivedType(*cptr, type);
+    if (result.second != nullptr)
+        *cptr = result.second;
+    return result.first != nullptr ? result.first : type;
 }
 
 std::set<PyObject *> BindingManager::getAllPyObjects()
diff --git a/sources/shiboken6/libshiboken/bindingmanager.h b/sources/shiboken6/libshiboken/bindingmanager.h
index 47db14975..281de2c73 100644
--- a/sources/shiboken6/libshiboken/bindingmanager.h
+++ b/sources/shiboken6/libshiboken/bindingmanager.h
@@ -5,9 +5,11 @@
 #define BINDINGMANAGER_H
 
 #include "sbkpython.h"
-#include <set>
 #include "shibokenmacros.h"
 
+#include <set>
+#include <utility>
+
 struct SbkObject;
 
 namespace Shiboken
@@ -39,6 +41,14 @@ public:
     PyObject *getOverride(const void *cptr, PyObject *nameCache[], const char *methodName);
 
     void addClassInheritance(PyTypeObject *parent, PyTypeObject *child);
+    /// Try to find the correct type of cptr via type discovery knowing that it's at least
+    /// of type \p type. If a derived class is found, it returns a cptr cast to the type
+    /// (which may be different in case of  multiple inheritance.
+    /// \param cptr a pointer to the instance of type \p type
+    /// \param type type of cptr
+    using TypeCptrPair = std::pair<PyTypeObject *, void *>;
+    TypeCptrPair findDerivedType(void *cptr, PyTypeObject *type) const;
+
     /**
      * Try to find the correct type of *cptr knowing that it's at least of type \p type.
      * In case of multiple inheritance this function may change the contents of cptr.
@@ -46,7 +56,7 @@ public:
      * \param type type of *cptr
      * \warning This function is slow, use it only as last resort.
      */
-    PyTypeObject *resolveType(void **cptr, PyTypeObject *type);
+    [[deprecated]] PyTypeObject *resolveType(void **cptr, PyTypeObject *type);
 
     std::set<PyObject *> getAllPyObjects();