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[cppyy] Fix type conversion for polymorphic classes #19374

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[cppyy] Fix type conversion for polymorphic classes #19374

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c1eaf62
[cppyy] Fix type conversion for polymorphic classes
Vipul-Cariappa Jul 15, 2025
7e52552
fixup this commit
Vipul-Cariappa Jul 16, 2025
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5 changes: 2 additions & 3 deletions bindings/pyroot/cppyy/CPyCppyy/src/Converters.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -2192,10 +2192,9 @@ template <bool ISCONST>
PyObject* CPyCppyy::InstancePtrConverter<ISCONST>::FromMemory(void* address)
{
// construct python object from C++ instance read at <address>
Cppyy::TCppScope_t actual_class = Cppyy::GetActualClass(fClass, *(void**)address);
if (ISCONST)
return BindCppObject(*(void**)address, actual_class); // by pointer value
return BindCppObject(address, actual_class, CPPInstance::kIsReference); // modifiable
return BindCppObject(*(void**)address, fClass); // by pointer value
return BindCppObject(address, fClass, CPPInstance::kIsReference); // modifiable
}

//----------------------------------------------------------------------------
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27 changes: 16 additions & 11 deletions bindings/pyroot/cppyy/CPyCppyy/src/ProxyWrappers.cxx
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Expand Up @@ -927,19 +927,24 @@ PyObject* CPyCppyy::BindCppObject(Cppyy::TCppObject_t address,
// successful, no down-casting is attempted?
// TODO: optimize for final classes
unsigned new_flags = flags;
if (!isRef && (gPinnedTypes.empty() || gPinnedTypes.find(klass) == gPinnedTypes.end())) {
Cppyy::TCppType_t clActual = Cppyy::GetActualClass(klass, address);

if (clActual) {
if (clActual != klass) {
intptr_t offset = Cppyy::GetBaseOffset(
clActual, klass, address, -1 /* down-cast */, true /* report errors */);
if (offset != -1) { // may fail if clActual not fully defined
address = (void*)((intptr_t)address + offset);
klass = clActual;
if (gPinnedTypes.empty() || gPinnedTypes.find(klass) == gPinnedTypes.end()) {
if (!isRef) {
Cppyy::TCppType_t clActual = Cppyy::GetActualClass(klass, address);

if (clActual) {
if (clActual != klass) {
intptr_t offset = Cppyy::GetBaseOffset(
clActual, klass, address, -1 /* down-cast */, true /* report errors */);
if (offset != -1) { // may fail if clActual not fully defined
address = (void*)((intptr_t)address + offset);
klass = clActual;
}
}
new_flags |= CPPInstance::kIsActual;
}
new_flags |= CPPInstance::kIsActual;
} else {
Cppyy::TCppType_t clActual = Cppyy::GetActualClass(klass, *(void**)address);
klass = clActual;
}
}

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