Code compiled in VS2008 doesn't in VS2013, const overloading - c++

Question

Now I'm migrating my project from Visual Studio 2008 to 2013 (with no updates installed), and facing a problem.
I have a sort of Variant type, CData< T>, that has a conversion operators to the contained type T.
template<class T> T& GetValue();
template<class T> const T& GetValue() const;
template<class T> T* GetValuePtr();
template<class T> const T* GetValuePtr() const;
template<class T> operator T&() { return GetValue<T>(); }
template<class T> operator const T&() const { return GetValue<T>(); }
template<class T> operator T*() { return GetValuePtr<T>(); }
template<class T> operator const T*() const { return GetValuePtr<T>(); }
There are methods in a class CDataArray:
CData& Get(int Index) { return At(Index); }
const CData& Get(int Index) const { return operator [](Index); }
template<class T>
T& Get(int Index) { return At(Index).GetValue<T>(); }
template<class T>
const T& Get(int Index) const { return operator [](Index).GetValue<T>(); }
and there is a call to it:
Data::PDataArray SGQuests;
Data::PParams SGQuest = SGQuests->Get(i);
Here, Data::PParams is going to be T.
In VS2008, it seems it used non-const non-template CDataArray::Get(), which returned CData&, and then this CData& was accessed with non-const template operator T&(), finally returning Data::PParams&.
In VS2013, it for some reason uses a const overload and it results in error:
1>PATH_TO_SRC\l1\data\type.h(126): error C2678: binary "=": no operator found that accepts left operand "const Ptr<Data::CParams>" (or there is no acceptable conversion)
1> PATH_TO_SRC\l1\data\ptr.h(29): may be "void Ptr<Data::CParams>::operator =(T *)"
1> with
1> [
1> T=Data::CParams
1> ]
1> PATH_TO_SRC\l1\data\ptr.h(28): or "void Ptr<Data::CParams>::operator =(const Ptr<Data::CParams> &)"
1> trying to match argument list "(const Ptr<Data::CParams>, const Ptr<Data::CParams>)"
1> PATH_TO_SRC\l1\data\type.h(125): compiling member function "void Data::CTypeImpl<T>::Copy(void **,void *const *) const" template class
1> with
1> [
1> T=const Ptr<Data::CParams>
1> ]
1> PATH_TO_SRC\l1\data\data.h(167): "Data::CTypeImpl<T>"
1> with
1> [
1> T=const Ptr<Data::CParams>
1> ]
1> PATH_TO_SRC\l1\data\data.h(97): "T &Data::CData::GetValue<T>(void)"
1> with
1> [
1> T=const Ptr<Data::CParams>
1> ]
1> PATH_TO_SRC\l3\quests\questmanager.cpp(307): "Data::CData::operator const T(void)<const Ptr<Data::CParams>>"
1> with
1> [
1> T=const Ptr<Data::CParams>
1> ]
I translated messages to English manually, so they can slightly differ from original EN compiler messages.
And finally, if I write explicit template argument:
Data::PParams SGQuest = SGQuests->Get<Data::PParams>(i);
It compiles OK.
The questions are:
How VS2013 template argument guessing differs from VS2008 one? Is there any place (standard, article or smth) that clearly explains, why my old code shouldn't compile? Any reference would be appreciated.
How should I write code in that situations? Do I have to write template arguments explicitly now, or just modify member overloads, or install some update?
P.S. Minimal code is available at https://www.dropbox.com/s/zjohnu5v87tyr2c/ConstOverload.zip?dl=0 . Full source code is at
https://code.google.com/p/deusexmachina/source/browse/branches/Dev/DEM/Src

Answer 1

This problem was solved by adding third overload to CData
template<class T> operator const T&() { return GetValue<T>(); }
Original solution is posted in:
Conversion operator error C2678 in VS2013, works in VS2008
Look there for possible further details.