Explicit Specialization in Non-Namespace Scope Does Not Compile in Gcc

Explicit specialization in non-namespace scope

VC++ is non-compliant in this case - explicit specializations have to be at namespace scope. C++03, §14.7.3/2:

An explicit specialization shall be declared in the namespace of which the template is a member, or, for member templates, in the namespace of which the enclosing class or enclosing class template is a member.

An explicit specialization of a member function, member class or static data member of a class template shall be declared in the namespace of which the class template is a member.

Additionally you have the problem that you can't specialize member functions without explicitly specializing the containing class due to C++03, §14.7.3/3, so one solution would be to let Verify() forward to a, possibly specialized, free function:

namespace detail {
    template <typename TL> void Verify     (int, int[]) {}
    template <>            void Verify<int>(int, int[]) {}
}

template<typename T> class CConstraint {
    // ...
    template <typename TL> void Verify(int position, int constraints[]) {
        detail::Verify<TL>(position, constraints);
    }
};

GCC error: explicit specialization in non-namespace scope

You just have to move your specializations of the member templates outside of the class body.

class VarData
{
public:
    template < typename T > bool IsTypeOf (int index) const
    {
        return IsTypeOf_f<T>::IsTypeOf(this, index);
    }
};

template <> bool VarData::IsTypeOf < int > (int index) const
{
    return false;
}

template <> bool VarData::IsTypeOf < double > (int index) const
{
    return false;
}

Explicit specialization in non-namespace scope error... Desperately need help

In this case overloading should suffice instead of specializing:

template <typename T> class Data_T
{
public:
    template<typename U> static bool IsEqual(const U& a, const U& b)
    {
        return a == b;
    }

    static bool IsEqual(const MyData& a, const MyData& b)
    {
        return MyDataTypeIsEqual (a, b);
    }

    template<typename U> bool IsRangeEqual(const U& a, const U& b, const U& delta)
    {
        return  (a >= b) ? (a - b <= delta) : (b - a <= delta);
    }

    bool IsRangeEqual(const MyData & a, const MyData & b, const MyData & accuracy)
    {
        return MyDataTypeIsRangeEqual (a, b, accuracy);
    }
};

Edit regarding update:

While for me the conversion from float to float __vector__ already fails, you seem to have a typo of:

template<typename U> static bool IsEqual(const T& a, const T& b)

vs.:

template<typename U> static bool IsEqual(const U& a, const U& b)

I fixed the above code accordingly.

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