I’m trying to downport some C++17 code which uses if constexpr to C++14. The code looks like this:

template<
    typename T,
    typename std::enable_if<std::is_integral_v<T> || std::is_floating_point_v<T> || std::is_same_v<std::decay_t<T>, std::string> ||
                std::is_same_v<std::decay_t<T>, SVSTD::string_view> || std::is_same_v<std::decay_t<T>, const char*> ||
                std::is_same_v<std::decay_t<T>, char*> || std::is_same_v<T, XLDateTime>>::type* = nullptr>

    XLCellValue(T value)    // NOLINT
    {
       // ===== If the argument is a bool, set the m_type attribute to Boolean.
       if constexpr (std::is_integral_v<T> && std::is_same_v<T, bool>) {
           m_type  = XLValueType::Boolean;
           m_value = value;
       }

       // ===== If the argument is an integral type, set the m_type attribute to Integer.
       else if constexpr (std::is_integral_v<T> && !std::is_same_v<T, bool>) {
           m_type  = XLValueType::Integer;
           m_value = int64_t(value);
       }
    
    ....

I’ve done some research and found a similar question where people suggest using enable_if to imitate what if constexpr does. I’ve tried to do that and came up with the following translation of the code above:

template<
    typename T,
    typename std::enable_if<std::is_integral<T>::value && std::is_same<T, bool>::value>>
                                            
    XLCellValue(T value)    // NOLINT
    {
        // ===== If the argument is a bool, set the m_type attribute to Boolean.
        m_type  = XLValueType::Boolean;
        m_value = value;
    }

template<
    typename T,
    typename std::enable_if<std::is_integral<T>::value && !std::is_same<T, bool>::value>>
                                            
    XLCellValue(T value)    // NOLINT
    {
        // ===== If the argument is an integral type, set the m_type attribute to Integer.
        m_type  = XLValueType::Integer;
        m_value = int64_t(value);
    }

Unfortunately, it doesn’t compile on a C++14 gcc. The compiler shows the following error:

struct std::enable_if<std::is_integral<T>::value && std::is_same<T, bool>::value is not a valid type for a template non-type parameter

I’ve also tried to use template <class T, std::enable_if<...>> instead of template <typename T, ...> as described in the similar question linked above but it shows the same error.

Being a C++ noob, I’m stuck here. Can anybody help?