// Impl.h
#pragma once

struct A {
    struct {
        int value;
    } valueA;
};

struct B {
    struct {
        int value;
    } valueB;
};

template<typename T>
int GetValue(T const &value);

// Impl.cpp
#include "Impl.h"
#include <type_traits>

using std::enable_if_t;
using std::remove_reference_t;

template<typename T, typename U, U(T::*Value)>
static inline int GetValueImpl(T const &value) {
    return (value.*Value).value;
}

template<typename T>
enable_if_t<T::valueA, int> GetValue(T const &value) {
    static constexpr auto T::*const Value = &T::valueA;
    typedef remove_reference_t<decltype(value.*Value)> ValueType;
    return GetValueImpl<T, ValueType, Value>(value);
}

template<typename T>
enable_if_t<T::valueB, int> GetValue(T const &value) {
    static constexpr auto T::*const Value = &T::valueB;
    typedef remove_reference_t<decltype(value.*Value)> ValueType;
    return GetValueImpl<T, ValueType, Value>(value);
}

template<> int GetValue(A const &); // C2912 here
template<> int GetValue(B const &); // C2912 here