t.cpp

#include <numeric>

template <typename T>
bool parse(const char* fromstr, T& dest) //T* still can be const T*, since cv is preserved
{
    //parse and return 1 if succeeded
    dest = T();
    return 1;
}

template<typename T>
int parser(char const*& format, char const* input,  T& value)
{
#if 0
     if (/*T doesn't match the format*/)
     {
        throw bad_format_t{};
     }
#endif

     return parse(input, value); //<- tries to write into const object
}

template<typename... Args>
int tscanf(char const* format, char const* value, Args&... args)
{
    auto count = {parser(format, value, args)...}; //<- lvalue refs again, cv preserved

    return std::accumulate(std::begin(count), std::end(count), 0);
}

int main()
{
    int test = 5;
    tscanf("","",test);

    //tscanf("","",5);

    int const test2 = 4;
    //tscanf("","",test2);
}