タイプ名のデマングル

type_name.cpp

#include <iostream>
#include <sstream>

#ifdef __GNUG__

#include <cstdlib>
#include <memory>
#include <cxxabi.h>

std::string demangle(const char *name) {
    int status = 0;
    std::unique_ptr<char, decltype(&std::free)> resource {
        abi::__cxa_demangle(name, nullptr, nullptr, &status),
        std::free
    };
    return (status == 0) ? resource.get() : name;
}

#else

std::string demangle(const char *name) { return name; }

#endif

template <typename T>
std::string type_name() {
    std::stringstream ss;
    if (std::is_const<T>::value) ss << "const ";
    if (std::is_volatile<T>::value) ss << "volatile ";
    ss << demangle(typeid(*(std::remove_reference_t<std::remove_cv_t<T>>*)nullptr).name());
    if (std::is_lvalue_reference<T>::value) ss << " &";
    if (std::is_rvalue_reference<T>::value) ss << " &&";
    return ss.str();
}

template <typename T>
std::string type_name(const T &) { return type_name<T>(); }

// ----------

struct foo {};

template <typename T, typename U>
auto bar(const T &t, const U &u) { return t + u; }

auto baz() {
    struct s {};
    return s{};
}

int main()
{
    auto a = bar(100.0f, 200U);
    std::cout << type_name(a) << " a = " << a << std::endl;
    
    auto b = (int *)nullptr;
    std::cout << type_name(b) << " b = " << b << std::endl;
    
    std::cout << type_name(123LL) << std::endl; 
    
    std::cout << type_name<const volatile int>() << std::endl; 
    std::cout << type_name<double &>() << std::endl; 
    std::cout << type_name<foo &&>() << std::endl;
    
    std::cout << type_name(baz()) << std::endl;
    return 0;
}