MSVC test pretty print of type and auto template args

auto_name.cpp

#include <iostream>
#include <string_view>

// typesig_s<T>() size of full pretty print output with template type arg T
template <typename>
constexpr auto typesig_s()
{
    return sizeof(__FUNCSIG__);
}

// type_name<T>() type name of template type arg T, from pretty-print output
template <typename>
constexpr auto type_name()
{
    std::string_view ret(__FUNCSIG__);
    constexpr auto prefix_size =        typesig_s<int>()
                               - sizeof(         "int>(void)");
    constexpr auto suffix_size = sizeof(            ">(void)")-1;
    ret.remove_prefix(prefix_size);
    ret.remove_suffix(suffix_size);
    return ret;
}

// autosig_s<v>() size of full pretty print output with template non-type arg v
template <auto>
constexpr auto autosig_s()
{
    return sizeof(__FUNCSIG__);
}

// auto_name<args...>() name of template non-type args..., from pretty-print output
template <auto...>
constexpr auto auto_name()
{
    std::string_view ret(__FUNCSIG__);
    constexpr auto prefix_size = autosig_s<nullptr>()
                               - sizeof  ("nullptr>(void)");
    constexpr auto suffix_size = sizeof(         ">(void)") - 1;
    ret.remove_prefix(prefix_size);
    ret.remove_suffix(suffix_size);
    return ret;
}

#define TYPE_NAME(Type) std::cout << "type_name <" << #Type << ">\n"\
                       "        -> " << type_name< Type >()
#define AUTO_NAME(...) std::cout << "auto_name <" << #__VA_ARGS__ << ">\n"\
                      "        -> " << auto_name< __VA_ARGS__ >()

struct C { bool b; char c(); }; // To test pointer-to-member

enum e { a, b, c };                      // Unscoped global
enum class E { a, b, c };                // Scoped global
struct U { enum e { a, b, c }; };        // Unscoped member
struct S { enum class E { a, b, c }; };  // Scoped member
namespace N { enum { a, b, c }; }        // Namespace anon

int main()
{
    enum m { a, b, c };                  // Unscoped local
    enum class M { a, b, c };            // Scoped local

    std::cout << "Issue 339663 tests: enumerator pretty-print\n"
                 "------------------\n";
    AUTO_NAME(::a,::b,::c,e(3)) << '\n';
    AUTO_NAME(E::a,E::b,E::c,E{4}) << '\n';
    AUTO_NAME(U::a,U::b,U::c,U::e(5)) << '\n';
    AUTO_NAME(S::E::a,S::E::b,S::E::c,S::E(6)) << '\n';
    AUTO_NAME(N::a,N::b,N::c,decltype(N::a)(7)) << '\n';
    AUTO_NAME(a,b,c,m(9)) << '\n';
    AUTO_NAME(M::a,M::b,M::c,M(10)) << '\n';

    std::cout << "\nIssue 339714 test: nullptr pretty-print\n"
                   "-----------------\n";
    AUTO_NAME(nullptr) << '\n';
    TYPE_NAME(decltype(nullptr)) << "  .......   ->   ********** Wrong! Type is printed as value! ********\n";

    std::cout << "\nPointer-to-member pretty printing:\n"
                   "-----------------\n";
    AUTO_NAME(&C::b,&C::c) << '\n';
}