Short utility to get the name of a type in C++

typename.hpp

template<class T> constexpr std::string_view type_name() {
	// clang: std::string_view ns::type_name() [T = int]
	// gcc:   constexpr std::string_view ns::type_name() [with T = int; std::string_view = std::basic_string_view<char>]
	// msvc:  const char *__cdecl ns::type_name<int>(void)
	auto substring_bounded_by = [](std::string_view sig, std::string_view l, std::string_view r) {
		assert(sig.find(l) != std::string_view::npos);
		assert(sig.rfind(r) != std::string_view::npos);
		assert(sig.find(l) < sig.rfind(r));
		auto i = sig.find(l) + l.length();
		return sig.substr(i, sig.rfind(r) - i);
	};
	#if defined(__clang__)
		return substring_bounded_by(__PRETTY_FUNCTION__, "[T = ", "]");
	#elif defined(__GNUC__) || defined(__GNUG__)
		return substring_bounded_by(__PRETTY_FUNCTION__, "[with T = ", "; std::string_view = ");
	#elif defined(_MSC_VER)
		return substring_bounded_by(__FUNCSIG__, "type_name<", ">(void)");
	#else
		// TODO: ?
		return __PRETTY_FUNCTION__;
	#endif
}