例如,我想使用：
auto money_i_owe_jack = -52_jpy;
这是我尝试使用gcc 4.7.2：
constexpr int64_t operator "" _jpy(long long l) { return static_cast<int64_t>(l); }
错误
Test_udl.cpp:60:47: error: ‘constexpr int64_t operator"" _jpy(long long int)’ has invalid argument list
constexpr int64_t operator "" _jpy(unsigned long long l) { return static_cast<int64_t>(l); }
