基于@chris注释，我认为以下代码可以完成这项工作:

Based on @chris comment, I think the following code will do the job:

#if __has_cpp_attribute(__cpp_lib_atomic_value_initialization)
std::atomic_flag a { };
#else
std::atomic_flag a = ATOMIC_FLAG_INIT;
#endif

所需的宏在< memory> ，< atomic> 和< version> 头文件之一中定义.我当然不想写已经被弃用的东西(即允许使用，但由于某些原因而劝阻).

The required macros are defined in either one of <memory>, <atomic>, and <version> header files. I certainly don't want to write something that is already deprecated (ie, the use is allowed, but discouraged for some reason).