The old -std=c++0x is only needed for older compiler versions that did not support -std=c++11 and they chose that name to express the preliminary and unstable nature of features (and the ABI) of the then upcoming C++11 (and when it was still unclear whether that would eventually become C++10 or C++12). They changes some of the details adapting to the changing working drafts of the standard at the time before the C++11 standard was officially released.If your compiler supports -std=c++11, there is no reason to use -std=c++0x. Concerning compatibility: There might even be differences and incompatibilities, but these are not just bound to the use of -std=c++0x, but to specific versions of the compiler. When the compiler supports both, they should be identical.
旧的-std=c++0x 只针对那些不支持 -std=c++11的旧编译器版本，他们选择这个名称来表示随后的( 当它还不清楚是否最终会变成 C++10 或者 C++12 时)的特性的初步和不稳定特性。 在C++11标准正式发布之前，他们更改了适应标准变更工作草稿的一些细节。
如果编译器支持 -std=c++11，则没有理由使用 -std=c++0x 。 有关兼容性：甚至可以能存在差异和不兼容性，但这些不仅限于 -std=c++0x的使用，而是编译器的特定版本。 当编译器同时支持两者时，它们应该是相同的。
参考
https://stackoverflow.com/questions/9538701/what-is-the-difference-between-c0x-and-c11
https://www.zhihu.com/question/20141092
https://www.douban.com/note/577010219/
https://www.tutorialspoint.com/What-is-the-difference-between-Cplusplus0x-and-Cplusplus11
