__STDC_VERSION__ : What C dialect c89, c99,gnu90 kernel compiies

Hi All, I am building out of tree kernel module. I am trying to include user-space lib into kernel module This API gives me the following warning : "__STDC_VERSION__" is not defined, evaluates to 0 But continues and resulted module works, I see from https://gcc.gnu.org/onlinedocs/cpp/Standard-Predefined-Macros.html that _STDC_VERSION__ is a built-in gcc macro, so I think that evenh kernel compilation should be able to see it. Please comment Lev.