-// <regex> in gcc is unusable in versions less than 4.9.0
-// see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53631
-// clang defines __GNUC__ but how do the versions match?
-#ifndef LYX_USE_STD_REGEX
-# if (__GNUC__ == 4 && __GNUC_MINOR__ >= 9) || __GNUC__ > 4 || defined(USE_LLVM_LIBCPP)
-# define LYX_USE_STD_REGEX
-# endif
-#endif
-