- if(GCC_VERSION VERSION_LESS 4.9)
- # Drop support for gcc versions prior to 4.9
- message(FATAL_ERROR "gcc >= 4.9 is required.")
+ if(GCC_VERSION VERSION_LESS 4.6)
+ message(FATAL_ERROR "gcc >= 4.6 is required.")
+ elseif(GCC_VERSION VERSION_LESS 4.9)
+ # <regex> in gcc is unusable in versions less than 4.9.0
+ # see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53631
+ set(LYX_USE_STD_REGEX 0)