https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95800
--- Comment #2 from Teo Samarzija <teo.samarzija at gmail dot com> --- (In reply to Jakub Jelinek from comment #1) > Perhaps log2 is in DJGPP a macro (which the C standard allows)? > In that case, you either need to #undef that macro, or > use double (log2)(double x) { ... } I am sorry, apparently it is defined as a macro. I don't know why I am getting linker errors telling me "log2" is undefined.