https://gcc.gnu.org/bugzilla/show_bug.cgi?id=16358
niva at niisi dot msk.ru changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |niva at niisi dot msk.ru --- Comment #9 from niva at niisi dot msk.ru --- ISO C treats redefinition of a macro as an error (6.10.3 2). IMHO it is reasonable to add a gcc/cpp option which provides treating redefinition of a macro as an error.