https://bugs.openldap.org/show_bug.cgi?id=9215
--- Comment #3 from Konstantin Andreev grapvar@gmail.com --- Standard selection macros may alter system API, e.g. (pseudocode)
#if (_POSIX_C_SOURCE >= 200112L) && ! _GNU_SOURCE int strerror_r( ... // XSI else char *strerror_r( ... // GNU
It may be preferable to provide the same standard selection macros to all source files to be sure they share the same and consistent system view.