[cfarm-users] Where did XL C/C++ predefined macros go on GCC112?

[Jeffrey Walton]

I've got a compile failure on GCC112 with IBM XL C/C++. It is a Linux
ppc64-le machine.

This is a relatively new failure (or I have not tested in a while).
The compiler avoids an XLC code guarded by defined(__xlc__) ||
defined(__xlC__), and drops into a GCC code path. XLC then fails to
compile __builtin_vec_vcipher (and friends).

   $ xlC -qshowmacros -qarch=pwr8 -qaltivec -E rijndael-simd.cpp | grep -i xlc
   #define __XLC_BUILTIN_VAARG__ 1

There's only a single macro, which is very unusual.

   $ xlC -qversion
   IBM XL C/C++ for Linux, V13.1.6 (Community Edition)
   Version: 13.01.0006.0001
   /opt/ibm/xlC/13.1.6/bin/.orig/xlC ...

Where did XL C/C++  predefined macros go on GCC112? How do I get them back?