I know this sounds crazy but it's true: there's an AIX header which unconditionally defines rem_size:

/usr/include/sys/xmem.h
struct xmem {
...
#define rem_size u2._subspace_id2
};

This will of course break the compilation of CompactibleFreeListSpace::splitChunkAndReturnRemainder() which uses a local variable of the same name.

Until now, we've worked around this problem by simply undefining 'rem_size' in the platform specific file os_aix.inline.hpp but after "8042195: Introduce umbrella header orderAccess.inline.hpp" this doesn't seems to be enough any more.

So before introducing yet another ugly platform dependent hack I suggest so simply rename the local variable.