When compiling on Mac OS X using Apple LLVM version 8.0.0 (clang-800.0.38) the following error is seen
gcc -c -o regions.o -I.. -iquote -DNMEMDEBUG -DSIZEOF_VOIDP=4 -Wall -g -O2 regions.c
In file included from regions.c:288:
../libregion/pages.c:272:56: error: use of undeclared identifier 'zeroregion'; did you mean 'newregion'?
set_region_range(newp, (char *)newp + request_bytes, FREEPAGE);