Unknown attribute __unused__
A build with the Studio 12.2 produces this error:
"../../../common/bzip2/compress.c", line 244: attribute "__unused__" is unknown, ignored (E_ATTRIBUTE_UNKNOWN)
cc: acomp failed for ../../../common/bzip2/compress.c
dmake: Warning: Command failed for target `obj64/bz2compress.o'
The solution is to patch bzlib_private.h, in usr/src/common/bzip2, to define unused to null for a non-gcc compiler. I'm attaching the patch file.