Quoting Richard Guenther <richard.guent...@gmail.com>:
Well. Some things really ought to stay as macros. You can always error out if a multi-target compiler would have conflicts there at configure time.
So what are we going to do about all the tree optimizers and frontends that use BITS_PER_UNIT? Should they all include tm.h, with the hazard that more specific macros creep in? Or do we want to put this in a separate header file?