There are CPUs around which don't care that the rest of the world have stacks which grow from large to small adresses. HPPA is an example for this. While it might look neat to the engineers who did it, it breaks our code. Another thing which breaks the code are small data types (eg. |WORD|, |UBYTE|, etc), because most systems put only integers or longs and pointers on the stack. So if some Msg structure expects |WORD| (see include:intuition/gadgetclass.h), this fails on every system but the Amiga. Then there are rumours about CPUs which use 32bit numbers and 64bit pointers or the other way round. On these CPUs, |SetAttrs()| and all other function which pass TagLists over the stack will fail. To overcome this, we introduce this rule:
To solve special problems on certain CPUs, we try to get a compiler which gets it right or, if that is impossible, we write a small preprocessor which replaces the dubious code by calls to the array versions.