Cross platform support about oberon-lang HOT 2 OPEN

I very much like the idea of standardizing/defining how wide each type is w.r.t. to the target platform! The proposal you made for the different platforms looks reasonable to me!

My impression is that no version of Oberon ever truly targeted a 64-bit platform. For example, I've been looking at Andreas Pirklbauer's Extended Oberon as part of my effort to port some of the standard modules to oberon-lang. In Texts.WriteInt the argument is LONGINT, but is immediately assumed to be 32-bit on line 447.

IF ROR(x, 31) = 1 THEN WriteString(W, " -2147483648")

In dealing with legacy code and Oberon-07, I think it would make sense to have a switch to use 32-bit sizes, even on a 64-bit platform. Depending on how we detect the width of the platform, this could maybe even be achieved by "cross-compilation" based on the target triplet.

from oberon-lang.

Yes, high probability legacy code would fail here anyway this is arranged with 64bit sizes in the mix.

On the XDS compiler the type LONGLONGINT is introduced to keep LONGINT 32bit.
Then there is need for separate type for SYSTEM.ADR and LEN will be limited to 32bit
which is not ideal, but legacy code will continue to work.

Note I changed the size of SHORTINT to be 8bit on all platforms.
It seems the use cases I could find was operation on ORD(ch) or SYSTEM.VAL(BYTE, var)
as arithmetic with numbers are not allowed on CHAR and BYTE.

GCC and CLANG have the -m16 .. -m32 flags to select the integer sizes.
This could probably be reused here.

The default width could be taken from the target triple with the possibility of override with the -m flag.
If LONGINT is forced to 32bit on a 64bit target with the -m32 flag, obviously SYSTEM.ADR
would not work any more and a warnings probably should be given.

from oberon-lang.