Re: Package building

[David Chisnall]

On 20/11/2019 09:55, Richard Frith-Macdonald wrote:
> I have never used a mixed configuration, but from what David's said in the past 
> (I expect he will correct me if I'm wrong),  for the libraries ARC should work 
> whether or not GNUstep is built with clang.

ARC and non-ARC work well together, but ARC depends on the non-fragile 
ABI, so you can't mix ARC and GCC-compiled code reliably.

In theory, the GNUstep runtime 1.x ABI supports mixing GCC-compiled code 
and non-fragile ABI code and it should work as long as the older ABI 
classes are closer to the roots of the class hierarchy than the newer 
ones.  In practice, there's a bug in the Linux (glibc?) run-time linker 
that means that ivar offsets are sometime incorrect when you do this.

The GNUstep Runtime 2.0 ABI is not supported by GCC and is a backwards 
compatibility break.  In hindsight, I probably should have done this 
from the start because there's a lot of legacy in the GCC runtime ABI 
(which is a minor tweak to the NeXTSTEP runtime ABI) that makes 
supporting newer language features very difficult.

David