Re: newbee question

[David Chisnall]

On 2 Aug 2008, at 12:14, hns@computer.org wrote:

> > 1) Someone at Apple, whose name escapes me, is backporting their
> > front-end changes to GNU GCC.  This will add all of the features that
> > don't require runtime support (properties and so on) to GNU GCC.
>
> Here is a link to the patches Apple has applied to gcc-4.2:
>
> http://www.opensource.apple.com/darwinsource/10.5.4/gcc_42-5531/
> (also go to the parent directory, there are more patches to gcc)

The state of ObjC in GCC is a bit of a mess.  First, NeXT tried to  
create a closed shared library with ObjC support in it, which end  
users would link against GCC.  The FSF forced them to open it, and so  
they delivered a big blob of ugly code to the GCC team, which only  
supported the NeXT runtime.

The GNU guys (I think possibly RMS at this time) wrote a new ObjC  
runtime, and scattered a few #ifdefs into the GCC code to support  
it.  The NeXT guys never imported these changes.

The Apple branch of GCC does not and never has had support for the  
GNU runtime.  It's not just a matter of applying patches from the  
Apple branch to the GNU branch - you need to see what they did and  
then do the same thing in mainline GCC.  It's made worse by the  
paranoid mindset of GCC devs (in and outside NeXT) in the late '90s  
refusing to implement layering in case people stole their code, so  
there is no separation between runtime-specific and runtime-agnostic  
portions.

Someone in Apple's GCC team was working on back-porting some of their  
changes to GNU GCC, but I don't remember who it was.  They released  
patches to support properties, but I don't think these have made it  
into mainline yet.

David