Re: Interesting discussion on gcc about objc

[Vincent Richomme]

On Mon, 13 Sep 2010 12:58:20 +0100, David Chisnall
<address@hidden> wrote:
> On 13 Sep 2010, at 10:38, Vincent Richomme wrote:
> 
>> Seach : Merging Apple's Objective-C 2.0 compiler changes
>> http://gcc.gnu.org/ml/gcc/2010-09/threads.html#00151
> 
> I think you and I have different definitions of 'interesting' - a
> load of posts by people who aren't lawyers discussing legal matters
> (particularly incompetently, since none of them bothered to cite the
> SFLC's statement on precisely the matter that they were discussing),
> and two posts of vague technical interest.
> 
> Nicola, I'll reply here since you read this list, and you can forward
> anything of interest to the gcc discussion:
> 
> This was about the only reply to your message to say anything of interest.
> 
>> GNU ObjC
>> has so few users that it seems hardly worth the effort to upgrade the
>> GNU ObjC front end to ObjC 2.0. And there are other issues:
> 
> Translation: The GNU project doesn't care about GNUstep.
> 
>> * What standard is going to be implemented? ObjC 2.0 is not even a
>> documented language standard, so you probably end up with something
>> that is incompatible with Apple ObjC anyway. Without a documented
>> standard, the only "standard" is the Apple compiler, which you cannot
>> look at without risking copyright problems. The latest state of ObjC
>> 2.0 on apple branches on gcc.gnu.org may not be the "current" ObjC
>> 2.0.
> 
> There is an ObjC 2 language description.  It is not a formal
> specification, but it's better than nothing, and both Apple GCC and
> Clang follow it.
> 
>> * How do ObjC 2.0 and ObjC++ interact?
> 
> Badly.  But no worse than ObjC++ in general (which is unsupported on
> gcc anyway, and not included with the default build).  In particular,
> the dot syntax for properties makes parsing ObjC++ painful.
> 
>> Even now, there is already the
>> problem of the two exception handling models, and AFAIU that will only
>> get more complicated with ObjC 2.0.
> 
> This is no issue at all.  The GNU runtime solved this about five
> years before Apple introduced zero-cost exceptions, although it's a
> buggy implementation.  libobjc2 solves it properly and allows mixing
> of ObjC and C++ exceptions properly, and even allows you to catch C++
> exceptions boxed as ObjC objects (in theory - in practice LLVM
> contains some bugs that make this break - hopefully they'll be fixed
> by someone eventually).
> 
>> * What does it mean for existing GNU ObjC users to make the headers
>> and runtime compatible with NEXTnow? These changes break source
>> compatibility, I guess, and if that is indeed the case then the
>> question is whether that is acceptable or not.
> 
> We already have an MIT-licensed runtime in svn that implements the
> ObjC 2 runtime features and works with GNUstep, so this isn't a
> problem.
> 
> A much bigger issue is that the Apple patches are largely useless. 
> They are quite specific to the Apple runtime.  NeXT/Apple never merged
> the original GNU runtime support stuff into their branch, so the FSF's
> branch has a load of #ifdef crap that isn't present in Apple's branch
> and so merging from Apple's branch is nontrivial.
> 
> You might be able to import the declared properties stuff, since we
> implement the same runtime functions as the Apple runtime.  You won't
> be able to import any of the newer stuff for the nonfragile ABI,
> because this is implemented differently in libobjc2 (since we can't
> rely on being able to rewrite the loader on every platform we
> support).
> 
> If anyone in GCC cares (which I very much doubt), the libobjc2
> non-fragile ABI is actually documented (unlike the old GNU libobjc
> ABI), so it should be relatively easy to support.
> 
> I'm going to quote this again, because it pretty much sums up GCC's
> attitude to GNUstep since before I joined the project:
> 
>> GNU ObjC has so few users that it seems hardly worth the effort

In the same time do you have an idea of how many people are interested
in gnustep ?
I would be very curious to know it.
DO you some some fugures ?