[Patch, ObjC/C++ V2, Part1] Recognize attributes on class, category and protocol declarations.

[Nicola Pero]

> As observed before, we need fairly soon to identify the tags by which  
> various capabilities are to be discriminated.

I thought about this while writing 

http://gcc.gnu.org/ml/gcc-patches/2010-09/msg02168.html

[PS: Mike, that documentation patch is awaiting your approval ;-)]

and I would keep it really simple (for now):

 * "traditional" Objective-C (as documented in NeXTstep book and implemented by GCC 2.95).
Syntax always available when you compile Objective-C.

 * "traditional" Objective-C plus Objective-C exceptions.  Objective-C exceptions are already
enabled by the -fobjc-exceptions flag.  Without it, the compiler will @throw ;-) an error.

 * "Objective-C 2.0" - which is "traditional" Objective-C plus Objective-C exceptions plus
"Objective 2.0" extensions - the language that Apple shipped with Mac OS X 10.6.

Do you know what flags Apple has to control Objective-C 2.0 vs. Objective 1.0 ?

Our problem is that the new ABI won't be there for 4.6 - it's too late to implement it, but it's 
not too late to implement part of the new Objective-C 2.0 features that don't depend on the ABI 
(eg, class/protocol/method attributes, fast enumeration etc), so maybe we do want to separate 
the two things.

I guess it would make sense to have separate flags (-objc-lang=objc2 vs -fobjc-abi-version=2) ?

Comments welcome :-)

Thanks