GCC 4.x and ObjC/ObjC++ type encodings

[Ziemowit Laski]

Hello,

As some of you may have noticed, the Objective-C method signature, 
instance variable and
type encodings (including @encode expressions) have changed between GCC 
3.X and GCC 4.X
series of compilers.  The GCC 4.X implementation, although suffering 
from a couple of bugs,
is nevertheless an improvement over the previous schemes in that it is 
more orthogonal,
and handles ObjC qualifiers (e.g., 'bycopy', 'inout') in a more 
canonical fashion (though
further improvements are certainly possible).

Thing is, it turns out that this encoding rewrite has caused quite a 
bit of pain in the
Apple/Darwin world :-(.  As a result, I'm presently working on a patch 
(which will go into
apple-local-200502-branch for now) that will make GCC 4.X encodings 
match (to the extent
possible) what Apple's GCC 3.3 did.  This is neither pretty nor 
intellectually satisfying,
but is nonetheless necessary to preserve release-to-release binary 
compatibility for the
NeXT runtime.

However, this requirement may or may not hold for the _GNU_ runtime, 
which is why I'm
writing this e-mail.  Have folks in the GNU ObjC world experienced 
problems with the
encoding changes between GCC 4.x and earlier versions?  Would it be OK 
for the GNU runtime
to go back to GCC 3.x encodings?  (Doing so would clearly be easier for 
me :-) ).  If not,
could someone come up with a collection of GNU-runtime-specific test 
cases that capture
what the desired GNU encodings are, so that I don't break you guys once 
I start integrating
my encoding changes back into mainline in the future?

Thanks in advance,

--Zem
--------------------------------------------------------------
Ziemowit Laski                 1 Infinite Loop, MS 301-2K
Mac OS X Compiler Group        Cupertino, CA USA  95014-2083
Apple Computer, Inc.           +1.408.974.6229  Fax .5477