[Bug objc/39753] [4.3/4.4/4.5/4.6/4.7 Regression] Objective-C(++) and C90 strict-aliasing interaction bug

["nicola at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39753

Nicola Pero <nicola at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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             Status|WAITING                     |NEW
                 CC|                            |nicola at gcc dot gnu.org

--- Comment #10 from Nicola Pero <nicola at gcc dot gnu.org> 2011-03-19 00:22:52 UTC ---
Mike,

to clarify, the problem is that if you do not use -fno-strict-aliasing
when compiling Objective-C, then compiling any largish Objective-C project
(with perfectly correct Objective-C code) will generate many strict aliasing 
warnings.

The rumours that GNUstep compiles everything with -fno-strict-aliasing are 
correct - that is the case.  The reason is simply to avoid the warnings.

But I guess that this means that all C code that is scattered inside 
Objective-C source files is generally not optimized as much as it could be. :-(

So, it would be nice to clarify the problem once and for all, and make sure
it is safe to use -fstrict-aliasing in Objective-C (and it doesn't generate 
warnings), then GNUstep could stop using -fno-strict-aliasing and people
could get the full benefit of -O2. :-)

The next step is producing a few testcases showing the actual warnings, so we
have something to discuss about. :-)

Thanks