Re: [Darwin] Patch, take 2: enable linkonce support for Darwin

[Kevin B. Hendricks <kevin dot hendricks at sympatico dot ca>]

Hi Matt,

A quick general question about this patch, the OpenOffice.org porters 
to MacOSX ran into serious problems with "coalesced" symbols that were 
not fixed until the most recent Apple version of GCC 3.3.  The problem 
was most easily seen when linking in libstlport (STL) and finding that 
depending on the mix of the compiler optimization levels used we 
generated strange linker failures related to coalesced symbols not 
being present in each linker section (or only in the wrong section?)

For example, rebuilding one library with -O0 -g for debugging purposes 
seemed to create problems when trying to link with other libraries that 
typically did not exist if everything was compiled at -O2 or higher.  
Typically the error message looked like the following:

> ./STLport-4.5/lib/libstlport_gcc.dylib)
> ld: huh.o illegal reference for -dynamic code (section difference
> reference from section (__TEXT,__eh_frame) relocation entry (82) to
> symbol: _STL::__node_alloc<(bool)1, (int)0>::allocate(unsigned long)
> defined in dylib: ./STLport-4.5/lib/libstlport_gcc.dylib)

The GNU Darwin compiler gcc 3.3 *never* seemed to have the same 
problems at that time that the Apple compiler had until the August gcc 
3.3 update (but it did have problems with static objects in templates 
and other issues).

Has this problem of mixing optimization levels and potentially missing 
related coalesced been tested in the new Darwin build with your patch 
in place to make sure the same problem that existed until recently in 
Apple's gcc 3.3 is not being introduced mistakenly into Darwin?

I guess I am just being paranoid but that problem held up progress for 
us almost 2 years.  :-)

Now if we could just get the C++ static initialization to work reliably 
(I have a test case in case anyone is interested which shows static 
initialization of an object being re-entered in a single threaded app 
unless -bind_at_load or -single-module is used which horribly slows 
down the startup time of OpenOffice.org).  Please see the following url 
if interested.

http://porting.openoffice.org/servlets/ReadMsg?list=dev&msgId=916562

Thanks,

Kevin