[Bug target/47558] 163267 breaks exception traceback in xplor-nih

[howarth at nitro dot med.uc.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47558

--- Comment #25 from Jack Howarth <howarth at nitro dot med.uc.edu> 2011-02-01 18:22:45 UTC ---
Again, I would note Nick's original comments on these issues...

 This may be that the libgcc_s.dylib based unwinder is incompatible  
 with the darwin unwinder.  You cannot mix and match the two.  One of  
 the lines from the bugzilla comments shows:
 /sw/lib/gcc4.5/lib/libgcc_s.1.dylib (compatibility version 1.0.0,
 being used.   That will not work.  All of the libgcc_s.dylib  
 functionality has been subsumed into libSystem.dylib on SnowLeopard  
 (darwin10).   The gcc compiler that shipped with SnowLeopard leaves  
 the -lgcc_s off the link line when targeting SnowLeopard.   If there  
 is a newer libgcc_s with new functions added, then the link line needs  
 to change to "-lSystem -lgcc_s", that way the linker will find the  
 most routines in libSystem.dylib and only the new functions from  
 libgcc_s.dylib.  Thus all linkage units will use the same unwinder.

So for compatibility with any Apple gcc built software, we should never
allow the FSF gcc unwinder to become operational under any circumstances.