[mythtv] [mythtv-commits] Ticket #9426: MacOS X symbols missing

Michael T. Dean mtdean at thirdcontact.com
Sat Jan 22 22:13:21 UTC 2011


  On 01/22/2011 03:11 PM, MythTV wrote:
> #9426: MacOS X symbols missing
>
>
> Comment (by Dave Morrison<dave@…>):
>
>   Replying to [comment:12 stuarta]:
>   >  I'm not seeing this on Snow Leopard with the current XCode toolset.
>   >  What is it you are running on?
>
>   10.5.8 with gcc 4.0.1.  I see the following in the development notes for
>   gcc 4.2:

Our code in mythexp.h checks GCC version and defines MPUBLIC to 
__attribute__((visibility("default"))) for GCC >= 4, which matches up 
with our configure check for symbol visibility.  That said, symbol 
visibility on x86_64 failed to really work properly until 4.2 (vanilla, 
but RH backported the fixes to RH GCC 4.1.1, and other distros may have 
done the same--but I doubt Apple is).  The problem was with handling of 
relocatable code.

When we switched to symbol visibility as a default, I didn't think 
anyone was still using such ancient versions of GCC, so I didn't think 
there'd be problems.

Perhaps we should do a check for GCC 4.2+ in configure's 
gxx/symbol_visibility check and update mythexp.h.  That would disable it 
even on x86_32 for old GCC, but we've really made it default mainly for 
devs to catch issues before pushing them.

See http://www.gossamer-threads.com/lists/mythtv/users/241504#241504 for 
details of the bugs.

Mike


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