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[solved] Re: Exceptions between DSOs not working, how to find cause?

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[solved] Re: Exceptions between DSOs not working, how to find cause?

Subject: [solved] Re: Exceptions between DSOs not working, how to find cause?
From: Mario Emmenlauer <email@hidden>
Date: Tue, 24 Nov 2009 08:23:54 +0100

Mario Emmenlauer wrote:

before waisting someones time: I know this has been asked before
and I (think I) know the solution, i.e. a good starting point was
http://lists.apple.com/archives/Xcode-users/2006/Jul/msg00400.html

My problem: when I throw an exception from a dll, I can not catch
it in other static libraries - I can only 'catch (...)'.

Stated in the link above, typical problems are:
 - It doesn't work properly if your code doesn't obey the one definition
   rule: http://en.wikipedia.org/wiki/One_Definition_Rule
 - Your DSOs need to export all their symbols

I have added '-fvisibility=default' to CFLAGS, and explicitly set
'__attribute__((visibility("default")))' in the declaration of the
exception class. So the problem must be the ODR?


Same after adding -shared-libgcc to linker and compiler flags.
Same behavior with gcc-4.2.1.

We have a gigantic codebase, is there a way I can (simply) find if
ODR is violated? Can I look up the symbol of the Exception class
manually?


Finally, I found the problem. We have the exception class defined
in a static library. This library gets linked into our DSOs, so the
exception class is available with a different address in multiple
DSOs. Since gcc uses the address to compare typeinfo, the exceptions
can not be identified :-(

The solution probably is to have the exceptions defined in a
DSO, not a static library.

All the best,

   Mario

gcc-4.0.1
MacOS 10.6.2
compiled from qmake-generated Makefiles

Thanks for all help,

Mario


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References:  
  >Exceptions between DSOs not working, how to find cause? (From: Mario Emmenlauer <email@hidden>)
  >Re: Exceptions between DSOs not working, how to find cause? (From: Mario Emmenlauer <email@hidden>)
  >Re: Exceptions between DSOs not working, how to find cause? (From: Mario Emmenlauer <email@hidden>)




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