[Bug c++/23628] Typeinfo comparison code easily breaks shared libs

["ghost at cs dot msu dot su" <gcc-bugzilla@gcc.gnu.org>]

------- Additional Comments From ghost at cs dot msu dot su  2005-08-30 13:10 -------
To clarify what Marcus said, I've made a small example:  
http://zigzag.cs.msu.su/~ghost/rtti-4.0  
  
The third party library 'libhelper.so' is built with default visibility. I  
want my own library 'libhelper2.so' to be built with hidden visibility.  
However, my library contains this:  
 
    try 
    { 
        foo(); 
    } 
    catch(my_exception& e) 
    { 
 
Both 'foo' and 'my_exception' are defined in libhelper.so -- third party 
library. So, if I build my library with hidden visibility, 'catch' no longer 
works. 
 
I have two solutions: 
1. Add push/pops in other library headers, which is very inconvenient. 
2. Create wrapper headers and add push/pops there, which is very inconvenient. 
 
And if I forget just a single header (which was probably added in the last 
version of third party library), I'll get hard to diagnose bug. Usability cost 
is indeed high. 

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23628