Re: [boost] gcc visibility support

Subject: Re: [boost] gcc visibility support
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2009-06-07 16:33:15

Vladimir Prus wrote:
> Over in issue 2114 (https://svn.boost.org/trac/boost/ticket/2114), Jürgen has
> provided a patch to add gcc visiblity support to all separately compiled libraries.
> gcc visibility is a mechanism similar to dllexport on Windows, with the same
> benefits.
> 
> I have tried to apply it, and rebuild program_options. The the size of release 
> shared library went from 272K down to 224K. The number of relocations went
> from 972 to 872. Both changes seem to be good.

For the record, there was a discussion about visibility support and the 
patch:

http://lists.boost.org/Archives/boost/2008/12/146068.php

Last time I heard the patch broke program_options.

> It seems to be unlikely to get the authors of every compiled library to
> look at the patch, so it looks like an alternative approach is necessary.
> Does anybody have any objections to this approach? If not, I'll check
> this in somewhere before Jule 15 deadline, and will take care of checking
> regression results afterwards.

Perhaps we could search for exception classes and mark them as exported 
right away? We could do this, e.g., by looking for throw_exception or 
throw expressions. A lot of work, I know, but it has to be done anyway.

Maybe there are other procedures necessary to make sure it works. 
Boost.Exception comes to mind as a possible source of issues. It is 
related to both exceptions and dynamic_cast. I'm guessing, at least 
error_info should be exported, too.