Re: Libstdc++ as DLL on windows, alternative approach [was Re: cygwin patch review]

[Benjamin Kosnik <bkoz@redhat.com>]

>   Ok, so as we discussed before, this doesn't currently work.
> However it does sound like the right thing to do, so I've spun a new
> version of the patch that applies dllimport to the namespace.  We
> could commit this and then open a PR about dllimport not working on
> namespaces.  It's much smaller and cleaner than the version that adds
> markup everywhere, but I doubt I'll be able to fix the
> dllimport-vs-namespace bug in time for 4.5.  That's not the end of
> the world; getting dllimport right is a good optimisation, but we can
> live with the compromise of auto-import for now.

I like this plan. What's the PR number? And can you affix your
patch from here to it:
http://gcc.gnu.org/ml/gcc-patches/2009-11/msg00979.html

Thanks. 
 
>   Initial test results (c and c++ only) are posted(*) and look right,
> but I'll do a clean run on the same source revision for comparison
> anyway.  Note that I had to patch various testsuite/lib/ files to
> avoid the current utf-8 problem(**) that would otherwise have
> provoked many spurious 'excess errors' warnings.  That'll be the
> subject of a separate patch, I'll do the clean run using them as well
> so the comparison is fair.

It looks like (in later messages) you have an updated patch. But your
updated results here looks great:
http://gcc.gnu.org/ml/gcc-testresults/2009-11/msg01084.html

> libstdc++-v3/ChangeLog:
> 
> 	* libstdc++-v3/acinclude.m4 (GLIBCXX_ENABLE_SYMVERS): Don't
> disable on PE targets.
> 	* libstdc++-v3/configure: Regenerate.
> 	* libstdc++-v3/configure.host: Add libtool DLL options for
> Cygwin and MinGW platforms.
> 
> 	* libstdc++-v3/include/bits/c++config
> (_GLIBCXX_VISIBILITY_ATTR): On platforms that don't support
> visibility, allow them to declare a macro _GLIBCXX_PSEUDO_VISIBILITY
> that is applied in place of visibility.
> 
> 	* libstdc++-v3/config/os/newlib/os_defines.h
> 	(_GLIBCXX_PSEUDO_VISIBILITY_default): New macro for dllimport.
> 	(_GLIBCXX_PSEUDO_VISIBILITY_hidden): New empty macro.
> 	(_GLIBCXX_PSEUDO_VISIBILITY): Evaluate to one of the above.
> 	* libstdc++-v3/config/os/mingw32/os_defines.h
> 	(_GLIBCXX_PSEUDO_VISIBILITY_default,
> 	_GLIBCXX_PSEUDO_VISIBILITY_hidden,
> 	_GLIBCXX_PSEUDO_VISIBILITY): Likewise.
> 
>   So, is this any more like OK for head?

Yes, exactly. Thanks. This is OK with me.

best,
benjamin