[cfe-dev] C++ Language Support Library

[Chris Lattner]

On Nov 10, 2008, at 1:41 PM, Doug Gregor wrote:

>> What are the potential license issues of using libstdc++?  While we  
>> could
>> require a different implementation, it would really be nice for  
>> clang to
>> also/optionally support libstdc++.  Is there some strange wording  
>> in the
>> library license?
>
> No, libsupc++ is the same license as libstdc++, which is GPL with an
> exception for software compiled with the library:
>
> // As a special exception, you may use this file as part of a free  
> software
> // library without restriction.  Specifically, if other files  
> instantiate
> // templates or use macros or inline functions from this file, or  
> you compile
> // this file and link it with other files to produce an executable,  
> this
> // file does not by itself cause the resulting executable to be  
> covered by
> // the GNU General Public License.  This exception does not however
> // invalidate any other reasons why the executable file might be  
> covered by
> // the GNU General Public License.
>
> I don't think anything prevents us from supporting libstdc++, but I'm
> guessing we don't want to use it exclusively.

Ok.  libgcc (as of GPL2 days, the GPL3 wording *still* isn't finished  
yet) has strange wording that basically says "the code is GPL unless  
compiled by GCC".  For a random linux distro, for example, it would be  
fine to compile libstdc++ with GCC, and clang should be able to work  
with it.

I think that retaining compatibility with libstdc++ would be a very  
worthwhile goal (as is supporting the apache library, stlport, and/or  
whatever other ones exist, where reasonable).  What is the cost of  
doing this?  Does it use crazy GCC extensions that we don't want to  
implement?

-Chris