[cfe-dev] C++ Language Support Library

[Doug Gregor]

On Mon, Nov 10, 2008 at 4:33 PM, Chris Lattner <clattner at apple.com> wrote:
>
> On Nov 10, 2008, at 4:50 AM, Doug Gregor wrote:
>
>> Hi Sebastian,
>>
>> On Sun, Nov 9, 2008 at 11:23 AM, Sebastian Redl
>> <sebastian.redl at getdesigned.at> wrote:
>>>
>>> Hi,
>>>
>>> Regarding the C++ language support library, there are a few issues that
>>> I'd like to raise. Please note that this is only about the language
>>> support part of the C++ standard library.
>>>
>>> 1) Which support library do we use?
>>> There are basically two options here. We can write our own, or we can
>>> use libsupc++ from GCC.
>>
>> The licensing issues dominate, so we'll have to write out own. The
>> good news is that the primary entry points to libsupc++ are mainly
>> those functions required by the Itanium C++ ABI that GCC implements,
>> which is specified here:
>>
>>  http://www.codesourcery.com/public/cxx-abi/abi.html
>>
>> If we follow that, and allow for some tweaking, we should be able to
>> maintain compatibility with GCC.
>
> 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.

  - Doug