PATCH: (kind of) to improve support for libc++ with libsupc++

[Howard Hinnant]

On Sep 25, 2013, at 2:27 PM, Chandler Carruth <chandlerc at google.com> wrote:

> 
> On Wed, Sep 25, 2013 at 2:23 PM, Howard Hinnant <howard.hinnant at gmail.com> wrote:
> Yes, I object.  Please do not delete libcxx/src/typeinfo.cpp at this time.  This file is still in active use.  Instead #ifdef out any offending symbols.
> 
> I mean, I'm happy to... but that will be all of the offending symbols? And I'm not sure what #ifdef to use. How is it in active use? Understanding this would probably help me craft the correct patch.

Background:  libcxx used to define these symbols.  We are in the middle of migrating them from libcxx to libcxxabi, and for now we need to support both places (while in this transition period).  I would suggest #ifdef-ing on something that only will be defined in the environment where these symbols are causing a problem (users of libsupc++).  I don't know what the #ifdef will be for that environment.  But on some of my platforms of interest _LIBCPPABI_VERSION will not be defined, and I will need the symbols inside of that #ifdef (on the front side of this transition period).

A couple of years from now, then we can probably get rid of this file.

Howard