sharing libcpp between GDB and GCC

[Jim Blandy <jimb@redhat.com>]

At the moment, libcpp lives in the `gcc' directory of its source tree,
and it shares GCC's makefile and configure script.

I assume there's general agreement that, if GDB and GCC are going to
share libcpp, we'll want to pull libcpp out into its own top-level
directory, with its own makefile and configure script, and move its
header files into the top-level #include directory.  Is that so?

There are two approaches we could take; I'm not sure which is best.

- The GCC folks could do this extraction, ensuring that GCC continues
  to work.  Then we can copy that directory over into GDB's
  repository, and begin the libcpp/GDB integration.

- Or, the GDB folks could make their own libcpp directory and drop my
  simple-minded expander into it, along with its header file, ensuring
  that GDB continues to work.  Then, we wipe that out and replace it
  with libcpp, and do the libcpp/GDB integration as part of the same
  commit.

I think I prefer the former.  In the latter case, one has to do the
simple-minded-to-libcpp replacement simultaneously with the libcpp/GDB
adaptation, or else GDB will cease to work.  In the former case, we
can have libcpp sitting in GDB's repository, while GDB continues to
use the simple-minded expander, and do the libcpp/GDB reconciliation
(whatever is necessary) as a separate step.

Are the GCC folks willing to tackle this?  Do you agree that this
seems to be the next logical step?

(I've got some weird reverse-caffeine headache or something, so if
this is totally stupid, please be kind.)