Re: somewhat-auto-rebuilding libgcc.a with -fhonor-std

[Phil Edwards <pedwards at jaj dot com>]

> The general approach seems to make sense. I wouldn't spend too much time
> getting this to be super clean, as I think this is just going to have to
> be kluged due to the current way g++ builds libgcc.a.

If it gets too ugly, I'll just sign the ChangeLog as "A. Nonymous"...

Of course, now that I've announced that on a publicly-archived mailing
list, I'll have to choose a new name!


> If you can, just make the libgcc.a rebuild conditional on a
> --enable-runtime-rebuild=yes flag or something, and have it prompt
> the user for the proper sym link to the gcc build (src?) directory (or
> however you find it easiest to do the job).

How about 
  o   '--enable-libgcc-rebuild=path/to/gcc/builddir' turns it on
  o   'make'  by default does the work

It looks like the only difficulty is going to be the re-installation
of libgcc.a.  We could invoke gcc's "make install-libgcc" ourselves,
but we can't make any backup copies or set up any symlinks to let the
user switch back and forth (where libgcc.a gets placed isn't known to us
unless we try grepping it out of their Makefile).  Do we require the user
to do the installation?  (I'd vote yes.)


> Or you can just mandate people using --enable-runtime-rebuild keep their
> build (src?) dirs around. I don't see a problem with this.

Yeah, we need both build and src.  Not /all/ of both, but I'm not going to
try and discover the minimum sets of code, because I'm coming down with
a cold.  I'll just add a note to the docs saying, "If you've already
removed the builddir, you're being a chump.  Reconfigure gcc same as
before and then either read <my first email message> or just rebuild
everything and re-run 'make' in libstdc++."

Phil