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Re: How to get top-level library installed in lib/gcc-lib/...?



  In message <13706.3274.474623.435125@slsvhmt>you write:
  > Agreed, but for me the pros outweigh the cons.
Debatable :-)

  > Do you remember the
  > problems people were reporting which were caused by old include/g++
  > include files which have been deleted from the snapshots at a random
  > point in time? 
Certainly.  That's in fact one of the things that led me to suggest
this kind of solution to start with. :-)



  > I even agree with this. But, imagine the other way round: You've just
  > installed a new snapshot, which simply overwrites any existing egcs
  > release's or other snapshot's libs; unfortunately, the new lib's
  > interfaces have changed :-( What gives? The programs won't start,
  > either, or even worse, they'll start but won't work as they should.
Yup.  It's easy to devise ways to lose with either the status quo or
your change.

  > No, I guess the argument against a shared libgcc is mainly that we
  > expect to have more changes in it than in a shared libstdc++ or
  > libg++.
Actually, I'd expect the opposite.  The number of interface changes in
libgcc has been relatively small.  The recent inclusion of EH was probably
the only significant interface *change* in a long long time.

Whereas I've always had the impression due to various issues like
mangling, language issues, vtable layout, EH issues, etc that the
C++ runtime libraries have had many interface changes.  I would
expect the pace of those changes to dimish now that the language and
library specs are settling down though.

The other issue that arises with using shared libraries out of libsubdir
is it introduces a runtime dependency on the gcc libsubdir.  Bad if
it happens to be on an NFS server that's down.


  > Perhaps, this issue is mostly relevant to us gcc/g++/libstdc++ hackers 
  > only. What do you think about this:
  > 
  >   In a release tree shared libraries continue to be installed where
  >   they are right now. The change I've proposed with my patch in a
  >   separate e-mail concerning $(libsubdir) and $(gxx_include_dir) will
  >   only be applied to the snapshots.
That might be the way to go.  Though right now I'd probably lean towards
having configure do this based on flags rather than making it the
default.  But that's a gut feeling from a non-C++ person.


jeff


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