Re: C++ ABI testing issues, gcc-3.3 <-> gcc-3.2 compatibility

[Benjamin Kosnik <bkoz at redhat dot com>]

> > > (Brendan Kehoe, Jeff Law suggestion to run 'make check-c++' two
> > > ways, one with a new compiler and an old library, and the other
> > > with an old compiler and a new library, and look for testsuite
> > > regressions)
> > 
> > Indeed.  For reference, what's the best way to do this?
> 
> Swap libstdc++-v3/src/.libs/libstdc++.so.5.0.0 binaries between built
> 3.2 and trunk trees before running make check?

Exactly. What I did, which I will soon document in abi.txt, is:

1) mkdir ~/c++abitest
2) mkdir ~/c++abitest/3.2
3) mkdir ~/c++abitest/3.3
4) make a gcc (3.3) and gcc-3_2-branch (3.2) build, and run 
'make check-c++' in each to establish baselines.
5) copy the 3.3 libraries to a set directory:
  cd /mnt/hd/bld/bld-x86-gcc/i686-pc-linux-gnu/libstdc++-v3/src/.libs
  cp libstdc++.so.5.0.0 ~/c++abitest/3.3/
6) copy the 3.2 libraries to a set directory:
  cd
/mnt/hd/bld/bld-x86-gcc-3_2-branch/i686-pc-linux-gnu/libstdc++-v3/src/.
libs
  cp libstdc++.so.5.0.0 ~/c++abitest/3.2/
7) copy the 3.2 library into the 3.3 build directory, as above
8) copy the 3.3 library into the 3.2 build directory, as above
9) re-run 'make check-c++' in each build directory.


I've reproduced this again. Same stack trace as before, and binutils,
etc. are all the same. 

I'm not quite sure how to proceed, but I'd apprecaite it if first
somebody else could try to verify my results.

It looks like everything links, so I think the libstdc++ symbol
exporting is ok, but something else is wrong.

 -benjamin