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

[Jakub Jelinek <jakub at redhat dot com>]

On Sat, Aug 03, 2002 at 01:05:06PM +0200, Jakub Jelinek wrote:
> On Sat, Aug 03, 2002 at 12:36:07PM +0200, Jakub Jelinek wrote:
> > The last step was to make clean in libstdc++-v3 and exchange gcc subdirectories
> > in the two trees (so that 3.2 build tree ended up with gcc 3.3 compiler and
> > vice versa), then run make in libstdc++-v3 followed by make check (ie.
> > basically built 3.2 libstdc++-v3 using g++ 3.3 and 3.3 libstdc++-v3 using
> > g++ 3.2. This resulted in just those 25 XPASSes and 1 26_numeric FAIL.
> 
> Which is an obvious thinko in this last step, because make check was run
> with the same g++ as libstdc++.so.5.0.0.
> I've rerun the tests after swapping back gcc directories, ie.
> 3.2 libstdc++ source + built with g++ 3.3 + make check run against it with g++ 3.2
> 3.3 libstdc++ source + built with g++ 3.2 + make check run against it with g++ 3.3
> but the results were the same, ie. 25 XPASSes, 1 FAIL.

I've redone all the tests with vanilla gcc-3_2-branch and vanilla HEAD both
configured by plain configure, and in this case all 6 different make check
runs gave the same result.
This begs for the question whether if libstdc++ configured with
--enable-threads=posix and configured without this are not
binary compatible, we shouldn't default to
--enable-threads=posix --enable-__cxa_atexit
for linux native builds, so that
a) all linux distributions out there create binary compatible libstdc++
b) people who build gcc themselves and forget about --enable-threads=posix
   would be binary incompatible with vendor compilers

	Jakub