possible red flag for new C++ parser

[Wolfgang Bangerth]

> [Long text deleted]
> It would be interesting, first, to measure the number of possible
> regressions, then to sample them to get some idea of how they line up.
>
> Statistical sampling might reveal that:
>	1) Most apparent regressions aren't regressions at all, but
>           are bugs in the C++ code that the old parser didn't catch. 
>           (false regressions)
>	2) Most apparent regresssions are regresssions -- cases of
>           good code that the new parser fails on.  (true 
>           regressions)
>	3) Somehere in the middle between (1) and (2).
> [More long text deleted]

Rather than filibustering, I think real help would be more appreciated.

Tracking gcc-bugs would reveal the answers to all this speculation. Also 
asking practitioners of transitioning code might help -- I have done this 
with our 200k lines of template heavy code.

The real world situation is:
- lots of bugs in applications where compilers were just too lenient; 
  there's not much gcc can do about, but that also means that most 
  packages are not useful for testing the new parser; authors of that code 
  need to step in
- lots of bugs in the new parser; a lot is being done on this situation

Given that 3.4 will not be out until late this year at the earliest, 
application writers will have one year to fix their code. And Mark et al 
do and will certainly make sure that most regressions found by then will 
be fixed until the release. And even more time until vendors will use 3.4 
as the base for their releases.

So no reason to suggest that the new parser will be a serious threat to 
the gcc project, or that the end of the world is close. It will be a 
threat to projects that don't care to bring their sources into accordance 
with language standards, but that's not something that we should be 
concerned about. Also not a concern for the C++ packages everybody cares 
about (e.g. KDE), they'll certainly make sure their code is ok.

Regards
  Wolfgang

-------------------------------------------------------------------------
Wolfgang Bangerth             email:            bangerth@ticam.utexas.edu
                              www: http://www.ticam.utexas.edu/~bangerth/