"introduce no new bootstrap warning" criteria. was: Loop iv debugging, patch

[Geoff Keating]

> Date: Fri, 12 Jan 2001 11:07:39 -0500 (EST)
> From: "Kaveh R. Ghazi" <ghazi@caip.rutgers.edu>

> I looked into what it would take to turn on -Werror and/or
> -pedatic-errors and that doesn't seem possible.  There are too many
> unfixable messages requiring a pragma silencer and also many warnings
> only appear on unusual platforms so we'd have a real hard time getting
> this to work without breaking bootstrap on lots of systems.  Plus any
> time a new warning is added to -Wall, it would break systems until
> completely silenced also.

Why do we have unfixable warnings in -Wall?  They're not supposed to
be there.

> Instead, my suggestion would be to run some kind of regression checker
> like what we have for the testsuite.  Have it email whoever introduces
> warnings until they fix it, just like the testsuite nag.  That way we
> at least hold the line on the current warning count, and getting
> closer to zero is attainable.
> 
> I don't have time to make this happen, but I suspect it wouldn't be
> too hard using Geoff's current regression checker hooked up to the
> contrib/warn_summary script in some fashion.  Focus on the "Number of
> warning types:" but ignore line numbers or filename in case moving
> code around changes where the warning comes from.

There's a big gotcha here: the regression tester uses gcc 2.95.2 as
the host compiler.  Thus, it gets quite a number of spurious warnings
due to bugs in 2.95.2.  It's also not reproducible, because the
warnings you get on sparc-solaris are not the same set as the warnings
you get on x86-linux or even sparc-linux.  This is likely to be a
fatal problem for any such tool.

IMO, it would be better to switch off -Wall, switch on -Werror, and
switch on individual warning flags until something breaks.

-- 
- Geoffrey Keating <geoffk@geoffk.org>