[cfe-dev] How to deal with new build failures due to new warning? Was: Re: buildbot failure in LLVM on clang-with-lto-ubuntu

[David Blaikie via cfe-dev]

/probably/ not worth worrying about changing the build system to
disable/enable the flag - if there's pretty high confidence that you've
built all the things and fixed all the warnings, it's OK to commit it and
revert the patch if you missed. (I've committed and reverted patches (of
significant/greater complexity) maybe 4-5 time due to deeper and deeper
failures in buildbots - not ideal, to be sure, but not unheard
of/impractical)

But also seems worth understanding which case the Clang warning is firing
that the GCC warning is not - since the GCC warning is certainly caught and
fixed by some buildbots or users, so I wouldn't expect the LLVM codebase to
be too far from clean.

On Sat, Jun 10, 2017 at 11:07 AM Roman Lebedev via cfe-dev <
cfe-dev at lists.llvm.org> wrote:

> On Sat, Jun 10, 2017 at 8:47 PM, Mehdi AMINI <joker.eph at gmail.com> wrote:
> > Hi,
> >
> > I would first revert it *now* because the bot needs to stay green *now*.
> Reverted.
>
> > Then either the warnings can be fixed as a pre-commit to the added
> feature,
> > or if not possible the LLVM cmake config should first be updated to
> detect
> > and explicitly disable this warning.
> I think i'll attempt the following approach:
> 1. build all the llvm components i can with clang with the warning
> 2. fix all related warnings, commit after review
> 3. temporarily add -wno-error=cast-qual
> 4. recommit
> 5. revert -wno-error=cast-qual and see if anything breaks
> 6. either revert previous commit, and fix newly-catched issues, or all
> good.
>
> > --
> > Mehdi
> Roman.
>
> > 2017-06-10 10:40 GMT-07:00 Roman Lebedev via cfe-dev
> > <cfe-dev at lists.llvm.org>:
> >>
> >> Hi everyone.
> >>
> >> In D33102, -Wcast-qual was implemented for C++,
> >> so naturally it now produces warnings for clang codebase.
> >>
> >> That specific warning
> >> (cast from 'a' to 'b' must have all intermediate pointers const
> >> qualified to be safe)
> >> is clang-specific, i'm pretty sure gcc does not produce it.
> >>
> >> To be perfectly honest, i did not thought about trying
> >> to build llvm/clang with the clang with that warning beforehand.
> >>
> >> So here is the question: how to proceed?
> >> Revert? Disable that diagnostic? Etc?
> >>
> >> Roman.
> >>
> >> On Sat, Jun 10, 2017 at 8:28 PM,  <llvm.buildmaster at lab.llvm.org>
> wrote:
> >> > The Buildbot has detected a new failure on builder
> clang-with-lto-ubuntu
> >> > while building cfe.
> >> > Full details are available at:
> >> >  http://lab.llvm.org:8011/builders/clang-with-lto-ubuntu/builds/3249
> >> >
> >> > Buildbot URL: http://lab.llvm.org:8011/
> >> >
> >> > Buildslave for this Build: ps4-buildslave1a
> >> >
> >> > Build Reason: scheduler
> >> > Build Source Stamp: [branch trunk] 305147
> >> > Blamelist: lebedevri
> >> >
> >> > BUILD FAILED: failed build-stage2-LLVMgold.so
> >> >
> >> > sincerely,
> >> >  -The Buildbot
> >> >
> >> >
> >> >
> >> _______________________________________________
> >> cfe-dev mailing list
> >> cfe-dev at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
> >
> >
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