[lldb-dev] Interest in enabling -Werror by default

Wed Feb 17 05:48:30 PST 2016

I think the Linux-x86_64 build using clang is mostly warning free (1
warning on http://lab.llvm.org:8011/builders/lldb-x86_64-ubuntu-14.04-cmake)
but it isn't true for most of the other configuration.

I think -Werror can be enabled on the buildbots on a case by case bases
depending on the decision of the owner/maintainer. The main reason I think
it this way because a change like this will increase the number of build
failures what will give more work to the buildbot maintainer primarily
because most buildbot don't send out failure messages (flakiness) and I am
not convinced that the community will fix some warning based on a report
from a build bot.

As a partial maintainer of 5 different buildbots I don't want to enable
-Werror on any them as I think it will be too much additional maintenance
work compared to the benefit unless we enforce -Werror on local builds as
well (e.g. use -Werror if compiling with clang on an x86_64 platform).

On Wed, Feb 17, 2016 at 3:19 AM Saleem Abdulrasool <compnerd at compnerd.org>
wrote:

> On Tue, Feb 16, 2016 at 12:38 PM, Kamil Rytarowski <n54 at gmx.com> wrote:
>
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>> NetBSD builds with GCC 4.8.2 and it emits few warnings for LLDB.
>>
>> Before enabling -Werror please first iterate over build logs and help
>> to squash them. For example it detects undefined behavior IIRC for a
>> Darwin code part.
>
>
> Interesting.  On Linux, lldb had many warnings, and over time, I've
> managed to get mots of them cleaned up.  Right now, there are a couple of
> -Wtype-limits warnings and one -Wformat warning.  Is there a build bot that
> can be used to monitor what those warnings are?  If there aren't any
> buildbots, then this would be of no consequence since we wouldn't turn it
> on for user builds.
>
> I wish I had caught what I wrote versus what I was thinking before hitting
> send :-(.
>
>
>>
>> On 16.02.2016 20:01, Zachary Turner via lldb-dev wrote:
>> > You're talking about doing it on a per-bot basis and not a global
>> > policy, but just throwing in that on the MSVC side at least, we're
>> > not warning free right now and it's not trivial tog et warning free
>> > without disabling some warnings (which I don't want to do either)
>> >
>> > On Tue, Feb 16, 2016 at 10:31 AM Saleem Abdulrasool via lldb-dev
>> > <lldb-dev at lists.llvm.org <mailto:lldb-dev at lists.llvm.org>> wrote:
>> >
>> > On Tuesday, February 16, 2016, Tamas Berghammer
>> > <tberghammer at google.com <mailto:tberghammer at google.com>> wrote:
>> >
>> > If you want to enable it only on the bots then I think we can
>> > decide it on a bot by bot bases. For me the main question is who
>> > will be responsible for fixing a warning introduced by a change in
>> > llvm or clang causing a build failure because of a warning
>> > (especially when the fix is non trivial)?
>> >
>> >
>> > I think that the same policy as LLVM/clang should apply here.  The
>> > person making the change would be responsible for ensuring that
>> > nothing breaks as a result of their change.  The same situation
>> > exists when working on interfaces that effect clang: a fix for a
>> > warning introduced by a change in LLVM may be non-trivial in
>> > clang.
>> >
>> > Just to be clear, I'm merely suggesting this as an option.  If it
>> > is deemed too burdensome by most of the common committers, we state
>> > so and not do this.
>> >
>> >
>> >
>> > On Tue, Feb 16, 2016 at 4:31 PM Saleem Abdulrasool
>> > <compnerd at compnerd.org> wrote:
>> >
>> > On Tuesday, February 16, 2016, Tamas Berghammer
>> > <tberghammer at google.com> wrote:
>> >
>> > I would be happy if we can keep lldb warning free but I don't think
>> > enabling -Werror is a good idea for 2 reasons: * We are using a lot
>> > of different compiler and keeping the codebase warning free on all
>> > of them might not be feasible especially for the less used, older
>> > gcc versions. * Neither llvm nor clang have -Werror enabled so if
>> > we enable it then a clang/llvm change can break our build with a
>> > warning when it is hard to justify a revert and a fix might not be
>> > trivial.
>> >
>> >
>> > Err, sorry.  I meant by default on the build bots (IIRC, some
>> > (many?) of the build bots do build with -Werror for LLVM and
>> > clang).  Yes, a new warning in clang could cause issues in LLDB,
>> > though the same thing exists for the LLVM/clang dependency.  Since
>> > this would be on the build bots, it should get resolved rather
>> > quickly.
>> >
>> > In short term I would prefer to just create a policy saying
>> > everybody should write warning free code for lldb (I think it
>> > already kind of exists) and we as a community try to ensure it
>> > during code review and with fixing the possible things what slip
>> > through. In the longer term I would be happy to see -Werror turned
>> > on for llvm and clang first and then we can follow up with lldb but
>> > making this change will require a lot of discussion and might get
>> > some push back.
>> >
>> > On Tue, Feb 16, 2016 at 6:02 AM Saleem Abdulrasool via lldb-dev
>> > <lldb-dev at lists.llvm.org> wrote:
>> >
>> > Hi,
>> >
>> > It seems that enabling -Werror by default is within reach for lldb
>> > now.  There currently are three warnings that remain with gcc 5.1
>> > on Linux, and the build is clean of warnings with clang.
>> >
>> > There are two instances of type range limitations on comparisons in
>> > asserts, and one instance of string formatting which has a GNU
>> > incompatibility.
>> >
>> > Is there any interest in enabling -Werror by default to help keep
>> > the build clean going forward?
>> >
>> > -- Saleem Abdulrasool compnerd (at) compnerd (dot) org
>> > _______________________________________________ lldb-dev mailing
>> > list lldb-dev at lists.llvm.org
>> > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>> >
>> >
>> >
>> > -- Saleem Abdulrasool compnerd (at) compnerd (dot) org
>> >
>> >
>> >
>> > -- Saleem Abdulrasool compnerd (at) compnerd (dot) org
>> > _______________________________________________ lldb-dev mailing
>> > list lldb-dev at lists.llvm.org <mailto:lldb-dev at lists.llvm.org>
>> > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>> >
>> >
>> >
>> > _______________________________________________ lldb-dev mailing
>> > list lldb-dev at lists.llvm.org
>> > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>> >
>>
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>
>
>
> --
> Saleem Abdulrasool
> compnerd (at) compnerd (dot) org
>
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