[llvm-dev] [PROPOSAL] Add Bazel Build Configuration to the LLVM Monorepo

[Chris Lattner via llvm-dev]

Hi Adrian,

This proposal is not changing the LLVM build system.  We are sticking with cmake.  This is just checking in some extra files into the repository to help out a sub community that cares about bazel.  As others mentioned, this was discussed in depth in the proposal and related threads,

-Chris

> On Mar 25, 2021, at 1:10 PM, John Paul Adrian Glaubitz via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> Hello David!
> 
> On 3/25/21 7:12 PM, David Blaikie wrote:
>> (full disclosure, I am a Google employee)
>> 
>> I don't think this is appropriate content, communication, or tone for the
>> LLVM community.
> 
> Since English is not my native language, my wording may not convey 100% what I'm
> trying to say and my tone may seem inappropriate. However, is not my intention to
> be rude, I'm just trying to raise some concerns given the current state of Bazel
> and the personal experiences I made with some Google projects in the past.
> 
>>> Looking at the amount of copy-and-paste code in Bazel [1], I'm not really
>>> convinced
>>> that the code quality of Bazel speaks for itself.
>>> 
>> 
>> This patch doesn't seem to me to be reflective of "good" or "bad" code, nor
>> has anyone made any claim about the code quality of Bazel. It isn't
>> relevant to this discussion.
> 
> My personal concern is that Bazel will eventually have an impact on the portability
> of LLVM or any other projects that adopt it like Chromium did in the past with project
> adopting it as their HTML rendering engine. Looking at the current build status of Bazel
> in Debian, it builds on 6 of the 23 architecture/platform combinations that Debian
> supports,
> 
>> https://buildd.debian.org/status/package.php?p=bazel-bootstrap&suite=sid
> 
> which I find rather suboptimal for a build system. The build system should not be
> the limiting factor when it comes to portability and I know no other build system
> besides "gn" which has similar portability issues. cmake, meson, scons, qmake and
> so on don't have these portability limitations. They just work on any target you
> compile them for and they can also easily be bootstrapped.
> 
> For "gn", I needed to download a prebuilt build-enviroment (IIRC a whole chroot) to
> build it from source back then. I don't know if that has changed in the meantime.
> 
>>> I wish it would be more balanced and Google would allow patches in
>>> Chromium or V8
>>> to support more architectures if - on the other hand - they ask other
>>> upstream
>>> projects to carry support for their usecases.
>> 
>> These seem like unhelpful ad-hominem criticisms that aren't relevant to the
>> matter being discussed. This proposal has been specifically designed to be
>> minimally impactful to the community (should only be "there are some more
>> commits to the project/more commit list emails" - and if gn is anything to
>> go by, not many (<0.1% I'd wager, at a rough guess)).
> 
> I don't think that stating facts are ad-hominem attacks. I made similar experiences
> with Google projects and I found these experiences frustrating. In particular, one
> of the experiences was an endianness issue with Skia [1] which has also seen wider
> adoption in other projects which means missing portability hurts the portability of
> these projects. There was also a SPARC port for Go which got rejected due to lack of
> interest by the upstream project and the POWER port of Chromium [2] which got never
> merged for whatever reason. As a result, any project that adopts any of these technologies
> will reduce its portability.
> 
> KMail, KDE's email client, for example used to be highly portable and was available
> of all of Debian's supported architectures/platforms. Nowadays, KMail just runs
> on the few architectures that Chromium supports which I consider a step backwards.
> 
> So I personally would like to see that Bazel becomes as portable as any other commonly
> used build system before it is advertised as a versatile and advanced build system so
> that it's not going to have the same impacts on portability as Chromium does.
> 
> Adrian
> 
>> [1] https://bugs.chromium.org/p/skia/issues/detail?id=7808
>> [2] https://groups.google.com/a/chromium.org/g/chromium-dev/c/MYq1DPz9Tak
> 
> -- 
> .''`.  John Paul Adrian Glaubitz
> : :' :  Debian Developer - glaubitz at debian.org
> `. `'   Freie Universitaet Berlin - glaubitz at physik.fu-berlin.de
>  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913
> 
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