[llvm-dev] [RFC] Introduce an LLVM "Incubator" Process

[Renato Golin via llvm-dev]

Hi Chris,

I think this is a great idea. Indeed, MLIR would have been a good case.

In addition to your points, the problems we have to worry about are also:

 - The more subprojects we have, the larger the repo will be, the
harder it will be to know what's what.
 - Adding and removing projects can create infrastructure problems in
testing and downstream processes.

What is the community adoption rate we want to start a new project?
Couple of people "really" interested and fast moving? A lot of people
and a slow moving project? I think all of the above, but that would
pollute the monorepo, creating the second problem.

So, while the idea is great and I'd love to see it running, I think
some deeper consideration should be done in answering the question:
how do we decide where the new project is going to live?

I can see three possible answers: outside of the LLVM project, inside
the project as a new repo, inside the monorepo. Each with different
criteria, and a clause where community pressure can revise those
criteria at some time, and we could move (not necessarily remove) the
projects later.

Makes sense?

cheers,
--renato

On Sat, 20 Jun 2020 at 23:43, Chris Lattner via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>
> Hi all,
>
> Today, we maintain a high bar for getting a new subproject into LLVM: first a subproject has to be built far enough along to “prove its worth” to be part of the LLVM monorepo (e.g. demonstrate community, etc).  Once conceptually approved, it needs to follow all of the policies and practices expected by an LLVM subproject.
>
> This is problematic for a couple reasons: it implicitly means that projects have to start *somewhere else* but proactively decide to follow LLVM design methodology and principles in the hope of being accepted.  It is sometimes socially difficult to get these projects going because there are many other forces that could encourage other practices.  For example, I personally encountered this at Google with MLIR - “why aren’t you using Google coding standards?”, several of us are currently discussing this in a new skunkworks project in the “compilers for hardware” world, and the Flang and other projects have found this challenging in the past.  Once the project gets to a point of critical mass with the “wrong” approach, it is very difficult and expensive to convert to the LLVM style, and from a social perspective, inertia sometimes leads to forking off to separate projects instead of folding back in to LLVM.
>
> A former colleague recently suggested the idea of introducing an incubator process of some sort (e.g. xref the Apache version of this idea).  I think this is a really interesting idea, and it is much easier now that the majority of the “official” code is in the LLVM monorepo.
>
> Here is a sketch of how this could work:
>
>  - We maintain the same high bar to get into the LLVM monorepo, LLVM CI etc.  No change here.
>
>  - We have a very light-weight proposal process that allows people to create incubator projects in the LLVM organization, with no code up front.  The project would be required to have e.g. a charter document and README.
>
>  - Such projects are required to follow the LLVM developer policy, coding standards, CoC, etc, but can define their own stability and evolution process, code owners, etc.
>
>  - When the project is ready to graduate, it would follow the existing process for becoming a first-class part of the mono repo.
>
>  - We have some policy on when to retire/delete projects, which can be ironed out the first time it comes up (e.g. start with a nomination).
>
>  - We could even try to help encourage new projects to include a ‘mentor’ that has experience with the LLVM project to help nudge things in the right direction and encourage proper development approach.
>
> What do you think?  Is anyone interested in helping to write up a more detailed proposal?
>
> -Chris
>
>
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