[llvm-dev] Flang landing in the monorepo - next Monday!

Renato Golin via llvm-dev llvm-dev at lists.llvm.org
Wed Jan 8 11:01:57 PST 2020

On Wed, 8 Jan 2020 at 01:48, Eric Christopher via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> I am in favor of having a flang front end in tree. I have concerns about the design of flang versus other front ends, the lack of llvm based library use, and a number of other things that I tried to enumerate in previous emails. I don't know if anything has changed and the responses I got back originally were "we're going to do it anyway" so it didn't leave much room for engagement.

(Disclaimer: Not taking sides, I have no stake in Flang or Fortran).

I think David's comparison to LLDB is interesting. It started very
distant, and then with time merged with the codebase and now it's a
full fledged LLVM project.

The current Flang (F18) is meant to be much closer to LLVM than the
previous one, and the whole mindset was afaik to keep it that way. In
the same way that LLDB once was.

I do agree with Hal that there is a small but significant overlap of
communities, and I do agree with Rick that the longer it stays
separate, the harder it will be for that sub-community.

But LLDB started at a time where "being an LLVM project" was mostly
about being in our SVN repo. There was no mono-repo, and the cost of
being there was lower-ish.

I believe that can be solved with build semantics (CMake stuff?), not
a big problem, so the main issue is about community: will the project
move fast enough towards LLVM integration or will it dangle with
downstream implementations and be mostly useless upstream?

I think we have enough people that care about Flang publicly putting
their names forward. This makes me assume the former, so I'm
personally ok with the merge.

If it happens before the current branch or not, will depend on how
fast they're willing to work towards a working Fortran front-end.

I'd assume that, once it's in, the next release (July/20) would have
to have something minimally decent. But that's not a strong opinion,
so, salt & pepper.


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