[llvm-dev] Email list just for front end developers?

[Perry E. Metzger via llvm-dev]

Pardon the length of this reply, but it seemed useful to be explicit
about my concerns.

On Sun, 7 May 2017 00:55:51 +0800 C Bergstrom
<cbergstrom at pathscale.com> wrote:
> You don't seem to be listening, but one last try.

I listened. I respectfully disagree.

> If you have a FE related question - Ask on cfe-dev and if you don't
> get a response I'd be surprised.

I would not be surprised.

I'll be straightforward. It is very hard to get answers to questions
on any of the lists about simple front end stuff, especially stupid
newbie questions. It is also hard to get answers to simple questions
in the IRC chat room. (I've tried, believe me.)

I can understand why. It isn't anyone's fault, and it isn't
unexpected. These questions aren't very interesting to people who are
deeply involved in the Clang infrastructure or the LLVM optimization
infrastructure, they're probably quite repetitive, and I'm sure that
sometimes they're annoying because they're so obvious and basic to
people who live and breathe LLVM. That's entirely understandable.

However, there are many people out there, maybe even a lot more than
are developing Clang in fact (though it is hard to know), who are
developers using LLVM for other languages.

Yes, I agree there are more _users_ of Clang than there are of Rust
and Julia and Rubymotion and Crystal and Clasp and the dozens of
others out there. After all, Clang is Apple's compiler, so there are
huge numbers of users of Clang. However, in terms of people
_developing_ other front ends, I get the impression there are a very
large number of us, because, frankly, right now LLVM is the most
rational choice for any compiler developer, and the world has a lot of
compilers under development. (Indeed, it has more than it used to
partially because LLVM exists.)

It makes sense to have a place for us to talk to each other where
we're the dominant traffic, where our questions for each other aren't
concealed amidst a very large amount of traffic on Clang's internals
(or the rest of LLVM's), and where and our questions unrelated to local
concerns are not viewed as an annoyance.

Again, I suspect front end developers will generally be more
sympathetic to each other's problems and questions than people who are
worried much more about Clang's internals or the backend internals.

> Additionally, if you don't get a response

It isn't a question of "a" response. I myself have a new question
almost every day. After one sees what happens when people ask
questions, one gets intimidated and does not wish to continue.

Here's an example. This post about a month ago from someone having a
great deal of trouble with very basic things got not a single answer
in response:

http://lists.llvm.org/pipermail/llvm-dev/2017-March/111526.html

I think that gentleman's situation is very typical. I've had questions
almost identical to his, too. I've been reduced to reading source code
instead of documentation, painfully, and making very slow progress
because of it.

Again, I don't blame anyone for this state of affairs. LLVM is open
source software, and no one has any duty to answer my questions, write
documentation for me, etc. I cannot reasonably ask that people who are
working hard on a new processor back end or new optimizations or what
have you take time out to help me. It isn't their job.

I would just like a place that makes self help among other people in
my position and that of the gentleman whose query I link to above more
likely to succeed.

> from there maybe then follow-up with your idea of another list.

I understand that it may be too much trouble to ask the LLVM project
to set up another mailman mailing list.

If that is the case, given that I have my own mailman setup, perhaps
I'll just create the list on my own machine and advertise it, and
perhaps create a Wiki. It would be unofficial so fewer people would
find it, which might doom it, but as I've indicated, I would like to
have such a thing, and I suspect others would, too, so perhaps that's
the route to take.

I don't want to bother people associated with the project overly much,
as frankly I'd prefer that all of you spend your time making LLVM even
better, and if the project doesn't want to create such a list I won't
push, I'll just do it on my own if it continues to seem important to me.

> What you're describing would be extremely low traffic

I very, very much doubt that will be the case.

I understand that this isn't obvious to those who are very familiar
with the way LLVM works, but again, it is challenging getting started
with LLVM once one is past the tutorial. One has endless questions
about details the tutorial doesn't cover, and the documentation sadly
doesn't help with them. Even when one is past that stage, one keeps
encountering issues one would like to ask about.

There are also a lot of people out there working on LLVM based front
end projects, far more even than LLVM web site indicates. There are
also whole classes of undergrads using LLVM in compiler courses and I
suspect they have questions too.

And, once again, most of us learn very quickly that simple newbie
questions generally don't get answered by busy people who have other
interests. (And again, this is understandable.)

That's fine, I understand why it is the case. I don't want to bother
others who have other concerns. I just want a place to ask
questions. If such a list existed, I would be able to contribute quite
constructively -- I've learned the answers to many of my own questions
"the hard way" by having to read the sources, and I could help others
to avoid having to do the same thing with things I understand. I would
also probably feel less put off asking simple questions on such a
list. I bet one of the developers of Rust or the JavaScript JIT or the
Common Lisp front end or Crystal or Julia or any of the literally
dozens of others would probably be happy to answer my questions,
having had the same steep learning curve themselves.

> and I personally doubt you'd get as much expertise interested in
> order to keep it viable.

Then it will fail. That's a risk with any new mailing list. Luckily,
the cost of mailing lists is very low, so the only risk is that the
list gets no traffic. If that happens, well, so be it.

Perry
-- 
Perry E. Metzger		perry at piermont.com