[libcxx-commits] [PATCH] D111356: [runtimes] Use the new "runtimes" build by default and deprecate other builds

[Louis Dionne via Phabricator via libcxx-commits]

ldionne accepted this revision.
ldionne added a comment.
This revision is now accepted and ready to land.

In D111356#3065368 <https://reviews.llvm.org/D111356#3065368>, @bcain wrote:

> In D111356#3064401 <https://reviews.llvm.org/D111356#3064401>, @ldionne wrote:
>
>> I haven't seen a lot of discussion on this, either here or on the lists where I posted my RFC. Does this sounds reasonable to you all?
>>
>> Pinging @tstellar and @bcain in particular because I think they are using standalone builds at the moment, and I want to have their blessing that this is going to work for them. Actually folks, you could move to the new "default" build right away to try it out if you wanted.
>
> Louis, thanks so much for sending the notice to llvm-dev, it will really help us plan for this change.  We needed an incentive to switch and this is a great forcing function.  I was uncomfortable with the fact that we were using odd (less popular) build configurations downstream.

Awesome! That's what communication is for :-).

> Your question about whether "this is going to work" -- do you mean the deprecation, or the ultimate removal?

What I meant here was "do you think the new default build is going to work as a replacement for your existing standalone build setup?". The situation I want to avoid is one where we deprecate (and eventually remove) the standalone build, but without actually providing you a proper replacement. This whole deprecation process is based on the assumption that the new "default" build solves all the problems that the standalone build used to solve, but better. If that turns out not to be true for some users, I want to know about it so we can address these issues and make sure we cater to your needs.

> The ultimate change to only support runtimes-style builds is planned for post LLVM-14?  That works for us, we'll start changing downstream build configs pretty soon, in ~Nov/Dec 2021.  I can't identify any objection, I am hoping/expecting there's no issues for us moving to runtimes (or formerly-known-as-runtime).

Actually, to clarify, we will keep supporting two types of build. The first one will be the "default" build, where one builds the runtimes with the system compiler (similarly to what you did with the standalone builds). The second one is what we call the "Runtimes build" today (we're moving to the "Bootstrapping build" naming), where one builds Clang from source and then builds the runtimes using that Clang.

There is no plan to force people to build their own Clang before building the runtimes.

In D111356#3065931 <https://reviews.llvm.org/D111356#3065931>, @tstellar wrote:

> This is fine with me.

Awesome!

So what I'm going to do now is ship this since it's only a policy change anyway. We're still supporting all the same builds for now, but now at least we have a clear path forward and people can start moving to the new ways to build. If someone has an objection on this, please comment here (and perhaps ping me on Discord to make sure I don't miss it). Even though this will be closed, we can still discuss the details of how we're going to make this transition.


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https://reviews.llvm.org/D111356