Re: Latest LLVM breaks our code again

Hi,

On 2022-02-03 10:44:11 +0100, Fabien COELHO wrote:
> > I'm doubtful that tracking development branches of LLVM is a good
> > investment. Their development model is to do changes in-tree much more than we
> > do. Adjusting to API changes the moment they're made will often end up with
> > further changes to the same / related lines. Once they open the relevant
> > release-NN branch, it's a different story.
> >
> > Maybe it'd make sense to disable --with-llvm on seawasp>
> > and have ppppppa separate animal that tracks the newest release branch?
>
> The point of seawasp is somehow to have an early warning of upcoming
> changes, especially the --with-llvm part. LLVM indeed is a moving target,
> but they very rarely back down on their API changes…

The point is less backing down, but making iterative changes that require
changing the same lines repeatedly...

> About tracking releases: this means more setups and runs and updates, and as
> I think they do care about compatibility *within* a release we would not see
> breakages so it would not be very useful, and we would only get the actual
> breakages at LLVM release time, which may be much later.

LLVM's release branches are created well before the release. E.g 13 was afaics
branched off 2021-07-27 [1], released 2021-09-30 [2].

> For these reasons, I'm inclined to let seawasp as it is.

I find seawasp tracking the development trunk compilers useful. Just not for
--with-llvm. The latter imo *reduces* seawasp's, because once there's an API
change we can't see whether there's e.g. a compiler codegen issue leading to
crashes or whatnot.

What I was proposing was to remove --with-llvm from seawasp, and have a
separate animal tracking the newest llvm release branch (I can run/host that
if needed).

Greetings,

Andres Freund

[1] git show $(git merge-base origin/release/13.x origin/main)
[2] git show llvmorg-13.0.0