[m-rev.] for post-commit review: fix decision about parallel folds

[Zoltan Somogyi]

On Mon, 26 Aug 2024 17:25:55 +1000, Peter Wang <novalazy at gmail.com> wrote:
> I think the idea was that failing to set up the IPC for a parallel fold
> is unexpected, so we should stop ASAP.

I also think that is a good idea, but only if we report the actual problem
as the reason we stopped. The code the diff replaced reported the problem
as being with the program being compiled, which is very misleading.
Unfortunately, the make package's infrastructure has no way to distinguish
between "did not succeed due to a platform problem" and "did not succeed
due to an error in the program being compiled"; it assumes all failures
are of the latter kind.

We *could* improve the infrastructure to allow us to make this distinction.
The question is: is this kind of failure frequent enough to make that programming
effort worthwhile? I don't use mmc --make myself, but my guess is that the
answer to that is a resounding "no".

> But falling back to sequential
> operation could be okay.

I thought so too, which is why I made the diff.

Zoltan.