Windows build failing in a new way

[Ben Gamari]

lonetiger at gmail.com writes:

> Ah great,
>
> Triples again.. I still wonder why it is suddenly an issue. We haven’t
> touched the .m4 file in a while and no one changed libffi either
> right? This is just like last time the normalization bit us. Causing
> days of broken builds on different targets while everyone fixed the
> one they were interested in.
>
Well, the patch that Reid points out indeed does change the triple which
we pass to subproject configures. However, I have been utterly unable to
reproduce this locally nor on the Harbormaster machine (both with
./validate).

Nevertheless, I have a hypothesis for the cause and a proposed fix in
D3304.

> Why do we do the normalization? It doesn’t seem to give us any
> benefits at all.. Maybe we should stop doing it after the branch for
> 8.4?
>
Well, there are a few different normalizations which you might mean
here. The patch in question affects autoconf's canonicalization. The
patch in question actually removes what may be the last reference to the
autoconf-canonicalized triple. However, my proposed fix then
reintroduces the need for it, since I suspect the cause is that we are
passing an empty triple to subproject configures.

There is also the matter of GHC's own triple normalization (e.g.
GHC_CONVERT_OS and friends, defined in aclocal.m4). I'm frankly not
entirely sure this is doing much harm and replacing it with autoconf's
canonicalized triple would be a non-trivial amount of work. However, if
you want to try I wouldn't be opposed.

Cheers,

- Ben

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