[ANNOUNCE] GHC 8.2.1 release candidate 2

Alberto Valverde alberto at toscat.net
Fri May 26 09:11:05 UTC 2017


Hi Ryan,

Some preogress... The cabal issues I reported seem more of a nix issue but
I'm not sure what is causing them. FWIW, nix does not use cabal-install at
all but instead compiles the Setup.hs script and runs that.

The weird thing is that i'm trying to reproduce what the nix
haskell-package builder [1] does and the problem I described (no Main.hs
could be found) does not occur but instead the Main.hs module fails to
compile due to an unrelated error. So it seems that, somehow, the unrelated
compile error is being mistaken by a lack of module.

Even weirder is that the snap-server.cabal says that the failing
executables should only be built when flags are enabled (which are disabled
by default) but they are being built anyway when nix calls Setup, even when
I explicitly disable them via nix. The nix build log [2] even says that the
flags (build-pong and build-testserver) are disabled! However, If I
manually execute Setup the configure flags are honored.

I'll continue to investigate to try and make some sense of this but I think
it's not cabal's fault so feel free to ignore me for the meantime. I'll
chime back if/when I find it is an issue with the new Cabal.

Thanks,
Alberto

[1]
https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/haskell-modules/generic-builder.nix
[2]
https://gist.github.com/albertov/eee8af04eeca9f946ab107d416256a05#file-gistfile1-txt-L21

On Tue, May 23, 2017 at 6:28 PM, Ryan Scott <ryan.gl.scott at gmail.com> wrote:

> Alberto,
>
> > I've manage to reproduce the CK bug without any external dependencies and
> > opened a ticket with an attached module that fails to compile with
> > 8.2.1-rc2 (w/o explicit KindSignature) but compiles fine with 8.0.2.
>
> Thanks for doing this!
>
> > Will hopefully follow up soon with the Cabal issues I'm experiencing
>
> One thing that might be useful to do is to invoke Cabal with high
> verbosity (e.g., -v3) and post the logs somewhere. I wouldn't be surprised
> if Nix was passing some uncommonly used flags that have regressed in recent
> versions of Cabal.
>
> Ryan S.
>
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