Re: ghc-options: -threaded breaks some arches

[Neil Mitchell <ndmitchell@gmail.com>]

Hi

> trying to build hlint does not work on some architectures (at least
> alpha, s390, mips) where no threaded RTS is available. An example build
> log is available at
> http://buildd.debian.org/build.php?arch=alpha&pkg=hlint&ver=1.6.4-1
>
> This is caused by
>        ghc-options:        -fno-warn-overlapping-patterns -threaded
> in your hlint.cabal file.
>
> Is there an absolute reason (besides performance) why hlint needs a
> threaded RTS?

HLint supports +RTS -N3, i.e. running on 3 processors. See "Parallel
Operation" in the user manual. It's not absolutely essential, but
without -threaded you can't make use of multiple processors.

> If not, would it be possible to make this option dependent
> on the availability of a threaded RTS (either by direct support in cabal
> for checking it, similar to os(..) checks, or by passing a "-fthreaded"
> flag to setup configure)?

Yes, of course. What suits you? Any os checks would go wrong, so an
-fnothreaded flag seems sensible? I'd still like threading to be the
default.

Thanks, Neil