[Haskell-cafe] How to throw an error if using "cabal-install" < version XYZ?

[Carter Schonwald]

Hey Ryan,
I ran into a related issue, heres a a way you can do this safe IN the cabal
file (or at least you can modify my hack for your purposes)

heres a link to the workaround I did for making LLVM-hs work across >= 1.17
and < 1.17 cabal, but you could abuse it to make sure setup.hs barfs on old
cabal https://github.com/bos/llvm/blob/master/base/Setup.hs#L89-L116

heres a quick one off gist that takes my trick and does something helpful
for you variant + makes sure the tool can't build otherwise

https://gist.github.com/cartazio/5632636

I just wrote a snippet that you can just add to your setup.hs and it should
guarantee the setup.hs will barf with a helpful error message on cabal <
1.17.0


On Wed, May 22, 2013 at 10:50 PM, Ryan Newton <rrnewton at gmail.com> wrote:

> A cabal-install bug <https://github.com/haskell/cabal/issues/1284> was
> fixed recently that pertains to building C libraries with profiling.
>
> As a result, I want a certain package<http://hackage.haskell.org/package/atomic-primops-0.1.0.2>to test if cabal-install < 0.17.0 is used, and throw a preemptive error.
>  Otherwise this package fails in weird ways at runtime (it's a nasty one).
>
> I noticed with some surprise the following sequence:
>
> *   $ cabal --version*
> *   cabal-install version 1.16.0.2*
> *   using version 1.16.0.3 of the Cabal library*
> *   $ cabal clean*
> *   $ cabal install*
> *   $ cat dist/build/autogen/cabal_macros.h  | grep VERSION_Cabal*
> *   #define VERSION_Cabal "1.17.0"*
>
> Alright, so that, in retrospect, makes sense.  The version is which *my*
> library is linked with is the relevant one, not the one cabal-install was
> linked with [1].
>
> So the natural next thought is to move the MIN_VERSION_Cabal test into
> Setup.hs, and force cabal to use it by setting the build type to Custom.
>  But... I just learned from this ticket that the cabal macros are not
> available in Setup.hs:
>
>    http://hackage.haskell.org/trac/hackage/ticket/326
>
> Uh oh, what's left?
>
>  -Ryan
>
> [1] P.S. Personally I'm now using a bash function like below, to force the
> two versions to be the same:
>
> function safe_cabal_install () {
>   VER=`cabal --version | tail -n1 | awk '{ print $3 }'`
>   cabal install --constraint="Cabal==$VER" $*
> }
>
>
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