[Haskell-cafe] Cabal hell (8.2.1,/Haskell Package/MacOS X)

[Gershom B]

Thanks for the heads-up Albert, and for the good detective work. I’m digging into this now…

-g


On October 5, 2017 at 10:51:20 PM, Albert Y. C. Lai (trebla at vex.net) wrote:
> On 2017-10-05 11:47 AM, Mikhail Glushenkov wrote:
> > Hi,
> >
> > On 5 October 2017 at 16:29, Stuart A. Kurtz wrote:
> >> I have problems around trying to install some standard packages: hlint, aeson. A typical  
> error reported by cabal is
> >>
> >> : cannot satisfy -package-id hashable-1.2.6.1-14fEJP30YhAG9w115PODz0:  
> >> hashable-1.2.6.1-14fEJP30YhAG9w115PODz0 is unusable due to shadowed dependencies:  
> >> text-1.2.2.2-EGUst8sqNAZCw1xLPcmcMH
> >
> > This looks like a known Cabal 2.0 bug, which I haven't yet got around to fix:
> >
> > https://github.com/haskell/cabal/issues/4728
> >
> > IIUC, this affects both Stack and Cabal, but only when used with GHC
> > 8.2.1. Downgrading to GHC 8.0.2 should help for now.
>  
> I have found the cause (first-order cause anyway) and wrote it up on the
> cabal issue and the haskell-platform issue, and explained why the stack
> issue is unrelated, all on github. Please refer to those issues
> separately for details. Oh too bad the Haskell Platform people closed
> theirs, because it is totally a Haskell Platform build error for some
> builds.
>  
> In short, while I don't have Mac and so I need you to do the following
> checks, I have Linux and checked it. Best to start with a fresh install,
> full binary version, for minimum doubt:
>  
> 1. "ghc -v" to see you already have shadowing messages right from the
> start with a clean slate.
>  
> 2. "ghc-pkg field hashable abi-depends" for example and look at the
> oddity "text-...=inplace" in contrast to more common ones like
> "base-...=hexstring". This is why GHC says it can't find the right text
> for hashable. (See also "ghc-pkg field base abi" and "ghc-pkg field text
> abi", these are what GHC checks against.)
>  
> The Windows version doesn't have this problem because the abi-depends
> fields don't even exist there. This is probably because the Windows
> versions was built by Cabal 1.x.
>  
> The core versions don't have this problem.
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