[GHC] #11558: Using Cabal 1.22 against GHC 8.0 results in terrible errors

[GHC]

#11558: Using Cabal 1.22 against GHC 8.0 results in terrible errors
-------------------------------------+-------------------------------------
           Reporter:  bgamari        |             Owner:
               Type:  bug            |            Status:  new
           Priority:  highest        |         Milestone:  8.0.1
          Component:  Package        |           Version:  8.0.1-rc1
  system                             |
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Incorrect
  Unknown/Multiple                   |  warning at compile-time
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 GHC 8.0 will require Cabal >1.22 due to a variety of interface changes
 (see #10714, Phab:D1780, https://mail.haskell.org/pipermail/ghc-
 devs/2016-January/010978.html). Unfortunately things currently blow up
 late in compilation with a seemingly unrelated error when this requirement
 isn't met. Namely, we complain about missing interface files for
 dependencies. For instance,

 {{{
 Text/Parsec/Prim.hs:85:1: error:
     Bad interface file: /root/.cabal/lib/x86_64-linux-
 ghc-8.0.0.20160204/mtl-2.2.1-9wMhzcfsAXi7cNtl9n7svO/Control/Monad/Cont/Class.hi
         Something is amiss; requested module
 mtl-2.2.1 at mtl-2.2.1-1af5dabd2d7abb688f2145aec87badc4:Control.Monad.Cont.Class
 differs from name found in the interface file
 mtl_9wMhzcfsAXi7cNtl9n7svO:Control.Monad.Cont.Class
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11558>
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