[GHC] #16211: Recompiling results in a missing instance

[GHC]

#16211: Recompiling results in a missing instance
-------------------------------------+-------------------------------------
        Reporter:  crockeea          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  error/warning at compile-time      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by crockeea):

 Simon, it looks like you have a pretty outdated Hackage snapshot. Perhaps
 try a `cabal update`? The latest version of monad-classes is 0.3.2.2, but
 your failed installation was trying 0.3.2.0.

 {{{
 > ghc --version
 The Glorious Glasgow Haskell Compilation System, version 8.6.3

 > cabal --version
 cabal-install version 2.4.1.0
 compiled using version 2.4.1.0 of the Cabal library

 > cd bug

 > cabal sandbox init

 > cabal install --only-dependencies
 Starting     peano-0.1.0.1
 Starting     base-orphans-0.8
 Starting     reflection-2.1.4
 Starting     primitive-0.6.4.0
 Building     base-orphans-0.8
 Building     reflection-2.1.4
 Building     primitive-0.6.4.0
 Building     peano-0.1.0.1
 Completed    base-orphans-0.8
 Starting     transformers-compat-0.6.2
 Completed    peano-0.1.0.1
 Building     transformers-compat-0.6.2
 Completed    reflection-2.1.4
 Completed    transformers-compat-0.6.2
 Starting     mmorph-1.1.2
 Starting     transformers-base-0.4.5.2
 Building     transformers-base-0.4.5.2
 Building     mmorph-1.1.2
 Completed    transformers-base-0.4.5.2
 Starting     monad-control-1.0.2.3
 Completed    mmorph-1.1.2
 Completed    primitive-0.6.4.0
 Building     monad-control-1.0.2.3
 Completed    monad-control-1.0.2.3
 Starting     monad-classes-0.3.2.2
 Building     monad-classes-0.3.2.2
 Completed    monad-classes-0.3.2.2

 > cabal build
 <success>
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16211#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler