[GHC] #14594: 2 modules / 2500LOC takes nearly 3 minutes to build

[GHC]

#14594: 2 modules / 2500LOC takes nearly 3 minutes to build
-------------------------------------+-------------------------------------
        Reporter:  schyler           |                Owner:  dfeuer
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by dfeuer):

 Simon, here's a tiny repro:

 {{{#!hs
 {-# language RankNTypes #-}
 module T14594 where
 import Data.Data

 newtype Foo = Foo (Maybe Char)

 gfoldlFoo
   :: (forall d b. Data d => c (d -> b) -> d -> c b)
      -> (forall g. g -> c g) -> Foo -> c Foo
 gfoldlFoo k z (Foo a) = z Foo `k` a
 }}}

 Compile with `-O` and `-ddump-simpl`, and search for `Data (Maybe Char)`.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14594#comment:14>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler