[GHC] #13544: ghc panic

[GHC]

#13544: ghc panic
-------------------------------------+-------------------------------------
           Reporter:  shauryab98     |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.2
           Keywords:                 |  Operating System:  Windows
       Architecture:  x86_64         |   Type of failure:  Compile-time
  (amd64)                            |  crash or panic
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 I got this error:

 {{{
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.2 for x86_64-unknown-mingw32):
         initTc: unsolved constraints
   WC {wc_insol = [W] %_a1El :: t_a1Ek[tau:1] (CHoleCan: %)}
 }}}

 while compiling the following code
 {{{#!hs
 halveEvens :: [Integer] -> [Integer]
 halveEvens = map . filter (\c -> c%2 == 0)
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13544>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler