[GHC] #13880: panic initTc: unsolved constraints

[GHC]

#13880: panic initTc: unsolved constraints
-------------------------------------+-------------------------------------
           Reporter:  vanto          |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.2
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Compile-time
  Unknown/Multiple                   |  crash or panic
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 I'm trying to play with some piece of code in GHCi. Sorry if it's a
 duplicate bug.\\

 {{{
 {-# LANGUAGE TemplateHaskell #-}

 module Testbar where

 printf :: String -> String
 printf s = gen (parse s)

 $(printf "Error: %s at line %d")

 }}}

 {{{
 Prelude> :l testbar
 [1 of 1] Compiling Testbar          ( testbar.hs, interpreted )
 ghc.exe: panic! (the 'impossible' happened)
   (GHC version 8.0.2 for i386-unknown-mingw32):
         initTc: unsolved constraints
   WC {wc_insol =
         [W] gen_a10Q :: t_a10P[tau:1] (CHoleCan: gen)
         [W] parse_a10Z :: t_a10Y[tau:1] (CHoleCan: parse)}

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13880>
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