[GHC] #13736: GHC panic with DataKinds and TypeOperators

[GHC]

#13736: GHC panic with DataKinds and TypeOperators
-------------------------------------+-------------------------------------
        Reporter:  turion            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Description changed by turion:

@@ -15,0 +15,10 @@
+
+ The error message is:
+
+
+ {{{
+ ghc: panic! (the 'impossible' happened)
+   (GHC version 8.0.2 for x86_64-unknown-linux):
+         initTc: unsolved constraints
+   WC {wc_insol = [W] __aBJ :: t_aBI[tau:1] (CHoleCan: _)}
+ }}}

New description:

 The following program causes a GHC panic:
 {{{#!hs
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE TypeOperators #-}
 {-# LANGUAGE KindSignatures #-}
 import GHC.TypeLits

 data Proxy (n :: Nat) = Proxy

 data Foo a = Foo a

 foo :: Foo (Proxy (2 * 2))
 foo = Foo _
 }}}

 The error message is:


 {{{
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.2 for x86_64-unknown-linux):
         initTc: unsolved constraints
   WC {wc_insol = [W] __aBJ :: t_aBI[tau:1] (CHoleCan: _)}
 }}}

--

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13736#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler