[GHC] #13461: Panic on compile of file with a hole and nothing else

[GHC]

#13461: Panic on compile of file with a hole and nothing else
-------------------------------------+-------------------------------------
        Reporter:  Tritlo            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.0.2
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  MacOS X           |         Architecture:  x86_64
                                     |  (amd64)
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Old description:

> The example is very simple, just:
>
> {{{
> test :: Int -> Int
> test = _
> }}}
>
> which produces the panic:
>
> {{{
> [1 of 1] Compiling Main             ( manyIdsTest.hs, manyIdsTest.o )
> ghc: panic! (the 'impossible' happened)
>   (GHC version 8.0.2 for x86_64-apple-darwin):
>         initTc: unsolved constraints
>   WC {wc_insol = [W] __awc :: t_awb[tau:1] (CHoleCan: _)}
> }}}

New description:

 The example is very simple, just:

 {{{
 test :: Int -> Int
 test = _
 }}}

 which produces the panic:

 {{{
 [1 of 1] Compiling Main             ( manyIdsTest.hs, manyIdsTest.o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.2 for x86_64-apple-darwin):
         initTc: unsolved constraints
   WC {wc_insol = [W] __awc :: t_awb[tau:1] (CHoleCan: _)}
 }}}

 I suspect that there might be a missing case when there is nothing else in
 scope.

--

Comment (by Tritlo):

 Replying to [ticket:13461 Tritlo]:
 > The example is very simple, just:
 >
 > {{{
 > test :: Int -> Int
 > test = _
 > }}}
 >
 > which produces the panic:
 >
 > {{{
 > [1 of 1] Compiling Main             ( manyIdsTest.hs, manyIdsTest.o )
 > ghc: panic! (the 'impossible' happened)
 >   (GHC version 8.0.2 for x86_64-apple-darwin):
 >       initTc: unsolved constraints
 >   WC {wc_insol = [W] __awc :: t_awb[tau:1] (CHoleCan: _)}
 > }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13461#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler