[GHC] #13466: Ghci panics with type applications to unknown functions

[GHC]

#13466: Ghci panics with type applications to unknown functions
-------------------------------------+-------------------------------------
        Reporter:  aspiwack          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  GHCi              |              Version:  8.0.2
      Resolution:                    |             Keywords:
                                     |  TypeApplications
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by RyanGlScott):

 * keywords:   => TypeApplications


Comment:

 Actually, it's not #13106 for once! I can reproduce this on GHC HEAD as
 well:

 {{{
 GHCi, version 8.3.20170322: http://www.haskell.org/ghc/  :? for help
 Loaded GHCi configuration from /home/rgscott/.ghci
 λ> :set -XTypeApplications
 λ> :t nonexistant @[]
 ghc-stage2: panic! (the 'impossible' happened)
   (GHC version 8.3.20170322 for x86_64-unknown-linux):
         initTc: unsolved constraints
   WC {wc_insol =
         [WD] nonexistant_a1tE {0}:: t1_a1tD[tau:2] (CHoleCan:
 nonexistant)}
   Call stack:
       CallStack (from HasCallStack):
         prettyCurrentCallStack, called at
 compiler/utils/Outputable.hs:1191:58 in ghc:Outputable
         callStackDoc, called at compiler/utils/Outputable.hs:1195:37 in
 ghc:Outputable
         pprPanic, called at compiler/typecheck/TcRnMonad.hs:343:17 in
 ghc:TcRnMonad
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13466#comment:2>
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