[GHC] #11274: Confused type checker with typed holes and a missing instance (also panic)

[GHC]

#11274: Confused type checker with typed holes and a missing instance (also panic)
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           Reporter:  Xandaros       |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  7.10.3
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Compile-time
  Unknown/Multiple                   |  crash
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 If your file contains a typed hole and a case where an instance is
 missing, the type checker will not find the missing instance and only
 report the hole.
 If -fdefer-typed-holes is set, this results in a panic.
 (Using ghci, the panic occurs when any definition of the module is being
 evaluated)

 Minimal working example:
 {{{#!hs
 {-# OPTIONS_GHC -fdefer-typed-holes #-}
 data Asd = Asd

 someHole = _asd

 missingInstance :: Asd -> Asd -> Bool
 missingInstance x y = x == y

 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11274>
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