[GHC] #10946: Typed hole inside typed Template Haskell bracket causes panic

[GHC]

#10946: Typed hole inside typed Template Haskell bracket causes panic
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        Reporter:  jstolarek         |                Owner:
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.0.1
       Component:  Template Haskell  |              Version:  7.10.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash                              |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
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Comment (by jstolarek):

 This error is raised in `TcErrors.getSkolemInfo` called from
 `TcErrors.mkHoleError`. Quick look at the code tells me that "implication
 constraints" are expected to be non-empty but they are. Are implication
 constraints things that come in the contexts, ie. everything before a
 `=>`? Why are they expected to be non-empty?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10946#comment:1>
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