[GHC] #14884: Type holes cause assertion failure in ghc-stage2 compiler during type checking

[GHC]

#14884: Type holes cause assertion failure in ghc-stage2 compiler during type
checking
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        Reporter:  sighingnow        |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 I've seen this before.

 It arises during error reporting, when the (now quite elaborate)
 `TcErrors.validSubstitutions` code invokes the constraint solver. To avoid
 the assertion error we need to set the level correctly, and we aren't
 doing that yet.

 It's unsatisfactory, but I think harmless.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14884#comment:1>
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