[GHC] #11254: GHC panic

[GHC]

#11254: GHC panic
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        Reporter:  Iceland_jack  |                Owner:  goldfire
            Type:  bug           |               Status:  new
        Priority:  normal        |            Milestone:
       Component:  Compiler      |              Version:  7.11
      Resolution:                |             Keywords:
Operating System:  Linux         |         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 simonpj):

 * owner:   => goldfire


Comment:

 Richard, what is the story for deferred type errors?  We get a Lint error
 from the program as follows
 {{{
 cobox_aPt :: Ratio Integer ~# Int
 [LclId[CoVarId], Str=DmdType]
 cobox_aPt =
   typeError
     @ 'Unlifted
     @ (Ratio Integer ~# Int)
     "T11254.hs:16:12: error:...blah..blah... "#


 $cembed_aP2 :: Rational -> Frac Rational
 [LclId, Str=DmdType]
 $cembed_aP2 =
   (...blah....)
   `cast` (<Rational>_R -> Sub (cobox_aPt ; Sym TFCo:R:FracRatio[0])
 }}}
 So we have a top-level unboxed value.  That's not right.  What became of
 coercion holes?  Obviously the can't call `error`.

 Writing a `Note` about how deferred type errors fits with unlifted
 equalities would be great.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11254#comment:1>
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