[GHC] #10079: Coercible solver regression: Couldn't match rep of () with Const () b

[GHC]

#10079: Coercible solver regression: Couldn't match rep of () with Const () b
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        Reporter:  glguy             |                   Owner:  goldfire
            Type:  bug               |                  Status:  new
        Priority:  high              |               Milestone:  7.10.1
       Component:  Compiler (Type    |                 Version:  7.10.1-rc1
  checker)                           |                Keywords:
      Resolution:                    |            Architecture:
Operating System:  Unknown/Multiple  |  Unknown/Multiple
 Type of failure:  GHC rejects       |               Test Case:  indexed-
  valid program                      |  types/should_compile/T10079
      Blocked By:                    |                Blocking:
 Related Tickets:  #7788, #8550      |  Differential Revisions:  Phab:D653
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Comment (by simonpj):

 Richard has now completed a draft, at Phab:D653, but it's pretty big, and
 is unlikely to carry over to the 7.10 branch without a lot of fuss (and
 hence potential errors).  Austin will try and report.

 But otherwise we may just have to do without it.  We are very far down the
 road to 7.10 and I don't want to destablise it.

 Is that too terrible?  (Edward esp.)

 Simon

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10079#comment:21>
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