[GHC] #8644: 'Untouchable' error with constraint variable in rank-2 type

[GHC]

#8644: 'Untouchable' error with constraint variable in rank-2 type
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        Reporter:  sbarclay                      |            Owner:
            Type:  bug                           |           Status:
        Priority:  normal                        |  closed
       Component:  Compiler (Type checker)       |        Milestone:
      Resolution:  fixed                         |          Version:  7.7
Operating System:  Unknown/Multiple              |         Keywords:
 Type of failure:  GHC rejects valid program     |     Architecture:
       Test Case:                                |  Unknown/Multiple
  typecheck/should_compile/T8644                 |       Difficulty:
        Blocking:                                |  Unknown
                                                 |       Blocked By:
                                                 |  Related Tickets:
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Changes (by simonpj):

 * status:  new => closed
 * testcase:   => typecheck/should_compile/T8644
 * resolution:   => fixed


Comment:

 Great catch, thank you!  This showed (in a nice simple example) that the
 handling of equality floating was inadequate.

 Simon

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8644#comment:4>
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