[GHC] #8423: Less conservative compatibility check for closed type families (was: contraint solver doesn't reduce reducible closed type family expressions (even with undecidable instances!))

[GHC]

#8423: Less conservative compatibility check for closed type families
-------------------------------------+-------------------------------------
        Reporter:  carter            |                   Owner:
            Type:  feature request   |                  Status:  new
        Priority:  normal            |               Milestone:  ⊥
       Component:  Compiler (Type    |                 Version:  7.7
  checker)                           |
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:  #4259             |  Differential Revisions:
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Changes (by goldfire):

 * milestone:  8.0.1 => ⊥


Comment:

 New title and milestone to reflect the realities here.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8423#comment:15>
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