[GHC] #9316: GHC 7.8.3 no longer infers correct type in presence of type families and constraints

[GHC]

#9316: GHC 7.8.3 no longer infers correct type in presence of type families and
constraints
-------------------------------------+-------------------------------------
              Reporter:  ocharles    |             Owner:
                  Type:  bug         |            Status:  merge
              Priority:  normal      |         Milestone:  7.8.4
             Component:  Compiler    |           Version:  7.8.3
            Resolution:              |          Keywords:
Differential Revisions:              |  Operating System:  Unknown/Multiple
          Architecture:              |   Type of failure:  None/Unknown
  Unknown/Multiple                   |         Test Case:
            Difficulty:  Unknown     |          Blocking:
            Blocked By:              |
       Related Tickets:              |
-------------------------------------+-------------------------------------
Changes (by simonpj):

 * status:  new => merge
 * milestone:   => 7.8.4


Comment:

 I'm not honestly sure exactly what changed between 7.8.2 and 7.8.3, but
 the fixed code is much more robust.  Thank you for this test case.  I hope
 you can work around it for now.

 If we ever release 7.8.4 this should go in, so I'll make it patch status
 on that.

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9316#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler