[GHC] #10195: GHC forgets constraints when matching on GADTs

[GHC]

#10195: GHC forgets constraints when matching on GADTs
-------------------------------------+-------------------------------------
        Reporter:  crockeea          |                   Owner:
            Type:  bug               |                  Status:  merge
        Priority:  normal            |               Milestone:  7.10.2
       Component:  Compiler          |                 Version:  7.8.4
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |               Test Case:
      Blocked By:                    |  typecheck/should_compile/T10195
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
-------------------------------------+-------------------------------------
Changes (by simonpj):

 * status:  new => merge
 * testcase:   => typecheck/should_compile/T10195
 * milestone:   => 7.10.2


Comment:

 Very good!  Fixed.

 This is worth merging.

 Simon

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10195#comment:10>
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