[GHC] #10586: GHC 7.10.1 panic due to wildcard in data family instance

[GHC]

#10586: GHC 7.10.1 panic due to wildcard in data family instance
-------------------------------------+-------------------------------------
        Reporter:  WrenThornton      |                   Owner:
            Type:  bug               |                  Status:  closed
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.10.1
      Resolution:  fixed             |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:  #3699             |  Differential Revisions:
-------------------------------------+-------------------------------------

Comment (by thomasw):

 Replying to [comment:5 simonpj]:
 > Is it committed, or simply in Phab?   Is there a regression test?  If so
 can you update the "Test case" field?  If not can you add one?  Thanks

 [https://git.haskell.org/ghc.git/commit/058af6c90a0e8d122f2d1339b6b4fd0b5ec83d05
 Yes]. I have a test for a wild card in a type instance, I'll add one for
 this too then.

 I'm actually thinking about adding support for wild cards in data/type
 instances. I would just replace them with fresh meta variables. This would
 also address #3699. I don't think named wild cards or extra-constraints
 wild cards make sense here. What do you think?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10586#comment:6>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler