[GHC] #12072: GHC panic on type wildcard in left-hand side of data family

[GHC]

#12072: GHC panic on type wildcard in left-hand side of data family
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        Reporter:  andreash          |                Owner:
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      Resolution:  fixed             |             Keywords:
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  crash                              |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by simonpj):

 * status:  new => closed
 * resolution:   => fixed


Comment:

 Thanks. This is OK in HEAD (and I hope 8.0).  Wildcards are explicitly
 allowed on the LHS of type/data family instances.  See the
 [http://downloads.haskell.org/~ghc/master/users-guide/glasgow_exts.html
 #data-instance-declarations user manual Section 9.9.1.2].

 You are right that it's a bug in 7.10.3.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12072#comment:1>
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