[GHC] #12512: UnboxedTupleRep-related panic involving typeclasses

[GHC]

#12512: UnboxedTupleRep-related panic involving typeclasses
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        Reporter:  RyanGlScott       |                Owner:  goldfire
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:  8.0.2
       Component:  Compiler          |              Version:  8.0.1
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash                              |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #11723            |  Differential Rev(s):  Phab:D2557
       Wiki Page:                    |
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Comment (by Ryan Scott <ryan.gl.scott@…>):

 In [changeset:"9cb289abc582c9eb8337a2621baf58e35feeff46/ghc"
 9cb289ab/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="9cb289abc582c9eb8337a2621baf58e35feeff46"
 Remove hack put in place for #12512

 Summary:
 Previously, I added an ad hoc check for unboxed tuples and
 sums in standalone-derived instances to fix #12512, under the
 pretense that polymorphism over `UnboxedTupleRep` and
 `UnboxedSumRep` was a lie. But that is no longer the case, and so
 this ad hoc check can be removed entirely. Less code, and easier to
 understand.

 Test Plan: make test TEST=T12512

 Reviewers: bgamari

 Reviewed By: bgamari

 Subscribers: rwbarton, thomie, carter

 Differential Revision: https://phabricator.haskell.org/D4271
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12512#comment:7>
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