[GHC] #8426: one-shot compilation + TH doesn't see instances that is seen in batch mode

[GHC]

#8426: one-shot compilation + TH doesn't see instances that is seen in batch mode
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        Reporter:  errge             |                   Owner:
            Type:  bug               |                  Status:  infoneeded
        Priority:  normal            |               Milestone:  7.12.1
       Component:  Template Haskell  |                 Version:  7.7
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Other             |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:  #7867             |                Blocking:
                                     |  Differential Revisions:
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Comment (by ezyang):

 The patches are pretty short; I think the real reason this ticket is
 stalled is because simonpj never signed off on errge's suggested
 implementation strategy; and in the meantime, it seems this bug has been
 routed around. Perhaps we should just apply simonpj's original suggestion
 (remove `[InstanceDec]` from `ClassI` and `FamilyI`) and call this bug
 fixed.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8426#comment:10>
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