[GHC] #10819: Can't generate data decls deriving multiparam type classes with TH

[GHC]

#10819: Can't generate data decls deriving multiparam type classes with TH
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        Reporter:  spinda            |                Owner:  spinda
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Template Haskell  |              Version:  7.10.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:  th/T18019.hs
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1202
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"04ab55d9a6fe311b7cb544211738caca6c00c720/ghc"
 04ab55d9/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="04ab55d9a6fe311b7cb544211738caca6c00c720"
 Use Cxt for deriving clauses in TH (#10819)

 Summary:
 Deriving clauses in the TH representations of data, newtype, data
 instance, and newtype instance declarations previously were just [Name],
 which didn't allow for more complex derived classes, eg. multi-parameter
 typeclasses.

 This switches out [Name] for Cxt, representing the derived classes as
 types instead of names.

 Test Plan: validate

 Reviewers: goldfire, spinda, austin

 Reviewed By: goldfire, austin

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D1202

 GHC Trac Issues: #10819
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10819#comment:2>
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