[GHC] #15073: Unable to newtype derive `Prim` via DerivingStrategies

[GHC]

#15073: Unable to newtype derive `Prim` via DerivingStrategies
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        Reporter:  fosskers          |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:  deriving
Operating System:  Unknown/Multiple  |         Architecture:  x86_64
                                     |  (amd64)
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4620
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"0c7db226012b5cfafc9a38bfe372661672ec8900/ghc"
 0c7db226/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="0c7db226012b5cfafc9a38bfe372661672ec8900"
 Fix #15073 by suggesting UnboxedTuples in an error message

 Under certain circumstances, `GeneralizedNewtypeDeriving`
 can emit code which uses unboxed tuple types, but if `UnboxedTuples`
 wasn't enabled, the error message that GHC gave didn't make it very
 clear that it could be worked around by explicitly enabling the
 extension. Easily fixed.

 Test Plan: make test TEST=T15073

 Reviewers: bgamari

 Reviewed By: bgamari

 Subscribers: simonpj, thomie, carter

 GHC Trac Issues: #15073

 Differential Revision: https://phabricator.haskell.org/D4620
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15073#comment:8>
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