[GHC] #16208: map/coerce does not fire with all newtypes

[GHC]

#16208: map/coerce does not fire with all newtypes
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        Reporter:  monoidal          |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:  8.10.1
       Component:  Compiler          |              Version:  8.6.3
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
                                     |  simplCore/should_run/T16208
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |  https://gitlab.haskell.org/ghc/ghc/merge_requests/453
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Comment (by Marge Bot <ben+marge-bot@…>):

 In [changeset:"646b6dfbe125aa756a935e840979ba11b4a882c0/ghc"
 646b6dfb/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="646b6dfbe125aa756a935e840979ba11b4a882c0"
 Fix map/coerce rule for newtypes with wrappers

 This addresses Trac #16208 by marking newtype wrapper
 unfoldings as compulsory.

 Furthermore, we can remove the special case for newtypes
 in exprIsConApp_maybe (introduced in 7833cf407d1f).
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16208#comment:7>
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