[GHC] #15471: Polymorphism, typed splices and type inference don't mix

[GHC]

#15471: Polymorphism, typed splices and type inference don't mix
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        Reporter:  mpickering        |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Template Haskell  |              Version:  8.4.3
      Resolution:  fixed             |             Keywords:
                                     |  TypedTemplateHaskell
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:  th/T15471
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D5286,
       Wiki Page:                    |  https://gitlab.haskell.org/ghc/ghc/merge_requests/106
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Comment (by Matthew Pickering <matthewtpickering@…>):

 In [changeset:"c2455e647501c5a382861196b64df3dd05b620a2/ghc"
 c2455e64/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="c2455e647501c5a382861196b64df3dd05b620a2"
 Run typed splices in the zonker

 Summary:
 This fixes #15471

 In the typechecker we check that the splice has the right type but we
 crucially don't zonk the generated expression. This is because we might
 end up unifying type variables from outer scopes later on.

 Reviewers: simonpj, goldfire, bgamari

 Subscribers: rwbarton, carter

 GHC Trac Issues: #15471

 Differential Revision: https://phabricator.haskell.org/D5286
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15471#comment:20>
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