[GHC] #15725: Core Lint error: Trans coercion mis-match

[GHC]

#15725: Core Lint error: Trans coercion mis-match
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler          |              Version:  8.6.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #15703            |  Differential Rev(s):  Phab:D5217
       Wiki Page:                    |
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Comment (by Krzysztof Gogolewski <krz.gogolewski@…>):

 In [changeset:"48efbc04bd45d806c52376641e1a7ed7278d1ec7/ghc" 48efbc0/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="48efbc04bd45d806c52376641e1a7ed7278d1ec7"
 Fix #15725 with an extra Sym

 Summary:
 We were adding a `Sym` to one argument in the `InstCo`
 case of `optCoercion` but not another, leading to the two arguments
 to misaligned when combined via `Trans`. This fixes the issue with
 a well targeted use of `wrapSym`.

 Test Plan: make test TEST=T15725

 Reviewers: goldfire, ningning, bgamari

 Reviewed By: goldfire, ningning

 Subscribers: rwbarton, carter

 GHC Trac Issues: #15725

 Differential Revision: https://phabricator.haskell.org/D5217
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15725#comment:9>
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