[GHC] #12130: ghc: panic! (the 'impossible' happened): find_tycon Block []

[GHC]

#12130: ghc: panic! (the 'impossible' happened): find_tycon Block []
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        Reporter:  jeiea             |                Owner:  adamgundry
            Type:  bug               |               Status:  patch
        Priority:  high              |            Milestone:  8.0.2
       Component:  Template Haskell  |              Version:  8.0.1
      Resolution:                    |             Keywords:
                                     |  DisambiguateRecordFields
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash                              |            Test Case:  th/T12130
      Blocked By:                    |             Blocking:
 Related Tickets:  #11228            |  Differential Rev(s):  Phab:D2321
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"4d71cc89b4e9648f3fbb29c8fcd25d725616e265/ghc"
 4d71cc89/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="4d71cc89b4e9648f3fbb29c8fcd25d725616e265"
 Avoid find_tycon panic if datacon is not in scope

 When using TH to splice expressions involving record field construction,
 the parent datacon may not be in scope.  We shouldn't panic about this,
 because we will be renaming Exact RdrNames which don't require any
 disambiguation.

 Test Plan: new test th/T12130

 Reviewers: austin, bgamari

 Reviewed By: bgamari

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D2321

 GHC Trac Issues: #12130
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12130#comment:5>
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